3968
DUAL FULL-BRIDGE
PWM MOTOR DRIVER
WITH BRAKE
FUNCTIONAL BLOCK DIAGRAM
(one-half of circuit shown)
LOGIC
SUPPLY
LOAD
SUPPLY
OUTA
OUTB
INPUTA
V CC
+
V BB
UVLO
& TSD
INPUTB
CONTROL LOGIC
SOURCE
ENABLE
PWM LATCH
R
Q
S
BLANKING
GATE
CURRENT-SENSE
COMPARATOR
SENSE
TO OTHER
BRIDGE
÷4
+
–
TO OTHER
BRIDGE
GROUND
RC
OSC
TO OTHER
BRIDGE
RS
RT
CT
REFERENCE
Dwg. FP-036-4
A3968SA
SENSE
1
OUT
1B
LOAD
SUPPLY
REFERENCE
RC
LOGIC
SUPPLY
OUT
2B
SENSE
2
1
16
INPUT
1B
INPUT
1A
OUT
1A
GROUND
GROUND
OUT
2A
INPUT
2A
INPUT
2B
TRUTH TABLE
INPUT
A
L
L
H
H
INPUT
B
L
H
L
H
OUT
A
L
L
H
Z
OUT
B
L
H
L
Z
Description
Brake mode
“Forward”
“Reverse”
Disable
2
3
4
5
6
7
8
V
REF
RC
V
LOGIC
15
14
V
BB
13
12
11
Z = High impedance
CC
LOGIC
10
9
Dwg. PP-066-3
115 Northeast Cutoff, Box 15036
Worcester, Massachusetts 01615-0036 (508) 853-5000
Copyright © 1998, Allegro MicroSystems, Inc.
ALLEGRO [ ALLEGRO MICROSYSTEMS ]
