I'm having difficulty mounting the 7688 (not a Duo) to a board which has an on-board 3.3V regulator. I've looked at the 7688 schematic and read:
as well as many other threads/web pages that mention this but haven't gotten a real answer to move me forward. My 3.3V regulator is a 2A regulator. When I power-up the board/7688 combo, it starts to boot, the regulator gets blazing hot and after about 20 seconds into the boot process does a thermal shutdown. I put an amp meter in the middle and the 7688 was drawing an average of least 1.6A. I upped the ante and stuck a 3A 3.3V regulator on it, it did the same thing. I broke the regulator and 7688 out to a bread board, connecting to only pin 11 (Ground) and 13 (3.3V VIN) where the 3.3V 3A regulator had no heat sink and had the same problem - I was checking to see if I had a hidden board error somewhere. I read elsewhere the 7688 should not peak over 700ma and that is during the boot process - it seems I should have a little headroom. This same 7688 is quite happy running off a 5V USB supply but this is not appropriate for my project.
Has anybody had success powering the 7688 in this manner?
Could it be I have a bad LinkIt Smart??? Seems unlikely. I'm probably doing something wrong but I can't see it. I have two 7688's, unfortunately one bricked on first power-up and does not seem recoverable. I have more on order but until they arrive I'm stuck.