P channel mosfet

[klopar]

Hi everyone,

I will need help. Can somebody help me. I made a circiut like on picture. It's working well when I connect the burden 3A. When I connect burden to 6 A the mosfet getting hot. I need your help.

Image: http://file.slo-podnapisi.net/slikomat/datoteka/ntnjzxzjty2ynuzhwhjg.jpg

Thank you

 

[davenn]

Hi everyone,

I will need help. Can somebody help me. I made a circiut like on picture. It's working well when I connect the burden 3A. When I connect burden to 6 A the mosfet getting hot. I need your help.

Image: http://file.slo-podnapisi.net/slikomat/datoteka/ntnjzxzjty2ynuzhwhjg.jpg

Thank you

what is U3 and U4 ?

I assume the word you use "burden", you really mean "load"

what are the loads and what are they powered by ?

it sounds like you are exceeding the ratings of the mosfet


cheers
Dave

 

[Audioguru]

Your schematic is a backwards negative image that I can barely see. Why not use black lines on a white background like everyone else??

A Mosfet gets hot when its current is high and its gate voltage is not enough.
The datasheet for your Mosfet says that with a gate-source voltage of 4.5V then its on resistance max is 48milli-ohms when it is cool. Then with 6A in it, its heating is 6A squared x 48mΩ= 1.73W which is almost its maximum allowed heating without having a heatsink.

 

[klopar]

Hi,

Thanks for your answer. U4 and U3 are connector (input and output positive voltage). Yes, I thought load. I use mosfet for switching on/off. Load (light) uses 10A.

Best regards

 

[davenn]

Thanks for your answer. U4 and U3 are connector (input and output positive voltage).

that doesn't really make much sense

where do the 2 pins of U3 go to when they leave this circuit ?
show us.... tell us

where do the 2 pins of U4 go to when they leave this circuit ?
show us.... tell us

 

[klopar]

Negative voltage is connected direct on the load. Pin 1 on U3 is output here I have connect positive load. On pin 2 I have connect Vcc 12V to 23V. I have 2 difrent channel to switch. U4 is the same.

 

[(*steve*)]

The voltage you apply to the gate of the MOSFET is relative to the source terminal.

There is no connection shown on your circuit been your gate voltage part of the circuit and the source terminal of either mosfet.

I guess it's possible that your 12V Vcc and the sources son1 and son2 could share a positive rail, but that would be stretching credibility.

 

[klopar]

Here is my full schematic:




Link image: http://file.slo-podnapisi.net/slikomat/datoteka/wou05yt5yyoqetwgzw2y.jpg

 

[Audioguru]

The Mosfet and all the other parts can be replaced with a piece of wire because the light is always turned on.

 

[(*steve*)]

R2 should go between the gate and source.

Pulling the input (connected to R1) to ground will turn the light on.

It would be preferable to increase R2 to 10k (make it significantly larger than R1)