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IWR1443BOOST: Confusion about power management on dev board

Sabrina Chang
Prodigy 200 points
Part Number: IWR1443BOOST
Other Parts Discussed in Thread: IWR1443

We noticed the IWR1443 regulates the PMIC on the dev board (LP87524J) with I2C. We're confused how the chip is able to regulate its own power when its only source of power is from the PMIC. In other words, how is the IWR able to send/receive commands to/from the PMIC? Wouldn't there be some trouble in startup? Thanks in advance.

  • 0
    TI__Mastermind 33805 points

    Hi,

    Please see section 7.3.1.3 of the PMIC datatsheet

    The PMIC has a default startup mode, after startup  current measurements and other data transfer can be done via I2C.


    Regards,

    Charles O

  • 0 in reply to Charles Oladimeji
    Prodigy 200 points

    Thank you! That clears it up.

    Another question: in the launchpad datasheet it mentions the PMIC enable and PGOOD are for an external MCU to control the PMIC for power saving reasons. If we just opt to regulate the PMIC on board, I believe we should just pull up PMIC_EN like the other PMIC enable pins and leave PGOOD unconnected, but I wanted to double check here.

    We are planning to interface the IWR chip with a BLE chip and only draw power from the BLE's board when the boards are connected, aka not use the external BLE's MCU to control power for IWR but just to use single source of power for both boards. Is it reasonable to pass the 5V from BLE board (unregulated) directly to IWR board's PMIC through headers? I understand the datasheet mentions choosing between PMIC and MCU for 3.3V output, but if we're not using an external board for power optimization purposes then is it ok?

    Thank you!

  • 0 in reply to Sabrina Chang
    Prodigy 200 points
    Also sorry another clarification: since we are not looking to control the PMIC with an external MCU, the PMIC's CLK_IN can just be tied to ground, correct? I'm guessing the PMIC clk is for synchronizing with the external MCU for power optimization purposes from looking through the datasheets. Thanks.
  • 0 in reply to Sabrina Chang
    TI__Mastermind 33805 points
    Hi,

    Per the PMIC datasheet, you can connect the CLK_IN pin should be connected to ground if it is not used.
    Yes, you can pass the 5V to the PMIC input using headers, Please consider the current rating of the pin.

    Regards,
    Charles O