Low-Voltage, Full-Bridge Brushless DC Motor Driver with
Integrated Hall Sensor IC, PWM Speed Control, Soft-Switching,
and Reverse Battery and Short Circuit Protection
A1448
Functional Description
threshold will turn on the output bridge according to the applied
Soft Switching
The A1448 device includes a soft-switching algorithm that
controls the output switching slew rate for both output pins. As a
result, the A1448 device is ideal for use in applications requiring
low audible switching noise and low EMI. The resistance of the
output transistors is controlled to ensure the smooth switching of
the outputs, as illustrated in figure 1.
magnetic field. Applying a PWM signal to the CONTROL pin
will turn the bridge on and off according to the PWM duty cycle.
When the CONTROL pin is pulled to GND, the device initiates
its internal active braking algorithm to stop the motor. After
braking, the device enters micro-power sleep mode. The device
becomes active again when the CONTROL pin is pulled higher
CONTROL Pin Functionality: PWM, Braking, and Sleep
Mode Input
The CONTROL input pin accepts an external signal that can
control the speed of the output bridge, initiate active braking,
than VINHI
.
Antistall Algorithm
If a stall condition occurs, the device will execute an antistall
and put the device into sleep mode. Signals higher than the VINHI algorithm to re-start the motor.
V
V
OUT2
OUT1
t
SW
Figure 1. A1448 output soft switching with a 30 ꢀ resistive load
Allegro MicroSystems, Inc.
115 Northeast Cutoff
4
Worcester, Massachusetts 01615-0036 U.S.A.
1.508.853.5000; www.allegromicro.com
ALLEGRO [ ALLEGRO MICROSYSTEMS ]
