ST L6470 User Manual

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dSPIN fully integrated microstepping motor driver with motion

Features

■ Operating voltage: 8 - 45 V

■ 7.0 A out peak current (3.0 A r.m.s.)

■ Low R

■ Programmable speed profile and positioning

■ Programmable power MOS slew rate

■ Up to 1/128 microstepping

■ Sensorless stall detection

■ SPI interface

■ Low quiescent and standby currents

■ Programmable non-dissipative overcurrent

protection on high and low-side

■ Two levels of overtemperature protection

Application

■ Bipolar stepper motors

Description

The L6470, realized in analog mixed signal technology, is an advanced fully integrated solution suitable for driving two-phase bipolar stepper motors with microstepping. It integrates a dual low R

Power MOSFETs

DS(on)

DMOS full bridge with all of the

DS(on)

L6470

engine and SPI

Datasheet − production data

HTSSOP28POWERSO36

power switches equipped with an accurate onchip current sensing circuitry suitable for nondissipative current control and overcurrent protection. Thanks to a unique control system, a true 1/128 steps resolution is achieved. The digital control core can generate user defined motion profiles with acceleration, deceleration, speed or target position, easily programmed through a dedicated registers set. All commands and data registers, including those used to set analogue values (i.e. current control value, current protection trip point, deadtime, PWM frequency, etc.) are sent through a standard 5Mbit/s SPI. A very rich set of protections (thermal, low bus voltage, overcurrent, motor stall) allows the design of a fully protected application, as required by the most demanding motor control applications.

Table 1. Device summary

Order codes Package Packaging

L6470H HTSSOP28 Tube

L6470HTR HTSSOP28 Tape and reel

L6470PD POWERSO36 Tube

L6470PDTR POWERSO36 Tape and reel

June 2012 Doc ID16737 Rev 4 1/70

This is information on a product in full production.

www.st.com

Contents L6470

Contents

1 Block diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8

2 Electrical data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

2.1 Absolute maximum ratings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

2.2 Recommended operating conditions . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

2.3 Thermal data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

3 Electrical characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

4 Pin connection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16

4.1 Pin list . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17

5 Typical applications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19

6 Functional description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21

6.1 Device power-up . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21

6.2 Logic I/O . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21

6.3 Charge pump . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21

6.4 Microstepping . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22

6.4.1 Automatic full-step mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23

6.5 Absolute position counter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23

6.6 Programmable speed profiles . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23

6.6.1 Infinite acceleration/deceleration mode . . . . . . . . . . . . . . . . . . . . . . . . . 24

6.7 Motor control commands . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24

6.7.1 Constant speed commands . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24

6.7.2 Positioning commands . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25

6.7.3 Motion commands . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25

6.7.4 Stop commands . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26

6.7.5 Step-clock mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26

6.7.6 GoUntil and ReleaseSW commands . . . . . . . . . . . . . . . . . . . . . . . . . . . 26

6.8 Internal oscillator and oscillator driver . . . . . . . . . . . . . . . . . . . . . . . . . . . 27

6.8.1 Internal oscillator . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27

6.8.2 External clock source . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27

2/70 Doc ID16737 Rev 4

L6470 Contents

6.9 Overcurrent detection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28

6.10 Undervoltage lockout (UVLO) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29

6.11 Thermal warning and thermal shutdown . . . . . . . . . . . . . . . . . . . . . . . . . 29

6.12 Reset and standby . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30

6.13 External switch (SW pin) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30

6.14 Programmable DMOS slew rate, deadtime and blanking time . . . . . . . . . 31

6.15 Integrated analog-to-digital converter . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31

6.16 Internal voltage regulator . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31

6.17 BUSY\SYNC pin . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32

6.17.1 BUSY operation mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32

6.17.2 SYNC operation mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32

6.18 FLAG pin . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33

7 Phase current control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34

7.1 PWM sinewave generators . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34

7.2 Sensorless stall detection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35

7.3 Low speed optimization . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35

7.4 BEMF compensation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36

7.5 Motor supply voltage compensation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36

7.6 Winding resistance thermal drift compensation . . . . . . . . . . . . . . . . . . . . 37

8 Serial interface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38

9 Programming manual . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40

9.1 Registers and flags description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40

9.1.1 ABS_POS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41

9.1.2 EL_POS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41

9.1.3 MARK . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42

9.1.4 SPEED . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42

9.1.5 ACC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42

9.1.6 DEC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42

9.1.7 MAX_SPEED . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43

9.1.8 MIN_SPEED . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43

9.1.9 FS_SPD . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43

9.1.10 KVAL_HOLD, KVAL_RUN, KVAL_ACC and KVAL_DEC . . . . . . . . . . . . 44

Doc ID16737 Rev 4 3/70

Contents L6470

9.1.11 INT_SPEED . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44

9.1.12 ST_SLP . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45

9.1.13 FN_SLP_ACC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45

9.1.14 FN_SLP_DEC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45

9.1.15 K_THERM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45

9.1.16 ADC_OUT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46

9.1.17 OCD_TH . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46

9.1.18 STALL_TH . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46

9.1.19 STEP_MODE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47

9.1.20 ALARM_EN . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48

9.1.21 CONFIG . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49

9.1.22 STATUS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54

9.2 Application commands . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55

9.2.1 Command management . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56

9.2.2 Nop . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57

9.2.3 SetParam (PARAM, VALUE) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57

9.2.4 GetParam (PARAM) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58

9.2.5 Run (DIR, SPD) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58

9.2.6 StepClock (DIR) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 59

9.2.7 Move (DIR, N_STEP) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 59

9.2.8 GoTo (ABS_POS) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 60

9.2.9 GoTo_DIR (DIR, ABS_POS) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 60

9.2.10 GoUntil (ACT, DIR, SPD) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 61

9.2.11 ReleaseSW (ACT, DIR) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 61

9.2.12 GoHome . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 62

9.2.13 GoMark . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 62

9.2.14 ResetPos . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 62

9.2.15 ResetDevice . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 63

9.2.16 SoftStop . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 63

9.2.17 HardStop . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 63

9.2.18 SoftHiZ . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 63

9.2.19 HardHiZ . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 64

9.2.20 GetStatus . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 64

10 Package mechanical data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 65

11 Revision history . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 69

4/70 Doc ID16737 Rev 4

L6470 List of tables

List of tables

Table 1. Device summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

Table 2. Absolute maximum ratings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

Table 3. Recommended operating conditions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

Table 4. Thermal data. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

Table 5. Electrical characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

Table 6. Pin description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17

Table 7. Typical application values . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19

Table 8. CL values according to external oscillator frequency . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28

Table 9. Registers map. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40

Table 10. EL_POS register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41

Table 11. MIN_SPEED register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43

Table 12. Voltage amplitude regulation registers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44

Table 13. Winding resistance thermal drift compensation coefficient . . . . . . . . . . . . . . . . . . . . . . . . . 45

Table 14. ADC_OUT value and motor supply voltage compensation feature . . . . . . . . . . . . . . . . . . 46

Table 15. Overcurrent detection threshold . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46

Table 16. Stall detection threshold . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47

Table 17. STEP_MODE register. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47

Table 18. Step mode selection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47

Table 19. SYNC output frequency . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48

Table 20. SYNC signal source . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48

Table 21. ALARM_EN register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49

Table 22. CONFIG register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49

Table 23. Oscillator management. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49

Table 24. External switch hard stop interrupt mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50

Table 25. Overcurrent event . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50

Table 26. Programmable power bridge output slew rate values. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51

Table 27. Motor supply voltage compensation enable . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51

Table 28. PWM frequency: integer division factor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51

Table 29. PWM frequency: multiplication factor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52

Table 30. Available PWM frequencies [kHz]: 8-MHz oscillator frequency . . . . . . . . . . . . . . . . . . . . . 52

Table 31. Available PWM frequencies [kHz]: 16-MHz oscillator frequency . . . . . . . . . . . . . . . . . . . . 52

Table 32. Available PWM frequencies [kHz]: 24-MHz oscillator frequency . . . . . . . . . . . . . . . . . . . . 53

Table 33. Available PWM frequencies [kHz]: 32-MHz oscillator frequency . . . . . . . . . . . . . . . . . . . . 53

Table 34. STATUS register. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54

Table 35. STATUS register DIR bit. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54

Table 36. STATUS register MOT_STATE bits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55

Table 37. Application commands . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55

Table 38. Nop command structure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57

Table 39. SetParam command structure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57

Table 40. GetParam command structure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58

Table 41. Run command structure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58

Table 42. Stepclock command structure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 59

Table 43. Move command structure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 59

Table 44. GoTo command structure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 60

Table 45. GoTo_DIR command structure. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 60

Table 46. GoUntil command structure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 61

Table 47. ReleaseSW command structure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 61

Table 48. GoHome command structure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 62

Doc ID16737 Rev 4 5/70

List of tables L6470

Table 49. GoMark command structure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 62

Table 50. ResetPos command structure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 62

Table 51. ResetDevice command structure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 63

Table 52. SoftStop command structure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 63

Table 53. HardStop command structure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 63

Table 54. SoftHiZ command structure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 63

Table 55. HardHiZ command structure. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 64

Table 56. GetStatus command structure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 64

Table 57. HTSSOP28 mechanical data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 65

Table 58. POWERSO36 mechanical data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 67

Table 59. Revision history . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 69

6/70 Doc ID16737 Rev 4

L6470 List of figures

List of figures

Figure 1. Block diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8

Figure 2. HTSSOP28 pin connection (top view) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16

Figure 3. POWERSO36 pin connection (top view) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16

Figure 4. Bipolar stepper motor control application using L6470 . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20

Figure 5. Charge pump circuitry. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22

Figure 6. Normal mode and microstepping (128 microsteps) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22

Figure 7. Automatic full-step switching . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23

Figure 8. Speed profile in infinite acceleration/deceleration mode . . . . . . . . . . . . . . . . . . . . . . . . . . 24

Figure 9. Constant speed command examples . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25

Figure 10. Positioning command examples . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25

Figure 11. Motion command examples . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26

Figure 12. OSCIN and OSCOUT pin configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28

Figure 13. External switch connection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31

Figure 14. Internal 3 V linear regulator . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32

Figure 15. Current distortion and compensation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35

Figure 16. BEMF compensation curve. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36

Figure 17. Motor supply voltage compensation circuit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37

Figure 18. SPI timings diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38

Figure 19. Daisy chain configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39

Figure 20. Command with 3-byte argument . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56

Figure 21. Command with 3-byte response . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56

Figure 22. Command response aborted . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57

Figure 23. HTSSOP28 mechanical data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 66

Figure 24. POWERSO36 drawings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 68

Doc ID16737 Rev 4 7/70

Block diagram L6470

1 Block diagram

Figure 1. Block diagram

VDD OSCIN OSCOUT ADCIN VREG CP VBOOT

STBY/RST

FLAG

SDO

SDI

BUSY/SYNC

STCK

Charge

pump

VSA

boot

Current sensing

boot

AGND

VSA

OUT1A

OUT2A

PGND

VSB

OUT1B

OUT2B

PGND

Registers

Ext. Osc. driver

Clock gen.

Control

Logic

ADC

3 V

Vol tage Reg.

16MHz

Oscillator

SPI

Current DACs

Comparators

DGND

Temperature

sensing

AM02377v1

8/70 Doc ID16737 Rev 4

L6470 Electrical data

2 Electrical data

2.1 Absolute maximum ratings

Table 2. Absolute maximum ratings

Symbol Parameter Test condition Value Unit

GND, diff

boot

REG

ADCIN

OSC

Logic interface supply voltage 5.5 V

Motor supply voltage VSA = VSB = V

Differential voltage between AGND, PGND and DGND

48 V

±0.3 V

Bootstrap peak voltage 55 V

Internal voltage regulator output pin and logic supply voltage

Integrated ADC input voltage range (ADCIN pin)

OSCIN and OSCOUT pin voltage range

3.6 V

-0.3 to +3.6 V

Differential voltage between VSA,

, OUT2A, PGND and VSB,

out_diff

LOGIC

out

out_peak

tot

1. Maximum output current limit is related to metal connection and bonding characteristics. Actual limit must satisfy maximum thermal dissipation constraints.

