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MSP430F67471A: Questions about LCD charge pump

Keirs
Expert 2605 points
Part Number: MSP430F67471A

Hello,

I have 3 questions.

1.I think "Icp,load" value(50uA) at the page op 51 in the datasheet is additionnaly flowed at AVCC pin or DVCC pin during Time to charge CLCD when discharged(500ms).
   Is my understanding correct?

2.According to the datasheet page 30, it seems that the current consumption is larger when the charge pump is disabled than when the charge pump is enabled.
   It seems that the consumption current is larger when the charge pump is enabled, why is it the result of the above?

3.If I want to compare the current consumption of the whole MCU with the data sheet, is it OK to use only the DVCC pin and AVcc pin to measure the pin?

Regards,

uchida-k

  • 0
    TI__Genius 10980 points

    Hi,

    1. I am not sure I understand exactly what you mean by this one. This value is the maximum current measured at the charge pump. It is not measured at the AVCC or DVCC pins. There will be current flowing through those pins while the charge pump is charging, but that is not what directly is being measured.
    2. This is because the alternative to using the charge pump is AVCC, which uses more current than using the charge pump voltage generated from DVCC.
    3. Yes, the current flowing through both pins should give you the overall current draw of the MCU because those are the 2 supply pins.

    Regards,

    Nathan

  • 0 in reply to Nathan Siegel
    Expert 2605 points
    Hi Nathan,

    Thank you for your reply.
    Would you tell me about additional questions?

    1.Does the charge pump charge at the time indicated by tLCD, CP, on(max 500ms) on page 51 of the data sheet?

    2.Does the current consumption of ILPM 3 LCD int Bias on page 30 of the data sheet not contain any current to charge the charge pump(Icp, load) at all?

    Regards,
  • 0 in reply to Keirs
    TI__Genius 10980 points

    Hi Keirs,

    1. Yes, this is correct.
    2. Correct, this is the current drawn when the charge pump is disabled, and therefore the charge pump is not drawing any current at all.

    Regards,

    Nathan

  • 0 in reply to Nathan Siegel
    Expert 2605 points
    Hi Nathan,

    Thank you for your reply.

    >2.Correct, this is the current drawn when the charge pump is disabled, and therefore the charge pump is not drawing any current at all.

    Sorry, I want to know about "I LPM3 LCD,CP".
    Does the current consumption of I LPM3 LCD,CP on page 30 of the data sheet not contain any current to charge the charge pump(Icp, load) at all?

    Would you tell me additionnal question?

    >There will be current flowing through those pins while the charge pump is charging, but that is not what directly is being measured.

    When does the charge pump charge time occur? Is it done only once when the charge pump is enabled? Or do you regularly charge it?
    I'd like to know when the current of "Icp, load" is drawn.

    Regards,
  • 0 in reply to Keirs
    TI__Genius 10980 points
    Hi Keirs,

    I LPM3 LCD,CP is the typical current during the time of operation of the charge pump. It will continue to need to be charged while it is enabled. The current of "lcp,load" is the current that is being drawn the entire time that the charge pump is enabled. Please keep in mind that I LPM3 LCD,CP is the current of the entire LCD controller, which includes the charge pump.

    Regards,
    Nathan
  • 0 in reply to Keirs
    TI__Genius 10980 points
    Hi Keirs,

    Did this answer your question? If so, please mark it as answered.

    Regards,
    Nathan
  • 0 in reply to Nathan Siegel
    Expert 2605 points
    Hi Nathan,

    Sorry for delay.
    I understand.

    Thank you!

    Regards,

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