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MSP430F5507: Measuring 24uA in LPM4

ACP77
Prodigy 40 points
Part Number: MSP430F5507

Hi, I am working with a the TI MSP430F5507, I cannot seem to reduce the LPM4 current below 24uA. 

I have removed all peripheral circuitry and I am using standard TI LPM4 function.  See below

void LowPower4(void)

{

WDTCTL = WDTPW | WDTHOLD; // Stop WDT

// Setup UCS
UCSCTL4 = SELA_1; // Ensure VLO is ACLK source

// Port Configuration
P1OUT = 0x00;
P2OUT = 0x00;
P3OUT = 0x00;
P4OUT = 0x00;
P5OUT = 0x00;
P6OUT = 0x00;
PJOUT = 0x00;

P1DIR = 0xFF;
P2DIR = 0xFF;
P3DIR = 0xFF;
P4DIR = 0xFF;
P5DIR = 0xFF;
P6DIR = 0xFF;
PJDIR = 0xFF;

// Disable SVS
PMMCTL0_H = PMMPW_H; // PMM Password
SVSMHCTL &= ~(SVMHE | SVSHE); // Disable High side SVS
SVSMLCTL &= ~(SVMLE | SVSLE); // Disable Low side SVS

__bis_SR_register(LPM4_bits); // Enter LPM3
__no_operation();

}

  • 0
    TI__Mastermind 27560 points
    Hello ACP77,

    How are you measuring the power?
    Are you measuring while debugging using energy trace or something else?
    Are you measuring on the MSP430's power or the entire board? Is this a TI EVM or custom board?

    At first look, your firmware looks okay. I suspect that you may be measuring the power while debugging. If so, the debugger may actually be preventing the MCU from going into LPM4 mode. You can try removing the debugger or run the device in "free run" mode to allow it to sleep.

    Regards,
    JD
  • 0 in reply to JD Crutchfield
    Prodigy 40 points

    Hi JD

    Thanks for replying , I am using a DMM in uA settings. 

    In debug mode current is 211uA; then stopping debugger current reduces to 82uA 

    Removing the debug header from target, current reduces to 24uA.

    Target is being supplied by 3V from bench power supply, see below circuit. 

    Notes: Battery replaced by 3V PSU, C1 removed, R202 increased to 100k, still drawing 24uA

  • 0 in reply to ACP77
    TI__Mastermind 27560 points
    Hello ACP,

    Where are your DMM connections? Is the MSP430 power connections isolated vs the rest of the board? (IE. Are you measuring just MSP430 power or the entire PCB? )

    We have a LPM4 Example available for the MSP430F5507 availabe here, MSP430F55xx_LPM4.c: dev.ti.com/.../

    The main difference I see in is that the examples disables USB. Can you run the example as is and see what power you're measuring?

    If you are still measuring higher current when running the example, then I think that something else on the PCB is probably drawing it.

    Thanks,
    JD
  • 0 in reply to JD Crutchfield
    Prodigy 40 points

    Thanks for coming back to me JD

    DMM is connected as an ammeter from 3V PSU to PCB Vcc (also tried low side) 

    I have tested the following to ensure I am only measuring the micro-controller:-.

     -> Connected 1M ohm resistor across PSU, DMM & Leads = 3uA as expected with 3V supply 

    -> Removed the external 32k crystal and am using internal reference clock

    -> Removed micro from PCB and  connected 3V to PCB to ensure there is no current draw from rest of PCB (no current draw as expected)

    I have also found a FR4133 launch pad and have connected this up and can get 1uA in LPM4 & 5uA in LPM3 

  • 0 in reply to ACP77
    Prodigy 40 points
    This lines below resolved the issue, many thanks JD

    // Disable VUSB LDO and SLDO
    USBKEYPID = 0x9628; // set USB KEYandPID to 0x9628
    // access to USB config registers enabled
    USBPWRCTL &= ~(SLDOEN+VUSBEN); // Disable the VUSB LDO and the SLDO
    USBKEYPID = 0x9600; // access to USB config registers disabled

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