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MSP430F5419A Vref+

MichRFT
Expert 2110 points

Other Parts Discussed in Thread: MSP430F5419A, MSP430F149

Hello,

When using AVcc for VR+, is it advised to output it on P5.0 and to add a capacitor to filter it or is there no need at all because there is a buffer between the internal and external Vref+?

Best regards

Mich

  • 0
    Guru 74080 points

    VREF+ is for using the internal reference for external purposes or VeREF+ to feed in an external reference voltage. When using AVcc as VR+, then AVcc should have the capacitors according to the recommendations in the user's guide / datasheet (they should always have those). But no need for doing anything with VREF+ in that case. VR+ is internally connected to AVcc.

  • 0 in reply to Dennis Eichmann
    Expert 2110 points
    So it is different from the MSP430F1xx family (for this family this capacitor is mandatory)
  • 0 in reply to MichRFT
    Guru 74080 points

    Have a look into the datasheet of the MSP430F5419A - there are two tables, one is for using the internal reference and route them to VREF+ for applying it to something outside the micro:

    As you can see the pin doesn't like a capacitance at all. So a capacitive load would be a bad idea, too. The reference could get unstable / start oscillating.

    But if you feed in an external reference:

    Then it is recommended to add a capacitance of 10µF to the pin to buffer the voltage.

    And yes, you're right - the older processors like the MSP430F149 required an external (5µF min) 10µF + 100nF when using the internal reference.

    Dennis

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