3961

DUAL FULL-BRIDGE

PWM MOTOR DRIVER

DISCONTINUED

PRODUCT

—

FOR

REFERENCE

ONL

Y

E

SENSE

V

GROUND

GROUND

GROUND

REF

V

RC

GROUND

24

23

22

21

20

19

18

17

1

2

3

4

5

6

7

8

9

10

16

15

1

1

BB1

OUT

1

SENSE

V

FULL/PD

I

RC

2

BB2

2

PHASE

ENABLE

11

12

1

1

14

13

PHASE

ENABLE

2

2

REF

V

IN

V

CC

Designed for pulse-width modulated (PWM) current control of

bipolar stepper motors, the A3961S— is capable of continuous output

currents to

±800 mA and operating voltages to 45 V. Internal fixed

off-time PWM current-control circuitry can be used to regulate the

maximum load current to a desired value. An internal precision voltage

reference is provided to improve motor peak current control accuracy.

The peak load current limit is set by the user’s selection of an external

resistor divider and current-sensing resistors.

The fixed off-time pulse duration is set by user-selected external

RC timing networks. The capacitor in the RC timing network also

determines a user-selectable blanking window that prevents false

triggering of the PWM current control circuitry during switching transi-

tions. This eliminates the need for two external RC filter networks on

the current-sensing comparator inputs.

For each bridge the PHASE input controls load current polarity by

selecting the appropriate source and sink driver pair. For each bridge

the ENABLE input, when held high, disables the output drivers. Special

power-up sequencing is not required. Internal circuit protection includes

thermal shutdown with hysteresis, transient-suppression diodes, and

crossover-current protection.

The A3961S— is supplied in a choice of two power packages:

24-pin dual-in-line plastic package with copper heat-sink tabs and

24-lead plastic SOIC with copper heat-sink tabs. In both packages the

power tab is at ground potential and needs no electrical isolation.

FEATURES

s

±800 mA Continuous Output Current Rating

s 45 V Output Voltage Rating

s Internal PWM Current Control, Saturated Sink Drivers

s Internally Generated Precision 2.5 V Reference

s Internal Transient-Suppression Diodes

s Internal Thermal-Shutdown Circuitry

s Crossover-Current Protection, UVLO Protection

PART NUMBER

PACKAGE

A3961SB

24-Pin DIP

40

°C/W

6

°C/W

A3961SLB

24-Lead SOIC

55

°C/W

6

°C/W

Always order by complete part number:

DUAL FULL-BRIDGE PWM MOTOR DRIVER

Note the A3961SB (DIP) and the A3961SLB

(SOIC) are electrically identical and share a

common terminal number assignment.

ABSOLUTE MAXIMUM RATINGS

Logic Input Voltage Range,

Reference Output Current,

Package Power Dissipation,

Operating Temperature Range,

Storage Temperature Range,

* Output current rating may be limited by duty

cycle, ambient temperature, and heat sinking.

Under any set of conditions, do not exceed the

specified current rating or a junction tempera-

ture of 150˚C.

† Fault conditions that produce excessive

junction temperature will activate device

thermal shutdown circuitry. These conditions

can be tolerated but should be avoided.

3961