I'm using a PIC microcontroller and four P-channel power MOSFETs to switch four 12-volt automotive power sockets on and off. The PIC also measures the current through each of the sockets by measuring the voltage drop across shunt resistors. I've attached an image showing a portion of the circuit for one of those outlets.
The circuit works fine in most cases. The main exception is when it tries to switch on a 75W AC inverter. When it does, it usually causes the microcontroller to reset. This occurs even with no load attached to the inverter.
The odd thing is, if I first switch on a small load (like a 12 V DC fan), unplug the fan with the socket switched on, then plug the inverter in, the PIC won't reset and everything will work normally.
I'm presuming the inverter has a high capacitance that causes a high inrush current when the MOSFET is switched on, but I'm not certain of this.
How could I avoid this problem? What if I turned on the MOSFET using a PWM signal, to reduce the inrush current?
If I need to modify the circuit, I would prefer to stick with through-hole parts if possible.
The circuit works fine in most cases. The main exception is when it tries to switch on a 75W AC inverter. When it does, it usually causes the microcontroller to reset. This occurs even with no load attached to the inverter.
The odd thing is, if I first switch on a small load (like a 12 V DC fan), unplug the fan with the socket switched on, then plug the inverter in, the PIC won't reset and everything will work normally.
I'm presuming the inverter has a high capacitance that causes a high inrush current when the MOSFET is switched on, but I'm not certain of this.
How could I avoid this problem? What if I turned on the MOSFET using a PWM signal, to reduce the inrush current?
If I need to modify the circuit, I would prefer to stick with through-hole parts if possible.
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