2. HTSSOP28 mounted on EVAL6470H.

OUT1

, OUT2B, PGND pins

OUT1

Logic inputs voltage range -0.3 to +5.5 V

(1)

R.m.s. output current 3 A

(1)

Pulsed output current T

Operating junction temperature 150 °C

Storage temperature range -55 to 150 °C

Total power dissipation (TA = 25 ºC)

= VSB = V

PULSE

(2)

< 1 ms 7 A

48 V

Doc ID16737 Rev 4 9/70

Electrical data L6470

2.2 Recommended operating conditions

Table 3. Recommended operating conditions

Symbol Parameter Test condition Value Unit

Logic interface supply voltage

Motor supply voltage VSA = VSB = V

Differential voltage between

, OUT1A, OUT2A, PGND

out_diff

and V

PGND pins

REG,in

ADC

Logic supply voltage

Integrated ADC input voltage (ADCIN pin)

Operating junction temperature - 25 125 °C

2.3 Thermal data

Table 4. Thermal data

Symbol Parameter Package Typ. Unit

thJA

1. HTSSOP28 mounted on EVAL6470H rev 1.0 board: four-layer FR4 PCB with a dissipating copper surface of about 40 cm

2. POWERSO36 mounted on EVAL6470PD rev 1.0 board: four-layer FR4 PCB with a dissipating copper surface of about 40 cm

Thermal resistance junction-ambient

on each layer and 15 via holes below the IC.

3.3 V logic outputs 3.3

5 V logic outputs 5

= VSB = V

, OUT1B, OUT2B,

voltage imposed

REG

by external source

on each layer and 22 via holes below the IC.

HTSSOP28

POWERSO36

845V

45 V

3.2 3.3 V

(1)

(2)

REG

°C/W

10/70 Doc ID16737 Rev 4

L6470 Electrical characteristics

3 Electrical characteristics

VSA = VSB = 36 V; VDD = 3.3 V; internal 3 V regulator; TJ = 25 °C, unless otherwise specified.

Table 5. Electrical characteristics

Symbol Parameter Test condition Min. Typ. Max. Unit

General

SthOn

SthOff

SthHyst VS

j(WRN)

j(SD)

VS UVLO turn-on threshold 7.5 8.2 8.9 V

VS UVLO turn-off threshold 6.6 7.2 7.8 V

UVLO threshold hysteresis 0.7 1 1.3 V

Quiescent motor supply current

Thermal warning temperature 130 °C

Thermal shutdown temperature 160 °C

Charge pump

pump

pump,min

pump,max

boot

Voltage swing for charge pump oscillator 10 V

Minimum charge pump oscillator frequency

(1)

Maximum charge pump oscillator frequency

(1)

Average boot current

Output DMOS transistor

DS(on)

DSS

High-side switch on-resistance

Low-side switch on-resistance

Leakage current

Internal oscillator selected; VREG = 3.3 V ext; CP floating

= f

sw,A

= 15.6 kHz

sw,B

POW_SR = '10'

= 25 °C, I

= 125 °C,

= 25 °C, I

= 125 °C,

OUT = V

= 3 A 0.37

out

(2)

= 3 A 0.51

out

= 3 A 0.18

out

(2)

= 3 A 0.23

out

OUT = GND -0.3

0.5 0.65 mA

660 kHz

800 kHz

1.1 1.4 mA

Ω

3.1 mA

POW_SR = '00', I

Rise time

(3)

POW_SR = '11', I

POW_SR = '10', I

POW_SR = '01', I

= +1 A 100

out

= -1 A 80

out

= ±1 A 100

out

= ±1 A 200

lout

= ±1 A 300

out

Doc ID16737 Rev 4 11/70

Electrical characteristics L6470

Table 5. Electrical characteristics (continued)

Symbol Parameter Test condition Min. Typ. Max. Unit

out_r

out_f

Fall time

Output rising slew rate

Output falling slew rate

Deadtime and blanking

(3)

POW_SR = '00'; I

POW_SR = '11', I

POW_SR = '10', I

POW_SR = '01', I

POW_SR = '00', I

POW_SR = '11', I

POW_SR = '10', I

POW_SR = '01', I

POW_SR = '00', I

POW_SR = '11', I

POW_SR = '10', I

POW_SR = '01', I

= +1 A 90

out

= -1 A 110

out

= ±1 A 110

out

= ±1 A 260

out

= ±1 A 375

load

= +1 A 285

out

= -1 A 360

out

= ±1 A 285

out

= ±1 A 150

out

= ±1 A 95

out

= +1 A 320

out

= -1 A 260

out

= ±1 A 260

out

= ±1 A 110

out

= ±1 A 75

out

POW_SR = '00' 250

V/µs

blank

Deadtime

Blanking time

Source-drain diodes

SD,HS

SD,LS

rrHS

rrLS

High-side diode forward ON voltage I

Low-side diode forward ON voltage I

High-side diode reverse recovery time I

Low-side diode reverse recovery time I

(1)

POW_SR = '11', f

= 16 MHz

OSC

POW_SR = '10', f

= 16 MHz

OSC

POW_SR = '01', f

= 16 MHz

OSC

375

625

875

POW_SR = '00' 250

POW_SR = '11', f

= 16 MHz

OSC

POW_SR = '10', f

= 16 MHz

OSC

POW_SR = '01', f

= 16 MHz

OSC

= 1 A 1 1.1 V

out

= 1 A 1 1.1 V

out

= 1 A 30 ns

out

= 1 A 100 ns

out

375

625

875

12/70 Doc ID16737 Rev 4

L6470 Electrical characteristics

Table 5. Electrical characteristics (continued)

Symbol Parameter Test condition Min. Typ. Max. Unit

Logic inputs and outputs

logic

logic,STBY

STCK

Low logic level input voltage 0.8 V

High logic level input voltage 2 V

High logic level input current

Low logic level input current

Low logic level output voltage

(4)

(5)

(6)

High logic level output voltage

CS pull-up and STBY pull-down resistors

Internal logic supply current

Standby mode internal logic supply current

Step-clock input frequency 2 MHz

Internal oscillator and external oscillator driver

osc,i

osc,e

OSCOUTH

OSCOUTL

rOSCOUT

fOSCOUT

extosc

intosc

Internal oscillator frequency

Programmable external oscillator frequency 8 32 MHz

OSCOUT clock source high level voltage

OSCOUT clock source low level voltage

OSCOUT clock source rise and fall time Internal oscillator 20 ns

Internal to external oscillator switching delay 3 ms

External to internal oscillator switching delay 1.5 µs

SPI

CK,MAX

rCK

fCK

hCK

lCK

setCS

Maximum SPI clock frequency

SPI clock rise and fall time

SPI clock high and low time

Chip select setup time

(7)

5MHz

(7)

VIN = 5 V 1 µA

VIN = 0 V -1 µA

VDD = 3.3 V, IOL = 4 mA 0.3

VDD = 5 V, IOL = 4 mA 0.3

VDD = 3.3 V, IOH = 4 mA 2.4

= 5 V,

= 4 mA

CS = GND; STBY/RST = 5 V

3.3 V V

externally

REG

supplied, internal oscillator

3.3 V V

externally

REG

supplied

= 25 °C,

= 3.3 V

REG

4.7

335 430 565 kΩ

3.7 4.3 mA

22.5µA

-3% 16 +3% MHz

Internal oscillator 3.3 V V

externally supplied;

REG

OSCOUT

= 4 mA

2.4 V

Internal oscillator 3.3 V V

externally supplied;

REG

OSCOUT

= 4 mA

0.3 V

CL = 30 pF 25 ns

75 ns

350 ns

Doc ID16737 Rev 4 13/70

Electrical characteristics L6470

Table 5. Electrical characteristics (continued)

Symbol Parameter Test condition Min. Typ. Max. Unit

(7)

10 ns

800 ns

25 ns

20 ns

38 ns

47 ns

57 ns

37 ns

holCS

disCS

setSDI

holSDI

enSDO

disSDO

vSDO

holSDO

Chip select hold time

Deselect time

Data input setup time

Data input hold time

Data output enable time

Data output disable time

Data output valid time

Data output hold time

Switch input (SW)

PUSW

SW input pull-up resistance SW = GND 60 85 110 kΩ

PWM modulators

PWM

Programmable PWM frequency

PWM resolution 8 bit

Stall detection

STALL,MAX

STALL,MIN

STALL,RES

Maximum programmable stall threshold STALL_TH = '1111111' 4 A

Minimum programmable stall threshold STALL_TH = '0000000'

Programmable stall threshold resolution

Overcurrent protection

OCD,MAX

OCD,MIN

OCD,RES

OCD,Flag

OCD,SD

Maximum programmable overcurrent detection threshold

Minimum programmable overcurrent detection threshold

Programmable overcurrent detection threshold resolution

OCD to flag signal delay time dI

OCD to shutdown delay time

(1)

= 16 MHz 2.8 62.5

osc

= 32 MHz 5.6 125

osc

31.2 5

kHz

OCD_TH = '1111' 6 A

OCD_TH = '0000'

0.37 5

/dt = 350 A/µs 650 1000 ns

out

/dt = 350 A/µs

out

POW_SR = '10'

600 ns

Standby

= 8 V 26 34

qSTBY

STBY,min

logicwu

Quiescent motor supply current in standby conditions

Minimum standby time 10 µs

Logic power-on and wake-up time 38 45 µs

= 36 V 30 36

14/70 Doc ID16737 Rev 4

µA

L6470 Electrical characteristics

Table 5. Electrical characteristics (continued)

Symbol Parameter Test condition Min. Typ. Max. Unit

cpwu

Charge pump power-on and wake-up time

Power bridges disabled, Cp = 10 nF, C

Internal voltage regulator

REG

REG, drop

REG,STBY

Voltage regulator output voltage 2.9 3 3.2 V

Voltage regulator output current 40 mA

Voltage regulator output voltage drop I

= 40 mA 50 mV

REG

Voltage regulator standby output current 10 mA

Integrated analog-to-digital converter

ADC

ADC,ref

1. Accuracy depends on oscillator frequency accuracy.

2. Tested at 25 °C in a restricted range and guaranteed by characterization.

3. Rise and fall time depends on motor supply voltage value. Refer to SR time.

4. Not valid for STBY/RST

5. Not valid for SW and CS pins which have internal pull-up resistors.

6. FLAG

7. See Figure 18 – SPI timings diagram for details.

Analog-to-digital converter resolution 5 bit

Analog-to-digital converter reference voltage

Analog-to-digital converter sampling frequency

out

pin which has internal pull-down resistor.

, BUSY and SYNC open drain outputs included.

= 220 nF

boot

values in order to evaluate the actual rise and fall

650 µs

PWM

kHz

Doc ID16737 Rev 4 15/70

Pin connection L6470

4 Pin connection

Figure 2. HTSSOP28 pin connection (top view)

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6"/





63"



0'.$



/54" /54"

Figure 3. POWERSO36 pin connection (top view)

74"

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16/70 Doc ID16737 Rev 4

L6470 Pin connection

4.1 Pin list

Table 6. Pin description

No.

Name Type Function

HTSSOP POWERSO

17 24 VDD Power Logic outputs supply voltage (pull-up reference)

6 9 VREG Power

Internal 3 V voltage regulator output and 3.3 V external logic supply

Oscillator pin 1. To connect an external oscillator or

7 10 OSCIN Analog input

clock source. If this pin is unused, it should be left floating.

Oscillator pin 2. To connect an external oscillator.

8 11 OSCOUT Analog output

When the internal oscillator is used this pin can supply 2/4/8/16 MHz. If this pin is unused, it should be left floating.

10 13 CP Output Charge pump oscillator output

11 14 VBOOT Supply voltage

Bootstrap voltage needed for driving the high-side power DMOS of both bridges (A and B)

5 8 ADCIN Analog input Internal analog-to-digital converter input

2, 26 4, 5, 33, 34 VSA Power supply

12, 16 15, 16, 22, 23 VSB Power supply

Full bridge A power supply pin. It must be connected to VSB.

Full bridge B power supply pin. It must be connected to VSA.

27, 13 1, 19 PGND Ground Power ground pin

1 2, 3 OUT1A Power output Full bridge A output 1

28 35, 36 OUT2A Power output Full bridge A output 2

14 17, 18 OUT1B Power output Full bridge B output 1

15 20, 21 OUT2B Power output Full bridge B output 2

9 12 AGND Ground Analog ground.

4 7 SW Logical input

External switch input pin. If not used the pin should be connected to VDD.

