--- Quote Start ---
I do like your suggestion of using some form of power switch for different portions of circuitry. The only hurdle here is the on resistance of such a switch. The one you've identified is not up to my requirements (possibly up to 1Amp). However, the principle is good. A P-channel FET with a low on resistance may suffice.
It may also be possible to boost the 1.8V rail a little such that any voltage drop through the high side FET is negated and the other circuitry remains within spec (+/-5%). The Cyclone IV would be happy to operate at 1.8V+5%.
--- Quote End ---
Don't be afraid to use two regulators; the one for the FPGA could be a linear drawing a <100mA, whereas the 1A could use a switcher.
Cheers,
Dave
Honored Contributor
