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PCM2902B/C External Regulator Comment

Paul Schreiber
Prodigy 60 points

Other Parts Discussed in Thread: PCM2902

The Datasheet under Figure 37 has this little comment:

Audio performance may vary depending on [the voltage regular attached to the VCCCI pin #10].

Any clues on what the regulator parameters are than can effect a change and what exactly does 'audio performance' refer to (noise, THD, IMD, ....)?

REG103A not exactly cheap/small. Customer wants inexpensive SOT-23 part.

 

 

  • 0
    TI__Genius 16270 points

    Paul,

    Power supply noise can corrupt audio performance, and an external regulator with higher PSRR will improve audio performance by providing a cleaner VCCI rail.  On page 4 of the datasheet, it is shown that THD+N for the ADC of the PCM2902 is between 0.01% and 0.02% when using the REG103A, but can increase to 0.1% when using the internal regulator.  In general an external regulator is used for high performance applications, and while the datasheet specification was taken using the REG103A, the performance may change if using a different, unspecified external regulator.