- Some very small surface mount integrated H-bridges handle well over 1 amp in PWM mode in model railroad applications, with no heat sink. Sometimes with the entire ciruit wrapped in heat shrink. Common ratings on the overall ciruit are 1.5 amps continuous with a 2 amp peak (motor draw). I have no doubts a larger one could handle 3 amps or better - again they actually do, again in model railroad applications, where the output drive for track power is via such an H bridge, to the tune of 5, 8, or even 10 amps. Granted those are all heat sinked, but generally passive, no fans.