I just want to adjust voltage of a dc dc converter output with pwm signal...i used MOSFET but i get some heating effect..please tell me what model of MOSFET or ijbt or anything else which components is more reliable...

  • 1
    The rule of thumb: MOSFET for high current, IGBT for high voltage, and BJT for high frequency. Select a MOSFET with a low On resistance and considerably higher current capability than you need - and add a heatsink (they exist for a reason you know) – Majenko Oct 16 '20 at 16:40
  • Pmos or nmos which one preferred more for this – Jacob Oct 16 '20 at 16:43
  • That depends on the circuit. Are you wanting to switch the low or high side of a signal?# – Majenko Oct 16 '20 at 16:44
  • High side of a signal – Jacob Oct 16 '20 at 16:45
  • 1
    Acctually i just want to adjust output voltage of a dc-dc converter after compairing to a reference voltage so i thought to use Arduino and a sensor for sensing and after sensing the reference voltage Arduino generates a pwm signal to drive the MOSFET to control the dc dc converter to a needed voltage.. – Jacob Oct 16 '20 at 17:05


simulate this circuit – Schematic created using CircuitLab

There are not many P-Channel Mosfets with high current ratings. The circuit is an example of a buck with a high side N-Channel. If you want to use an N-Channel as the high side switch, you use and isolated DC-DC and isolated gate driver. The negative output of the DC-DC regulator gets referenced to the source of the N-Channel. Then the isolated driver's output signal is 15v referenced to the source. I would also recommend using a snubber because you're going to likely see voltage spikes across your mosfet. A 10ohm resistor and 3300pF would probably be a good start. You may need to go to a 200v or 250V mosfet if the spikes are bad enough.

  • where is Arduino in this? – Juraj Oct 16 '20 at 17:13
  • Can anyone give me a simple circuit for pmos with pwm. – Jacob Oct 16 '20 at 17:19
  • @Juraj the pwm signal is the output pin from the arduino. The 5v is the 5v that's supplied by the arduino board. – bunker89320 Oct 16 '20 at 17:21
  • @Jacob I can show you with a P-Channel, but you're not going to have any less parts and it will cost just as much if not more. You will still need a gate driver, and you will likely still need a 15v regulator because the P-Channel has a very limited selection for the ratings that you need and most won't work properly with a 5v gate signal. The circuit is going to be very similar as far as complexity goes. – bunker89320 Oct 16 '20 at 17:47
  • Thanks buddy for your reply..i will try this circuit – Jacob Oct 16 '20 at 17:52

Not the answer you're looking for? Browse other questions tagged or ask your own question.