21 28 DGND Ground Digital ground

By default, this BUSY pin is forced low when the

22 29 BUSY

\SYNC Open drain output

device is performing a command. Otherwise the pin can be configured to generate a synchronization signal.

18 25 SDO Logic output Data output pin for serial interface

20 27 SDI Logic input Data input pin for serial interface

19 26 CK Logic input Serial interface clock

23 30 CS

Logic input Chip select input pin for serial interface

Doc ID16737 Rev 4 17/70

Pin connection L6470

Table 6. Pin description (continued)

No.

Name Type Function

HTSSOP POWERSO

Status flag pin. An internal open drain transistor can pull the pin to GND when a programmed alarm

24 31 FLAG Open drain output

3 6 STBY\RST

25 32 STCK Logic input Step-clock input

EPAD EPAD Exposed pad Ground Internally connected to PGND, AGND and DGND pins

Logic input

condition occurs (step loss, OCD, thermal prewarning or shutdown, UVLO, wrong command, nonperformable command)

Standby and reset pin. LOW logic level resets the logic and puts the device into Standby mode. If not used, it should be connected to VDD.

18/70 Doc ID16737 Rev 4

L6470 Typical applications

5 Typical applications

Table 7. Typical application values

Name Value

VSPOL

REG

REGPOL

DDPOL

220 nF

100 µF

100 nF

47 µF

100 nF

10 µF

D1 Charge pump diodes

BOOT

FLY

220 nF

10 nF

39 kΩ

100 Ω

10 nF

2.7 kΩ (VS = 36 V)

62 kΩ (VS = 36 V)

Doc ID16737 Rev 4 19/70

Typical applications L6470

Figure 4. Bipolar stepper motor control application using L6470

20/70 Doc ID16737 Rev 4

L6470 Functional description

6 Functional description

6.1 Device power-up

At power-up end, the device state is the following:

● Registers are set to default

● Internal logic is driven by internal oscillator and a 2 MHz clock is provided by the

OSCOUT pin

● Bridges are disabled (High Z)

● UVLO bit in the STATUS register is forced low (fail condition)

● FLAG output is forced low.

During power-up, the device is under reset (all logic IOs disabled and power bridges in high impedance state) until the following conditions are satisfied:

● V

●

● Internal oscillator is operative.

Any motion command makes the device exit from High Z state (HardStop and SoftStop included).

is greater than V

REG

SthOn

REGth

= 2.8 V typical

6.2 Logic I/O

Pins CS, CK, SDI, STCK, SW and STBY\RST are TTL/CMOS 3.3 V - 5 V compatible logic inputs.

Pin SDO is a TTL/CMOS compatible logic output. VDD pin voltage sets the logic output pin voltage range; when it is connected to VREG or 3.3 V external supply voltage, the output is

3.3 V compatible. When VDD is connected to a 5 V supply voltage, SDO is 5 V compatible.

VDD is not internally connected to V

A 10 µF capacitor should be connected to the VDD pin in order to obtain a proper operation.

Pins FLAG

and BUSY\SYNC are open drain outputs.

6.3 Charge pump

To ensure the correct driving of the high-side integrated MOSFETs, a voltage higher than the motor power supply voltage needs to be applied to the VBOOT pin. The high-side gate driver supply voltage, V realizing a charge pump (see Figure 5).

, an external connection is always needed.

REG

, is obtained through an oscillator and a few external components

boot

Doc ID16737 Rev 4 21/70

Functional description L6470

Figure 5. Charge pump circuitry

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6.4 Microstepping

The driver is able to divide the single step into up to 128 microsteps. Stepping mode can be programmed by the STEP_SEL parameter in the STEP_MODE register (see Ta b le 1 8 ).

Step mode can only be changed when bridges are disabled. Every time the step mode is changed the electrical position (i.e. the point of microstepping sinewave that is generated) is reset to the first microstep and the absolute position counter value (see Section 6.5) becomes meaningless.

Figure 6. Normal mode and microstepping (128 microsteps)

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22/70 Doc ID16737 Rev 4

L6470 Functional description

6.4.1 Automatic full-step mode

When motor speed is greater than a programmable full-step speed threshold, the L6470 switches automatically to Full-step mode (see Figure 7); the driving mode returns to microstepping when motor speed decreases below the full-step speed threshold. The fullstep speed threshold is set through the FS_SPD register (see Section 9.1.9).

Figure 7. Automatic full-step switching

peak

Phase A

Phase B

sin(π/4) x I

peak

µStepping

(2N+1) x π/4 (2N+1) x π/4

6.5 Absolute position counter

An internal 22-bit register (ABS_POS) records the motor motion according to the selected step mode; the stored value unit is equal to the selected step mode (full, half, quarter, etc.). The position range is from -2

to +221-1 (µ)steps (see Section 9.1.1).

6.6 Programmable speed profiles

The user can easily program a customized speed profile defining independently acceleration, deceleration, maximum and minimum speed values by the ACC, DEC, MAX_SPEED and MIN_SPEED registers respectively (see Section 9.1.5, 9.1.6, 9.1.7 and

9.1.8).

When a command is sent to the device, the integrated logic generates the microstep frequency profile that performs a motor motion compliant to speed profile boundaries.

All acceleration parameters are expressed in step/tick expressed in step/tick; the unit of measurement does not depend on the selected step mode. Acceleration and deceleration parameters range from 2 (equivalent to 14.55 to 59590 step/s

The minimum speed parameter ranges from 0 to (2

976.3 step/s).

The maximum speed parameter ranges from 2

15.25 to 15610 step/s).

Full-Step

and all speed parameters are

12-1

)•2

-18

to (210-1)• 2

µStepping

-40

to (212-2)•2

-24

step/tick (equivalent to 0 to

-18

step/tick (equivalent to

-40

step/tick2

Doc ID16737 Rev 4 23/70

Functional description L6470

6.6.1 Infinite acceleration/deceleration mode

When the ACC register value is set to max. (0xFFF), the system works in “infinite acceleration mode”: acceleration and deceleration phases are totally skipped, as shown in

Figure 8.

It is not possible to skip the acceleration or deceleration phase independently.

Figure 8. Speed profile in infinite acceleration/deceleration mode

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6.7 Motor control commands

The L6470 can accept different types of commands:

● constant speed commands (Run, GoUntil, ReleaseSW)

● absolute positioning commands (GoTo, GoTo_DIR, GoHome, GoMark)

● motion commands (Move)

● stop commands (SoftStop, HardStop, SoftHiz, HardHiz).

For detailed command descriptions refer to Section 9.2 on page 55.

6.7.1 Constant speed commands

A constant speed command produces a motion in order to reach and maintain a userdefined target speed starting from the programmed minimum speed (set in the MIN_SPEED register) and with the programmed acceleration/deceleration value (set in the ACC and DEC registers). A new constant speed command can be requested anytime.

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24/70 Doc ID16737 Rev 4

L6470 Functional description

Figure 9. Constant speed command examples

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6.7.2 Positioning commands

An absolute positioning command produces a motion in order to reach a user-defined position that is sent to the device together with the command. The position can be reached performing the minimum path (minimum physical distance) or forcing a direction (see

Figure 10).

The performed motor motion is compliant to programmed speed profile boundaries (acceleration, deceleration, minimum and maximum speed).

Note that with some speed profiles or positioning commands, the deceleration phase can start before the maximum speed is reached.

Figure 10. Positioning command examples

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6.7.3 Motion commands

Motion commands produce a motion in order to perform a user-defined number of microsteps in a user-defined direction that are sent to the device together with the command (see Figure 11).

Doc ID16737 Rev 4 25/70

Functional description L6470

The performed motor motion is compliant to programmed speed profile boundaries (acceleration, deceleration, minimum and maximum speed).

Note that with some speed profiles or motion commands, the deceleration phase can start before the maximum speed is reached.

Figure 11. Motion command examples

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6.7.4 Stop commands

A stop command forces the motor to stop. Stop commands can be sent anytime.

The SoftStop command causes the motor to decelerate with programmed deceleration value until the MIN_SPEED value is reached and then stops the motor keeping the rotor position (a holding torque is applied).

The HardStop command stops the motor instantly, ignoring deceleration constraints and keeping the rotor position (a holding torque is applied).

The SoftHiZ command causes the motor to decelerate with programmed deceleration value until the MIN_SPEED value is reached and then forces the bridges in high impedance state (no holding torque is present).

The HardHiZ command instantly forces the bridges into high impedance state (no holding torque is present).

6.7.5 Step-clock mode

In Step-clock mode the motor motion is defined by the step-clock signal applied to the STCK pin. At each step-clock rising edge, the motor is moved one microstep in the programmed direction and the absolute position is consequently updated.

When the system is in Step-clock mode, the SCK_MOD flag in the STATUS register is raised, the SPEED register is set to zero and motor status is considered stopped whatever the STCK signal frequency (MOT_STATUS parameter in STATUS register equal to “00”).

6.7.6 GoUntil and ReleaseSW commands

In most applications the power-up position of the stepper motor is undefined, so an initialization algorithm driving the motor to a known position is necessary.

The GoUntil and ReleaseSW commands can be used in combination with external switch input (see Section 6.13) to easily initialize the motor position.

26/70 Doc ID16737 Rev 4

L6470 Functional description

The GoUntil command makes the motor run at the constant target speed until the SW input is forced low (falling edge). When this event occurs, one of the following actions can be performed:

● The ABS_POS register is set to zero (home position) and the motor decelerates to zero

speed (as a SoftStop command)

● The ABS_POS register value is stored in the MARK register and the motor decelerates

to zero speed (as a SoftStop command).

If the SW_MODE bit of the CONFIG register is set to ‘0’, the motor does not decelerate but it immediately stops (as a HardStop command).

The ReleaseSW command makes the motor run at the programmed minimum speed until the SW input is forced high (rising edge). When this event occurs, one of the following actions can be performed:

● The ABS_POS register is set to zero (home position) and the motor immediately stops

(as a HardStop command)

● The ABS_POS register value is stored in the MARK register and the motor immediately

stops (as a HardStop command).

If the programmed minimum speed is less than 5 step/s, the motor is driven at 5 step/s.

6.8 Internal oscillator and oscillator driver

The control logic clock can be supplied by the internal 16-MHz oscillator, an external oscillator (crystal or ceramic resonator) or a direct clock signal.

These working modes can be selected by EXT_CLK and OSC_SEL parameters in the CONFIG register (see Ta b le 2 3 ).

At power-up the device starts using the internal oscillator and provides a 2-MHz clock signal on the OSCOUT pin.

Attention: In any case, before changing clock source configuration, a

hardware reset is mandatory. Switching to different clock configurations during operation may cause unexpected behavior.

6.8.1 Internal oscillator

In this mode the internal oscillator is activated and OSCIN is unused. If the OSCOUT clock source is enabled, the OSCOUT pin provides a 2, 4, 8 or 16-MHz clock signal (according to OSC_SEL value); it is otherwise unused (see Figure 12).

6.8.2 External clock source

Two types of external clock source can be selected: crystal/ceramic resonator or direct clock source. Four programmable clock frequencies are available for each external clock source: 8, 16, 24 and 32 MHz.

When an external crystal/resonator is selected, the OSCIN and OSCOUT pins are used to drive the crystal/resonator (see Figure 12). The crystal/resonator and load capacitors (C

Doc ID16737 Rev 4 27/70

)

Functional description L6470

must be placed as close as possible to the pins. Refer to Ta bl e 8 for the choice of load capacitor values according to the external oscillator frequency.

Table 8. CL values according to external oscillator frequency

Crystal/resonator freq.

8 MHz 25 pF (ESR

16 MHz 18 pF (ESR

24 MHz 15 pF (ESR

32 MHz 10 pF (ESR

(1)

(2)

= 80 Ω)

max

= 50 Ω)

max

= 40 Ω)

max

= 40 Ω)

max

1. First harmonic resonance frequency.

2. Lower ESR value allows the driving of greater load capacitors.

If a direct clock source is used, it must be connected to the OSCIN pin and the OSCOUT pin supplies the inverted OSCIN signal (see Figure 12).

Figure 12. OSCIN and OSCOUT pin configuration

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Note: When OSCIN is UNUSED, it should be left floating.

When OSCOUT is UNUSED, it should be left floating.

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6.9 Overcurrent detection

When the current in any of the Power MOSFETs exceeds a programmed overcurrent threshold, the STATUS register OCD flag is forced low until the overcurrent event has

28/70 Doc ID16737 Rev 4

L6470 Functional description

expired and a GetStatus command is sent to the IC (see Section 9.1.22 and 9.1.17). The overcurrent event expires when all the Power MOSFET currents fall below the programmed overcurrent threshold.

