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Performance data for TPS23752 PoE DC-DC Converter Efficiency at High temperature

Rajkiran Subramani
Prodigy 80 points
Other Parts Discussed in Thread: TPS23752, TPS23754EVM-383, TPS23751EVM-104, TPS23752EVM-145, TPS23754, TPS23751, TIDA-00617

Hi,


We plan to directly re-use the TI's TPS23752 PoE DC-DC converter circuit to one of our internal reference design. We really concern about the PoE converter performance and efficiency at high operating temperature since the EVM data manual doesn't mention about .As part of internal bench test qualification we should need to validate the converter efficiency across 0~70 deg C under real functional mode of our system.

Please share TI's internal bench-test report for the same.

Regards,

Rajkiran

  • 0
    TI__Mastermind 41770 points

    Hi Rajkiran,

    Unfortunately we do not have this information for the TPS23752 EVM. However, I have done this exercise in the past from 25C-85C and the efficiency reduced by 2-3% with increasing temperature. You can use this as reference to gauge your expected performance. Also you can order an EVM and test its performance under the expected operating conditions of your application.

  • 0 in reply to Darwin Fernandez
    Prodigy 80 points

    Hi Darwin,

    Thanks for your feedback. We have the EVM kit already and testing it for our application.

    Will come back if there are any queries.

    Regards,

    Rajkiran

  • 0 in reply to Rajkiran Subramani
    Prodigy 80 points
    Hi Darwin,

    Do we get a dedicated local contact support from TI?
    We will start a new email thread for discussions since we may need a design review support as well at later point of time.

    Regards,
    Rajkiran
  • 0 in reply to Rajkiran Subramani
    Prodigy 80 points
    Hi Darwin,

    We bought three different reference EVM boards from TI( i.e. "TPS23751EVM-104"(VOUT -> 5V @ 5A),"TPS23752EVM-145"(VOUT -> 5V@4.5A) and "TPS23754EVM-383" (12V@2.5A) to test it with our internal reference design applications that should be powered from PoE input supply.
    Here we are actually looking for a PoE converter that would provide better efficiency values at 12V output under full load operations(let's say 24W). Just Incase if you could recommend the other two 5V modules(TPS23751 or TPS23752 designs) would provide better efficiency rating than TPS23754 design @ 12V, we may also even consider stepping down the VOUT supply from 12V to 5V output for our application.
    Please suggest us on which TI EVM design would best suitable for our requirement?

    Thanks,
    Rajkiran
  • 0 in reply to Rajkiran Subramani
    TI__Mastermind 41770 points
    Hi Rajkiran,

    For highest converter efficiency for class 4 applications, I recommend TIDA-00617. However, if looking for an EVM to evaluate a board with, I recommend TPS23752EVM-145.
  • 0 in reply to Darwin Fernandez
    Prodigy 80 points

    Hi Darwin,

    Thanks for your response.

    May we have your response for the below questions,

    • Do we know which EVM schematics design that you should recommend us to follow and implement in our reference designs?, we just currently follow the schematics design/BOM referred in "TPS23752EVM" manual to create our base design. http://www.ti.com/lit/ug/slvu753/slvu753
    • What are the design changes / reworks that would be needed to closely match TPS23752EVM-145 hardware for TIDA-00617 operation?
    • What is the design tool used for creating schematics and layout database? Can we share us the design files / CAD databases for reference?

    Thanks,

    Rajkiran

  • 0 in reply to Rajkiran Subramani
    TI__Mastermind 41770 points

    Hi Rajikiran,

    TIDA-00617 was tested on the TPS23752EVM board. So if looking for the highest efficiency, I recommend using the TIDA-00617 BOM/schematic.

    However, attached is the design files for the EVM to give you a head start on your schematic. This was designed using PADS.

    TPS23752EVM-145_Design.zip

  • 0 in reply to Darwin Fernandez
    Prodigy 80 points
    Hi Darwin,
    Thanks for sharing the design database.

    1. Do you have any recommended Manufacturer part number for current sense resistor R34 i.e. 0.09 Ohms?. We couldn't find the exact part number from TIDA-00617 BOM. Let us know the vendor details to enable component sourcing.
    2. TIDA-00617 board image shows the "T3" gate drive transformer was mounted with Pulse device(PA0184NL) on TPS23752EVM-145 board, but TIDA-00617 BOM had used Linksys device "LTC0266-50" .Which one should we choose here?

    Thanks,
    Rajkiran
  • 0 in reply to Rajkiran Subramani
    TI__Mastermind 41770 points
    Hi Rajkiran,

    1. As long as the power rating, accuracy, size (2010 package), and value are same, you can choose any resistor in digikey for example. ERJ resistors are a good start.
    www.digikey.com/.../5885646

    2. T3 can be either gate drive transformer. LinkCom and Pulse will give you options for second sourcing.
  • 0 in reply to Darwin Fernandez
    Prodigy 80 points

    Hi Darwin,

    Thanks for sharing the details.

    We are almost in final verge of completing the PoE circuit  implementation for TPS23751 DC-DC converter based on TI reference schematics. However, we would also have plan to include 5V external adapter to feed board's main 5V while PoE 5V is actually cut-off.  Rather we have known clearly how to disable PoE power when it detects 5V supply by disabling DEN (enable) pin of TPS23751 device to make it shut down properly.

    We actually thought of using very low VF Schottky diode to switch between two supply source.Do you have any other recommended switching circuit for the same? The max power consumption in external adapter mode wouldn't exceed 30W in that case.

    Please let us know the procedure to get engaged in direct email discussions for support with TI team/engineers? Because our team wants to start a new email thread with TI technical team to initiate Schematics/Layout review.

    Let us know your thoughts. 

    Regards,

    Rajkiran

  • 0 in reply to Rajkiran Subramani
    TI__Mastermind 41770 points
    Hi Rajikiran,

    I see no issues with using ORing diodes as this is commonly used. You can also look at TI's active ORing controller solutions if diode losses are too high.
    www.ti.com/.../oring-and-smart-diodes-overview.page

    As for an offline review, I can email you. Is your email correct in your my.ti.com profile? Thanks!
  • 0 in reply to Darwin Fernandez
    Prodigy 80 points

    Hi Darwin,

    Thanks for your Recommendations. We will review and get back with our solution

    Yes, you can email @ rajkiras@qti.qualcomm.com

    Regards,

    Rajkiran