Description
Designed for pulse width modulated (PWM) current control
of two DC motors, the A3974 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.
Independent 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 A3974 is supplied in a 44-pin plastic PLCC with 3 internally
fused pins on each side, for maximum heat dissipation. The fused
pins are at ground potential and need no electrical isolation.
29319.35C
Features and Benefits
▪ ±1.5 A, 50 V continuous output rating
▪ Low r
DS(on)
DMOS output drivers
▪ Programmable slow, fast, and mixed current-decay modes
▪ Serial-interface controls chip functions
▪ Synchronous rectification for low power dissipation
▪ Internal UVLO and thermal shutdown circuitry
▪ Crossover-current protection
▪ Sleep and idle modes
DMOS Dual Full-Bridge PWM Motor Driver
Package: 44-pin PLCC with internally
fused pins (suffix ED)
Pin-out Diagram
Not to scale
A3974
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
28
27
26
25
24
23
22
21
20
19
18
Dwg. PP-073
GND
GND
LOGIC
SUPPLY
GND
GND
SENSE
1
OUT
1A
NC
STROBE
CLOCK
DATA
GND
GND
REF
1
REF
2
NC
OUT
2A
NC
SENSE
2
GND
GND
GND
LOAD
SUPPLY
2
ENABLE
2
OUT
2B
NC
V
REG
SLEEP
OSC
GND
GND
CP
CP1
CP2
NC
OUT
1B
NC
ENABLE
1
LOAD
SUPPLY
1
GND
NC
NC
NC
NC
PROGRAM
PWM TIMER
CHARGE PUMP
V
DD
V
BB1
V
BB2
LOGIC
LOGIC
PROGRAM
PWM TIMER
