DJ Delorie wrote: > I promised an update to this, and here it is. > > I got the LM25575 eval board and wired it up to the powermeter board's > bulk supply, so I could compare theirs to mine side-by-side (kinda the > whole point, yes?). > > A pin-by-pin comparison of the two supplies showed that most pins were > acting the same, except one - the FB pin (feedback - it's the output > of the error comparison amplifier) had a clocked signal on it on my > board, but was a steady DC on theirs. None of the nearby pins had a > clock on it, the solder joint was good, the PDF showed no reason why > there would be a clock on it. Diagnosis: bad chip. >
FB would be the input of the error amp: http://www.national.com/an/AN/AN-1578.pdf And yes, if the FB pin spits out pulses the chip is busted. > So, I replaced the chip with the new one I had ordered. Now it works > fine. > > As an aside - the ENC28J60, R8C, FTDI232R, and two ADE7753 chips, use > a total of 164 mA. The board holds 16 ADEs so 14 x 5 mA is another 70 > mA, total 235 mA - well short of the expected 600 mA worst case. The > ENC28J60 is spec'd at 250 mA all by itself. > Maybe you can get carbon credits for the saved 365mA :-) -- Regards, Joerg http://www.analogconsultants.com/ _______________________________________________ geda-user mailing list geda-user@moria.seul.org http://www.seul.org/cgi-bin/mailman/listinfo/geda-user