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TPS63000-Q1: When VIN is in the range of 1.8V to 2.2V, current limiting occurs.

Part Number: TPS63000-Q1

Hello
we are using TPS63000IDRCRQ1 in our project.
When VIN is in the range of 1.8V to 2.2V, a large current flows through the device independently, causing current limiting(The power supply unit will flow up to the limiter 800mA).
VCC5.3V=0mA (no load).
Please tell us the cause and the solution.
Thank you.

L1 3.3uH
C2 0.1u
C4 10u
C5 100p
C8 0.1u
C9 47uF
R5 100
R15 1.74M
R16 180k

-NG Waveform(VIN=1.8V)                                                     -OK Waveform(VIN=2.5V)

  • Hi,

    UVLO triggered when VIn is 1.8V.  To avoid unexpected UVLO, you should increase your input cap, a small cap in parallel with R15 will help too.

    The power supply is battery or something esle? If it is battery, it will never start-up when it is voltage is 1.8V, right? always start-up with a higher input.

    Regards

    Tao

  • Thank you for the prompt response.

    It seems that we are implementing the following two measures. I will give them a try:
    - Measure 1: Increase the input capacitance by adding more to C4 and C5.

    - Measure 2: Add a small capacitance in parallel with R15, which has a resistance of 1.74 MΩ.

    The power source is a battery. It will not start up whenever the voltage is 1.8V; it will start up only when the voltage is above 2.2V.

  • Hi 

    Sounds good.

    Since the start-up voltage will be 2.2V or higher and EN is under control, i think another way to avoid unexpected UVLO is set a delay of EN.  to make device start switching when Vin is stable high.

    Regards

    Tao

  • Hi

    I followed the advice and tried connecting a small-capacity capacitor in parallel with R15.
    The current limit no longer occurs.
    Thank you for the advice.