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MSP430F6736: Power On But Not Work

Joyce Gao
Expert 3200 points

Part Number: MSP430F6736

Tool/software:

Hi expert,

Customer developed a charging pile product using the MSP430F6736 chip.

Sometimes the chip will not work when powered on (the internal crystal oscillator does not run, and the program does not run). Could this because the GPIO port voltage is ahead of VCC, causing this problem?

Before VCC is powered on, are there any requirements that the voltage of this GPIO port cannot exceed a certain threshold? Or are there any requirements for the current sinking to this GPIO port before VCC is powered on?

For the GPIO power on sequence, here's our test:

During the power-on process, the chip's GPIO port P1.1 pin has a voltage of about 1V before VCC is powered on, about 90ms ahead of VCC. The waveform of this pin and the MCU power supply waveform are as follows:

Yellow line is 5V power supply, blue line is MCU's 3.3V VCC, red line is MCU's P1.1 GPIO.

Please confirm if this could be the root cause or any other insights. Many thanks!

Joyce

  • 0
    TI__Genius 16050 points

    Hi Joyce,

    Yes this issue could be caused by the voltage applied to P1.1 before VCC ramps up. If you take a look at the device datasheet in section 5.1, you can see the maximum voltage applied to any pin is VCC + 0.3, so the waveform above indicates that this is being violated.

    In tables 5-4 and 5-5 you can also see current based limitations. I can't tell from the provided information whether this is being violated but please check the design against these tables.

    It is also possible to accidentally "back power" the device by applying too large of a voltage to a GPIO pin, so again this could lead to an interrupted startup sequence and incorrect device behavior. I'd recommend making sure the pins don't violate the first spec in datasheet section 5.1, then re-testing. If still failing please check the current, if still failing after all of these please update the thread and we will look further into this.

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