I want to design a PWM switch for general purpose loads, meaning I don't know if it is used with a 12V pump, a fan or LED lights. I want to pack 4 of these as tightly as possible and each has to provide at least 3A.
Consider that these "intelligent switches" are performing slow switching to reduce EMI, so pwm frequencies should be moderate, e.g. a few 100 Hz up to 1 kHz. And there should be a freewheeling means for inductive loads.