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TPS5405: VSENSE and Compensation pin design guidance.

Tim Eames
Prodigy 10 points
Part Number: TPS5405
Other Parts Discussed in Thread: TPS54335A

I have two questions regarding a design using the TPS5405 buck converter. My design is 12V Input, 5V Output. 0.5-1A current output.

1)
In the datasheet for the TPS5405, Pin 5 (VSENSE) is shown in an application diagram to be connected directly to VOUT.


However I found a separate application diagram from the same chip (TPS5405) where pin 5 (VSENSE) was connected to VOUT through a resistor divider

So i am wondering whether or not this resistor divider is necessary between Pin 5 and VOUT

https://www.ti.com/lit/df/tidrfx4/tidrfx4.pdf?ts=1637012592808&ref_url=https%253A%252F%252Fwww.ti.com%252Fproduct%252FTPS5405

I found the above schematic under "reference designs" on the TPS5405 TI webpage


2)
I am also curious about how to set the resistor and capacitor value for Pin 6 (Compensation)

I do not see any guidance listed in the datasheet on how to choose these values.

-Tim

  • 0
    TI__Genius 9280 points

    Hi Tim,

    1. Both of them are reasonable . The sch in DS is okay as this is a fixed 5V output and can save BOM. Another one is also good to me, as you may need measure the bode plot and you can take this Vout 5V as the reference voltage .

    2.For the compensation part, you can refer TPS54335A DS for this calculation.

    And may I check with you why you need this part for 12Vin ? 

    BRs,

    Young

  • 0 in reply to Young Zhao
    Prodigy 10 points

    Hi Young,

    Thank you for the responses, this helps.

    This part is in stock right now while a lot of others are not.  The TPS5405 also meets my current and voltage output requirements.  That is why I chose this part.

  • 0 in reply to Tim Eames
    TI__Genius 9280 points

    Hi Tim,

    Got it. 

    And I will close this case first, pls feel free to let us know if you have any other question.

    BRs,

    Young