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PCM1861 - INT pin discrepancy

Other Parts Discussed in Thread: PCM1861

Hello,

The datasheet for the PCM1861 has the following information for the INT (no. 19) pin:

Page 5 - "Pull High for Active Mode, Pull Low for Idle."

Page 53 - "The INT pin is ideally designed to be used with a microcontroller that can treat the pin as both an input (when used as an interrupt) and as an output to pull the pin high, and force power-down."

Page 57 - "Configure the microcontroller INT pin to be an input for interrupts, or change the function to output to pull high to power down the PCM1861."

A few questions please:

1) Which is the correct polarity for active mode / power down mode?

2) The pin description on page 5 says "Pull high... Pull low..." but the application information says to pull it high or to connect it to a (microcontroller) input (with no mention of a pull resistor).  Is this pin required to be pulled in both directions or does it have an internal pull-down or...?

3) If one wasn't interested in the output (Energysense) function of the pin, would it be acceptable to connect the pin to a microcontroller GPIO pin (always configured as an output) through a series R? If so, what value R would be recommended?

Thank you.

  • Hi Kabigon,

    Welcome to E2E and thank you for your interest in our products!

    The INT pin is an interrupt output from PCM1861; this pin is drive high internally when analog input is detected. But when this pin is inactive, it can be externally driven high by a MCU to make the PCM1861 enter in Standby mode; this function is described in section 8.22.1.1 "PCM1861 Hardware Device Power Down Functions".
    If there is no interest in this pin function it can be connected to a MCU input pin to avoid entering standby mode unintentionally.

    Best regards,
    Iván Salazar
    Texas Instruments
  • Thank you for your reply Iván.

    Just to be clear on a couple of points:

    1) Please confirm that the INT pin description on page 5 of the datasheet is wrong (and that the others are correct).

    2) I have no interest in the output function of this pin. However, I do have an interest in controlling the standby function. In that case, would it be acceptable to connect the pin to a microcontroller GPIO pin (always configured as an output) through a series R? If so, what value R would be recommended? (I believe that the value of this R may depend on any internal pull-down on the INT pin)

    Thank you in advance for your reply.

  • Hi Kabigon,

    The INT pin description on page 5 seems to be specific for the EVM hardware ("Active" for entering standby mode and "Idle" for no-use of this pin); you can check this out on section 4.4 "Solder options" in the PCM1861 User's Guide. Its functionality is as I explained previously.

    This pin is specially designed for interfacing with an external MCU, so the connection can be direct from the PCM1861 to the MCU. You can check out the EVM schematic on Figure 15 in the PCM1861 User's Guide for an example.

    Hope this help you.

    Regards,

    Iván Salazar

    Texas Instruments