TS4909 - high white noise output

[AMart.11]

Hi all!

I've been strugling with this TS4909 for 2 weeks now, and cannot get it work properly...

I've designed a custom application with TS4909 as audio amp.

The problem is is has high white noise on the output.

My power supply is clean (from LDO), no noise on it, also tried to directly connect a 3,6V lithium bat on it, with nothing else connected from the circuit, also still the same.

This White noise is present even if the inputs are shunted.

My design follows the AN and datsheet design.

Any help solving this?

thanks

[AMart.11]

Hi ST Community!

I'm comming back to this topic after a while with some update...

The reported high noise related was due to feedback resistor miss-value - having thus an very high gain and noise...

After correcting this I finally had a clear amplified sound on output, as expecteed. The issue now is, with no input sound I still have a low white noise (like "shhhhhhhh....") remaining. I've isolated the inout source and shunted inputs to ground, but the noise is always there. I have no gain now (all feedback resistor = 20k, so Gain = 1) - it's working only as an impedance adapter for 32 Ohm speakers, so I do not know where this noise comes from. PSU is coming direct from 3,6V bat.

The only difference I can find from AN2622 is not using electrolytic capacitors on VCC + BPS pins, but ceramic instead.

Any help please?