Description
The A3966 is designed to drive both windings of a two-phase
bipolar stepper motor. The device includes two full-bridges
capable of continuous output currents of ±650 mA and operating
voltages to 30 V. Motor winding current can be controlled by
the internal fixed-frequency, pulse-width modulated (PWM),
current-control circuitry. The peak load current limit is set
by user selection of a reference voltage and current-sensing
resistors.
The fixed-frequency pulse duration is set by a user-selected
external RC timing network. The capacitor in the RC timing
network also determines a user-selectable blanking window that
prevents false triggering of the PWM current-control circuitry
during switching transitions.
To reduce on-chip power dissipation, the full-bridge power
outputs have been optimized for low saturation voltages. The
sink drivers feature the Allegro
™
patented Satlington
®
output
structure. The Satlington outputs combine the low voltage drop
of a saturated transistor and the high peak current capability
of a Darlington.
For each bridge, a PHASE input controls load-current polarity
by selecting the appropriate source and sink driver pair. For
29319.25K
Features and Benefits
▪ ±650 mA continuous output current
▪ 30 V output voltage rating
▪ Internal fixed-frequency PWM current control
▪ Satlington® sink drivers
▪ User-selectable blanking window
▪ Internal ground-clamp and flyback diodes
▪ Internal thermal-shutdown circuitry
▪ Crossover-current protection and UVLO protection
Dual Full-Bridge PWM Motor Driver
Continued on the next page…
Package: 16 pin SOICW (suffix LB)
Typical Application
Not to scale
A3966
Dwg. EP-047-4A
PHASE
2
ENABLE
2
47 μF
+
+24 V
56 kΩ
680 pF
PHASE
1
ENABLE
1
+5 V
39 k
Ω
10 kΩ
0.5 Ω
+5 V
0.5 Ω
LOGICLOGIC
1
2
3
14
15
16
6
017
11
98
RC
4
5
V
REF
13
12
V
BB
V
CC
V
BB
