From various chip manufacturer articles and other post in this site, I still have doubts on my circuit for switching inductive loads.
I have two setup here that both switches an inductive but using diferent MOSFET one is a P-Channel and the Other is N-Channel. A zener diode is placed on the Gate and source of both, the value for this zener is calculated to be greater than your typical Vgate voltage and less than the Fets Maximum Vgs rating.
The best suppression for inductive seems to be a Schottky and zenner parrallel to the inductive load. Schottkey should atleast handle the full current of the inductor (1A to 2A which is pretty common). For the Zener selection is seems to be geater than supply voltage yet less than the fets Vds(max).
As for my questions:
- When the coil collapses, are there danger of the current going back through the mosfets?
- For the NMOS setup in blue line is there danger of it going back to the power rails? I do not want to stress my PMICs
- For the PMOS is that ground safe to be connected directly to the logic grounds? I would like the setup to be able to have an alternate function where it can power digital ICs where having the same ground is important