• State TI Thinks Resolved
  • Locked Locked
  • Replies 12 replies
  • Answers 5 answers
  • Subscribers 64 subscribers
  • Views 1004 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.

TPS23521: Request the Reference Design for -48V, 1.6KW

Louis Han15
Genius 4680 points
Part Number: TPS23521
Other Parts Discussed in Thread: , LM5067

hello

My Customer Request the Reference Design for -48V, 1.6KW.

What should I do when Retry Behavior status?

Load Condition : -48V, 7A

Used TPS23521EVM-001.


  • 0
    TI__Guru** 105611 points
    Hi Louis Han,

    Can you please elaborate the statement "What should I do when Retry Behavior status?" and test waveform.

    Best Regards,
    Rakesh
  • 0 in reply to Rakesh
    Genius 4680 points

    Hi Rakesh

    I Tested the TPS23521EVM-001 for below Condition.

    VIN : -48V

    VOUT : -48V

    LOAD Current : 7A

    When Q2 Gate Enable, It does not operate due to inrush current.

    but When the load current is reduced to 2A, it does operate.

    TPS23521EVM-001 support the 1.2kw.

    What should I do to operate for have 7A load current?

    Regards.

  • 0 in reply to Louis Han15
    TI__Guru** 105611 points
    Hi Louis Han,

    What is the end equipment for this reference design? What is the downstream load - is it DC-DC?
    Are you trying to start load of 7A. TPS23521EVM-001 supports start up load less than 1.5A. Can you please have a look at "9.2.2 Detailed Design Procedure" in the datasheet.
    To start higher loads, use PG signal to enable the downstream load.

    Best Regards,
    Rakesh
  • 0 in reply to Rakesh
    Prodigy 150 points

    You comment that "TPS23521EVM-001 supports start up load less than 1.5A. ... To start higher loads, use PG signal to enable the downstream load."

    And according to its datasheet (page 24), "It is critical to keep the downstream DC/DC off while the hot swap is charging the bulk capacitor."

    So, I think TPS23521 only allows the sequential ON for downstream load (for example DC-DC module). That is the downstream load should be turned on after hot swap turning on (maybe until charing the output bulk capacitor)

    If not, let me know that how the hot swap circuit to turn-on simultaneously with its downstream load (in case that the load is greater than 1.5A) 

  • 0 in reply to Michael Chang
    TI__Guru** 105611 points
    Hi Michael Chang,

    This comment holds true for all the hot-swap devices. It is not possible to power up the down stream load while charging large bulk capacitor, as this situation causes severe SOA stress for the Hot-swap FET.

    However, simultaneous turn-on the downstream is possible if the system uses minimal bulk capacitor.

    Best Regards,
    Rakesh
  • 0 in reply to Rakesh
    Genius 4680 points
    Hi Rakesh
    Thanks for your support
    i will feedback to test result after use PG Signal.
    Regards.
  • 0 in reply to Louis Han15
    TI__Guru** 105611 points
    Hi Louis Han,

    Do you have any further questions on this? else can you please close this thread

    Best Regards,
    Rakesh
  • 0 in reply to Rakesh
    Prodigy 150 points

    Dear

    I agree with your comment, that is "It is not possible to power up the down stream load while charging large bulk capacitor". 

    The downstream load would be turned on after some delay. However there seems to have some difference between other hot swap controller and TPS23521. 

    Assuming that the downstream have bulky capacitance and no sequential turning-on circuit, TPS23521 cannot fully turned on and will enter into hiccup mode. In some other hot swap controller, they will start successfully and after some delay the downstream load will turn-on automatically. The latter needs for no forced delay circuit. 

    Is it right or wrong?

  • 0 in reply to Michael Chang
    TI__Guru** 105611 points
    Hi Michael,

    The one major difference between TPS2352x and other hot swap controllers is TPS2352x provides dual current limit for better FET SOA protection. TPS2352x sets lower current limit during startup (high Vds), which increases startup time while charging large cap loads.
    However, when the system has large output cap (for example mF range), it is difficult to simultaneously power load while charging so PG signal has to be used even for other hot-swap controllers.

    Best Regards,
    Rakesh
  • 0 in reply to Rakesh
    Prodigy 150 points

    Thank for your reply.

    But you seem to misunderstand my query. I understand that the hot swap and its downstream cannot turn on simultaneously under bulky output capacitance. 

    Unlike TPS23521, LM5067 never enter into hiccup mode during start-on (although its output capacitance is over 1mF) . Of course LM5067 also have some delay time until its downstream load turns on.

    I want to ask another question - that is TPS23521 can handle load of 1600W@48V maximum?

    If not, pls recommend proper hot swap IC.

  • 0 in reply to Michael Chang
    TI__Guru** 105611 points
    Hi Michael,

    LM5067-1 latches off and does not enter hiccup mode where as LM5067-2 (auto-retry version) does hiccup mode similar to TPS23521.

    TPS23521 can be used to support 1600W@48V.

    Best Regards,
    Rakesh
  • 0 in reply to Rakesh
    Prodigy 150 points
    You're exactly right. They used LM5067-1 (latch-off version). But I still wonder, ... If LM5067-1 enter into protection and then latched-off, how to restart automatically without recycling input voltage or enable signal.