Telephony box I am working on is using a pair of AKM2304 quad codecs, they work very nicely most of the time. But they have always been very sensitive to the powersupply. With certain PSUs that issue too high a voltage, eg, 5.4V instead of 5V, they are prone to stopping working and getting hot, too hot to touch. On giving them the correct voltage they start working again. In addition on fitting the chips to a board they have a relatively high dropout rate, again either working or getting irretrievably hot.
Yesterday I decided to examine the problem closer, since we are nearing production. I reviewed the datasheet and saw the configuration of Digital and Analog powersupply decoupling I remembered, a 10R series resistor between the digital DVdd that took the 5V directly and the Analog. But then I did a double-take... in fact the datasheet showed the Analog power getting it directly and a 10R in series on the DVdd side. This made sense when combined with a warning note in the datasheet that AVdd must not fall below DVdd or there could be "damage"... their idea was to kneecap DVdd slightly and give AVdd the full 5V feed to avoid this. I shorted out the 10R series resistor I had wrongly placed in AVdd and now these codecs are happy with 5.4V... subtle...
