DRV8828_15 Datasheet, PDF (8/21 Pages) Texas Instruments – H-BRIDGE MOTOR CONTROLLER IC

DRV8828
SLVSA11F – OCTOBER 2009 – REVISED DECEMBER 2013
FUNCTIONAL DESCRIPTION
www.ti.com
PWM Motor Drivers
The DRV8828 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. The logic inputs ENBL and PHASE have internal pulldown resistors of
100 kΩ. 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
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 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.
The PWM chopping current in the bridge is set by a comparator which compares the voltage across a current
sense resistor connected to the ISEN pin, multiplied by a factor of 5, with a reference voltage. The reference
voltage is input from the xVREF pins, and is scaled by a 5-bit DAC that allows current settings of zero to 100% in
an approximately sinusoidal sequence.
8
Submit Documentation Feedback
Copyright © 2009–2013, Texas Instruments Incorporated
Product Folder Links: DRV8828