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 additonal circuitry? please do help. Thank You.