Yes, my reading of the datasheet was the same. 18V in would be fine for 15V output. My concern would be how noisy the output would be. I have 9 of the from China ebay boards here (gave one to my boss to play with). I should wire one up and take a look. At any rate, I think a turn or two of the output wires through a ferrite bead would be in order. The data sheet shows a secondary filter of 3uH/180uF as well which I'd certainly want to use to feed a 5680A. Shouldn't do any harm, might do some good.
Orin. On Thu, Sep 12, 2013 at 7:19 PM, Robert LaJeunesse < rlajeune...@sbcglobal.net> wrote: > Looking at the LM2596 datasheet the switch transistor saturation voltage > is 1.5V max at 3A (1.16v typ). That and an educated guess of about 0.25V > for inductor loss combine to set the minimum difference between input and > output. The 1.23V reference is about +/-3% accurate, so after setting the > "buckboard" to 15.00V out (at 25C) expect it to shift at most 0.5V over > time and temp. Add that to the minimum in-out difference and now you are at > a minimum safe input of 2.25V above the nominal 15V output, or 17.25V in. > An old 19V 3A laptop supply might be a good supply to use for this, if you > were local I'd hand you one. > > As for efficiency, that just tells you the amount of heat the regulator, > plus inductor, plus diode, etc. will throw off. FWIW the datasheet Figure 5 > indicates you should expect about 88% or better efficiency for 15V out and > at least 2V higher input voltage. (Doing some switching power supply design > for a living does help with my understanding of them, but not ever enough!) > > Bob LaJeunesse > _______________________________________________ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.