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Launchpad RM57L843 Power Domains

Nicholas Brown
Intellectual 460 points

Other Parts Discussed in Thread: RM57L843

Hi,

This is a combination of questions and thoughts, so I selected the 'Discussion' option. I have been working to reduce the power consumption of my Launchpad RM57L843 kit (currently powered via its USB port with a 5 volt Kindle AC adapter) using various means.

Just a heads-up: i'm using a 120 volt energy use monitor to measure its power consumption since I plug it in, and it is only accurate to 0.1 watts. :D

I used the pmmTurnOFFLogicPowerDomain(); function to turn off power domains 2, 5, and 6, and the power consumption was reduced from 1.8 watts to 1.3. I also turned down the GCLK frequency to 20 MHZ.

When I used pmmTurnOFFLogicPowerDomain(PMM_LOGICPD3); to turn off domain 3, the two LEDs on the ethernet port turned on, and power consumption went back up to 1.4-1.5 watts. Could someone clarify what happened?

Thank you for your time!

  • Intellectual 460 points
    Also, would powering it via the VCC pins instead of the USB port reduce its power consumption much? If so, which pins should I connect my power supply to? (and which jumpers need to be removed, if any)
  • TI__Guru**** 191886 points
    Hi Nicolas,

    Not really have an idea why the power consumption went up after you attempt to turn off power domain 3. The unexpected reading may have something to do with the inaccuracy of your measurement tool.

    The power domain 3 contains the following modules.

    • MibADC2
    • MIBSPI4
    • MIBSPI5
    • DCAN3
    • DCAN4
    • SCI3
    • SCI4
    • I2C1
    • I2C2
    • NHET2
    • HTU2

    What does LOGICPDPWRSTAT1 register show after you turn off the power domain 3?

    BTW, what is your intended application when you pretty much try to turn off all the power domains. You can not use any of the modules within the turned-off power domains.
  • in reply to Charles Tsai
    Intellectual 460 points

    Hi Charles,

    I will get that info as soon as I reboot back into Windows and check it. I have just been turning them off one-by-one for learning purposes to see the impact they have on power consumption. I will turn back on the ones I do need eventually.

    Thanks.