The overcurrent threshold can be programmed through the OCD_TH register in one of 16 available values ranging from 375 mA to 6 A with steps of 375 mA (see Ta bl e 9 ,

Section 9.1.17).

It is possible to set whether an overcurrent event causes or not the MOSFET turn-off (bridges in high impedance status) acting on the OC_SD bit in the CONFIG register (see

Section 9.1.21). The OCD flag in the STATUS register is raised anyway (see Ta bl e 3 4 , Section 9.1.22).

When the IC outputs are turned off by an OCD event, they cannot be turned on until the OCD flag is released by a GetStatus command.

Attention: The overcurrent shutdown is a critical protection feature. It is

not recommended to disable it.

6.10 Undervoltage lockout (UVLO)

The L6470 provides a motor supply UVLO protection. When the motor supply voltage falls below the V

threshold voltage, the STATUS register UVLO flag is forced low. When a

SthOff

GetStatus command is sent to the IC, and the undervoltage condition has expired, the UVLO flag is released (see Section 9.1.22 and 9.2.20). The undervoltage condition expires when the motor supply voltage goes over the V

threshold voltage. When the device is

SthOn

in undervoltage condition, no motion command can be performed. The UVLO flag is forced low by logic reset (power-up included) even if no UVLO condition is present.

6.11 Thermal warning and thermal shutdown

An internal sensor allows the L6470 to detect when the device internal temperature exceeds a thermal warning or an overtemperature threshold.

When the thermal warning threshold (T register is forced low (see Section 9.1.22) until the temperature decreases below T and a GetStatus command is sent to the IC (see Section 9.1.22 and 9.2.20).

When the thermal shutdown threshold (T shutdown condition: the TH_SD bit in the STATUS register is forced low, the power bridges are disabled bridges in high impedance state and the HiZ bit in the STATUS register is raised (see Section 9.1.22).

The thermal shutdown condition only expires when the temperature goes below the thermal warning threshold (T

j(WRN)

On exiting thermal shutdown condition, the bridges are still disabled (HiZ flag high); any motion command makes the device exit from High Z state (HardStop and SoftStop included).

) is reached, the TH_WRN bit in the STATUS

j(WRN)

) is reached, the device goes into thermal

j(OFF)

j(WRN)

Doc ID16737 Rev 4 29/70

Functional description L6470

6.12 Reset and standby

The device can be reset and put into Standby mode through a dedicated pin. When the STBY

\RST pin is driven low, the bridges are left open (High Z state), the internal charge pump is stopped, the SPI interface and control logic are disabled and the internal 3 V voltage regulator maximum output current is reduced to I

REG,STBY

heavily reduces the power consumption. At the same time the register values are reset to default and all protection functions are disabled. STBY least for t

STBY,min

in order to ensure the complete switch to Standby mode.

\RST input must be forced low at

On exiting Standby mode, as well as for IC power-up, a delay of up to t before applying a new command to allow proper oscillator and logic startup and a delay of up to t

must be given to allow the charge pump startup.

cpwu

On exiting Standby mode, the bridges are disabled (HiZ flag high) and any motion command makes the device exit High Z state (HardStop and SoftStop included).

Attention: It is not recommended to reset the device when outputs are

active. The device should be switched to high impedance state before being reset.

; as a result, the L6470

must be given

logicwu

6.13 External switch (SW pin)

The SW input is internally pulled up to VDD and detects if the pin is open or connected to ground (see Figure 13).

The SW_F bit of the STATUS register indicates if the switch is open (‘0’) or closed (‘1’) (see

Section 9.1.22); the bit value is refreshed at every system clock cycle (125 ns). The

SW_EVN flag of the STATUS register is raised when a switch turn-on event (SW input falling edge) is detected (see Section 9.1.22). A GetStatus command releases the SW_EVN flag (see Section 9.2.20).

By default, a switch turn-on event causes a HardStop interrupt (SW_MODE bit of CONFIG register set to ‘0’). Otherwise (SW_MODE bit of CONFIG register set to ‘1’), switch input events do not cause interrupts and the switch status information is at the user’s disposal (see Ta bl e 3 4, Section 9.1.22).

The switch input may be used by the GoUntil and ReleaseSW commands as described in

Section 9.2.10 and 9.2.11.

If the SW input is not used, it should be connected to VDD.

30/70 Doc ID16737 Rev 4

L6470 Functional description

Figure 13. External switch connection

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6.14 Programmable DMOS slew rate, deadtime and blanking time

Using the POW_SR parameter in the CONFIG register, it is possible to set the commutation speed of the power bridges output (see Ta bl e 2 6, Section 9.1.21).

6.15 Integrated analog-to-digital converter

The L6470 integrates an N

bit ramp-compare analog-to-digital converter with a

ADC

reference voltage equal to VREG. The analog-to-digital converter input is available through the ADCIN pin and the conversion result is available in the ADC_OUT register (see

Section 9.1.16).

Sampling frequency is equal to the programmed PWM frequency.

The ADC_OUT value can be used for motor supply voltage compensation or can be at the user’s disposal.

6.16 Internal voltage regulator

The L6470 integrates a voltage regulator which generates a 3 V voltage starting from the motor power supply (VSA and VSB). In order to make the voltage regulator stable, at least 22 µF should be connected between the VREG pin and ground (suggested value is 47 µF).

The internal voltage regulator can be used to supply the VDD pin in order to make the device digital output range 3.3 V compatible (Figure 14). A digital output range, 5 V compatible, may be obtained connecting the VDD pin to an external 5 V voltage source. In both cases, a 10 µF capacitance should be connected to the VDD pin in order to obtain a correct operation.

The internal voltage regulator is able to supply a current up to I consumption included (I that can be supplied is I

If an external 3.3 V regulated voltage is available, it can be applied to the VREG pin in order to supply all the internal logic and to avoid power dissipation of the internal 3 V voltage regulator (Figure 14). The external voltage regulator should never sink current from the VREG pin.

). When the device is in Standby mode, the maximum current

logic

REG, STBY

, internal consumption included (I

REG,MAX

logic, STBY

, internal logic

Doc ID16737 Rev 4 31/70

Functional description L6470

Figure 14. Internal 3 V linear regulator

VBAT

VREG VDD VSA VSB

3.3V REG.

VREG VDD VSA VSB

µC

Logig supplied by

INTERNAL voltage regulator

6.17 BUSY\SYNC pin

This pin is an open drain output which can be used as the busy flag or synchronization signal according to the SYNC_EN bit value (STEP_MODE register).

6.17.1 BUSY operation mode

The pin works as busy signal when the SYNC_EN bit is set low (default condition). In this mode the output is forced low while a constant speed, absolute positioning or motion command is under execution. The BUSY executed (target speed or target position reached). The STATUS register includes a BUSY flag that is the BUSY pin mirror (see Section 9.1.22).

In the case of daisy chain configuration, BUSY pins of different ICs can be hard-wired to save host controller GPIOs.

AGNDDGND

Logig supplied by

EXTERNAL voltage regulator

pin is released when the command has been

AGNDDGND

6.17.2 SYNC operation mode

The pin works as synchronization signal when the SYNC_EN bit is set high. In this mode a step-clock signal is provided on the output according to a SYNC_SEL and STEP_SEL parameter combination (see Section 9.1.19).

32/70 Doc ID16737 Rev 4

L6470 Functional description

6.18 FLAG pin

By default, an internal open drain transistor pulls the FLAG pin to ground when at least one of the following conditions occurs:

● Power-up or standby/reset exit

● Stall detection on A bridge

● Stall detection on B bridge

● Overcurrent detection

● Thermal warning

● Thermal shutdown

● UVLO

● Switch turn-on event

● Wrong command

● Non-performable command.

It is possible to mask one or more alarm conditions by programming the ALARM_EN register (see Section 9.1.20, Tab le 2 1 ). If the corresponding bit of the ALARM_EN register is low, the alarm condition is masked and it does not cause a FLAG pin transition; all other actions imposed by alarm conditions are performed anyway. In the case of daisy chain configuration, FLAG

pins of different ICs can be or-wired to save host controller GPIOs.

Doc ID16737 Rev 4 33/70

Phase current control L6470

7 Phase current control

The L6470 controls the phase current applying a sinusoidal voltage to motor windings. Phase current amplitude is not directly controlled but depends on phase voltage amplitude, load torque, motor electrical characteristics and rotation speed. Sinewave amplitude is proportional to the motor supply voltage multiplied by a coefficient (K 0 to 100% and the sinewave amplitude can be obtained through the following formula:

Equation 1

VAL

). K

ranges from

VAL

Different K

OUTVSKVAL

values can be programmed for acceleration, deceleration and constant speed

VAL

⋅=

phases and when the motor is stopped (HOLD phase) through the KVAL_ACC, KVAL_DEC, KVAL_RUN and KVAL_HOLD registers (see Section 9.1.10). KVAL value is calculated according to the following formula:

Equation 2

where K

VAL

is the starting K

VAL_X

BEMF_COMP+()VSCOMP K_THERM××[]microstep×=

value programmed for present motion phase (KVAL_ACC,

VAL

KVAL_DEC, KVAL_RUN or KVAL_HOLD), BEMF_COMP is the BEMF compensation curve value, VSCOMP and K_THERM are the motor supply voltage and winding resistance compensation factors and microstep is the current microstep value (fraction of target peak current).

The L6470 offers various methods to guarantee a stable current value, allowing the compensation of:

● low speed optimization (Section 7.3 7.3)

● back electromotive force value (Section 7.4 7.4)

● motor supply voltage variation (Section 7.5 7.5)

● windings resistance variation (Section 7.67.6).

7.1 PWM sinewave generators

The two voltage sinewaves applied to the stepper motor phases are generated by two PWM modulators.

The PWM frequency (f obtained through the following formula:

Equation 3

'N' is the integer division factor and 'm' is the multiplication factor. 'N' and 'm' values can be programmed by the F_PWM_INT and F_PWM_DEC parameters in the CONFIG register (see Ta bl e 2 8 and Ta bl e 2 9, Section 9.1.21).

Available PWM frequencies are listed in Section 9.1.21 from Ta bl e 3 0 to Tab le 3 3 .

34/70 Doc ID16737 Rev 4

) is proportional to the oscillator frequency (f

PWM

OSC

PWM

---------------------

512 N⋅

) and can be

OSC

m⋅=

L6470 Phase current control

7.2 Sensorless stall detection

Depending on motor speed and load angle characteristics, the L6470 offers a motor stall condition detection using a programmable current comparator.

When a stall event occurs, the respective flag (STEP_LOSS_A or STEP_LOSS_B) is forced low until a GetStaus command or a system reset occurs (see Section 9.2.20).

7.3 Low speed optimization

When the motor is driven at a very low speed using a small driving voltage, the resulting phase current can be distorted. As a consequence, the motor position is different from the ideal one (see Figure 15).

The L6470 implements a low speed optimization in order to remove this effect.

Figure 15. Current distortion and compensation

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)

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7ITHLOWSPEEDOPTIMIZAZION

)

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The optimization can be enabled setting high the LSPD_OPT bit in the MIN_SPEED register (see Section 9.1.8) and is active in a speed range from zero to MIN_SPEED. When low speed optimization is enabled, speed profile minimum speed is forced to zero.

Doc ID16737 Rev 4 35/70

Phase current control L6470

7.4 BEMF compensation

Using the speed information, a compensation curve is added to the amplitude of the voltage waveform applied to the motor winding in order to compensate the BEMF variations during acceleration and deceleration (see Figure 16).

The compensation curve is approximated by a stacked line with a starting slope (ST_SLP) when speed is lower than a programmable threshold speed (INT_SPEED) and a fine slope (FN_SLP_ACC and FN_SLP_DEC) when speed is greater than the threshold speed (see

Section 9.1.11, Section 9.1.12, Section 9.1.13 and Section 9.1.14).

Figure 16. BEMF compensation curve

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To obtain different current values during acceleration and deceleration phases, two different final slope values, and consequently two different compensation curves, can be programmed.

The acceleration compensation curve is applied when the motor runs. No BEMF compensation is applied when the motor is stopped.

7.5 Motor supply voltage compensation

The sinewave amplitude generated by the PWM modulators is directly proportional to the motor supply voltage (V the motor phases are driven with an incorrect voltage. The L6470 can compensate motor supply voltage variations in order to avoid this effect.

