• State Resolved
  • Locked Locked
  • Replies 3 replies
  • Answers 1 answer
  • Subscribers 63 subscribers
  • Views 274 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.

TPS23754: TPS23754 design-in questions

Borge Strand-Bergesen
Intellectual 710 points
Part Number: TPS23754

Hi, 

I'm in the process of implementing the tps23754 as a modified copy of the TPS23754EVM-383 reference design. To finish my implementation, please help out with the following questions:

- I have no external power adapters. Can I then short VDD to VDD1?

- We wish to use the end product outdoor. Section 8.2.2.2 in the datasheet says "Outdoor transient levels or special applicatons require additional protection". Do you have recomendations or reference literature on such additional protection?

- Reference design slvu304c.pdf Figure 1: Does the active output rectification need a DC path or discharge of Q3 and Q5 gate pins?

Thanks,

Børge

  • 0
    TI__Mastermind 21320 points

    Hello Borge,

    Thank you for your interest in TI PoE solutions. To answer your questions:

    - Yes short VDD and VDD1. Please refer to datasheet for more information

    - 

    - I am not sure what you mean, but the circuitry on the output is necessary. The circuits connected to the gate of Q3 and Q5 force a faster turn off which we have found to be necessary. We include this on almost all active clamp forward designs, especially since this design is 12V. 

    If this answers your question, please mark the thread as resolved. Thank you!

    Regards,

    Michael Pahl

  • 0 in reply to Michael Pahl
    Intellectual 710 points

    Hi Michael, 

    Thank you very much! I'm getting close to finishing the design and ordering the prototype PCB. Just one more question if you don't mind:

    The soft start circuits in datasheet (tps23754.pdf Figure 35, Dss) and reference design (slvu304c.pdf Figure 1, D11) are slightly different. Which one should I use? 

    Thanks,

    Børge

  • 0 in reply to Borge Strand-Bergesen
    TI__Mastermind 21320 points

    Hello Borge,

    Good question. Use the one in the reference design slvu304c . 

    The one in the datasheet is a simplified version, more like a suggestion. The one in the reference design is how it 'actually' plays out in a circuit, and the design we follow for most all of our opto feedback systems. 

    If this post answers your question, please indicate so by marking this thread as resolved. Thank you.

    Regards,

    Michael Pahl