PCM2903C: Question on LPF

Cameron Perl

Part Number: PCM2903C
Other Parts Discussed in Thread: OPA2353

Hey team,

Can you please provide some additional information on the LPF circuit that is reference in the datasheet? We don't provide much information on the benefits of using it / the downsides of not.

A customer is experiencing buzzing / cracking noise when audio ends in their application and are trying to determine the necessity of the additional filtering. Can it be achieved through a simpler / more cost effective RC circuit or is the additional amplification required?

Thanks,

Cameron

7 months ago

0 Jeff McPherson 7 months ago

TI__Mastermind 33015 points

Hi Cameron,

The LPF is generic here. The exact filtering that's required is more dependent on the amp itself. From the PCM2903C point of view, the filter isn't required.

Normally an LPF is used to remove out of band signals before getting amplified by the amp to improve noise performance.

Best regards,
Jeff McPherson

0 Cameron Perl 7 months ago in reply to Jeff McPherson

TI__Expert 4535 points

Thanks for the quickly reply Jeff. Based on your comment, do we expect the solution to look more like this?

Audio Codec Output --> LPF --> OPA2353 for gain?

+1 Jeff McPherson 7 months ago in reply to Cameron Perl

TI__Mastermind 33015 points

Hi Cameron,

Yes that would be a clearer solution than what the picture shows. AC coupling caps would still be recommended.

Best regards,
Jeff McPherson

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PCM2903C: Question on LPF