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PCM3070: PCM3070 Abnormal reverse voltage in IOVDD

Gabriel Xu
Intellectual 2065 points
Part Number: PCM3070

Hi teams

My customer encounters an abnormal phenomenon during using PCM3070.

Customer supply LDO IN with 3.3V voltage, disable DLDO through LDO_select pin and disable ALDO through register.

They supply AVDD & DVDD and IOVDD with 1.8V LDO and tie it together. But when they power up the device they found 1.8V supply being charged to 2.3V.

They locate the abnormal power is from IOVDD through disconnect the connection between 1.8V LDO and IOVDD pin. Without any connection the IOVDD still output 2.3V.

Could you help me to figure it out what is going on?

  • 0
    TI__Guru 57800 points

    Hi, Gabriel,

    This is not an expected behavior, IOVDD pin of the PCM3070 is used as reference for the digital signals logic-high voltage. Can you please verify if the digital signals of the codec are referenced to the 1.8V logic level?. Also, is this issue happening only at power-up or during normal operation?

    Best Regards, 

      -Diego Meléndez López
       Audio Applications Engineer

  • 0 in reply to Diego Melendez
    TI__Intellectual 2065 points
    Hi Diego
    This issue happened only in power-up.
    I have told customer to check are any abnormal digital signal present in I/O pin.
    I also suspect are this voltage come from LDO IN?
    Are any posibility that LDO IN voltage flow though to IOVDD ?
    If customer use 3.3V supply LDO IN and 1.8V for AVDD/DVDD/IOVDD, what should be notice about power up time sequence?
  • 0 in reply to Gabriel Xu
    TI__Guru 57800 points

    Hi, Gabriel,

    The voltage in LDOIN pin should not affect IOVDD, but if any of the digital signals is connected to 3.3V, some issues may happen with IOVDD voltage level. Regarding the power sequence, it is recommended to provide the IOVDD supply before or at the same time as the other supply pins while holding the RESET pin low until all supplies stabilize. 

    Best Regards,

      -Diego Meléndez López
       Audio Applications Engineer