AnsweredAssumed Answered

PB137ACV Problem

Question asked by alexander.david on Sep 24, 2013
Greetings:

I've apparently destroyed 3 of these, so time to appeal to a higher authority.

Circuit is same as application circuit in data sheet.  Battery to charge is Amstron 12V 22Ahr SLA.  Power supply is TDK-Lambda LS35-15 adjusted to about 17Vdc.  Battery is nearly full (13.1V).  Heat sink is 2.5" x 2" x 1" extruded aluminum for TO220, screwed on tight, with thermal grease.

First time battery is connected, PB137 puts out about 1.25A, which rapidly falls off to about 200mA (10-15s).  Nothing smokes, nothing gets hot, everything looks normal.  Second time it's connected, current into cell goes up to about 2A, and part gets really HOT.  Seems to be shorted.  If I disconnect the battery and check the dc resistances between the pins, I get about 4 Ohms, vs about 40K Ohms out of the box.

I tried 3 parts, all three did the same thing.  Data sheet says the part is "essentially indestructible."  I'm very curious to know what I'm doing to break them.  Any help is appreciated.

Attachments

Outcomes