Hi all,
I am trying to make an adjustable power supply. The supply will be attached directly to a computer PSU 12v. I just need to be able to trim the 12v down, to whatever i want and I can do that now.
For adjustment and PWM signal I use an Arduino, switching at 62,5khz. I boost the signal from the Arduino with a mosfet driver (MIC4421), just to be sure I get the mosfet FDB7030BL fully saturated.
Between the outputs I have a schottky diode to protect the mosfet from self inductance coming from the load.
My big problem is that I have a lot of spike voltage, - going to approx 50v, and the spikes seems to be there no matter if I use it to adjust fans, pumps or peltier elements, heavy load and with nearly no load. I have read that this voltage spikes is related to the corrent pushing the mosfets body diode, - not sure if thats the case. But how can I remove it. My mosfet can handle up to 30v, so I am afraid the voltage spikes will kill it.
I am trying to make an adjustable power supply. The supply will be attached directly to a computer PSU 12v. I just need to be able to trim the 12v down, to whatever i want and I can do that now.
For adjustment and PWM signal I use an Arduino, switching at 62,5khz. I boost the signal from the Arduino with a mosfet driver (MIC4421), just to be sure I get the mosfet FDB7030BL fully saturated.
Between the outputs I have a schottky diode to protect the mosfet from self inductance coming from the load.
My big problem is that I have a lot of spike voltage, - going to approx 50v, and the spikes seems to be there no matter if I use it to adjust fans, pumps or peltier elements, heavy load and with nearly no load. I have read that this voltage spikes is related to the corrent pushing the mosfets body diode, - not sure if thats the case. But how can I remove it. My mosfet can handle up to 30v, so I am afraid the voltage spikes will kill it.
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