3951
FULL-BRIDGE PWM MOTOR DRIVER
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.
A3951SB
LOAD
SUPPLY
1
2
16
NC
REF/BRAKE
RC
V
BB
15 OUT
B
14 GROUND
13 GROUND
3
4
GROUND
GROUND
LOGIC
5
6
12
11 SENSE
GROUND
LOGIC
SUPPLY
V
CC
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.
7
8
10
9
PHASE
OUT
A
V
LOAD
SUPPLY
BB
ENABLE
Dwg. PP-056-1
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.
ABSOLUTE MAXIMUM RATINGS
Load Supply Voltage, VBB ................... 50 V
Output Current, IOUT
(tw ≤ 20 µs) .................................. 3.5 A
(Continuous) ............................... 2.0 A
Logic Supply Voltage, VCC .................. 7.0 V
Logic Input Voltage Range,
VIN ........................ -0.3 V to VCC + 0.3 V
Sense Voltage, VSENSE ........................ 1.5 V
Reference Voltage, VREF ....................... VCC
Package Power Dissipation,
PD ....................................... See Graph
Operating Temperature Range,
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
I
I
I
I
I
I
I
2 A Continuous Output Current Rating
50 V Output Voltage Rating
Internal PWM Current Control
Internal Transient Suppression Diodes
Under-Voltage Lockout
Internal Thermal Shutdown Circuitry
Crossover-Current Protection
Default Brake Current Limit
TA ............................... –20°C to +85°C
Junction Temperature, TJ ............. +150°C*
Storage Temperature Range,
TS ............................. –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.
Always order by complete part number:
* Fault conditions that produce excessive junction
temperature will activate device thermal shutdown
circuitry. These conditions can be tolerated but
should be avoided.
Part Number
Package
RθJA
RθJT
A3951SB
A3951SW
16-Pin DIP
12-Pin Power-Tab SIP
43°C/W
36°C/W
6.0°C/W
2.0°C/W
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