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TPS3897: delay time calculation

Ann_Lien
Genius 14360 points
Part Number: TPS3897

Hello expert,

Customer has two questions about TPS3897 on the delay time setting. According to datasheet equation (2), it seems like it is not match about below table value. And also, do we have maximum delay time limitation? Customer is testing with 2*0.047uF and power on is fail. Could you kindly help on this case? Thanks a lot!!

Best regards,

Ann Lien

  • +1
    TI__Guru 56345 points

    Hi Ann,

    I have check the equation and compared the typ value in the datasheet and both values matches.  This is how I calculated the time:

    tpd(r) = (0.047 * 4) + 40uS = 188.04ms.

    The equation requires the capacitor value to be in uF and the customer may be mistaken by using (0.047 * 10^-6) instead of just using (0.047).

    I need to look into the max delay time limitation so I ask for your patience.

    Ben

  • +1 in reply to Ben C
    TI__Guru 56345 points

    Hi Ann,

    According to the validation data, the max delay time limitation is around 12 seconds or about 3uF.  The result was done only at room temp.

    Ben 

  • 0 in reply to Ben C
    TI__Guru 56345 points

    Hi Ann,

    If I have answered all of your questions, please click on "resolved" to close the thread.

    Ben