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MSP430F6779A: Select capacitors for MSP430 power.

Motoyasu Hattori
Genius 12950 points

Part Number: MSP430F6779A
Other Parts Discussed in Thread: MSP430F6779

Hi,

From MSP430F6779 datasheet(page 42), TI recommend capacitor 4.7uF and 0.47uF for power. But my customer concerns capacitor characteristic (capacitance may be reduce   because tolerance, aging, DC bias voltage, temperature).

Could you please let us know the minimum capacitance?  In other words, Could you please confirm whether the following capacitor is no issue as follows?

Part number CC0402KRX5R5BB475 (4.7uF, 10%, 6.3V, X5R, SMD 0402) for 4.7uF
Part Number CC0402KRX5R6BB474 (0.47uF, 10%, 10V, X5R, SMD 0402) for 0.47uF

Please advise us.

Thanks and best regards,
M.HATTORI.

  • 0
    TI__Genius 17960 points

    Hello Motoyasu-San,

    unfortunately it is not possible to deliver such a confirmation. The values for these capacitors in the datasheet are just nominal / typ. values due to various reasons. To name the most important ones:

    - The impact on the performance is heavily dependent on the HW design. This includes the quality of the entire layout design, but especially also the placement and connection of the capacitors to the MSP430 and the rest of the supply system.

    - The values of these capacitors are also dependent on the EMI performance of the customer specific HW design, and in dependency of it, different values might deliver better performance.

    - The other point might be aging or other factors influencing the capacitance.

    Basically the top level recommendation from our side is, to start with the values defined in the datasheet, but then basically during the R&D process run respective tests on metering and EMI robustness performance, testing the impact of these capacitors, testing the margins, and then select and adjust the values for these capacitors accordingly.

    Best regards

    Peter

  • 0 in reply to Peter Spevak
    TI__Genius 17960 points

    Hello Motoyasu-San,

    please let us know, whether there's still something we can do for you on this topic. Many thanks in advance.

    Best regards

    Peter

  • 0 in reply to Peter Spevak
    TI__Genius 12950 points

    Hi,

    I got the additional following question from my customer.

    Could you please tell us for specification of capacitors that used test as below, layout placing capacitor on meter including test result and decision point?

    Thanks and best regards,
    M.HATTORI

  • 0 in reply to Motoyasu Hattori
    TI__Genius 12950 points

    Hi,

    I got the additional following question from my customer.

    Could you please tell us for specification of capacitors that used test as below, layout placing capacitor on meter including test result and decision point?

    Basically the top level recommendation from our side is, to start with the values defined in the datasheet, but then basically during the R&D process run respective tests on metering and EMI robustness performance, testing the impact of these capacitors, testing the margins, and then select and adjust the values for these capacitors accordingly.

    Thanks and best regards,
    M.HATTORI.

  • 0 in reply to Motoyasu Hattori
    TI__Genius 17960 points

    Hello Motoyasu-San,

    the tests I was speaking here about are e.g. the required tests for the customer's application. This can be e.g. the required tests for CE certification, like IEC61000-4-5 or similar tests. Some customers apply due to their internal quality requirements even harder test criteria than required for the application certification. So the tests I was speaking about are not MSP430 or TI specific, or defined by TI, but application related tests usually required for certification of the application by external certification authorities or defined by the customer's own quality management.

    The minimum test criteria for those are of course meeting the test requirements of the applied test.

    On top of these again the customer can have additional, let it be parametric or functional requirements. Thus again something to be defined on the customer's side. This could be e.g. no undesired resets under operation during the applied test conditions.

    Of course the discussed capacitors are not the only criteria for passing those tests. Thus in reality if not reaching the targets of the applied tests, an analysis on the root cause needs to happen. If that root cause reveals a dependency on the discussed capacitors, then the values need to be corrected accordingly. From the MSP430 specification though, it is not recommended to go below the recommended values.

    I hope this addresses your / the customer's question.

    Best regards

    Peter

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