2.2 MOSFET Driver Output Gets Stuck High if Power OFF Sequence is not Appropriate

If VIN is powered down or VDD goes low, and VDR is present, while PDRV1/PDRV2 is High or while being High during a switching cycle, then PDRV1/PDRV2 might remain stuck High.

This can cause power switch to be stuck ON and the power train to be damaged.

Workaround

Power OFF must be ensured, so that VDR does not remain High while VDD goes low.

A recommended implementation for correct power DOWN sequencing can be found in Schematic 1.

If VDR needs to be supplied with a voltage higher than VDD, Schematic 2 is recommended to be used.

If VIN gets LOW, diode D must be selected to have enough current capability to discharge the VDR filter capacitors before VDD capacitors are discharged

The Power OFF Timing Diagram can be used as an example for correct power down sequence. Timing recommendations can be found in Table 2-2.

Time t2 must not be longer than t1.