). When the motor supply voltage is different from its nominal value,

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The motor supply voltage should be connected to the integrated ADC input through a resistor divider in order to obtain V

/2 voltage at the ADCIN pin when VS is at its nominal

REG

value (see Figure 17).

The ADC input is sampled at f

36/70 Doc ID16737 Rev 4

frequency, which is equal to PWM frequency.

L6470 Phase current control

Figure 17. Motor supply voltage compensation circuit

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Motor supply voltage compensation can be enabled setting high the EN_VSCOMP bit of the CONFIG register (see Ta b le 2 2 , Section 9.1.21). If the EN_VSCOMP bit is low, the compensation is disabled and the internal analog-to-digital converter is at the user’s disposal; sampling rate is always equal to PWM frequency.

7.6 Winding resistance thermal drift compensation

The higher the winding resistance, the greater the voltage to be applied in order to obtain the same phase current.

The L6470 integrates a register (K_THERM) which can be used to compensate phase resistance increment due to temperature rising.

The value in the K_THERM register (see Section 9.1.15) multiplies the duty cycle value allowing a higher phase resistance value to be faced.

The compensation algorithm and the eventual motor temperature measurement should be implemented by microcontroller firmware.

Doc ID16737 Rev 4 37/70

Serial interface L6470

8 Serial interface

The integrated 8-bit serial peripheral interface (SPI) is used for a synchronous serial communication between the host microprocessor (always master) and the L6470 (always slave).

The SPI uses chip select (CS output (SDO) pins. When CS

), serial clock (CK), serial data input (SDI) and serial data

is high, the device is unselected and the SDO line is inactive

(high-impedance).

The communication starts when CS

is forced low. The CK line is used for synchronization of

data communication.

All commands and data bytes are shifted into the device through the SDI input, most significant bit first. The SDI is sampled on the rising edges of the CK.

All output data bytes are shifted out of the device through the SDO output, most significant bit first. The SDO is latched on the falling edges of the CK. When a return value from the device is not available, an all zero byte is sent.

After each byte transmission the CS

input must be raised and be kept high for at least t

disCS

in order to allow the device to decode the received command and put the return value into the SHIFT register.

All timing requirements are shown in Figure 18 (see Section 3: Electrical characteristics for values).

Multiple devices can be connected in daisy chain configuration, as shown in Figure 19.

Figure 18. SPI timings diagram

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L6470 Serial interface

Figure 19. Daisy chain configuration

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Doc ID16737 Rev 4 39/70

Programming manual L6470

9 Programming manual

9.1 Registers and flags description

The following is a map of the user registers available (detailed description in respective paragraphs):

Table 9. Registers map

Address

[Hex]

Len. [bit]

Reset

Hex

Reset

value

Remarks

h01 ABS_POS Current position 22 000000 0 R, WS

h02 EL_POS Electrical position 9 000 0 R, WS

h03 MARK Mark position 22 000000 0 R, WR

h04 SPEED Current speed 20 00000 0 step/tick (0 step/s) R

h05 ACC Acceleration 12 08A

h06 DEC Deceleration 12 08A

125.5e-12 step/tick

)

step/s

125.5e-12 step/tick

step/s

)

(2008

h07 MAX_SPEED Maximum speed 10 041 248e-6 step/tick (991.8 step/s) R, WR

h08 MIN_SPEED Minimum speed 13 000 0 step/tick (0 step/s) R, WS

h15 FS_SPD Full-step speed 10 027

h09 KVAL_HOLD Holding K

VAL

h0A KVAL_RUN Constant speed K

h0B KVAL_ACC

h0C KVAL_DEC

Acceleration starting K

VAL

Deceleration starting K

VAL

8 29 0.16·VS R, WR

150.7e-6 step/tick (602.7 step/s)

h0D INT_SPEED Intersect speed 14 0408 15.4e-6 step/tick (61.5 step/s) R, WH

h0E ST_SLP Start slope 8 19 0.038% s/step R, WH

(1)

R, WS

R, WR

h0F FN_SLP_ACC

h10 FN_SLP_DEC

h11 K_THERM

h12 ADC_OUT ADC output 5 XX

Acceleration final slope

Deceleration final slope

Thermal compensation factor

8 29 0.063% s/step R, WH

401.0 R, WR

(2)

h13 OCD_TH OCD threshold 4 8 3.38A R, WR

h14 STALL_TH STALL threshold 7 40 2.03A R, WR

h16 STEP_MODE Step mode 8 7 128 microsteps R, WH

h17 ALARM_EN Alarm enable 8 FF All alarms enabled R, WS

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L6470 Programming manual

Table 9. Registers map (continued)

Address

[Hex]

h18 CONFIG IC configuration 16 2E88

h19 STATUS Status 16 XXXX

h1A RESERVED Reserved address

h1B RESERVED Reserved address

1. R: readable, WH: writable only when outputs are in high impedance, WS: writable only when motor is stopped, WR: always writable.

2. According to startup conditions.

Len. [bit]

Reset

Hex

Reset

value

Internal oscillator, 2 MHz OSCOUT clock, supply voltage compensation disabled, overcurrent shutdown enabled, slew rate = 290 V/µs PWM frequency = 15.6 kHz.

High impedance state,

(2)

UVLO/Reset flag set.

Remarks

R, WH

9.1.1 ABS_POS

The ABS_POS register contains the current motor absolute position in agreement with the selected step mode; the stored value unit is equal to the selected step mode (full, half, quarter, etc.). The value is in 2's complement format and it ranges from -2

At power-on the register is initialized to “0” (HOME position).

to +221-1.

(1)

Any attempt to write the register when the motor is running causes the command to be ignored and the NOTPERF_CMD flag to rise (see Section 9.1.22).

9.1.2 EL_POS

The EL_POS register contains the current electrical position of the motor. The two MSbits indicate the current step and the other bits indicate the current microstep (expressed in step/128) within the step.

Table 10. EL_POS register

Bit 8 Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0

STEP MICROSTEP

When the EL_POS register is written by the user, the new electrical position is instantly imposed. When the EL_POS register is written, its value must be masked in order to match with the step mode selected in the STEP_MODE register in order to avoid a wrong microstep value generation (see Section 9.1.19); otherwise the resulting microstep sequence is incorrect.

Any attempt to write the register when the motor is running causes the command to be ignored and the NOTPERF_CMD flag to rise (see Section 9.1.22).

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Programming manual L6470

9.1.3 MARK

The MARK register contains an absolute position called MARK according to the selected step mode; the stored value unit is equal to the selected step mode (full, half, quarter, etc.). It is in 2's complement format and it ranges from -2

to +221-1.

9.1.4 SPEED

The SPEED register contains the current motor speed, expressed in step/tick (format unsigned fixed point 0.28).

In order to convert the SPEED value in step/s, the following formula can be used:

Equation 4

28–

SPEED 2

step/s[]

----------- ------------- ------------- ---=

where SPEED is the integer number stored in the register and tick is 250 ns.

The available range is from 0 to 15625 step/s with a resolution of 0.015 step/s.

Note: The range effectively available to the user is limited by the MAX_SPEED parameter.

Any attempt to write the register causes the command to be ignored and the NOTPERF_CMD flag to rise (see Section 9.1.22).

⋅

tick

9.1.5 ACC

The ACC register contains the speed profile acceleration expressed in step/tick2 (format unsigned fixed point 0.40).

In order to convert ACC value in step/s

Equation 5

where ACC is the integer number stored in the register and tick is 250 ns.

The available range is from 14.55 to 59590 step/s

When the ACC value is set to 0xFFF, the device works in infinite acceleration mode.

Any attempt to write to the register when the motor is running causes the command to be ignored and the NOTPERF_CMD flag to rise (see Section 9.1.22).

9.1.6 DEC

The DEC register contains the speed profile deceleration expressed in step/tick2 (format unsigned fixed point 0.40).

In order to convert DEC value in step/s

, the following formula can be used:

step/s

[]

ACC 2

------------ ------------- ------=

, the following formula can be used:

40–

⋅

tick

with a resolution of 14.55 step/s2.

Equation 6

[]

step/s

42/70 Doc ID16737 Rev 4

DEC 2

------------ ------------- ------=

tick

40–

⋅

L6470 Programming manual

where DEC is the integer number stored in the register and tick is 250 ns.

The available range is from 14.55 to 59590 step/s2 with a resolution of 14.55 step/s2.

When the device is working in infinite acceleration mode, this value is ignored.

Any attempt to write the register when the motor is running causes the command to be ignored and the NOTPERF_CMD flag to rise (see Section 9.1.22).

9.1.7 MAX_SPEED

The MAX_SPEED register contains the speed profile maximum speed expressed in step/tick (format unsigned fixed point 0.18).

In order to convert it in step/s, the following formula can be used:

Equation 7

step/s[]

MAX_SPEED 2

------------ ------------- ------------- ----------- -------=

tick

where MAX_SPEED is the integer number stored in the register and tick is 250 ns.

The available range is from 15.25 to 15610 step/s with a resolution of 15.25 step/s.

18–

⋅

9.1.8 MIN_SPEED

The MIN_SPEED register contains the following parameters:

Table 11. MIN_SPEED register

Bit 12 Bit 11 Bit 10 Bit 9 Bit 8 Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0

LSPD_OPT MIN_SPEED

The MIN_SPEED parameter contains the speed profile minimum speed. Its value is expressed in step/tick and to convert it in step/s, the following formula can be used:

Equation 8

where MIN_SPEED is the integer number stored in the register and tick is the ramp 250 ns.

The available range is from 0 to 976.3 step/s with a resolution of 0.238 step/s.

When the LSPD_OPT bit is set high, the low speed optimization feature is enabled and the MIN_SPEED value indicates the speed threshold below which the compensation works. In this case the minimum speed of the speed profile is set to zero.

An attempt to write the register when the motor is running causes the NOTPERF_CMD flag to rise.

step/s[]

MIN_SPEED 2

------------- ------------- ------------- ---------- -----=

tick

24–

⋅

9.1.9 FS_SPD

The FS_SPD register contains the threshold speed. When the actual speed exceeds this value, the step mode is automatically switched to full-step two-phase on. Its value is

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Programming manual L6470

expressed in step/tick (format unsigned fixed point 0.18) and to convert it in step/s, the following formula can be used.

Equation 9

step/s[]

FS_SPD 0.5+()2

------------- ------------- ------------- ---------- -------------=

tick

18–

⋅

If the FS_SPD value is set to hFF (max.) the system always works in microstepping mode (SPEED must go beyond the threshold to switch to Full-step mode). Setting FS_SPD to zero does not have the same effect as setting Step mode to full-step two-phase on: the zero FS_SPD value is equivalent to a speed threshold of about 7.63 step/s.

The available range is from 7.63 to 15625 step/s with a resolution of 15.25 step/s.

9.1.10 KVAL_HOLD, KVAL_RUN, KVAL_ACC and KVAL_DEC

The KVAL_HOLD register contains the K

value that is assigned to the PWM modulators

VAL

when the motor is stopped (compensation excluded).

The KVAL_RUN register contains the K

value that is assigned to the PWM modulators

VAL

when the motor is running at constant speed (compensation excluded).

The KVAL_ACC register contains the starting K

value that can be assigned to the PWM

VAL

modulators during acceleration (compensation excluded).

The KVAL_DEC register contains the starting K

value that can be assigned to the PWM

VAL

modulators during deceleration (compensation excluded).

The available range is from 0 to 0.996 x V

with a resolution of 0.004 x VS, as shown in

Ta bl e 1 2.

Table 12. Voltage amplitude regulation registers

KVAL_X [7..0] Output voltage

00000000 0

00000001 V

…

11111110 V

11111111 V

…

x (1/256)

x (254/256)

x (255/256)

…

9.1.11 INT_SPEED

The INT_SPEED register contains the speed value at which the BEMF compensation curve changes slope (see Section 7.4). Its value is expressed in step/tick and to convert it in step/s, the following formula can be used:

Equation 10

INT SPEED– 2

step s⁄[]

where INT_SPEED is the integer number stored in the register and tick is 250 ns.

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----------- ------------- ------------- ---------- -------=

tick

26–

⋅

L6470 Programming manual

The available range is from 0 to 976.5 step/s with a resolution of 0.0596 step/s.

