https://drive.google.com/open?id=1dKRqG1LQ1H4h1G7cS3nGl8tlvMfenlTm
I am working on a pwm charge controller. My charging current is at 10A and wish to amp it up to 20A. I am using an IRF9540 Pmos and i have narrowed my search down to an IRF5303 Pmos as a replacement for the same. I have attached the schematic in the above link. my question is can i just replace the old one with the new one or do i have to provide additional circuitry? The circuit works perfectly fine for 10A and i have tested the same. please do help. Thank You.

 

The only thing different is D1, if that will take the current then it's ok, put the transistors and diode on a fan assisted heatsink for better cooling.

 

My charging current is at 10A and wish to amp it up to 20A

Is your charging source capable of producing 20A? Just changing a mosfet won't amplify the current alone.

 

Is your charging source capable of producing 20A? Just changing a mosfet won't amplify the current alone.

No. Changing the panel can do the same. This was just a test for 10A charging. Have to test for 20A. Just needed to know a scenario where if the charging current was 20A, would the other mosfet work just by changing them.

 

Looking at both mosfets data sheets I personally wouldn't pick either one for my circuit. You didn't say what voltage your working with so that also could be a factor.

You first(the one used now) is barely up to the job dependably now, it's only rated at 19A at 25C and 13A at 100C, and 100V. The second one is even worse since it is only a 30V component.

 

Looking at both mosfets data sheets I personally wouldn't pick either one for my circuit. You didn't say what voltage your working with so that also could be a factor.

You first(the one used now) is barely up to the job dependably now, it's only rated at 19A at 25C and 13A at 100C, and 100V. The second one is even worse since it is only a 30V component.

The entire system voltage is 25V.

 

Erm... but there is no inductor in this circuit, surely it is extremely bad for the battery?!

 

The entire system voltage is 25V.

In electronics it is better to use a higher rated component, both voltage and current wise. Your 100V mosfets would be good, but using a 30V one for a 25V circuit wouldn't be very wise. My earlier reply was in regard to the amperage they can transfer at a certain temperature. Look for a mosfet that has around double both your working voltage and amperage. Double would be the minimum to look for more is better.