DRV8829 Datasheet, PDF (6/17 Pages) Texas Instruments – H-BRIDGE MOTOR DRIVER IC

DRV8829
SLVSA74B – MAY 2010 – REVISED MAY 2011
FUNCTIONAL DESCRIPTION
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PWM Motor Drivers
The DRV8829 contains one H-bridge motor driver with current-control PWM circuitry. A block diagram of the
motor control circuitry is shown in Figure 1. A bipolar stepper motor is shown, but the driver can also drive a DC
motor.
Figure 1. Motor Control Circuitry
Note that there are multiple VM, ISEN, OUT, and VREF pins. All like-named pins must be connected together on
the PCB.
Bridge Control
The PHASE input pin controls the direction of current flow through the H-bridge. The ENBL input pin enables the
H-bridge outputs when active high. Table 2 shows the logic.
ENBL
0
1
1
Table 2. H-Bridge Logic
PHASE
X
1
0
OUT1
Z
H
L
OUT2
Z
L
H
The control inputs have internal pulldown resistors of approximately 100 kΩ.
Current Regulation
The current through the motor winding is regulated by a fixed-frequency PWM current regulation, or current
chopping. When the H-bridge is enabled, current rises through the winding at a rate dependent on the DC
voltage and inductance of the winding. Once the current hits the current chopping threshold, the bridge disables
the current until the beginning of the next PWM cycle.
For stepping motors, current regulation is normally used at all times, and can changing the current can be used
to microstep the motor. For DC motors, current regulation is used to limit the start-up and stall current of the
motor.
If the current regulation feature is not needed, it can be disabled by connecting the ISENSE pins directly to
ground and the VREF pins to V3P3.
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