JAJSSJ5 December 2023 DRV8234
PRODUCTION DATA
When the motor is driven by external force, it acts as a generator and pumps back current to the supply voltage rail. This can potentially damage other circuits connected to the supply rail. In low-power sleep mode or when the H-bridge is disabled (High-Z), if the voltage of the output nodes rise above the supply voltage by about 200 mV, the DRV8234 turns on the two low-side MOSFETs. This allows the device to actively brake a motor connected to the outputs by shorting the back emf across the motor terminals.
The overvoltage protection (OVP) function is enabled by default. After power-up, the EN_OVP bit can be made 0b to disable this feature. The EN_OVP logic state is latched, so that in sleep mode the device bahves as per the EN_OVP bit setting, even though the internal digital logic is reset.
In sleep mode, if there is a short circuit to power supply fault present in the power stage, a simple overcurrent detector circuit is provided to disable the low-side MOSFET if a high current event is detected while braking. This is needed since the normal overcurrent protection circuits are disabled during the low-power sleep mode.