Push-pull configuration over single mosfet

Question

I'm dealing with a simple application in which I need to drive a pure resistive load and to control it by voltage. I control the load through a pwm signal coming from a microcontroller in 5V logic. The pwm frequency can be easily set from a few hertz to several kHz. The supply voltage is 24V and the maximum absorbed current is 15A. I wonder, what are the advantages in using a more complex push-pull configuration over using a single power mosfet? I am aware that push-pull configurations are usually considered more efficient, but what about using a single mosfet with extremely low rdson? In example, a single IRFS7430-7PPBF would be enough? With the current values required this mosfet seems to be dissipating only 0.17 W in worst conditions. At this point I would prefer the single mosfet configuration over a more complex and costly push-pull configuration. What about if there is a need of linearizing the output of the driving stage with an inductor and a capacitor? Would the push-pull configuration offer bigger benefits over the single mosfet?

Answer 1

If you don't mind that the resistive load receives a "power amplified" PWM signal then a single MOSFET being switched at the PWM frequency will be the most effective.

If you do mind (because you want a linear looking voltage proportional to duty cycle across the load) then a push-pull with inductor and capacitor filtering will be most efficient. Next most efficient would be a single MOSFET with back-emf capture diode but the diode would dissipate quite a few watts.

However, the single MOSFET solution is trickier to get right with respect to mark-space ratio. The push pull version produces an average output voltage which is duty * input voltage i.e. is largely load value dependent.

You could engineer a purely linear solution with one MOSFET but that would produce a lot of heat.