• State Resolved
  • Locked Locked
  • Replies 4 replies
  • Subscribers 63 subscribers
  • Views 179 views
  • Users 0 members are here
Support feedback
Options
Options
Similar topics

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.

Original question:

TPS56221: Problems with TPS56221

TPS56221: Low current max.

Jeremy howell
Prodigy 20 points
Part Number: TPS56221

When i try use a circuit i got from the WEBENCH that is supposed to able to source 25A the maximum current i can get is 500mA.  

Design ID: 11
Part Number: TPS56221DQPR
Design Name: TPS56221DQPR 5V-5V to 1.50V @ 25A
The ouput voltage is correct but the current is low.
Thank you.
  • 0
    TI__Genius 9280 points

    Hi,

    Do you mean the max loading current is 0.5A on your application ?

    What's the clamp current of your sourcing ?

    BRs,

    Young

  • 0 in reply to Young Zhao
    Prodigy 20 points

    The max current of the dummy load i am using should be around 12 A but all i am getting is 500 mA.  I am using a 5A power supply for the source at the moment. 

  • 0 in reply to Jeremy howell
    TI__Genius 14455 points

    Hi Jeremy

          The average input current with Vout=1.5V and 25A is 8.19A. So the input power supply will definitely limit it. Also, the input caps need to supply peak Iout of 29A when the load is 25A. If the input capacitors are not sufficient it would cause the input to drop.

    When you powered up with 0 load, did you get 1.5V at the output?

    When you increased the load current beyond 500mA, did the Vout drop or did the device shutdown?

    Can you please send us scope shots of the SW node and Vout when this is happening?

    Can you try replacing the source with something that is capable of supplying a higher current?

    Regards,

    Gerold

  • 0 in reply to Jeremy howell
    TI__Genius 9280 points

    Hi ,

    5A supply current can not support your out put on this condition .

    Assume eff=~87%, you can get the input current IVIN=VOUT*IOUT/Eff/VIN=8.6A > 5A .

    Please use a higher capacity source and check the output . thanks .

    And please also check the other component whether they can support on this application . thanks .

    BRs,

    Young