3968
DUAL FULL-BRIDGE
PWM MOTOR DRIVER
WITH BRAKE
FUNCTIONAL BLOCK DIAGRAM
(one-half of circuit shown)
INPUTA
V CC
+
V BB
UVLO
& TSD
INPUTB
GROUND
PWM LATCH
R
Q
S
BLANKING
GATE
CURRENT-SENSE
COMPARATOR
+
–
TO OTHER
BRIDGE
SENSE
TO OTHER
BRIDGE
OSC
÷4
RS
RC
TO OTHER
BRIDGE
CT
RT
Dwg. FP-036-4
A3968SA (DIP)
SENSE 1 1
OUT1B 2
LOAD
SUPPLY 3
REFERENCE 4 VREF
V BB
RC 5 RC
LOGIC
SUPPLY
6V
CC
OUT 2B 7
SENSE 2 8
16 INPUT1B
15 INPUT1A
14 OUT1A
13 GROUND
12 GROUND
11 OUT2A
10 INPUT2A
9 INPUT2B
Dwg. PP-066-3
TRUTH TABLE
INPUTA
L
L
H
H
INPUTB
L
H
L
H
OUTA
L
L
H
Z
OUTB
L
H
L
Z
Description
Brake mode
“Forward”
“Reverse”
Disable
Z = High impedance
115 Northeast Cutoff, Box 15036
Worcester, Massachusetts 01615-0036 (508) 853-5000
Copyright © 1997, 2003 Allegro MicroSystems, Inc.