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TIDEP-0091: reprogramming the PMIC upon each power up?

Viktorija Cecil
Mastermind 18491 points
Part Number: TIDEP-0091
Other Parts Discussed in Thread: IWR1443, , LP87524J-Q1

Team,

This low power ref design uses I2C and MSP432 to program PMIC so that radar operates in lower power mode.

Is there a way not to have to reprogram upon each power-up? 

Customer is referencing page 8, first bullet: http://www.ti.com/lit/ug/tidud26b/tidud26b.pdf

  • MSS Boot ROM – This software is preprogrammed for functional boot, flashing boot, and SPI and QSPI / Control UART / and QSPI peripherals

Thanks!

Viktorija

  • 0
    TI__Guru 50240 points
    Hi Viktorija,

    The PMIC is actually programmed by the MSP432 so it only needs to be reprogrammed when the MSP432 (or customer's host processor) is powered off. The PMIC will stay programmed regardless of power to the 1443.

    Does this answer your question?


    Cheers,
    Akash
  • 0 in reply to Akash Gondalia
    Prodigy 80 points
    It makes sense that the PMIC retains its configuration as long as power continues to be supplied to the PMIC.

    What amount of power savings does programming the PMIC achieve? If the IWR1443 is unpowered most of the time, it may not be significant.

    Regards,
    Chris
  • 0 in reply to Chris Turcotte
    Prodigy 80 points
    The following description was previously provided, "On the TIDEP-0091 improvement in the power management topology is being tried where in Host processor such as MSP432 could control the I2C lines of PMIC and control the power management modes of the device. Concept here is configure the PMIC in PFM mode when Radar is not chirping which is the lowest power state for the PMIC and Radar and configure it to PWM mode when Radar is actively chirping. This configuration provides additional ~30% savings (This benefit would be seen when Radar is not actively chirping i.e. Inter frame periods). "

    That does not sound like a one-time programming of the PMIC, rather that it would have to be programmed twice per power-up of the IWR1443 (PFM mode followed by PWM mode).

    Is this how the TIDEP-0091 example actually operates?

    Regards,
    Chris
  • 0 in reply to Chris Turcotte
    TI__Guru 50240 points
    Hi Chris,

    Yes this is correct, this technique is what helps to achieve the 30% savings.

    We also recommend using the j variant of the LP87524J-Q1 PMIC.


    Cheers,
    Akash
  • 0 in reply to Akash Gondalia
    Prodigy 80 points
    Hi Akash,

    I examined the TIDEP-0091 example MSP430 source code. At initialization, the code configures the PMIC, apparently setting BUCK 2 and BUCK 3 to PFM auto mode.

    txBuffer[0] = 0x0E; //BUCK2_VOUT reg
    txBuffer[1] = 0x89; //Set to 1.3V
    txBufferBUCK2[0] = 0x06; //BUCK2 control reg
    txBufferBUCK2[1] = 0xc4; //BUCK2 set PFM auto
    txBufferBUCK3[0] = 0x08; //BUCK3 control reg
    txBufferBUCK3[1] = 0xc4; //BUCK3 set PFM auto

    I do not see any other configuration of the PMIC. Please explain how and when the PMIC is set to PWM mode.

    Regards,
    Chris
  • 0 in reply to Chris Turcotte
    TI__Guru 50240 points
    Hi Chris,

    This is performed on startup because by default the PMIC is in Forced PWM mode. During chirp-time the PMIC will change back to PWM mode due to the higher current draw.


    Cheers,
    Akash
  • 0 in reply to Akash Gondalia
    Prodigy 80 points
    Hi Akash,

    Interesting automatic PMIC mode switch capability.
    Thanks for the explanation.

    Regards,
    Chris