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MSP430F6638: High standby current after partial shutdown

Part Number: MSP430F6638

On my circuit, with the MSP430f6638 micro controller and some other chips (most of which I have removed)

I have the device running in low power mode and drawing about 15 microamps.  If I disconnect power and let the voltage drop (capacitor discharge) to right about 0.9 V, and then turn power back on, the device will draw about 3 milliamps when it is low power mode.  If I reconnect power when the voltage is greater than about a volt or less than 0.7V, it always is in the normal 15 microamp mode for standby.

It won’t exit the 3 milliamps standby “mode” unless I unplug power and let the voltage drop below about 0.7 V before turning back on.

Restarting the micro without letting power discharge always doesn’t resolve the situation.

  • Hi Nicholas,

    What is happening is you are attempting to restart the MCU when it's BOR (brown-out reset) voltage level is in an "undefined" region.  Typically VCC should be near 0v when power is applied for the BOR circuit to start working and bring the device out of reset.

    At any other voltage the BOR may not work and the system is in an unknown state and will draw larger currents.  For proper operation always make sure VCC is allowed to go to 0v before re-applying power.

  • Hello Nicholas,

    I haven’t heard from you for a couple of days now, so I’m assuming you were able to resolve your issue.
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    If this thread locks, please click the "Ask a related question" button and in the new thread describe the current status of your issue and any additional details you may have to assist us in helping to solve your issues.

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