• State TI Thinks Resolved
  • Locked Locked
  • Replies 2 replies
  • Answers 1 answer
  • Subscribers 63 subscribers
  • Views 218 views
  • Users 0 members are here
Support feedback
Options
Options
Related

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

TPS7A94: Need clarification on setting V_EN_UV externally

Al Sa
Prodigy 10 points
Part Number: TPS7A94

Hi,

I would like to set EN_UV externally using a voltage divider.  Sheet 33 isn't quite clear though.  Normally, I would expect that if I have Vin, Rtop, Rbottom per Fig 8-6, that the expected voltage at which the regulator turns on would be Vin * Rbottom/(Rtop + Rbottom).  However, in Equations (1) for Rtop, I'm unclear as to what Von and Vih(uv_en) are. 

Let's say that my target voltage for Vout is 3.3V (OUT pins).  My input Vin is 5V and I would like the regulator to turn on when Vin reaches 4.3V.  Then do I set Von to 4.3V in equation (1)?  And is Vih(uv_en) always typically 1.2V or is this what I want to set to 4V, and Von should be something else?

Thanks

  • 0
    Prodigy 10 points

    typo -  I meant 4.3V in the last question.

  • 0 in reply to Al Sa
    TI__Expert 5430 points

    Hello Al,

    V_ON is the targeted voltage at which the regulator turns on. V_IH(EN_UV) is the EN_UV trip point rising to enable the device which ratings are specified in the datasheet (typical 1.2V).

    In this case if you want LDO to turn on when Vin reaches 4.3V, then that will be you V_ON. Yes, V_IH(EN_UV) is typically 1.2V so you will input this into Equation 1 of section 8.1.2 of datasheet. Which simplifies to: R(Top) <= R(Bottom) x 21.5.

    Best,

    Eunize Tobias