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TPS55288EVM-045: Leakage on output when 0x06 set to 0x20 (as default)

Max Guan
Prodigy 50 points
Part Number: TPS55288EVM-045

During the test on TPS55288-045 EVM, a problem was observed that there is always a leakage on the output when I only applied 20V on VIN of the EVM. My EVM shows around 2-3V voltage on the output by default. 

I can set 0x06 to 0x30 to enable the output discharge then it goes 0 as expected, while as long as I set it to 0x20, the voltage rise again.

Is this expected? If not what can be the problem? And if yes, is there any method I can eliminate this?

Thanks

Max

  • 0
    TI__Mastermind 20480 points

    Hi Max,

    Thanks for reaching out. It is expected, we recommend to set DISCHG bit to 1 after power up.

    Regards,

    Bryce

  • 0 in reply to Bryce Xun
    Prodigy 50 points

    Hi Bryce,

    Thanks for confirming it. 

    I'm thinking about the system power loss in this case. I'll test later to check the extra power consumption cause by enabing this feature, Not sure but if internally the 100mA is generated through a current mirror, then I assume the extra power will be concerned in some mobile applications.

    By the way, could you quantify the leakage current from output into GND pin in this case? I want to check  the possibility to apply a pull-down resistance.

    Thanks

    Max

  • 0 in reply to Max Guan
    TI__Mastermind 20480 points

    Hi Max,

    The DISCHG will not cause power loss in steady state since discharge FET only turns on in shutdown mode(EN=0 or OE=0). So the external pull-down resistor is not needed and only need to enable DISCHG to make Vout=0V before write to OE=1.

    Regards,

    Bryce

  • 0 in reply to Bryce Xun
    TI__Mastermind 20480 points

    Hi Max,

    Since we have not seen an update from you for 9days, so I assume the questions are answered.

    I close this thread now. If there is still something open, please reply and the thread will get opened again.

    If you have any other question or of the thread has been locked, please open a new one.

    Clicking the Resolved Button also helps us to maintain this forum.

    Regards,

    Bryce