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TPS2556: over-current response time for TPS2556

Oliver Ou
Intellectual 2845 points
Part Number: TPS2556

Hi, Team,

Customer found the over current response time in TPS2556 is longer than the topical values on datasheet. Could you help to check and give a comment? Thanks,

Oliver Ou

--------------

Figure 1 is a current-limit circuit using the TPS2556 chip on the USB side. When P5V_USB1 is short-circuited to test the short-circuit current, the waveform we caught is shown in Figure 2:
Among them, tios = 14.5us, but the over-current pulse time in the spec is about 3.5us.
I would like to ask you what factors are affected by the value of tios?
  • 0
    TI__Mastermind 26390 points

    Oliver,

    The response to this E2E by the most knowledgeable person will be delayed because most of the support team is out of the office for the Chinese National holiday.  I do not have enough detailed knowledge of the part to answer this question.

    Someone will get back to you in early February.  I apologize for the delay.

    Regards

    Chuck\

  • 0
    TI__Expert 3275 points

    Hi Oliver,

    How do you test the waveform, Could you help check below?

    1. Could you check below, what's the Vin cap, Vout cap for test circuit?

    2. How do you short the OUT?

    Best regards,

    Feifei

  • 0 in reply to Feifei Shen
    TI__Intellectual 2845 points

    Hi Feifei,

    1, the input cap is 0.1uF/16V and closer to the input pin of IC.

    2. short the output to Ground directly with tweezers.

    The current is tested from the input side.  

    Could you verify it on our EVM board since we do not have it on hand?

    Thanks a lot. 

    Oliver Ou

  • 0 in reply to Oliver Ou
    TI__Expert 3275 points

    Hi Oliver,

    For our datasheet test, pls use below:

    1. Suggest input cap close to IC pin and increase to 22uF + 0.1uF, make sure Vin is not drop during the transient;

    2. Decrease output cap to 0.1uF;

    3. Short the output again and check the Iout current;

    Best regards,

    Feifei