• State
  • Locked Locked
  • Replies 6 replies
  • Subscribers 63 subscribers
  • Views 292 views
  • Users 0 members are here
Support feedback
Options
Options
Related

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.

TPS63900: Issue with High Quiescent Current (Iq) at No Load: Layout Review

Ashok R41
Intellectual 360 points
Part Number: TPS63900

We are using TPS63900 in one of our designs. At no load, the TPS63900 is drawing 6mA, a value significantly higher than the specified quiescent current (Iq) of 75nA as indicated in the datasheet. The problem might be related to the layout, and we need someone to review it. The placement and layout of the TPS63900 are displayed below. The battery is connected through a 75mm cable. Should we consider adding one more bulk capacitor at the input of the TPS63900?

Schematic:

Placement:

 

Layout:

  • 0
    TI__Mastermind 32350 points

    Hi,

    Seems your schematic and layout are both ok, it should not cause a high consumption by them. is it possible you can help to capture the current of inductor?

    Except unexpected high consumption, other behaviors are ok, right?

    About more input caps, it is depend on  model of input cable, just make sure there is no big ripple and overshot at input is enough.

    Regards

    Tao

  • 0 in reply to Tao Zhang
    Intellectual 360 points

    Hi,

    Thank you for reviewing the layout. I forgot to mention that it's a 4 layer board. The nearest ground (GND) via to the ground terminal of the input capacitor is 4mm away. Could this lead to an increase in current?

    Regards

    Ashok

  • 0 in reply to Ashok R41
    TI__Mastermind 32350 points

    Hi  Ashok,

    It should not cause a high consumption at no load too.

    Regards

    Tao

  • 0 in reply to Ashok R41
    TI__Guru 65200 points

    Hello Ashok,

    How do you measure the input current? In addition, are you sure that there is absolutely no load current? E.g. some resistor dividers for something on the output or so.

    Best regards,
    Brigitte

  • 0 in reply to Brigitte
    Intellectual 360 points

    Hi Brigitte,

    The current input is measured using a multimeter connected in series between the battery and the input of TPS63900. The output of TPS63900 is open.

    Regards

    Ashok

  • 0 in reply to Ashok R41
    TI__Guru 65200 points

    Hello Ashok,

    The TPS63900 is achieving the low current by long sleep times between the pulses. So if you are using a multimeter you need to make sure that it samples very often before it shows a value to get an accurate value. Multimeters very often give RMS current which is in general higher than average current if you have pulsed currents.

    Please as well check the leakage of the input capacitor you are using.

    You could for example as well check to remove TPS63900 from the board and then check the input current you are measuring on the board with the external components alone.

    Best regards,

    Brigitte