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MSP-EXP430FR2311: MSP430FR2311 LPM3 current consumption

Vyacheslav Prokopiy
Expert 1305 points
Part Number: MSP-EXP430FR2311
Other Parts Discussed in Thread: MSP430WARE

Hello.

I'm trying to get the lowest possible current consumption in LPM3.

SLASE58B says, that maximum possible current in this mode could achieve 5.25 uA (the worst case). And a typical value is 1.16 uA.

I've took a LaunchPad and a standart example from MSPWare "MSP430Ware_3_70_00_05\examples\devices\MSP430FR2xx_4xx\MSP430FR231x_Code_Examples\C\msp430fr231x_LPM3_02.C"

After program was compiled and downloaded, I've detached all the pins of MCU from emulator and from external components(LEDs and LightSensor) on LaunchPad by removing jumpers.

By measuring current from external supply to LaunchPad (currentmeter was inserted in high side) I've got 17.3 uA.

What could be a reason of extra 16 uA of consumption? And how to get 1uA in LPM3 on LaunchPad?

Thank you for support.

 

  • 0
    TI__Guru**** 207137 points
    Hello Vyacheslav,

    The code example you referred to uses REFOCLK as the ACLK source, Table 5-7 of the Datasheet shows that the REFO oscillator consumes an average 15 uA of current which accounts for the overhead you are experiencing. You will need to populate the LaunchPad with a 32 kHz crystal and make changes to the code such that ACLK is sourced by XT1CLK instead.

    Regards,
    Ryan
  • 0 in reply to Ryan Brown1
    Expert 1305 points

    Ryan, thank you.

    Is it possible to use only VLO for clocking an RTC, which will wake an MCU from LPM3?

    How to disable REFOCLK in this case? (I can't find this in MSPWare)

  • 0 in reply to Vyacheslav Prokopiy
    TI__Guru**** 207137 points
    Hi Vyacheslav,

    ACLK is only sourced by either XT1CLK or REFOCLK and remains active through LPM3. You could use LPMx.5 and wake up through the RTC sourced by VLOCLK, ACLK/REFOCLK will be disabled in this case. REFO is also commonly a source for the FLLREFCLK but consumes not power when not in use.

    Regards,
    Ryan

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