Has anyone had any experience regarding damage to the TI Audio Codec TLV320AIC3254IRHBT analog channel? (LOR/LOL)This has occoured in several codecs.
The codec is supplied with a voltage of 1.9V via AVDD and LDOIN.A seperate 1.9V voltage is supplied to DVDD, and a 3.3V voltage to IOVDD.LDO_SELECT input in connected to the Ground (internal digital regulator is disabled).I'm using LOR and LOL analog outputs in differential mode.LOR and LOL are connected directly to the inputs of an audio transformer 1:1 with an impedance of 600 Ohm and a DC resistance of 115 Ohm. (transform used: SM-LP-5001 of Bourns).
After connecting the transformer outputs to the rest of our setup - damage is caused to LOR and LOL (Digital signal from DIN doesn't appear as an analog signal on LOR and LOL).
Several attempts have been made to try and reproduce the problem:1. Short has been made on the transformer outputs, with and without a signal on its inputs.2. Transformer output has been connected to a 3.3V DC voltage.3. Caused spikes on LOR and LOL by connecting and disconnecting 3.3V DC voltage on transformer outputs.4. Connected transformer outputs to a AC 1 KHz 6V signal. Done while codec powered on, and in addition while codec powered off.All of these 4 attempts resulted with a fully functioning codec at the end of the process!Unable to reproduce to damage problem described above!!Can you help? Have you encountered such a problem (damage to LOR and LOL) in the past?Thanks.
Sorry we missed your post. Did you get this figured out?
Audio Applications Engineering Manager
Dallas, TX USA
I think the analog inputs died on the codec of my EVM-U module, but I am not 100% sure as I seem to have software issues at the same time. After I swapped the codec chip and reflashed the firmware of the EVM, it started sampling correctly again.
The EVM has no protection of the inputs, just a series capacitor. I likely touched a 5V stabilizer of another board with the line in jack tip acciedentaly, the two boards had no ground connection at that time. I think that caused an overvoltage spike on the line-in pin. After that incident the AD converter sampled from none of the 6 programmable inputs.
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