Data Sheet
29319.35
3974
DMOS DUAL FULL-BRIDGE
PWM MOTOR DRIVER
Designed for pulse-width modulated (PWM) current control
of two dc motors, the A3974SED is capable of output currents to
±1.5 A and operating voltages to 50 V. Internal fixed off-time
PWM current-control timing circuitry can be programmed via a
serial interface to operate in slow, fast, and mixed current-decay
modes.
Independant ENABLE input terminals are provided for use in
controlling the speed and torque of each dc motor with externally
applied PWM control signals.
Synchronous rectification circuitry allows the load current to
flow through the low r
DS(on)
of the DMOS output driver during
the current decay. This feature will eliminate the need for
external clamp diodes in most applications, saving cost and
external component count, while minimizing power dissipation.
Internal circuit protection includes thermal shutdown with
hysteresis, undervoltage monitoring of V
DD
and the charge
pump, and crossover-current protection. Special power-up
sequencing is not required.
The A3974SED is supplied in a 44-lead plastic PLCC with
four copper batwing tabs for maximum heat dissipation. The
power tabs are at ground potential and need no electrical isola-
tion.
FEATURES
a73 ±1.5 A, 50 V Continuous Output Rating
a73 Low r
DS(on)
DMOS Output Drivers
a73 Programmable Slow, Fast, and Mixed Current-Decay Modes
a73 Serial-Interface Controls Chip Functions
a73 Synchronous Rectification for Low Power Dissipation
a73 Internal UVLO and Thermal Shutdown Circuitry
a73 Crossover-Current Protection
a73 Sleep and Idle Modes
ABSOLUTE MAXIMUM RATINGS
at T
A
= +25°C
Load Supply Voltage, V
BB
............................ 50 V
Output Current, I
OUT
.................................. ±1.5 A
Logic Supply Voltage, V
DD
.......................... 7.0 V
Logic Input Voltage Range, V
IN
Continous ................... -0.3 V to V
DD
+ 0.3 V
t
W
< 30 ns ................... -1.0 V to V
DD
+ 1.0 V
Reference Voltage, V
REF
................................. 3 V
Sense Voltage (dc), V
S
Continous .............................................. 0.5 V
t
W
< 1 µs ................................................ 2.5 V
Package Power Dissipation, P
D
.................. 3.9 W
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, and heat sinking. 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: A3974SED .
SERIAL PORT
6 5 4 3 2 1
44 43 42 41 40
7
8
9
10
11
12
13
14
15
16
17 29
30
39
38
37
36
35
34
33
32
31
2827262524232221201918
Dwg. PP-073
GND
GND
LOGIC
SUPPLY
GNDGNDSENSE
1
OUT
1A
NC
STROBE
CLOCK
DATA
GND
GND
REF1
REF2
NC
OUT
2A
NC
SENSE
2
GNDGND GND
LOAD
SUPPLY
2
ENABLE
2
OUT
2B
NC
VREG
SLEEP
OSC
GND
GND
CP
CP1
CP2
NC
OUT
1B
NCENABLE
1
LOAD SUPPLY
1
GND
NC NC
NCNC
PROGRAM
PWM TIMER
CHARGE PUMP
÷
VDD
VBB1
VBB2
÷
LOGIC
LOGIC
PROGRAM
PWM TIMER