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TPS3890: Rpu value and diviation of tPD(t)

Y.Ottey
Mastermind 6145 points
Part Number: TPS3890

Dear all,

I would like to know about Rpu and tPD(t) of TPS389033DSER.

Could you answer questions below?

1. According to Datasheet, The range of Rpu values is different between ”pin functions” on p. 3 and "Recommended Operating Conditions" on p.4. 

which one is correct?

(Please see the figure below)

2.When tPD(t) was calculated using ICT and VCT as typ values at CcT = 0.3 μF, it was about 320 ms.

In this case, what is the deviation of tPD (t)?

Best Regards,

Y.Ottey

  • 0
    TI__Genius 9375 points

    Hi Y.Ottey,

    To answer your first question, they are essentially saying the same thing as 1000 kΩ is equivalent to 1 MΩ for the top end, so I assume you meant the minimum resistance, which differs at 1 kΩ in the table vs 10 kΩ in the pin functions. The minimum is 1 kΩ but we recommend at least 10 kΩ.

    To your second question, you can use this equation here to calculate tPD(r).

    The 25 us added at the end is a nominal value and since we don't spec the min and max, I would assume a general +/- 5% around that value.

    Thanks,
    Abhinav.

  • 0 in reply to Abhinav.Sharma
    Mastermind 6145 points

    Hi Sharma,

    Thank you for your reply.

    I would like to ask more question.

    Why you say that The minimum is 1 kΩ but we recommend at least 10 kΩ?

    Regards,

    Y.Ottey

  • 0 in reply to Y.Ottey
    TI__Genius 9375 points

    Y.Ottey,

    We generally recommend 10 kΩ pull up across our devices. As listed in the datasheet, you can get by with a 1 kΩ as the minimum and it should not cause any issues. Using a higher value could mitigate issues with heat from current draw. This is a very wide range between 1 kΩ and 1 MΩ, so it really depends on how you prioritize your strength of your pull up resistor.

    Thanks,
    Abhinav.