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MSP430F5437A multiple Dvcc and Vcore

ggreen125
Prodigy 40 points


I noticed there are 4 Dvccs. Do I need to have all four of them connected to power or can I only have one connected? If only one is connected can I leave the other not connected or does there need to be caps there? If so what size?

Do I need Vcore connected? I'm a little confused on what I need to do with it.

  • 0
    Guru 34773 points

    VCore need to be grounded over 470 nF cap.(noted on Recommended Operating Conditions in datasheet).

    AFAIK, DVCCx/DVSSx are related to different logic units inside chip, and they are not connected internally. Even they have same description in datasheet Digital power supply / Digital ground supply. I usually connect all DVCC/AVCC lines together to 3.3V.

    For details you can check http://www.ti.com/lit/ug/slau263g/slau263g.pdf with MSP-EXP430F5438 Experimenter Board schematic.

  • 0
    Guru 227245 points

    The four DVCCs ar einternally connected. In theory, connnecting one is sufficient. It is, however, recommended to split teh blocking capacitance (>4,7µF) between all DVCC/DVSS pairs.

    Now external connectiosn are better for higher currents than internal ones. If you draw lots of currents from a port that is at the opposite side of the die than the DVCC pin wiht the supply, then the current needs to go through the die, causing some voltage drops and additional heat. If you only have small currents, then it shouldn't make a difference.

    AVCC shouldn't be directly connected to DVCC. Instead a 010 Ohms series resistor and a 100nF ceramic and 10µF Tantalum cap shoudl be between the two, so AVcc is separated from digital current ripples.
    AVss should not be connected to DVss too, as the currents on the DVss signal path cause voltage ripples due to the trace resistance. DVss shoudl be routed separately to the GND reference point at the power supply.

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