I'm using one of the Dallas DS89C4x0 flash micros to drive a set of 16 N-channel MOSFETs. I feel there is undue redundancy in the structure I am using to drive the MOSFETs and maybe the total parts count could be reduced.


Current plan:

Port pin ----> PNP transistor -----> optoisolator ----> high-side driver ----> N-channel MOSFET


Optoisolators are available with 4 units per package.

I was considering the IR2117 (in-phase) high-side driver if I use a PNP transistor or the IR2118 (out of phase) high-side driver if I use an NPN transistor.

I've considered building or using a voltage booster to replace the high-side drivers but doubt it would simplify design and parts count. Supply voltage is a maximum of about 15 volts. Known available packaged voltage boosters don't have an operating window large enough for reliability. I've considered P-channel MOSFETs, but would like to keep the N-channels as the primary option.


sidenote:
The Dallas users' guide states "Sink and source currents should not exceed 10 mA total per port (8 bits) and 25 mA total per package".


Thanks,

Dan