DUAL FULL-BRIDGE PWM MOTOR DRIVER

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

stepper motors, the A3964SB and A3964SLB are capable of continuous

output currents to ±800 mA and operating voltages to 30 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 transitions. 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 A3964SB is supplied in a 24-pin plastic DIP with copper heat sink

tabs; A3964SLB is supplied in a 20-lead plastic SOIC with copper heat sink

tabs, and is available in a lead (Pb) free version with 100% matte tin

leadframe plating. The power tabs are at ground potential and need no

electrical isolation.

FEATURES

■ ±800 mA Continuous Output Current Rating

■ 30 V Output Voltage Rating

■ Internal PWM Current Control, Saturated Sink Drivers

■ Internally Generated, Precision 2.5 V Reference

■ Internal Transient-Suppression Diodes

■ Internal Thermal-Shutdown Circuitry

■ Crossover-Current Protection, UVLO Protection

3964

ABSOLUTE MAXIMUM RATINGS

(continuous) . . . . . . . . . . . . . ±800 mA*

Logic Input Voltage Range,

Reference Output Current,

Package Power Dissipation,

Operating Temperature Range,

+150½°†

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 temperature of 150°C.

† Fault conditions that produce excessive junction

temperature will activate the device’s thermal shutdown

circuitry. These conditions can be tolerated but should

be avoided.

A3964SLB

1

2

1

2

3

4

5

6

7

9

20

19

18

17

16

15

14

13

12

11

10

9

8

2

1

GROUND

GROUND

GROUND

GROUND

2

RC

1

RC

2B

OUT

2A

OUT

1A

OUT

1B

OUT

LOAD

SUPPLY

LOGIC

SUPPLY

Dwg. PP-047-1

Part Number

Pb-free*

Package

Packing

A3964SLB-T

Yes

20-Lead SOIC

37 per tube

A3964SLBTR-T

Yes

20-Lead SOIC

1000 per reel

footnote are in production but have been determined to be LAST TIME BUY. This

classification indicates that sale of this device is currently restricted to existing

customer applications. The variants should not be purchased for new design

applications because obsolescence in the near future is probable. Samples are no

longer available. Status change: October 31, 2006. Deadline for receipt fo LAST TIME

BUY orders: April 27, 2007. These variants include: A3964SB, A3964SLB, and

A3964SLBTR.