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TLV320DAC3203: Channel separation at HP-output.

Mochi
Genius 4175 points
Part Number: TLV320DAC3203


Hello,

Our customer is facing lower channel separation performance at HP-output.

Using EVM, observed clear performance difference caused by common mode voltage setting at 3.3V HP power as below.

 

P1,R10,D4-6                              1KHz FSR              L to Rch      R to Lch

Common mode=Full chip　　　　　　　    　　     108.0ｄB　 108.2dB

Common mode=1.65V　　　　　　　　　   　　      74.4ｄB　   82.4dB

Common mode=1.65V(Remove AVDD bypass cap)  80.2ｄB  　 89.2dB

 

It is interesting that AVDD cap made 6dB difference, it seems power line is so sensitive.

How can we get 100dB over separation using LDOIN(HPpower)=3.3V and Common mode=1.65V configuration?

 

Regards,

Mochizuki

  • 0
    TI__Mastermind 18545 points

    Hello Mochizuki, 

    Our team is looking into this thread and will respond as soon as possible. 

    Best Regards, 

    Justin Beigel

  • 0
    TI__Guru** 110765 points

    Hi Mochizuki-san,

    The channel separation spec is 92dB, although it is not specified what common mode configuration is used.
    I'm checking this out, perhaps the spec is based on common mode = full chip. Will check if processing block could make a difference.

    Best regards,
    -Ivan Salazar
    Applications Engineer - Low Power Audio & Actuators

  • 0 in reply to Ivan Salazar
    Genius 4175 points

    Hello Ivan,

    Our customer had confirmed key parameter is only common mode voltage setting.

    To get higher output power under 3.3V supply, change common mode voltage then channel separation become reduce.

    Our expectation is that DAC3203 does not have external bypass cap for common voltage.

    That is why HP-amp stage get kind of CMRR influence maybe...

    Is there any way to improve this performance?

    Regards,

    Mochizuki

  • 0 in reply to Mochi
    TI__Guru** 110765 points

    Hi Mochizuki-san,

    Did you also tried changing the capacitor value on REF pin?
    I'll try to ask for the internal bias distribution, but I would expect all internal bias levels to be decoupled on the same point.

    Best regards,
    -Ivan Salazar
    Applications Engineer - Low Power Audio & Actuators

  • 0 in reply to Ivan Salazar
    Genius 4175 points

    Hi Ivan,

    Our customer confirmed to increase bypass cap at Ref pin to 100uF on EVM.

    But separation is not improved.

    Regards,

    Mochizuki 

  • 0 in reply to Mochi
    TI__Guru** 110765 points

    Hi Mochizuki-san,

    Unfortunately I don't think there is other thing to try. The channel separation spec is taken using full-chip common mode configuration. This mode has better decoupling as it comes from the actual decoupling outside of the device.
    Internal reference voltage are all decoupled at the same point, does not have individual decoupling connections out of the device.

    Best regards,
    -Ivan Salazar
    Applications Engineer - Low Power Audio & Actuators