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

	Order code	Package
	E-TEA3718SDP	Power DIP
	E-TEA3718DP
	E-TEA3718SFP	SO20
	E-TEA3718SFPTR	SO20 (tape and reel)
	E-TEA3718SP	Multiwatt™ 15

Power DIP 12+2+2

SO20

Multiwatt™ 15

Figure 1. Block diagram

Motor winding

OUT A OUT B

COMPARATOR
INPUT									ALARM
PHASE
									(TEA3718SP)
PULSE TIME
									PRE-ALARM
			TEA3718
IN0									(TEA3718SFP)
IN1									SENSE
REFERENCE									RESISTOR

TM: Multiwatt is a trademark of STMicroelectronics

January 2009

Rev 2

1/26

www.st.com

Pin connections

1 Pin connections

Figure 2. Package pin locations (top views)

E	-TEA3718SP	E-TEA3718SFP	E-TEA3718DP
	(Multiwatt 15)	(SO20)	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 VSS, VS and VR . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18

5.7

Analog control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

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		transistors. The pulse generator is a monostable triggered by the rising edge of the
		output of the comparators (toff = 0.69 RT CT).
VS(B)		Supply voltage input for half output stage
GND		Ground connection. In SO20 and power DIP these pins also conduct heat from die to
		printed circuit copper.
VSS		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.
		SeeTable 8: Truth table.
		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,
		Toff = 0.69 RT CT.
		A voltage applied to this pin sets the reference voltage of the three comparators.
REFERENCE		Reference voltage with the value of RS and the two inputs IN0 and IN1 determines the
		output current.
VS(A)		Supply voltage input for half output stage
OUTA		See pin OUT B
SENSE RESISTOR		Connection to lower emitters of output stage for insertion of current sense resistor
ALARM		When Tj reaches T1 oC the alarm output becomes low (TEA3718SP)
PRE-ALARM		When Tj reaches T2 oC the pre-alarm output becomes low (T2<T1) (TEA3718SFP)

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

3.1Absolute maximum ratings

	Table 4.	Absolute maximum ratings
	Symbol	Parameters	Value	Unit
	VSS	Supply voltage	7	V
	VS		50
		Input voltage:
	VI	– logic inputs	6	V
		– analog inputs	VSS
		– reference input	15
		Input current:
	ii	– logic inputs	-10	mA
		– analog inputs	-10
	IO	Output current	±1.5	A
	T	Junction temperature	+150	oC
	J
	T	Operating ambient temperature range	0 to 70	oC
	op
	T	Storage temperature range	-55 to +150	oC
	stg

3.2Recommended operating conditions

Table 5.	Recommended operating conditions
Symbol	Parameters	SO20	Power DIP	Multiwatt 15	Unit
VSS	Supply voltage	4.75	5	5.25	V
Vs	Supply voltage	10	-	45	V
Im	Output current	0.020	-	1.2	A
T	Ambient temperature	0	-	70	oC
amb
tr	Rise time for logic inputs	-	-	2	µs
tf	Fall time for logic inputs	-	-	2	µs

7/26

Electrical specifications

3.3Thermal data

Table 6.	Thermal data
Symbol	Parameters	SO20	Power DIP	Multiwatt 15	Unit
Rth(j-c)	Maximum junction-case thermal resistance	16	11	3	oC/W
Rth(j-a)	Maximum junction-ambient thermal resistance	60(1)	45(1)	40	oC/W

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

Figure 5. Maximum power dissipation

Figure 6. Typical external component configuration

RS = 1 ohm inductance free

RC = 470 ohms

CC = 820 pF ceramic

Rt = 56 kohms

Ct = 820 pF ceramic

P = 500 ohms

R2 = 1 kohm

8/26