LM1971: the max attenuation of lm1971 is about 20db,but attenuation of the datasheet is 62db?

Hi, 

Thank you for your details on this issue.

Could you disconnect the LM1971 from the TPA3138D2 and test different gain values, please? Is the gain always fixed at 20dB even if you try with lower or higher gain values?

Best regards,
Luis Fernando Rodríguez S.

we all Test LM1971 based on disconnect the TPA3138D2,but get the same result(max attenuation is 20db). the lower  gain work well (such as 6db、12db、18db),cann't set higher gain value.when power on the LM1971 without set the gain, the LM1971 should be mute mode(gain is 92db),but the gain only 20d,following figures are output and input :

Hi,

Thank you for your feedback. Some other questions:

- Have you tested different units just to verify that the unit was not damaged?

- In addition, do you see the same results in all the possible higher gains?

Best regards,
Luis Fernando Rodríguez S.

we tested three units,all test results are the same;

we see the same results in all the possible higher gains(than 20db);

Hi,

Thank you for your update.

Could you share some captures of the serial data where you could correctly configure the attenuation and where you couldn't get the expected attenuation?

This is just to verify that everything is correct.

Best regards,
Luis Fernando Rodríguez S.

the up figures we tested when don`t set the lm1971,but in datasheet should be mute mode.

Hi,

Thank you for the information you provided. However, I cannot see the figures you mentioned.

Could you share some captures of the serial data where you could correctly configure the attenuation and where you couldn't get the expected attenuation?

Thank you.

Best regards,
Luis Fernando Rodríguez S.