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TPS62136: FB2 as GND for FB pin

Bernhard Boehmer
Expert 1110 points
Part Number: TPS62180
Other Parts Discussed in Thread: TPS62136

Hello TI,

Paragraph 10.3.4 of slvsdv2 refers to noise on the GND connection and in Figure 80 suggests using the FB2 pin (with VSEL high) as a cleaner GND reference for the SS pin.

Would this method also pertain to the FB pin resistors (when not otherwise utilising the FB2 feature)? I.e. is FB2 used in this fashion a better GND reference for FB (than GND) since the power current demand is not shared here?

  • 0
    TI__Guru**** 150770 points
    Hi Bernhard,

    The TPS62180 does not have a VSEL pin. The SLVSDV2 that you refer to is for the TPS62136. Did you also have a question on something with the TPS62180?

    On the TPS62136, we do not see high noise which would make this needed, as in the case of the SS/TR pin under some conditions. Let me check if there would anything against doing this.
  • 0 in reply to Chris Glaser
    Expert 1110 points

    Hello Chris,

    Correct, sorry, I got the parts mixed up. I was indeed referring to the TPS62136 (could you perhaps fix the P/N in this thread?).

    It would be great if you could check, thanks.

  • 0 in reply to Bernhard Boehmer
    TI__Guru**** 150770 points
    Thanks for clarifying. I changed the part number in the title.

    This would not be an improvement for the FB divider. First, the Vout regulation is already very tight so there is little room to improve. Second, the internal structure of the SS/TR pin has different considerations than the FB pin, which make the application circuit in Figure 80 possible.