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The capacitor for Vref of PCM1795

user4157284
Prodigy 10 points
Other Parts Discussed in Thread: PCM1795

Hello.

Regarding PCM1795 DAC, I want to know the Low ESR typed capacitors can be used as the decoupling capacitor for Vref. (VcomL, VcomR).

If not, please let me know why it is impossible to be used.

FYI, we found strange symptoms like followings

■ symptom - The voltage level of Vref at VcomL and VcomR is exceed 2.5V when supply voltage level (Vcc) is 5V. (about 3~4.5V)

■ condition - Vcc 5V, internal bias decoupling capacitor : ELNA 100uF 6.3V (PVO, LOW ESR)

There is no guidance on the datasheet.

Regards.

  • 0
    TI__Guru**** 189399 points

    Hi,

    That should be ok. Is the voltage at the terminals stable, or is it oscillating? I believe this voltage is generated from a resistor divider, not an LDO, so it shouldn't need ESR for stability.

    Check your PCB for leakage paths or mis-connection to explain the higher than expected voltages.

    -d2