Any attempt to write the register when the motor is running causes the command to be ignored and the NOTPERF_CMD flag to rise (see Section 9.1.22).

9.1.12 ST_SLP

The ST_SLP register contains the BEMF compensation curve slope that is used when the speed is lower than the intersect speed (see Section 7.4). Its value is expressed in s/step and the available range is from 0 to 0.004 with a resolution of 0.000015.

When ST_SLP, FN_SLP_ACC and FN_SLP_DEC parameters are set to zero, no BEMF compensation is performed.

Any attempt to write the register when the motor is running causes the command to be ignored and the NOTPERF_CMD flag to rise (see Section 9.1.22).

9.1.13 FN_SLP_ACC

The FN_SLP_ACC register contains the BEMF compensation curve slope that is used when the speed is greater than the intersect speed during acceleration (see Section 7.47.4). Its value is expressed in s/step and the available range is from 0 to 0.004 with a resolution of

0.000015.

When ST_SLP, FN_SLP_ACC and FN_SLP_DEC parameters are set to zero, no BEMF compensation is performed.

Any attempt to write the register when the motor is running causes the command to be ignored and the NOTPERF_CMD flag to rise (see Section 9.1.22).

9.1.14 FN_SLP_DEC

The FN_SLP_DEC register contains the BEMF compensation curve slope that is used when the speed is greater than the intersect speed during deceleration (see Section 7.47.4). Its value is expressed in s/step and the available range is from 0 to 0.004 with a resolution of

0.000015.

When ST_SLP, FN_SLP_ACC and FN_SLP_DEC parameters are set to zero, no BEMF compensation is performed.

Any attempt to write the register when the motor is running causes the command to be ignored and the NOTPERF_CMD flag to rise (see Section 9.1.22).

9.1.15 K_THERM

The K_THERM register contains the value used by the winding resistance thermal drift compensation system (see Section 7.6).

The available range is from 1 to 1.46875 with a resolution of 0.03125, as shown in Ta b le 1 3 .

Table 13. Winding resistance thermal drift compensation coefficient

K_THERM [3..0] Compensation coeff.

0000 1

0 0 0 1 1.03125

…

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…

Programming manual L6470

Table 13. Winding resistance thermal drift compensation coefficient (continued)

K_THERM [3..0] Compensation coeff.

1110 1.4375

1 1 1 1 1.46875

9.1.16 ADC_OUT

The ADC_OUT register contains the result of the analog-to-digital conversion of the ADCIN pin voltage; the result is available even if the supply voltage compensation is disabled.

Any attempt to write to the register causes the command to be ignored and the NOTPERF_CMD flag to rise (see Section 9.1.22).

Table 14. ADC_OUT value and motor supply voltage compensation feature

Greater than V

S,nom

VS,

Lower than V

9.1.17 OCD_TH

The OCD_TH register contains the overcurrent threshold value (see Section 6.9). The available range is from 375 mA to 6 A, in steps of 375 mA, as shown in Ta b le 1 5 .

Table 15. Overcurrent detection threshold

OCD_TH [3..0] Overcurrent detection threshold

0000 375 mA

0001 750 mA

…

ADC_OUT

[4..0]

…

+ 50% > 24/32 1 1 X X X 0.65625

S,nom

+ 50% 24/32 11000 0.65625

…

VS,

nom

…

– 50% 8/32 01000 1.968875

nom

– 50% < 8/32 0 0 X X X 1.968875

S,nom

ADCIN/VREG

…

16/32 10000 1

…

Compensation

coefficient

…

………… …

1 1 1 0 5.625 A

1111 6 A

9.1.18 STALL_TH

The STALL_TH register contains the stall detection threshold value (see Section 7.2). The available range is from 31.25 mA to 4 A with a resolution of 31.25 mA.

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L6470 Programming manual

Table 16. Stall detection threshold

STALL_th [6..0] Stall detection threshold

0000000 31.25 mA

0 0 0 0 0 0 1 62.5 mA

………………… …

1111110 3.969 A

1111111 4 A

9.1.19 STEP_MODE

The STEP_MODE register has the following structure:

Table 17. STEP_MODE register

Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0

SYNC_EN SYNC_SEL 0

1. When the register is written, this bit should be set to 0.

(1)

STEP_SEL

The STEP_SEL parameter selects one of eight possible stepping modes:

Table 18. Step mode selection

STEP_SEL[2..0] Step mode

000Full-step

001Half-step

0 1 0 1/4 microstep

0 1 1 1/8 microstep

1 0 0 1/16 microstep

1 0 1 1/32 microstep

1 1 0 1/64 microstep

1 1 1 1/128 microstep

Every time the step mode is changed, the electrical position (i.e. the point of microstepping sinewave that is generated) is reset to the first microstep.

Warning: Every time STEP_SEL is changed, the value in the ABS_POS

Any attempt to write the register when the motor is running causes the command to be ignored and the NOTPERF_CMD flag to rise (see Section 9.1.22).

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Programming manual L6470

When the SYNC_EN bit is set low, BUSY/SYNC output is forced low during command execution, otherwise, when the SYNC_EN bit is set high, BUSY

/SYNC output provides a

clock signal according to the SYNC_SEL parameter.

Table 19. SYNC output frequency

STEP_SEL (fFS is the full-step frequency)

000 001 010 011 100 101 110 111

000 fFS /2 fFS /2 fFS /2 fFS /2 fFS /2 fFS /2 fFS /2 fFS /2

001 NA f

010 NA NA 2· f

011 NA NA NA 4· f

100 NA NA NA NA 8· f

2· f

4· f

2· f

4· f

8· f

2· f

4· f

8· f

2· f

4· f

8· f

SYNC_SEL

101 NA NA NA NA NA 16· f

110 NA NA NA NA NA NA 32· f

111 NA NA NA NA NA NA NA 64· f

16· f

32· f

The synchronization signal is obtained starting from electrical position information (EL_POS register) according to Tab l e 1 0:

Table 20. SYNC signal source

SYNC_SEL[2..0] Source

0 0 0 EL_POS[7]

0 0 1 EL_POS[6]

0 1 0 EL_POS[5]

0 1 1 EL_POS[4]

1 0 0 EL_POS[3]

1 0 1 EL_POS[2]

1 1 0 EL_POS[1]

1 1 1 EL_POS[0]

9.1.20 ALARM_EN

The ALARM_EN register allows the selection of which alarm signals are used to generate the FLAG output. If the respective bit of the ALARM_EN register is set high, the alarm condition forces the FLAG pin output down.

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L6470 Programming manual

Table 21. ALARM_EN register

ALARM_EN bit Alarm condition

0 (LSB) Overcurrent

1 Thermal shutdown

2 Thermal warning

3 Undervoltage

4 Stall detection (Bridge A)

5 Stall detection (Bridge B)

6 Switch turn-on event

7 (MSB) Wrong or non-performable command

9.1.21 CONFIG

The CONFIG register has the following structure:

Table 22. CONFIG register

Bit 15 Bit 14 Bit 13 Bit 12 Bit 11 Bit 10 Bit 9 Bit 8

F_PWM_INT F_PWM_DEC POW_SR

Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0

OC_SD RESERVED EN_VSCOMP SW_MODE EXT_CLK OSC_SEL

The OSC_SEL and EXT_CLK bits set the system clock source:

Table 23. Oscillator management

EXT_C

0000

0001

0010

0011

1000Internal oscillator: 16 MHz Unused

1001Internal oscillator: 16 MHz Unused

1010Internal oscillator: 16 MHz Unused

OSC_SEL[2..0] Clock source OSCIN OSCOUT

Internal oscillator: 16 MHz Unused Unused

Supplies a 2-MHz

clock

Supplies a 4-MHz

clock

Supplies an 8-MHz

clock

1011Internal oscillator: 16 MHz Unused

Doc ID16737 Rev 4 49/70

Supplies a 16-MHz

clock

Programming manual L6470

Table 23. Oscillator management (continued)

EXT_C

0100

0101

0110

0111

1100

1101

1110

1111

OSC_SEL[2..0] Clock source OSCIN OSCOUT

External crystal or resonator: 8

MHz

External crystal or resonator:

16 MHz

External crystal or resonator:

24 MHz

External crystal or resonator:

32 MHz

Ext clock source: 8 MHz (Crystal/resonator driver

disabled)

Ext clock source: 16 MHz

(Crystal/resonator driver

disabled)

Ext clock source: 24 MHz

(Crystal/resonator driver

disabled)

Ext clock source: 32 MHz

(Crystal/resonator driver

disabled)

Crystal/resonator

driving

Crystal/resonator

driving

Crystal/resonator

driving

Crystal/resonator

driving

Clock source

Crystal/resonator

driving

Crystal/resonator

driving

Crystal/resonator

driving

Crystal/resonator

driving

Supplies inverted

OSCIN signal

Supplies inverted

OSCIN signal

Supplies inverted

OSCIN signal

Supplies inverted

OSCIN signal

The SW_MODE bit sets the external switch to act as HardStop interrupt or not:

Table 24. External switch hard stop interrupt mode

SW_MODE Switch mode

0 HardStop interrupt

1 User disposal

The OC_SD bit sets whether an overcurrent event causes or not the bridges to turn off; the OCD flag in the STATUS register is forced low anyway:

Table 25. Overcurrent event

OC_SD Overcurrent event

1 Bridges shut down

0 Bridges do not shut down

The POW_SR bits set the slew rate value of power bridge output:

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L6470 Programming manual

Table 26. Programmable power bridge output slew rate values

POW_SR

[1..0]

Output slew rate

[V/µs]

00 180

01 180

10 290

11 530

(1)

1. See S

Rout_r

and S

parameters in Table 5 for details.

Rout_f

The EN_VSCOMP bit sets whether the motor supply voltage compensation is enabled or not.

Table 27. Motor supply voltage compensation enable

EN_VSCOMP Motor supply voltage compensation

0 Disabled

1 Enabled

The F_PWM_INT bits set the integer division factor of PWM frequency generation.

Table 28. PWM frequency: integer division factor

F_PWM_INT

[2..0]

000 1

001 2

010 3

011 4

Integer division factor

100 5

101 6

110 7

111

The F_PWM_DEC bits set the multiplication factor of PWM frequency generation.

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Programming manual L6470

Table 29. PWM frequency: multiplication factor

F_PWM_DEC [2..0] Multiplication factor

000 0.625

001 0.75

010 0.875

011 1

100 1.25

101 1.5

110 1.75

111 2

In the following tables all available PWM frequencies are listed according to oscillator frequency, F_PWM_INT and F_PWM_DEC values (CONFIG register OSC_SEL parameter must be correctly programmed).

Table 30. Available PWM frequencies [kHz]: 8-MHz oscillator frequency

F_PWM_DEC

F_PWM_

INT

000 9.8 11.7 13.7 15.6 19.5 23.4 27.3 31.3

001 4.9 5.9 6.8 7.8 9.8 11.7 13.7 15.6

010 3.3 3.9 4.6 5.2 6.5 7.8 9.1 10.4

011 2.4 2.9 3.4 3.9 4.9 5.9 6.8 7.8

100 2.0 2.3 2.7 3.1 3.9 4.7 5.5 6.3

101 1.6 2.0 2.3 2.6 3.3 3.9 4.6 5.2

110 1.4 1.7 2.0 2.2 2.8 3.3 3.9 4.5

000 001 010 011 100 101 110 111

Table 31. Available PWM frequencies [kHz]: 16-MHz oscillator frequency

F_PWM_DEC

F_PWM_INT 000 001 010 011 100 101 110 111

000 19.5 23.4 27.3 31.3 39.1 46.9 54.7 62.5

001 9.8 11.7 13.7 15.6 19.5 23.4 27.3 31.3

010 6.5 7.8 9.1 10.4 13.0 15.6 18.2 20.8

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Table 31. Available PWM frequencies [kHz]: 16-MHz oscillator frequency

F_PWM_DEC

F_PWM_INT 000 001 010 011 100 101 110 111

011 4.9 5.9 6.8 7.8 9.8 11.7 13.7 15.6

100 3.9 4.7 5.5 6.3 7.8 9.4 10.9 12.5

101 3.3 3.9 4.6 5.2 6.5 7.8 9.1 10.4

110 2.83.33.94.55.66.77.88.9

Table 32. Available PWM frequencies [kHz]: 24-MHz oscillator frequency

F_PWM_DEC

F_PWM_INT 000 001 010 011 100 101 110 111

000 29.3 35.2 41.0 46.9 58.6 70.3 82.0 93.8

001 14.6 17.6 20.5 23.4 29.3 35.2 41.0 46.9

010 9.8 11.7 13.7 15.6 19.5 23.4 27.3 31.3

011 7.3 8.8 10.3 11.7 14.6 17.6 20.5 23.4

100 5.9 7.0 8.2 9.4 11.7 14.1 16.4 18.8

101 4.9 5.9 6.8 7.8 9.8 11.7 13.7 15.6

110 4.2 5.0 5.9 6.7 8.4 10.0 11.7 13.4

Table 33. Available PWM frequencies [kHz]: 32-MHz oscillator frequency

F_PWM_DEC

F_PWM_

INT

000 39.1 46.9 54.7 62.5 78.1 93.8 109.4 125.0

001 19.5 23.4 27.3 31.3 39.1 46.9 54.7 62.5

010 13.0 15.6 18.2 20.8 26.0 31.3 36.5 41.7

011 9.8 11.7 13.7 15.6 19.5 23.4 27.3 31.3

100 7.8 9.4 10.9 12.5 15.6 18.8 21.9 25.0

000 001 010 011 100 101 110 111

101 6.5 7.8 9.1 10.4 13.0 15.6 18.2 20.8

110 5.6 6.7 7.8 8.9 11.2 13.4 15.6 17.9

Doc ID16737 Rev 4 53/70

Programming manual L6470

Any attempt to write the CONFIG register when the motor is running causes the command to be ignored and the NOTPERF_CMD flag to rise (see Section 9.1.22).

