ST TEA3718 User Manual

TEA3718

Stepper motor driver

Features

■ Half-step and full-step mode

■ Bipolar drive of stepper motor for maximum

motor performance

■ Built-in protection diodes

■ Wide range of current control 5 to 1500 mA

■ Wide voltage range 10 to 50 V

■ Designed for unstabilized motor supply voltage

■ Current levels can be selected insteps or

varied continuously

■ Thermal overload protection

■ Alarm output or pre-alarm output

Applications

The TEA3718 is a bipolar monolithic integrated
circuit intended to control and drive the current in
one winding of a bipolar stepper motor.

Description

The circuits consist of an LS-TTL compatible logic
input, a current sensor, a monostable and an
output stage with built-in protection diodes. Two
TEA3718 ICs and a few external components
form a complete control and drive unit for LS-TTL
or microprocessor-controlled stepper motor
systems.

Table 1. Device summary

Power DIP 12+2+2

Multiwatt™ 15

Figure 1. Block diagram

Motor winding

OUT A

OUT B

COMPARATOR

INPUT

PHASE

PULSE TIME

IN0

IN1

REFERENCE

TEA3718

SO20

ALARM
(TEA3718SP)
PRE-ALARM
(TEA3718SFP)

SENSE
RESISTOR

Order code Package

TM: Multiwatt is a trademark of STMicroelectronics

E-TEA3718SDP

Power DIP

E-TEA3718DP

E-TEA3718SFP SO20

E-TEA3718SFPTR SO20 (tape and reel)

E-TEA3718SP Multiwatt™ 15

January 2009 Rev 2 1/26

www.st.com

26

Pin connections

1 Pin connections

Figure 2. Package pin locations (top views)

E-TEA3718SP

(Multiwatt 15)

E-TEA3718SFP

(SO20)

E-TEA3718DP

E-TEA3718SDP

(Power DIP 12+2+2)

2/26

Contents

Contents

1 Pin connections . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

2 Device diagrams . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

3 Electrical specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7

3.1 Absolute maximum ratings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7

3.2 Recommended operating conditions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7

3.3 Thermal data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8

3.4 Electrical characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

4 Functional blocks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

4.1 Alarm output (TEA3718SP, TEA3718DP and TEA3718SDP) . . . . . . . . . 14

4.2 Pre-alarm output (TEA3718SFP) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15

4.3 Current reduction in alarm condition . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15

4.4 Typical application . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16

5 Functional description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17

5.1 Input logic . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17

5.2 Phase input . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17

5.3 Current sensor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17

5.4 Single-pulse generator . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18

5.5 Output stage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18

5.6 V

5.7 Analog control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18

, VS and V

SS

R . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18

3/26

Contents

6 Application notes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19

6.1 Motor selection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19

6.2 Unused inputs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19

6.3 Interference . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19

6.4 Operating sequence . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20

7 Package mechanical data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21

Revision history . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25

4/26

Device diagrams

2 Device diagrams

Figure 3. Detailed block diagram (TEA3718SFP)

Figure 4. Detailed block diagram (TEA3718SP)

5/26

Device diagrams

Table 2. Pin functions

Name Function

OUTB

Output connection (with pin OUT A). The output stage is a "H" bridge formed by four
transistors and four diodes suitable for switching applications.

A parallel RC network connected to this pin sets the OFF time of the lower power

PULSE TIME

V

(B) Supply voltage input for half output stage

S

GND

V

SS

transistors. The pulse generator is a monostable triggered by the rising edge of the
output of the comparators (t

= 0.69 RT CT).

off

Ground connection. In SO20 and power DIP these pins also conduct heat from die to
printed circuit copper.

Supply voltage input for logic circuitry

This pin and pin IN0 are logic inputs which select the outputs of three comparators to set

IN1

the current level. Current also depends on the sensing resistor and reference voltage.

Ta b l e 8 : Tr ut h ta bl e

See

.

This TTL-compatible logic input sets the direction of current flow through the load. A

PHASE

high level causes current to flow from OUT A (source) to OUT B (sink). A Schmidt trigger
on this input provides good noise immunity and a delay circuit prevents output stage
short circuits during switching.

IN0 See IN1

Input connected to the three comparators. The voltage across the sense resistor is
feedback to this input through the low pass filter RCCC. The lower power transistor are

COMPARATOR INPUT

disabled when the sense voltage exceeds the reference voltage of the selected
comparator. When this occurs the current decays for a time set by RT CT,

= 0.69 RT CT.

T

off

A voltage applied to this pin sets the reference voltage of the three comparators.

REFERENCE

Reference voltage with the value of R
output current.

(A) Supply voltage input for half output stage

V

S

OUTA See pin OUT B

and the two inputs IN0 and IN1 determines the

S

SENSE RESISTOR Connection to lower emitters of output stage for insertion of current sense resistor

ALARM When T

PRE-ALARM When T

reaches T1 oC the alarm output becomes low (TEA3718SP)

j

reaches T2 oC the pre-alarm output becomes low (T2<T1) (TEA3718SFP)

j

Table 3. Device comparison table

Device Current Package Alarm Pre-alarm

TEA3718SDP 1.5 A Power DIP 12+2+2 Not connected

TEA3718SFP 1.5 A SO20 Connected

TEA3718SP 1.5 A Multiwatt 15 Connected

TEA3718DP 1.5 A Power DIP 12+2+2 Not connected

6/26

Electrical specifications

3 Electrical specifications

3.1 Absolute maximum ratings

Table 4. Absolute maximum ratings

Symbol Parameters Value Unit

V

SS

V

S

Supply voltage

50

7

V

Input voltage:

V

I

– logic inputs
– analog inputs
– reference input

V

6

SS

15

V

Input current:

i

i

I

O

T

J

T

op

T

stg

– logic inputs
– analog inputs

-10

-10

mA

Output current ±1.5 A

Junction temperature +150

o

Operating ambient temperature range 0 to 70 oC

Storage temperature range -55 to +150 oC

C

3.2 Recommended operating conditions

Table 5. Recommended operating conditions

Symbol Parameters SO20 Power DIP Multiwatt 15 Unit

V

SS

Vs Supply voltage 10 - 45 V

Supply voltage 4.75 5 5.25 V

I

T

t

t

m

amb

r

f

Output current 0.020 - 1.2 A

Ambient temperature 0 - 70

o

Rise time for logic inputs - - 2 µs

Fall time for logic inputs - - 2 µs

7/26

C

Electrical specifications

3.3 Thermal data

Table 6. Thermal data

Symbol Parameters SO20 Power DIP Multiwatt 15 Unit

(j-c) Maximum junction-case thermal resistance 16 11 3

R

th

R

(j-a) Maximum junction-ambient thermal resistance 60

th

1. Soldered on a 35 µm thick 4 cm2 PC board copper area

(1)

45

(1)

40

o

C/W

o

C/W

Figure 5. Maximum power dissipation

Figure 6. Typical external component configuration

RS = 1 ohm inductance free

= 470 ohms

R

C

CC = 820 pF ceramic
Rt = 56 kohms
Ct = 820 pF ceramic
P = 500 ohms
R2 = 1 kohm

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