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TPS1HB50-Q1: TPS1HB50-Q1 - Not proper power on

Selvakumar Sonai
Prodigy 80 points
Part Number: TPS1HB50-Q1

Hi Team,

Please find the schematic, we have seen some glitches at every power on its output.

Scope image :  

Please review the schematic and scope images. Let us know what are the reason may cause this problem, Let me know how do fix this. 

Thanks,

Selva

  • 0
    TI__Genius 16390 points

    Hi Selva,

    Could you probe the SNS pin voltage as well as the current so we can get more information? Also what's the load profile?

    Regards,

    Yichi

  • 0 in reply to Yichi Zhang.
    Prodigy 80 points

    Hi Yichi,

    Please find the change in the circuit, I changed the ISNS resistor value to 406 ohms.

    I removed the ILIMIT resistor, now it is in the open state. 

    and capture waveform at initial power on.

    Waveform 

    By calculation it is loading 7A during the power up condition.

    Thanks,

    selva 

  • 0 in reply to Selvakumar Sonai
    Prodigy 80 points

    Hi Yichi,

     Please find the Waveform 

    Channel 1 - Output 12V

    Channel 2 - ISNS - Current sense from pin 2 of TPS1HB50A-Q1

    Channel 3 - Current Probe at Input 12V.

    Current probe 100mV/A - So 1V peak is measured during power on. 1V/100mV = 10A.  

    Thanks,

    Selva

  • 0 in reply to Selvakumar Sonai
    TI__Genius 16390 points

    Hi Selva,

    This is likely due to current hits the current limit and shut off immediately. The SNS voltage is reading I(SNSFH)*R indicates there's a fault. Although the current reading is 10A compared to the internal threshold 14A, could you use a current probe and zoom in to see if it hits around 14A? 

    Is this behavior okay during start up? If not, maybe version B with higher current limit is more suitable in this application.

    Please let me know if you have additional questions.

    Regards,

    Yichi