3974
LOAD
43
SUPPLY
1
SENSE
1
OUT
1A
ENABLE
1
GND
GND
GND
NC
OUT
1B
NC
NC
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.
41
44
42
40
2
4
6
5
3
1
Data Sheet
29319.35
V
BB1
NC
STROBE
CLOCK
7
39
NC
CP2
CP1
CP
GND
GND
GND
OSC
SLEEP
V
REG
NC
8
9
CHARGE PUMP
SERIAL PORT
38
37
36
35
34
33
PROGRAM
PWM TIMER
LOGIC
DATA
10
GND
11
GND
12
GND
13
REF
1
14
REF
2
15
LOGIC
16
SUPPLY
NC
17
V
DD
÷
÷
PROGRAM
PWM TIMER
LOGIC
32
31
30
29
V
BB2
OUT
2A
18
NC
20
21
GND
22
23
GND
24
25
ENABLE
2
26
NC
19
SENSE
2
LOAD
SUPPLY
2
OUT
2B
28
GND
NC
27
Dwg. PP-073
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.
FEATURES
s
±1.5
A, 50 V Continuous Output Rating
s
Low
r
DS(on)
DMOS Output Drivers
s
Programmable Slow, Fast, and Mixed Current-Decay Modes
s
Serial-Interface Controls Chip Functions
s
Synchronous Rectification for Low Power Dissipation
s
Internal UVLO and Thermal Shutdown Circuitry
s
Crossover-Current Protection
s
Sleep and Idle Modes
Always order by complete part number:
A3974SED
.
ALLEGRO [ ALLEGRO MICROSYSTEMS ]
