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PMP40286: REF to REF_RTN Connection

Genius 4635 points

Replies: 2

Views: 110

Part Number: PMP40286

In the datasheet for the TPS25810-Q1 is says to connect REF to REF_RTN with a 100k 1% resistor. In the layout guidelines it even lists some specifics:

The resistor attached to the REF pin of the device has several requirements:

  • It is recommended to use a 1% 100-kΩ low-temperature-cocoefficient resistor.
  • It should be connected to the REF and REF_RTN pins (pins 9 and pin 10, respectively).
  • The REF_RTN pin should be isolated from the GND plane. See Figure 29.
  • The trace routing between the REF and REF_RTN pins of the device should be as short as possible to reduce parasitic effects on current-limit and current-advertisement accuracy. These traces should not have any coupling to switching signals on the board

In the reference design schematic they list pin 9 as a ground pin and appear to treat it as just another pin. Further reading of the datasheet does state that REF_RTN is internally connected to ground but I think this schematic is not correct and could be overlooked by people reviewing it.

  • Hi George,
    I designed the project with the original datasheet. At the datasheet, pin9 is named GND, it is recommended to connect 1% 100-kΩ resistor between REF and GND. I tested the board, and didn't find any issue. However, the datasheet has been updated, we suggest that please follow the new datasheet for your design.

    Regards
    Linda
  • In reply to Linda Ye:

    Hi Linda,

    Thank you again for following up on this. It would be a good idea to add this information to the reference design so other's know the reason for the design not following the current datasheet.

    Regards,
    George

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