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Original question:

TPS61022: Reverse current in shutdown mode

TPS61022: shutdown and quiescent current

Martin Palenkic
Prodigy 30 points
Part Number: TPS61022

Tool/software:

Hello,

I am having a problem with high shutdown and quiescent currents. They are much higher than stated in the datasheet. 


You can see from the pictures below the input voltage and current with no load attached.

Shutdown current is 7.27 uA and it should be ~0.25 uA and

quiescent current is 44.4 uA and it should be ~0.9 uA

Can anyone help me understand what is happening? I am testing on a TPS61022RWU evaluation module and the only modification I did was to change the output voltage to 3.8V by adding a 530k resistor in place of R1 to adjust the output voltage. 

Other than that the controller works fine. But I need it for a battery powered device so these currents are too high.

Thank you in advance,

Martin

  • +1
    TI__Mastermind 18760 points

    Hi Martin,

    For the shutdown current measurement, could you try again with the C1 removed?

    For the Iq measurement, do you force 700mV at the FB pin?

    Regards

    Lei

  • 0 in reply to Lei Zhong
    Prodigy 30 points

    Hi Lei,

    Removing that 150 uF capacitor helped a lot. But I am still seeing higher current consumption when controller is turned off. Now it is around 4 uA. 

    In the figure below you can see input current and voltage measurements. First and third cursor ranges are with EN tied to GND and the middle one is with EN tied to Vin. No load was connected to the output, and MODE pin was tied to GND.

    I have also measured the Input, output and FB pin voltages. Please look at the results below.

    CH1 is input, CH2 is output and CH3 is FB pin.

  • 0 in reply to Martin Palenkic
    TI__Mastermind 18760 points

    Hi Martin,

    I just verified the shutdown current on one new EVM, only with the 150μF capacitor removed and no other changes.

    Then test when Vin = 5V, EN = GND, MODE = GND, no load. The measured shutdown current is around 0.25μA, matched with the datasheet spec well.

    If available, please check whether the accuracy of the current meter or tool used in your measurement is enough.

    Regards

    Lei 

  • 0 in reply to Lei Zhong
    Prodigy 30 points

    Hi Lei,

    You are right. I forgot to remove oscilloscope probes, and they were the cause for the higher current. 

    Now my device uses around 0.2 uA in shutdown mode and 30 uA in active mode. 

    Thank you for your assistance and help.

    Best regards,

    Martin