DRV8829_15 Datasheet, PDF (9/27 Pages) Texas Instruments – DRV8829 5-A 45-V Single H-Bridge Motor Driver

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DRV8829
SLVSA74E – MAY 2010 – REVISED SEPTEMBER 2015
7.3 Feature Description
7.3.1 PWM Motor Drivers
The DRV8829 contains one H-bridge motor driver with current-control PWM circuitry. Figure 3 shows a block
diagram of the motor control circuitry. A bipolar stepper motor is shown, but the driver can also drive a DC motor.
Figure 3. Motor Control Circuitry
There are multiple VM, ISEN, OUT, and VREF pins. All like-named pins must be connected together on the PCB.
7.3.2 Blanking Time
After the current is enabled in the H-bridge, the voltage on the ISEN pin is ignored for a fixed period of time
before enabling the current sense circuitry. This blanking time is fixed at 3.75 μs. The blanking time also sets the
minimum on time of the PWM.
7.3.3 nRESET and nSLEEP Operation
The nRESET pin, when driven active low, resets the internal logic. It also disables the H-bridge drivers. All inputs
are ignored while nRESET is active.
Driving nSLEEP low will put the device into a low-power sleep state. In this state, the H-bridge is disabled, the
gate drive charge pump is stopped, the V3P3OUT regulator is disabled, and all internal clocks are stopped. In
this state all inputs are ignored until nSLEEP returns inactive high. When returning from sleep mode, some time
(approximately 1 ms) needs to pass before the motor driver becomes fully operational. The nRESET and
nSLEEP have internal pulldown resistors of approximately 100 kΩ. These signals need to be driven to logic high
for device operation.
7.3.4 Protection Circuits
The DRV8829 is fully protected against undervoltage, overcurrent and overtemperature events.
7.3.4.1 Overcurrent Protection (OCP)
An analog current limit circuit on each FET limits the current through the FET by removing the gate drive. If this
analog current limit persists for longer than the OCP time, all FETs in the H-bridge will be disabled and the
nFAULT pin will be driven low. The device will remain disabled until either nRESET pin is applied, or VM is
removed and re-applied.
Overcurrent conditions on both high and low side devices; that is, a short to ground, supply, or across the motor
winding will all result in an overcurrent shutdown. The overcurrent protection does not use the current sense
circuitry used for PWM current control, and is independent of the I_SENSE resistor value or VREF voltage.
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