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TPS706: The current of is not in the range of the datasheet.

Lian Wu
Genius 5250 points
Part Number: TPS706

Dears:

We are testing the TPS70630's Ground pin current under no load.

And the value is about 9uA, however, from the datasheet the value is between 1.3 and 2.55uA.

Why do it happen?

Pls. help us.

Thanks a lot!

Best regards

Luck Wu

  • 0
    Guru 140200 points
    Hi Lian,

    this could have to do with the input voltage. If it is too small the supply current can rise. Is the input voltage at least 1V higher than the output voltage?

    Kai
  • 0 in reply to kai klaas69
    TI__Guru 55940 points
    Hi Luck,

    The method of measurement as well as test conditions can impact the test results. How are you measuring Ignd?

    Very Respectfully,
    Ryan
  • 0 in reply to kai klaas69
    Genius 5250 points

    Hi Kai:

    OK, I will check it.

    Thanks!

    Best regards

    Luck Wu

  • 0 in reply to Ryan Eslinger
    Genius 5250 points

    Hi Ryan:

    Pls. refer the schematic, and we only weld TPS70630's circuit and no other chip to test Ignd by multimeter.

    Pls. kindly help to give some other advice.

    Thanks a lot!

    Best regards

    Luck Wu

  • 0 in reply to Lian Wu
    Guru 140200 points
    Hi Lian,

    and how do you measure the GND pin current of TPS70630? Do you open the connection from the "GND" pin to GND and insert the multimeter? Or do you measure the current flowing into the "IN" pin? This would be nearly the same, if you want to measure the current under no load.

    And how high is your input voltage?

    Kai
  • 0 in reply to kai klaas69
    TI__Guru 55940 points

    Hi Lian,

    Thanks to Kai for being a little more clear than me with asking how you are making the measurement.  In general we recommend against breaking the GND pin connection to the GND plane of the PCB in favor of Kai's other suggestion of measuring the current entering IN.  Measuring the IN current will equal Ignd as long as you allow the output capacitors to fully charge before taking the measurement since any leakage through the capacitors is negligible.  This measurement method is far easier to implement and reduces the risk of causing instability by providing a more direct connection to GND.

    Very Respectfully,

    Ryan