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Original question:

TPS54325: Frequency responce for DCAP2

TPS54325: Power Good Resister

Ryoma Ohashi
Intellectual 2900 points
Part Number: TPS54325

Hi team,

My customer is using TPS54325 and have a question with it.

In the datasheet 8.3.2 "Power Good", it says:

" R_PG resister value ,which is connected between PG and VREG5, is required from 20 kΩ to 150 kΩ"

But currently, my customer is not putting this resister.

So my questions is,

What would happen if they don't put that R_PG?

i know that it is required, so I will ask the customer to install it.

But I would like to know the reason why it is needed, to explain it to the customer.

Regards,

Ohashi

  • +1
    TI__Mastermind 23120 points

    Hi Ohashi-san,

    I do not have the history behind the power good resistor range chosen here but it may be a combination of the maximum current through the PG pin and also how much current the VREG5 pin (internal LDO) can handle while supplying internal circuits like gate drive as an example. I would recommend sticking to the datasheet specified range.

    Thanks,

    Amod

  • 0 in reply to Amod Vaze
    TI__Intellectual 2900 points

    I have an additional question.

    When Vcc is 5V, and PG pin is pulled up by 3.3V DC,

    does the customer have to put R_PG between PG pin and VREG5?

    Regards,

    Ohashi

  • +1 in reply to Ryoma Ohashi
    TI__Mastermind 23120 points

    Hi Ohashi-san,

    R_PG is the pull-up resistor to be connected between PG and the source pulling up the PG pin, in this case, the 3.3V source.

    By default, we recommend using the VREG5 voltage to pull up PG pin so the R_PG resistor is between PG and VREG5.

    Thanks,

    Amod