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Original question:

PCM6020-Q1: PCM6020-Q1

PCM6020-Q1: PCM6020-Q1 unpowered state

Madhaiyan Kodi
Prodigy 50 points
Part Number: PCM6020-Q1

Tool/software:

For DC coupled Mic input, when PCM6020 in unpowered state, if mic input has any voltage (short to battery or any other voltage connected to Mic+/Mic- pin) will there any latchup problem to the IC?. 

What is the state of Mic input pin and Mic bias pin when PCM6020 is unpowered?

Thanks 

  • 0
    TI__Intellectual 1820 points

    Hi Madhaiyan, 

    1. Yes, there may be a latchup problem if you apply a voltage higher than the maximum ratings to these pins while the device is unpowered. Please refer to section 8.3.3, figure 8-14, and figure 8-15 for more information. 

    2. When unpowered, the pins are in a high impedance state. 

    In the event that a microphone becomes disconnected from the inputs, the microphone bias resistors pull INxP
    to MICBIAS and INxM to ground. The combination of INxP shorted to MICBIAS and INxM shorted to ground for
    the same channel in a diagnostic sweep results in an open input fault condition. Thanks.

    Regards,

    Sam

  • 0 in reply to Sam Yang
    Prodigy 50 points

    Hi Sam,

    Regarding the point 1. Can we use the series 1kohm resistor to Mic inputs pins and its already in high impedance state, do you see any issues if we apply voltage on input pins when device is unpowered?. 

  • 0 in reply to Madhaiyan Kodi
    TI__Genius 15590 points

    Hi Madhaiyan,

    Applying a voltage to the input pins will not damage the device when unpowered unless the absolute maximum ratings are exceeded. Please see the max ratings in section 7.1

    Adding a resistor is okay as well, however this does impact the effective impedance of the input pin, so please take this note. You can see the internal circuitry of the input pin for your own calculations in this file: https://www.ti.com/tool/download/SBAC263

    Regards,