XCore Exchange

EDIT: The threshold for the NCP1521B enable pin is .7v. Could I just use a charging capacitor on that w/ a current limiting resistor?

That kind of trick is perfectly acceptable IMHO but watch the tolerances. lack of hysteresis/feedback makes this slightly less predictable and you may have to play with the values and measure the timings under load conditions to get optimum values.

Once optimised it should be consistent with those components, but beware subtle changes in components choices can often catch you out later..

regards
Al

I am thinking 100nf and 5 million ohms series. That should give a 100ms delay, leaves room for error.

Will capacitor leakage be a major problem? Really never worked with these small capacitances, mainly large caps for my railgun.

That's probably overkill, as long as the 3.3v supply is 3volts before the core supply gets to about 0.5volts you should be fine, choose a lower resistor..

Will capacitor leakage be a major problem? Really never worked with these small capacitances, mainly large caps for my railgun.

No leakage will not be an issue, freaking railguns, dude we are talking multi Farad caps right..

regards
Al

Hey,
I will try several values on the board.

Did the railgun a year back. It was 400v, and around .2F for a total of 12,000 joules:
http://rp181.fortscribe.com/?cat=8