TLV320AIC3254: Difference between common Mode CM1 and CM2

Mario Raffin

Part Number: TLV320AIC3254

Hi,

Trying to understand the difference between CM1 and CM2 (the DS and the AN do not contain many information about it), I found this post which makes sense.

In this regard it is not clear to me the difference between these two situations:

A) {Register, Value}

{0x00,0x01} //page 1
{0x34,0x40}, // leftP ->IN1L
{0x36,0x01}, // leftN ->CM2L
{0x37,0x00}, //rightP OFF
{0x39,0x00}, //rightN OFF
{0x3b,0x1d}, //left micpga
{0x3c,0x1d}, //right micpga
{0x33,0x68}, //mic bias

and B)

same as A) but

{0x36,0x40}, //leftN ->CM1L

With A) using CM2L I can hear the signal, with B) i.e. CM1L I can't.

Thank you.

over 6 years ago

0 Diego Melendez over 6 years ago

TI__Guru 57800 points

Hi, Peregrinus,

The information you found in the post you mention is correct. There should be no particular issue with the selection of any of the CM paths available. I made a quick test with the EVM and was able to use either CM1 or CM2 without any issues, also tried changing them on-the-fly [not recommended] and was able to hear audio at all times. Is there any special sequence used when trying to program CM2?

Best Regards,

-Diego Meléndez López
Audio Applications Engineer

0 Mario Raffin over 6 years ago in reply to Diego Melendez

Expert 2355 points

Thank you for the reply Diego.

You are right. I found that the problem was related to a bad connection on the handset cable.

Sorry to disturb you, but i tested the configuration A and it did not work, then B worked, then A did not work again and finally B was OK :-(.

Next time I will collect more statistically significant serie.

Best regards.

mario

0 Diego Melendez over 6 years ago in reply to Mario Raffin

TI__Guru 57800 points

Hi, Mario,

No worries!, we are glad to hear the issue was solved.

Best Regards,

-Diego Meléndez López
Audio Applications Engineer

Audio

Audio forum

TLV320AIC3254: Difference between common Mode CM1 and CM2