3951
Data Sheet
29319.4†
ABSOLUTE MAXIMUM RATINGS
Load Supply Voltage, V
BB
................... 50 V
Output Current, I
OUT
(t
w
≤ 20 µs) .................................. ±3.5 A
(Continuous) ............................... ±2.0 A
Logic Supply Voltage, V
CC
.................. 7.0 V
Logic Input Voltage Range,
V
IN
........................ -0.3 V to V
CC
+ 0.3 V
Sense Voltage, V
SENSE
........................ 1.5 V
Reference Voltage, V
REF
....................... V
CC
Package Power Dissipation,
P
D
....................................... See Graph
Operating Temperature Range,
T
A
............................... –20°C to +85°C
Junction Temperature, T
J
............. +150°C*
Storage Temperature Range,
T
S
............................. –55°C to +150°C
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
V
CC
OUT
B
OUT
A
V
BB
V
BB
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
a73 ±2 A Continuous Output Current Rating
a73 50 V Output Voltage Rating
a73 Internal PWM Current Control
a73 Internal Transient Suppression Diodes
a73 Under-Voltage Lockout
a73 Internal Thermal Shutdown Circuitry
a73 Crossover-Current Protection
a73 Default Brake Current Limit
Always order by complete part number:
Part Number Package R
θJA
R
θJT
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