When using a MOSFET as a load switch, how do I reduce the inrush current that occurs?

Increasing the gate-resistor Rgate connected to the outside of MOSFET slows the switching-up and suppresses inrush current.

Fig. 1: Explanation of inrush current (Rush current)
Fig. 1: Explanation of inrush current (Rush current)

Generally, large capacitor Co for voltage stabilization is connected to the output side of the MOSFET.
When the MOSFET turns on, inrush current IRUSH flows to charge this capacitor.
This inrush current is reduced by increasing the series gate resistor Rgate.
When the gate resistance increases, the rising output current becomes less pronounced.
However, if increasing gate resistance affects the switching speed and loss, it is necessary to select the suitable gate resistance on your using condition. Refer to the following application notes for details on how to determine the gate resistance.

Document: MOSFET Gate Drive Circuit Application Note (PDF:1.56MB)

Back to FAQs of MOSFETs / Bipolar Transistors / IGBTs

A new window will open