Author Topic: P-Channel MOSFET always on  (Read 648 times)

0 Members and 1 Guest are viewing this topic.

Offline AankurTopic starter

  • Newbie
  • Posts: 8
  • Country: in
P-Channel MOSFET always on
« on: May 16, 2022, 09:06:07 am »
Hello

I am using a MOSFET driver circuit with SI2303 as p-channel mosfet and SI2302 as n-channel mosfet.

I have given control signal (of 5V) on the gate of n-channel mosfet to turn-on and off the p-channel mosfet.



However, the p-channel mosfet is not getting off and I am constantly finding voltage on Output (marked as Point-A).

Please let me know what is the problem in this circuit.

Thanks
 

Offline Zero999

  • Super Contributor
  • ***
  • Posts: 19494
  • Country: gb
  • 0999
Re: P-Channel MOSFET always on
« Reply #1 on: May 16, 2022, 10:26:06 am »
There are three most likely possibilities:

1) One or both of the MOSFETs is bad.

2) One or both of the MOSFETs is connected backwards.

3) Your multimeter is measuring the tiny leakage and it will be fine.
 

Offline VooDust

  • Regular Contributor
  • *
  • Posts: 70
  • Country: ch
Re: P-Channel MOSFET always on
« Reply #2 on: May 16, 2022, 11:49:05 am »
to measure this properly, you need to connect a dummy load from your output to ground. You can use a resistor for that.

 

Offline strawberry

  • Super Contributor
  • ***
  • Posts: 1161
  • Country: lv
Re: P-Channel MOSFET always on
« Reply #3 on: May 16, 2022, 06:00:09 pm »
1uA DS leakage current - 100k resistor = 0.1V + noise
0.6Vgs(threshold)
 


Share me

Digg  Facebook  SlashDot  Delicious  Technorati  Twitter  Google  Yahoo
Smf