TLV2760: Help with the Microphone preamplifier circuit

Connor

Part Number: TLV2760

Tool/software:

Hi Teams,

I am using the analog microphone on the BOOSTXL-AUDIO.

With my limited knowledge of the Analog Electronics, I would like to ask for help on understanding the function block on the schematic and the specific value of the resistor and capacitor calculating method.

If there any docs, It is much better.

Could you please help on follow question:

What are the functional parts of the whole circuit? Those resistors and capacitors make up the filter circuit, bias circuit, etc.
How to calc the specific value?

I follow SBOA291 andSBOA290 doc. But I found it can not match all the details.

BR,

Connor.

over 1 year ago

+1 Ron Michallick over 1 year ago

TI__Guru**** 167546 points

Hello Connor,

The MIC raw gets a filtered (R30, C13) power source though 8.2k ohms. These value are based on what the microphone needs.

The DC bias for input is filtered (R32, C22) and set by (R35+R32) , R38. These value set bias to mid point. C19 needs to be big enough to pass lowest frequency desired.

TLV2760 is a very low voltage op amp, do not exceed its maximum voltage.

0 Connor over 1 year ago in reply to Ron Michallick

TI__Prodigy 650 points

Hello Ron,

This preamplifier design is for Electret Condenser Microphone. What if the analog microphone is the Analog output MEMS microphone(e.g. AMM-2738-2-B), how to modify this circuit? For example, which resisters or capacitors need to be removed or anything else.

Is there any EERD of the Analog output MEMS microphone preamplifier? like SBOA291.

Thanks.

0 Ron Michallick over 1 year ago in reply to Connor

TI__Guru**** 167546 points

Conner,

I was able to get data for the MEMS microphone, our web protection protocols didn't work with that website. You can look at that microphone's data sheet and just copy the recommenced way to connect to the microphone.

I see here ; https://e2e.ti.com/support/amplifiers-group/amplifiers/f/amplifiers-forum/874223/mems-microphone-amplifier-design that power is likely a separate pin. So R30, C13, R34 are not needed for the MIC analog output line.

0 Connor over 1 year ago in reply to Ron Michallick

TI__Prodigy 650 points

Hi Ron,

I have noticed this thread. Thanks.

I think it might be a good point to output a technical article for the MEMS microphone preamplifier. Just a tip.

Thanks.

BR,

Connor

Amplifiers

Amplifiers forum

TLV2760: Help with the Microphone preamplifier circuit