I was wondering how they were going to manage 3.3v support on the
stock 3000 psu.
The only way i could see it was a linear. Hot idea there indeed.. can you report here when you have tested it?
I wont test it. I just know how much current is drawn by modern 3.3V PCI cards (like the Sonnet... erm SharkPPC I mean
, which I have tested in Prometheus).
Assume 2A power drawn, and using 5V line for linear regulation (which is nasty, as 5v is usually already well loaded in Amiga systems). You end up with (5-3.3)x2 W = 3.4 W of pure heat being dissipated.
Better would be to use a +12V -> 3.3V stepdown regulator, which achieve 90% and more efficiency... but these cost more than a few cent (as a cheap LDO does).
Using the +12V rail would also give some load balancing in favour of +5V rail.
Michael
