TPA6166A2: Schematic review?

Steve Fenwick

Part Number: TPA6166A2
Other Parts Discussed in Thread: LM358

Would you be able to review the attached schematic? It's largely taken from the TPA6166A2 EVM. "SPKR" and "MIC" are expected to be line level, with a high-impedance single-ended load on MIC. ESD diodes added at the TRRS jack as the system is expected to be used in a poorly-controlled environment. SCL and SDA pull-ups to 1.8V are elsewhere in the schematic.

There's a low-pass filter on SPKR as there may be noise sources in the system >10kHz and this system is mainly to handle speech only. The audio source is mono.

For summing the microphone outputs of two or more of these devices, what do you recommend--10k series terminations on each, connected together at the input to an opamp?

Thanks!

Steve

over 2 years ago

0 Arthur Brown over 2 years ago

TI__Mastermind 18245 points

Hi Steve,

Sorry for the delay on this schematic review much of the team is Out of the office at the moment. I can review the schematic/ discuss with the team about the best option on summing the mic outputs. I will give a thoughtful reply tomorrow

Regards,

Arthur

0 Steve Fenwick over 2 years ago in reply to Arthur Brown

Prodigy 40 points

Is there a reply on this? Haven’t seen anything.

Best,

Steve

0 Steve Fenwick over 2 years ago in reply to Arthur Brown

Prodigy 40 points

Is there a reply on this? Haven’t seen anything.

Best,

Steve

0 Brian Donoghue over 2 years ago in reply to Steve Fenwick

TI__Intellectual 2620 points

Hi Steve,

Sorry for the delay here, we will get you a response today.

Brian

0 Brian Donoghue over 2 years ago in reply to Brian Donoghue

TI__Intellectual 2620 points

Steve,

I took a look at this with another apps engineer and we don't see any major concerns with the schematic. Using 10k summing resistors should work fine for multiple devices, but note you might need to adjust the value of the capacitor C2 to make sure it does not affect the frequency response as you add more 10k summing resistors. Depending on the loading you may or may not need a buffer. Keep in mind a long cable will add capacitance and a buffer would be useful in that case.

Brian

0 Steve Fenwick over 2 years ago in reply to Brian Donoghue

Prodigy 40 points

Thanks for sending this. This and the summing are all on one PCB. I could put an LM358 on each mic output, before the 10k summing resistors, to get around the frequency shift from the summing. Put in some no-stuff zeros to let us play with it a bit.

Thanks!
Steve

Audio

Audio forum

TPA6166A2: Schematic review?