A3952SW ALLEGRO [Allegro MicroSystems], A3952SW Datasheet - Page 10

• Manufacturer Part Number: A3952SW
• Description: FULL-BRIDGE PWM MOTOR DRIVER
• Manufacturer: ALLEGRO [Allegro MicroSystems]

motor is more linear than in the case of ENABLE PWM
control (which produces a discontinuous current at low-
current levels).
nal can be used for mechanical direction control. Similar
to when braking the motor dynamically, abrupt changes in
the direction of a rotating motor produce a current gener-
ated by the back EMF. The current generated will depend
on the mode of operation. If the internal current-control
circuitry is not being used, then the maximum load current
generated can be approximated by
where V
internal slow-decay current-control circuitry is used, then
the maximum load current generated can be approximated
by I
to ensure the maximum ratings of the device are not
exceeded. If the internal fast-decay current-control
circuitry is used, then the load current will regulate to a
value given by
3952
FULL-BRIDGE
PWM MOTOR DRIVER
LOAD
With bidirectional dc servo motors, the PHASE termi-
= V
BEMF
BEMF
is proportional to the motor’s speed. If the
/R
I
LOAD
LOAD
I
LOAD
. For both cases, care must be taken
= (V
= V
BEMF
ENABLE
PHASE
REF
BRAKE
+ V
/(10•R
BB
)/R
S
).
+5 V
LOAD
Typical DC Servo Motor Application
2
3
1
4
5
6
7
8
V
CC
LOGIC
V
V
BB
BB
the motor is changed abruptly, the kinetic energy stored in
the motor and load inertia will be converted into current
that charges the V
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.
“Functional Description,” above.
115 Northeast Cutoff, Box 15036
Worcester, Massachusetts 01615-0036 [phone]
CAUTION: In fast-decay mode, when the direction of
See also, the sections on brake operation under
16
15
14
13
12
10
11
9
V
BB
47 F
BB
supply bulk capacitance (power
Dwg. EP-047
MODE