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TPA3140D2: SD and Fault Pin for TPA3140D2

yoshiki hasebe
Mastermind 6385 points
Part Number: TPA3140D2

Dear Sirs,

My customer asked us about additional capacitor between SD&FAULT pins to GND for TPA3140D2.

SD and FAULT pins are shorted.

Additional capacitor rating is 0.1uF.

Is it OK to add this capacitor?

Although I think that addition of a capacitor is no problem, I think that confirmation of the time constant at Power ON / OFF is necessary.

Is this correct?

Also, the SD / FAULT pins are connected with 10 kΩ in the recommended circuit on page 21 of the data sheet.

Please tell me the reason for setting this value.

Best Regards,

Y.Hasebe

  • 0
    TI__Mastermind 24835 points

    Hi Hasebe-san,
    The pull-up resistor value on the SD/FAULT pin can't be too low, because too low value causes high idle current. And also it can't be too large, because too larger value causes long RC time constant. So 10kohm resistor is usually a good choice that can cover both these two requirements. You could add one appropriate capacitor on the SD/FAULT pin to decoupling the noise on them.
    Best regards,
    Shawn Zheng

  • 0 in reply to Shawn Zheng
    Mastermind 6385 points
    Hello Shawn-san,

    Thank you for your reply.
    Again confirming, my question concerns Capacitor connected to GND.
    I do not ask questions about Pull-up resistance.
    The resistance of the data sheet is a series resistance.
    Although the / FAULT pin is Open / Drain, there is no Pull-UP or Pull-Down resistance in case of / SD pin and short circuit, and it is a circuit of series connection resistance (10 kΩ).
    I think that there is no problem as long as the connection with the microprocessor etc. connected as a control of Shutdown is connected via this 10 kΩ.
    Is this correct?
    I also understand by configuring the time constant of RC with this series resistor and the capacitor added by my customers.
    Is this correct?

    Best Regards,
    Y.Hasebe
  • 0 in reply to yoshiki hasebe
    TI__Mastermind 24835 points
    Hi Hasebe-san,
    Thanks for your explanation. Your understanding is correct.
    Best regards,
    Shawn Zheng
  • 0 in reply to Shawn Zheng
    Mastermind 6385 points
    Hello Shawn-san,

    Thank you for your reply.
    I understand them.
    I will explain them to my customer.

    Best Regards,
    Y.Hasebe