DRV8842_15 Datasheet, PDF (12/27 Pages) Texas Instruments – DC Motor Driver IC

DRV8842
SLVSAB8F – MAY 2010 – REVISED DECEMBER 2015
www.ti.com
7.3.6 Protection Circuits
The DRV8842 device is fully protected against undervoltage, overcurrent and overtemperature events.
7.3.6.1 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; i.e., a short to ground, supply, or across the motor
winding will all result in an overcurrent shutdown. 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.
7.3.6.2 Thermal Shutdown (TSD)
If the die temperature exceeds safe limits, all FETs in the H-bridge will be disabled and the nFAULT pin will be
driven low. Once the die temperature has fallen to a safe level operation will automatically resume.
7.3.6.3 Undervoltage Lockout (UVLO)
If at any time the voltage on the VM pins falls below the undervoltage lockout threshold voltage, all circuitry in the
device will be disabled and internal logic will be reset. Operation will resume when V_M rises above the UVLO
threshold.
7.4 Device Functional Modes
7.4.1 nRESET and nSLEEP Operation
The nRESET pin, when driven active low, resets the internal logic. It also disables the H-bridge driver. 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-bridges are 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. Note that nRESET and
nSLEEP have internal pulldown resistors of approximately 100 kΩ. These signals need to be driven to logic high
for device operation.
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