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MSP430F6779: Power to external circuit

user5845893
Intellectual 690 points
Part Number: MSP430F6779

I want to have two possible sources to power MSP430 in my board, both 3V3. I want to connect first to DVCC pin and second to AUXVCC1. It might happen, that only one of these two sources will be available. How I should then connect any peripheral circuits that require 3V3, for example pull up resistors for I2C?

Can I connect it to VDSYS? In that case AUX will decide, which source is present and supply MCU?

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    TI__Genius 17490 points

    If I am understanding your system correctly, you have 2 power sources, one on the main DVCC and one on the backup AUXVCC1. You want to know how to power the other peripherals that would require the same 3.3v source?

    I suggest reading the Digital I/Os and Auxiliary Supplies section (4.2.8) in the MSP430x6xx Family User's Guide. The Vdsys is a output pin with the currently used source so it does switch with the DVCC and AUX depending on which has the highest voltage at start-up (or if it gets switched) and needs the recommended capacitor. The only potential issue would be current draw, as going over the max can damage the device. Device specifics on operating ranges can be found in the Datasheet.

    Here is another thread that I believe is asking the same thing. Can VDSYS or DVSYS be used to source power.

    Regards,

    Luke

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