9.1.22 STATUS

Table 34. STATUS register

Bit 15 Bit 14 Bit 13 Bit 12 Bit 11 Bit 10 Bit 9 Bit 8

SCK_MOD STEP_LOSS_B STEP_LOSS_A OCD TH_SD TH_WRN UVLO WRONG_CMD

Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0

NOTPERF_CMD MOT_STATUS DIR SW_EVN SW_F BUSY HiZ

When the HiZ flag is high, it indicates that the bridges are in high impedance state. Any motion command makes the device exit from High Z state (HardStop and SoftStop included), unless error flags forcing a High Z state are active.

The UVLO flag is active low and is set by an undervoltage lockout or reset events (power-up included).

The TH_WRN, TH_SD, OCD flags are active low and indicate, respectively, thermal warning, thermal shutdown and overcurrent detection events.

STEP_LOSS_A and STEP_LOSS_B flags are forced low when a stall is detected on bridge A or bridge B respectively.

The NOTPERF_CMD and WRONG_CMD flags are active high and indicate, respectively, that the command received by SPI cannot be performed or does not exist at all.

The SW_F flag reports the SW input status (low for open and high for closed).

The SW_EVN flag is active high and indicates a switch turn-on event (SW input falling edge).

The UVLO, TH_WRN, TH_SD, OCD, STEP_LOSS_A, STEP_LOSS_B, NOTPERF_CMD, WRONG_CMD and SW_EVN flags are latched: when the respective conditions make them active (low or high), they remain in that state until a GetStatus command is sent to the IC.

The BUSY bit reflects the BUSY

pin status. The BUSY flag is low when a constant speed, positioning or motion command is under execution and is released (high) after the command has been completed.

The SCK_MOD bit is an active high flag indicating that the device is working in Step-clock mode. In this case the step-clock signal should be provided through the STCK input pin. The DIR bit indicates the current motor direction:

Table 35. STATUS register DIR bit

DIR Motor direction

1Forward

0Reverse

MOT_STATUS indicates the current motor status:

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Table 36. STATUS register MOT_STATE bits

MOT_STATUS Motor status

0 0 Stopped

01 Acceleration

10 Deceleration

1 1 Constant speed

Any attempt to write to the register causes the command to be ignored and the NOTPERF_CMD flag to rise (see Section 9.1.22).

9.2 Application commands

The command summary is given in Ta b le 3 7 .

Table 37. Application commands

Command mnemonic

Command binary code

Action

[7..5] [4] [3] [2..1] [0]

NOP 000 0 0 00 0 Nothing

SetParam(PARAM,VALUE) 000 [PARAM] Writes VALUE in PARAM register

GetParam(PARAM) 001 [PARAM] Returns the stored value in PARAM register

Run(DIR,SPD) 010 1 0 00 DIR Sets the target speed and the motor direction

StepClock(DIR) 010 1 1 00 DIR

Move(DIR,N_STEP) 010 0 0 00 DIR

GoTo(ABS_POS) 011 0 0 00 0 Brings motor into ABS_POS position (minimum path)

GoTo_DIR(DIR,ABS_POS) 011 0 1 00 DIR

GoUntil(ACT,DIR,SPD) 100 0 ACT 01 DIR

ReleseSW(ACT, DIR) 100 1 ACT 01 DIR

GoHome 011 1 0 00 0 Brings the motor into HOME position

GoMark 011 1 1 00 0 Brings the motor into MARK position

ResetPos 110 1 1 00 0 Resets the ABS_POS register (set HOME position)

Puts the device into Step-clock mode and imposes DIR direction

Makes N_STEP (micro)steps in DIR direction (Not performable when motor is running)

Brings motor into ABS_POS position forcing DIR direction

Performs a motion in DIR direction with speed SPD until SW is closed, the ACT action is executed then a SoftStop takes place.

Performs a motion in DIR direction at minimum speed until the SW is released (open), the ACT action is executed then a HardStop takes place.

ResetDevice 110 0 0 00 0 Device is reset to power-up conditions.

SoftStop 101 1 0 00 0 Stops motor with a deceleration phase

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Table 37. Application commands (continued)

Command binary code

Command mnemonic

[7..5] [4] [3] [2..1] [0]

HardStop 101 1 1 00 0 Stops motor immediately

Action

SoftHiZ 101 0 0 00 0

HardHiZ 101 0 1 00 0 Puts the bridges into high impedance status immediately

GetStatus 110 1 0 00 0 Returns the STATUS register value

RESERVED 111 0 1 01 1 RESERVED COMMAND

RESERVED 111 1 1 00 0 RESERVED COMMAND

9.2.1 Command management

The host microcontroller can control motor motion and configure the L6470 through a complete set of commands.

All commands are composed by a single byte. After the command byte, some bytes of arguments should be needed (see Figure 20). Argument length can vary from 1 to 3 bytes.

Figure 20. Command with 3-byte argument

3$)

FROMHOST

3$/

TOHOST

By default, the device returns an all zero response for any received byte, the only exceptions are the GetParam and GetStatus commands. When one of these commands is received, the following response bytes represent the related register value (see Figure 21). Response length can vary from 1 to 3 bytes.

#OMMANDBYTE

X X X X

Puts the bridges into high impedance status after a deceleration phase

!RGUMENTBYTE

-3"

!RGUMENTBYTE

!RGUMENTBYTE

,3"

Figure 21. Command with 3-byte response

3$)

FROMHOST

3$/

TOHOST

#OMMANDBYTE

./0 ./0 ./0

2ESPONSEBYTE

-3"

During response transmission, new commands can be sent. If a command requiring a response is sent before the previous response is completed, the response transmission is aborted and the new response is loaded into the output communication buffer (see

Figure 22).

56/70 Doc ID16737 Rev 4

2ESPONSEBYTEX

2ESPONSEBYTE

,3"

L6470 Programming manual

Figure 22. Command response aborted

3$)

FROMHOST

3$/

TOHOST

#OMMAND

BYTERESPEXPECTED

#OMMAND

NORESPEXPECTED

2ESPONSEBYTE

When a byte that does not correspond to a command is sent to the IC, it is ignored and the WRONG_CMD flag in the STATUS register is raised (see Section 9.1.22).

9.2.2 Nop

Table 38. Nop command structure

Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0

00000000 from host

Nothing is performed.

9.2.3 SetParam (PARAM, VALUE)

Table 39. SetParam command structure

-3"

#OMMAND

BYTERESPEXPECTED

2ESPONSEBYTEX

#OMMANDRESPONSE

ISABORTED

#OMMAND

NORESPEXPECTED

2ESPONSEBYTE

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Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0

0 0 0 PARAM

VALUE Byte 2 (if needed)

from host

VALUE Byte 1 (if needed)

VALUE Byte 0

The SetParam command sets the PARAM register value equal to VALUE; PARAM is the respective register address listed in Ta b le 1 2 .

The command should be followed by the new register VALUE (most significant byte first). The number of bytes making up the VALUE argument depends on the length of the target register (see Ta bl e 1 2 ).

Some registers cannot be written (see Ta b le 1 2 ); any attempt to write one of those registers causes the command to be ignored and the WRONG_CMD flag to rise at the end of the command byte as if an unknown command code were sent (see Section 9.1.22).

Some registers can only be written in particular conditions (see Ta b le 1 2 ); any attempt to write one of those registers when the conditions are not satisfied causes the command to be ignored and the NOTPERF_CMD flag to rise at the end of the last argument byte (see

Section 9.1.22).

Any attempt to set an inexistent register (wrong address value) causes the command to be ignored and the WRONG_CMD flag to rise at the end of the command byte as if an unknown command code were sent.

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9.2.4 GetParam (PARAM)

Table 40. GetParam command structure

Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0

0 0 1 PARAM from host

ANS Byte 2 (if needed) to host

ANS Byte 1 (if needed) to host

ANS Byte 0 to host

This command reads the current PARAM register value; PARAM is the respective register address listed in Ta bl e 1 2 .

The command response is the current value of the register (most significant byte first). The number of bytes making up the command response depends on the length of the target register (see Ta bl e 1 2 ).

The returned value is the register one at the moment of GetParam command decoding. If register values change after this moment, the response is not accordingly updated.

All registers can be read anytime.

Any attempt to read an inexistent register (wrong address value) causes the command to be ignored and the WRONG_CMD flag to rise at the end of the command byte as if an unknown command code were sent.

9.2.5 Run (DIR, SPD)

Table 41. Run command structure

Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0

0101000DIR from host

X X X X SPD (Byte 2) from host

SPD (Byte 1) from host

SPD (Byte 0) from host

The Run command produces a motion at SPD speed; the direction is selected by the DIR bit: '1' forward or '0' reverse. The SPD value is expressed in step/tick (format unsigned fixed point 0.28) that is the same format as the SPEED register (see Section 9.1.4).

Note: The SPD value should be lower than MAX_SPEED and greater than MIN_SPEED

otherwise the Run command is executed at MAX_SPEED or MIN_SPEED respectively.

This command keeps the BUSY flag low until the target speed is reached.

This command can be given anytime and is immediately executed.

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9.2.6 StepClock (DIR)

Table 42. Stepclock command structure

Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0

0101100DIR from host

The StepClock command switches the device in Step-clock mode (see Section 6.7.5) and imposes the forward (DIR = '1') or reverse (DIR = '0') direction.

When the device is in Step-clock mode, the SCK_MOD flag in the STATUS register is raised and the motor is always considered stopped (see Section 6.7.5 and 9.1.22).

The device exits from Step-clock mode when a constant speed, absolute positioning or motion command is sent through SPI. Motion direction is imposed by the respective StepClock command argument and can by changed by a new StepClock command without exiting Step-clock mode.

Events that cause bridges to be forced into high impedance state (overtemperature, overcurrent, etc.) do not cause the device to leave Step-clock mode.

The StepClock command does not force the BUSY flag low. This command can only be given when the motor is stopped. If a motion is in progress, the motor should be stopped and it is then possible to send a StepClock command.

Any attempt to perform a StepClock command when the motor is running causes the command to be ignored and the NOTPERF_CMD flag to rise (see Section 9.1.22).

9.2.7 Move (DIR, N_STEP)

Table 43. Move command structure

Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0

0100000DIR from host

X X N_STEP (Byte 2) from host

The Move command produces a motion of N_STEP microsteps; the direction is selected by the DIR bit ('1' forward or '0' reverse).

The N_STEP value is always in agreement with the selected step mode; the parameter value unit is equal to the selected step mode (full, half, quarter, etc.).

This command keeps the BUSY flag low until the target number of steps is performed. This command can only be performed when the motor is stopped. If a motion is in progress, the motor must be stopped and it is then possible to perform a Move command.

Any attempt to perform a Move command when the motor is running causes the command to be ignored and the NOTPERF_CMD flag to rise (see Section 9.1.22).

