Tool/software:
Hello,
We have a board that has 1.5 mF input capacitance. We are using the TPS4811 with a Vishay SQJQ184E Mosfet to manage the power input to the board.
Nominal voltage is 28 V, over voltage threshold is set to 33V.
Naturally we forgot about the input capacitance and while testing for the over-voltage threshold the Mosfet worked fine to switch off the power input but while testing the recovery level we had 32.5 V switching onto 1.5 mF. This resulted in the Mosfet Gate and Source shorting probably due to the substantial inrush current.
We currently have that the gate pull up turn on slowed down to 2 ms with a 68 kOhm series resistor.
For what I understand the best approach would be first to reduce the input capacitance as much as possible without impacting the performance of the rest of the circuit.
Second would be to adjust the gate pull up time.
Should I go slower? Aim for 20 to 50 ms turn on time? Or should I just go faster?
The pre charge circuit would have been ideal but we require the over voltage protection.
