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MSP430FR5969: Problem running at 1.8V

Dalton Paull
Prodigy 110 points
Part Number: MSP430FR5969


I'm working on a low power application and I'm attempting to run the msp430fr5969 at 1.8V to save power. I'm prototyping/debugging using the IMSP-EXP430FR5969 board. The idea is that my power supply is initially set to 2.5V and then when the program starts executing, I turn off the SVS and then use a GPIO pin to set the supply to 1.8V.

The problem I'm running into is that the MSP430 stops executing when the voltage drops below 1.87V and restarts at 1.9V, without a full reboot (tested with a bench supply). I tried decreasing my clock from 4MHz to 1MHz with no change. The only peripherals that I'm using are the ADC, TIMER A and the UART. Turning off the UART doesn't help but I have not attempted to run without the timer or ADC.

I also haven't been able to figure out how to use the debugger to diagnose the problem because as soon as I start debugging, the VCC increases to ~3V. I believe this is due to the logic levels on the JTAG pins.

Any suggestions for getting the debugger to run at 1.8V or what might be causing the MSP430 to stop executing would be appreciated.

  • 0
    TI__Mastermind 46765 points

    Hi,

    I checked the datasheet that the ADC, timer A and the UART should work at 1.8V. 

    What do you mean by "turn off the SVS and then use a GPIO pin to set the supply to 1.8V"? Have you power the MCU from a GPIO pin not the VCC pins?

    Best regards,

    Cash Hao

  • 0
    Guru 34773 points
    Dalton Paull said:
    Any suggestions for getting the debugger to run at 1.8V or what might be causing the MSP430 to stop executing would be appreciated.

    FR device must start at minimum about 2.0V. Same voltage is minimum for SBW / JTAG debugging also.

    Once device is powered up / started / released from debugger, voltage can go down to 1.8V.

  • 0 in reply to Cash Hao11
    Prodigy 110 points

    I'm powering the the MSP430 with a switch mode power supply that has digitally selectable voltage levels. I use the GPIO pin to change the voltage selection from 2.5V to 1.8V once the program has started and the SVS has been turned off.

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