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TPS54A20: Why do you recommend a pullup resistor between the values of 10kΩ and 100kΩ ?

gomi.ryota
Prodigy 140 points
Part Number: TPS54A20

Hi, TI expert

Why do you recommend a pullup resistor between the values of 10kΩ and 100kΩ ?

When connected to VG+, I think that the voltage value obtained by dividing 5V with the internal resistance of the PGOOD pin and the pull-up resistance can be measured.

With that balance in mind, do you recommend 10k to 100kΩ?

If so, please tell me what the internal resistance value is in ohms.

Also, when PGOOD is high, I assume that VPGOOD = VG - RPGOOD*IPGOOD [V] is input to the IC, what is it used for?

Best regards.

  • +1
    TI__Expert 6986 points

    Hi Ryota-san,

    PGOOD pin is an open-drain output, with high impedance (~5MΩ) when PGOOD is pulled high and low impedance (~150Ω) when PGOOD is pulled down.

    Between 10kΩ and 100Ω is what we recommend. Lower resistance will dissipate more power, so it's not recommended. Higher resistance will create a weak pull-up, so it's also not recommended.

    PGOOD signal is an output that can be used for applications such as voltage sequencing, etc. If not used, you can leave this pin open.