3951

ABSOLUTE MAXIMUM RATINGS

Load Supply Voltage, V

Output Current, I

OUT

(t

(Continuous) ...............................

Logic Supply Voltage, V

Logic Input Voltage Range,

V

-0.3 V to V

Sense Voltage, V

Reference Voltage, V

Package Power Dissipation,

P

D

....................................... See Graph

Operating Temperature Range,

T

A

............................... –20

Junction Temperature, T

J

............. +150

Storage Temperature Range,

T

S

............................. –55

Output current rating may be limited by duty cycle,

ambient temperature, heat sinking and/or forced

cooling. 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 device thermal shutdown

circuitry. These conditions can be tolerated but

should be avoided.

A3951SB

1

2

3

4

5

6

7

8

9

10

11

12

13

14

15

16

GROUND

GROUND

GROUND

LOGIC

SUPPLY

PHASE

GROUND

GROUND

RC

SENSE

LOAD

SUPPLY

Dwg. PP-056-1

REF/

LOAD

SUPPLY

OUTB

OUTA

LOGIC

ENABLE

BRAKE

NC

Designed for bidirectional pulse-width modulated current control of

inductive loads, the A3951SB and A3951SW are capable of continuous

output currents to

±2 A and operating voltages to 50 V. Internal fixed

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

maximum load current to a desired value. The peak load current limit is

set by the user’s selection of an input reference voltage and external

sensing resistor. The fixed off-time pulse duration is set by a user-

selected external RC timing network. Internal circuit protection includes

thermal shutdown with hysteresis, transient suppression diodes, and

crossover-current protection. Special power-up sequencing is not

required. The A3951SB and A3951SW are improved replacements for

the UDN2953B and UDN2954W, respectively. For new system de-

signs, the A3952SB/SEB/SLB/SW are recommended.

With the ENABLE input held low, the PHASE input controls load

current polarity by selecting the appropriate source and sink driver pair.

A user-selectable blanking window prevents false triggering of the PWM

current control circuitry. With the ENABLE input held high, all output

drivers are disabled.

When a logic low is applied to the BRAKE input, the braking

function is enabled. This overrides ENABLE and PHASE to turn off

both source drivers and turn on both sink drivers. The brake function

can be safely used to dynamically brake brush dc motors.

The A3951SB is supplied in a 16-pin dual in-line plastic package

with copper heat-sink contact tabs. The lead configuration enables

easy attachment of a heat sink while fitting a standard printed wiring

board layout. The A3951SW, for higher package power dissipation

requirements, is supplied in a 12-pin single in-line power-tab package.

In either package style, the batwing/power tab is at ground potential

and needs no isolation.

FEATURES

I ±2 A Continuous Output Current Rating

I 50 V Output Voltage Rating

I Internal PWM Current Control

I Internal Transient Suppression Diodes

I Under-Voltage Lockout

I Internal Thermal Shutdown Circuitry

I Crossover-Current Protection

I Default Brake Current Limit

Always order by complete part number:

Part Number

Package

A3951SB

16-Pin DIP

43

°C/W

6.0

°C/W

A3951SW

12-Pin Power-Tab SIP

36

°C/W

2.0

°C/W

FULL-BRIDGE PWM MOTOR DRIVER