3951
FULL-BRIDGE
PWM MOTOR DRIVER
For both cases, care must be taken to ensure that the
maximum current ratings of the device are not exceeded.
The load current will limit at a value
V
+5 V
BB
ILOAD = VREF/(10•RS).
1
2
16
15
14
13
12
11
V
CAUTION: When the direction of the motor is changed
abruptly, the kinetic energy stored in the motor and load
inertia will be converted into current that charges the VBB
supply bulk capacitance (power supply output and
decoupling capacitance). Care must be taken to ensure
the capacitance is sufficient to absorb the energy without
exceeding the voltage rating of any devices connected to
the motor supply.
BB
47 µF
3
4
LOGIC
5
6
V
CC
7
8
10
9
See also, the section on brake operation under
“Functional Description”, above.
PHASE
V
BB
ENABLE
Dwg. EP-047-1
Stepper Motor Applications
The A3951SB and A3951SW may be used for
bidrectional control of bipolar stepper motors with continu-
ous output currents to 2 A and peak start-up currents as
high as 3.5 A.
Typical DC Servo Motor Application
V
+5 V
BB
47 µF
+
V
BB
ENABLE
1
0.5 Ω
V
PHASE
1
REF2
LOGIC
V
CC
V
LOGIC
CC
PHASE
2
V
REF1
ENABLE
2
V
BB
820 pF
25 kΩ
Dwg. EP-048-1
Typical Bipolar Stepper Motor Application
www.allegromicro.com
9
SANKEN [ SANKEN ELECTRIC ]