N_STEP (Byte 1) from host

N_STEP (Byte 0) from host

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9.2.8 GoTo (ABS_POS)

Table 44. GoTo command structure

Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0

0 1 1 00000 from host

X X ABS_POS (Byte 2) from host

ABS_POS (Byte 1) from host

ABS_POS (Byte 0) from host

The GoTo command produces a motion to ABS_POS absolute position through the shortest path. The ABS_POS value is always in agreement with the selected step mode; the parameter value unit is equal to the selected step mode (full, half, quarter, etc.).

The GoTo command keeps the BUSY flag low until the target position is reached.

This command can be given only when the previous motion command has been completed (BUSY flag released).

Any attempt to perform a GoTo command when a previous command is under execution (BUSY low) causes the command to be ignored and the NOTPERF_CMD flag to rise (see

Section 9.1.22).

9.2.9 GoTo_DIR (DIR, ABS_POS)

Table 45. GoTo_DIR command structure

Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0

0110100DIR from host

X X ABS_POS (Byte 2) from host

ABS_POS (Byte 1) from host

ABS_POS (Byte 0) from host

The GoTo_DIR command produces a motion to ABS_POS absolute position imposing a forward (DIR = '1') or a reverse (DIR = '0') rotation. The ABS_POS value is always in agreement with the selected step mode; the parameter value unit is equal to the selected step mode (full, half, quarter, etc.).

The GoTo_DIR command keeps the BUSY flag low until the target speed is reached. This command can be given only when the previous motion command has been completed (BUSY flag released).

Any attempt to perform a GoTo_DIR command when a previous command is under execution (BUSY low) causes the command to be ignored and the NOTPERF_CMD flag to rise (see Section 9.1.22).

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9.2.10 GoUntil (ACT, DIR, SPD)

Table 46. GoUntil command structure

Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0

1 0 0 0 ACT 0 1 DIR from host

X X X X SPD (Byte 2) from host

SPD (Byte 1) from host

SPD (Byte 0) from host

The GoUntil command produces a motion at SPD speed imposing a forward (DIR = '1') or a reverse (DIR = '0') direction. When an external switch turn-on event occurs (see

Section 6.13), the ABS_POS register is reset (if ACT = '0') or the ABS_POS register value is

copied into the MARK register (if ACT = '1'); then the system performs a SoftStop command.

The SPD value is expressed in step/tick (format unsigned fixed point 0.28) that is the same format as the SPEED register (see Section 9.1.4).

The SPD value should be lower than MAX_SPEED and greater than MIN_SPEED, otherwise the target speed is imposed at MAX_SPEED or MIN_SPEED respectively.

If the SW_MODE bit of the CONFIG register is set low, the external switch turn-on event causes a HardStop interrupt instead of the SoftStop one (see Section 6.13 and 9.1.21).

This command keeps the BUSY flag low until the switch turn-on event occurs and the motor is stopped. This command can be given anytime and is immediately executed.

9.2.11 ReleaseSW (ACT, DIR)

Table 47. ReleaseSW command structure

Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0

1 0 0 1 ACT 0 1 DIR from host

The ReleaseSW command produces a motion at minimum speed imposing a forward (DIR = '1') or reverse (DIR = '0') rotation. When SW is released (opened), the ABS_POS register is reset (ACT = '0') or the ABS_POS register value is copied into the MARK register (ACT = '1'); the system then performs a HardStop command.

Note that resetting the ABS_POS register is equivalent to setting the HOME position.

If the minimum speed value is less than 5 step/s or low speed optimization is enabled, the motion is performed at 5 step/s.

The ReleaseSW command keeps the BUSY flag low until the switch input is released and the motor is stopped.

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9.2.12 GoHome

Table 48. GoHome command structure

Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0

01110000 from host

The GoHome command produces a motion to the HOME position (zero position) via the shortest path.

Note that this command is equivalent to the “GoTo(0…0)” command. If a motor direction is mandatory, the GoTo_DIR command must be used (see Section 9.2.9).

The GoHome command keeps the BUSY flag low until the home position is reached. This command can be given only when the previous motion command has been completed. Any attempt to perform a GoHome command when a previous command is under execution (BUSY low) causes the command to be ignored and the NOTPERF_CMD to rise (see

Section 9.1.22).

9.2.13 GoMark

Table 49. GoMark command structure

Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0

01111000from host

The GoMark command produces a motion to the MARK position performing the minimum path.

Note that this command is equivalent to the “GoTo (MARK)” command. If a motor direction is mandatory, the GoTo_DIR command must be used.

The GoMark command keeps the BUSY flag low until the MARK position is reached. This command can be given only when the previous motion command has been completed (BUSY flag released).

Any attempt to perform a GoMark command when a previous command is under execution (BUSY low) causes the command to be ignored and the NOTPERF_CMD flag to rise (see

Section 9.1.22).

9.2.14 ResetPos

Table 50. ResetPos command structure

Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0

11011000 from host

The ResetPos command resets the ABS_POS register to zero. The zero position is also defined as HOME position (see Section 6.5).

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9.2.15 ResetDevice

Table 51. ResetDevice command structure

Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0

11000000 from host

The ResetDevice command resets the device to power-up conditions (see Section 6.1).

Note: At power-up the power bridges are disabled.

9.2.16 SoftStop

Table 52. SoftStop command structure

Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0

10110000 from host

The SoftStop command causes an immediate deceleration to zero speed and a consequent motor stop; the deceleration value used is the one stored in the DEC register (see

Section 9.1.6).

When the motor is in high impedance state, a SoftStop command forces the bridges to exit from high impedance state; no motion is performed.

This command can be given anytime and is immediately executed. This command keeps the BUSY flag low until the motor is stopped.

9.2.17 HardStop

Table 53. HardStop command structure

Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0

10111000 from host

The HardStop command causes an immediate motor stop with infinite deceleration.

When the motor is in high impedance state, a HardStop command forces the bridges to exit from high impedance state; no motion is performed.

This command can be given anytime and is immediately executed. This command keeps the BUSY flag low until the motor is stopped.

9.2.18 SoftHiZ

Table 54. SoftHiZ command structure

Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0

10100000 from host

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Programming manual L6470

The SoftHiZ command disables the power bridges (high impedance state) after a deceleration to zero; the deceleration value used is the one stored in the DEC register (see

Section 9.1.6). When bridges are disabled, the HiZ flag is raised.

When the motor is stopped, a SoftHiZ command forces the bridges to enter into high impedance state.

This command can be given anytime and is immediately executed. This command keeps the BUSY flag low until the motor is stopped.

9.2.19 HardHiZ

Table 55. HardHiZ command structure

Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0

10101000 from host

The HardHiZ command immediately disables the power bridges (high impedance state) and raises the HiZ flag.

When the motor is stopped, a HardHiZ command forces the bridges to enter into high impedance state.

This command can be given anytime and is immediately executed. This command keeps the BUSY flag low until the motor is stopped.

9.2.20 GetStatus

Table 56. GetStatus command structure

Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0

11010000 from host

The GetStatus command returns the STATUS register value.

The GetStatus command resets the STATUS register warning flags. The command forces the system to exit from any error state. The GetStatus command DOES NOT reset the HiZ flag.

STATUS MSByte to host

STATUS LSByte to host

64/70 Doc ID16737 Rev 4

L6470 Package mechanical data

10 Package mechanical data

In order to meet environmental requirements, ST offers these devices in different grades of

ECOPACK specifications, grade definitions and product status are available at: www.st.com. ECOPACK

Table 57. HTSSOP28 mechanical data

packages, depending on their level of environmental compliance. ECOPACK®

is an ST trademark.

Dim.

Min. Typ. Max.

A 1.2

A1 0.15

A2 0.8 1.0 1.05

b 0.19 0.3

c 0.09 0.2

(1)

D1 5.5

E 6.2 6.4 6.6

(2)

E2 2.8

E0.65

9.6 9.7 9.8

4.3 4.4 4.5

L 0.45 0.6 0.75

L1 1.0

K0° 8°

Aaa 0.1

1. Dimension “D” does not include mold flash, protrusions or gate burrs. Mold flash, protrusions or gate burrs

must not exceed 0.15 mm per side.

2. Dimension “E1” does not include interlead flash or protrusions. Interlead flash or protrusions must not

exceed 0.25 mm per side.

Doc ID16737 Rev 4 65/70

Package mechanical data L6470

Figure 23. HTSSOP28 mechanical data

66/70 Doc ID16737 Rev 4

!-V

L6470 Package mechanical data

Table 58. POWERSO36 mechanical data

Dim.

Min. Typ. Max.

A 3.60

a1 0.10 0.30

a2 3.30

a3 0 0.10

b 0.22 0.38

c 0.23 0.32

D(1) 15.80 16.00

D1 9.40 9.80

E 13.90 14.50

E1(1) 10.90 11.10

E2 2.90

E3 5.8 6.2

e 0.65

e3 11.05

G 0 0.10

H 15.50 15.90

h 1.10

L 0.80 1.10

N 10°

S 0° 8°

Doc ID16737 Rev 4 67/70

Package mechanical data L6470

Figure 24. POWERSO36 drawings

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68/70 Doc ID16737 Rev 4

L6470 Revision history

11 Revision history

Table 59. Revision history

Date Revision Changes

06-Nov-2009 1 Initial release

05-Nov-2010 2 Document status promoted from preliminary data to datasheet

18-May-2011 3

19-Jun-2012 4

Updated: Tab le 4 , Ta bl e 5 Added: Section 6.7.6, Section 6.4.1

Added device in POWERSO36 and Figure 3 Updated: Tab le 2 , Ta bl e 3 , Table 4, Table 5, Table 6, Tab le 9 and

Section 9.1.11.

Minor text changes.

Doc ID16737 Rev 4 69/70

L6470

Please Read Carefully:

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ST L6470 User Manual

Specifications and Main Features

Frequently Asked Questions

User Manual

Table 1. Device summary

1 Block diagram

Figure 1. Block diagram

2 Electrical data

2.1 Absolute maximum ratings

Table 2. Absolute maximum ratings

2.2 Recommended operating conditions

Table 3. Recommended operating conditions

2.3 Thermal data

Table 4. Thermal data

3 Electrical characteristics

Table 5. Electrical characteristics

4 Pin connection

Figure 2. HTSSOP28 pin connection (top view)

Figure 3. POWERSO36 pin connection (top view)

4.1 Pin list

Table 6. Pin description

5 Typical applications

Table 7. Typical application values

Figure 4. Bipolar stepper motor control application using L6470

6 Functional description

6.1 Device power-up

6.2 Logic I/O

6.3 Charge pump

Figure 5. Charge pump circuitry

6.4 Microstepping

Figure 6. Normal mode and microstepping (128 microsteps)

6.4.1 Automatic full-step mode

Figure 7. Automatic full-step switching

6.5 Absolute position counter

6.6 Programmable speed profiles

6.6.1 Infinite acceleration/deceleration mode

Figure 8. Speed profile in infinite acceleration/deceleration mode

6.7 Motor control commands

6.7.1 Constant speed commands

Figure 9. Constant speed command examples

6.7.2 Positioning commands

Figure 10. Positioning command examples

6.7.3 Motion commands

Figure 11. Motion command examples

6.7.4 Stop commands

6.7.5 Step-clock mode

6.7.6 GoUntil and ReleaseSW commands

6.8 Internal oscillator and oscillator driver

6.8.1 Internal oscillator

6.8.2 External clock source

Table 8. CL values according to external oscillator frequency

Figure 12. OSCIN and OSCOUT pin configuration

6.9 Overcurrent detection

6.10 Undervoltage lockout (UVLO)

6.11 Thermal warning and thermal shutdown

6.12 Reset and standby

6.13 External switch (SW pin)

Figure 13. External switch connection

6.14 Programmable DMOS slew rate, deadtime and blanking time

6.15 Integrated analog-to-digital converter

6.16 Internal voltage regulator

Figure 14. Internal 3 V linear regulator

6.17 BUSY\SYNC pin

6.17.1 BUSY operation mode

6.17.2 SYNC operation mode

6.18 FLAG pin

7 Phase current control

7.1 PWM sinewave generators

7.2 Sensorless stall detection

7.3 Low speed optimization

Figure 15. Current distortion and compensation

7.4 BEMF compensation

Figure 16. BEMF compensation curve

7.5 Motor supply voltage compensation

Figure 17. Motor supply voltage compensation circuit

7.6 Winding resistance thermal drift compensation

8 Serial interface

Figure 18. SPI timings diagram

Figure 19. Daisy chain configuration

9 Programming manual