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TPS2419: TPS2419 leakage current

?? ??
Prodigy 10 points
Part Number: TPS2419

Tool/software:

Dear TI

Regarding the TPS2419 circuit, why is 12VCAP outputting about 1.2V when V1 switch is OFF and V2 switch is ON?

We have confirmed that the gate signal of TR515 is 0V.

I suspect that the leakage current of IC510 is the cause, so I put a 1kΩ resistor between 12VCAP and GND and checked it, but it was about 0.6V.

How should I take countermeasures?

  • 0
    TI__Mastermind 30730 points

    Hi,

    It can be because of leakage from C to A internally.

    Bleeder resistor should minimize the voltage buildup on 12VCAP.

    Regards,

    Shiven Dhir

  • 0 in reply to Shiven Dhir
    Prodigy 10 points

    Hello Shiven Dhir,

    Please give me specification values and actual measured data of leakage current from C to A.
    Voltage condition is 12V.

  • 0 in reply to ?? ??
    TI__Mastermind 30730 points

    Hi,

    We donot have EVM for TPS2419, since you have a board ready, can you add resistors in the path as shown and check for voltage drop across them?

    This will help in knowing the current entering and leaving. You can repeat this experiment with external MOSFET installed and removed.

    Regards,

    Shiven Dhir

  • 0 in reply to Shiven Dhir
    Prodigy 10 points

    Hi,

    With TR515 unmounted, I confirmed that IC510 C: sink current 4.23mA IC510 A: source current 0.79mA is generated.

    Are these current values correct as IC characteristics?

    I am confirming gate OFF. Is the condition of gate OFF included in “Gate in active region” in the following table?

    If not, please tell us the A current value and C current value of the gate OFF condition.

    The voltage requirement on the cathode side is 12V.

    What is the path of leakage current from C to A?

    Is it mainly due to resistance + diode (leakage)?

  • 0 in reply to ?? ??
    Prodigy 10 points

    Hi,

    This is just a friendly reminder that we have not yet received your response.

    Regards.

  • 0 in reply to Shiven Dhir
    Prodigy 10 points

    Hello Shiven Dhir,

    This is an important matter, please respond.

    Regards,

  • 0 in reply to ?? ??
    TI__Mastermind 30730 points

    Hi,

    Can you measure GATE and BYP voltages as well.

    Next, can you tie EN resistor ladder to C and repeat the test?

    Regards,

    Shiven Dhir

  • 0 in reply to Shiven Dhir
    Prodigy 10 points

    Hello Shiven Dhir,

    The terminal voltage of TPS2419 was measured.

    (1) Before circuit change

    A[V] C[V] GATE[V] BYP[V] EN[V]
    0.657 11.915 0.016 11.070 0.657

    (2)After circuit modification (Connect the EN resistor to C)

    A[V] C[V] GATE[V] BYP[V] EN[V]
    0.655 11.910 0.014 11.063 2.929

    Regards,

  • 0 in reply to ?? ??
    TI__Mastermind 30730 points

    Hi,

    Wasnt the leakage voltage at ANODE pin = 1.2V? Did anything change in setup that we have 0.6V now.

    Also, thanks for the voltage levels. I will continue to find the leakage path.

    Regards,

    Shiven Dhir

  • 0 in reply to Shiven Dhir
    TI__Mastermind 30730 points

    Hi,

    We do have some leakage path from C to A which is caused by some diodes and cannot be quantified because of very low value.

    Keeping ANODE floating is the cause of some voltage build up. Adding a pulldown resistor of 1Meg range should help and you won't see voltage.

    Regards,

    Shiven Dhir

  • 0 in reply to Shiven Dhir
    Prodigy 10 points

    Hello Shiven Dhir,

    I am aware of the diode leakage current value.
    I added 1MΩ pull-down resistor as you suggested, but the A voltage resulted in 1.36V.
    With a 47kΩ pull-down resistor, the A voltage is 0.94V, and with a 22kΩ pull-down resistor, the A voltage is almost 0V.
    I would like to keep the A voltage as low as possible (0.3V or lower if possible),with a pull-down resistor of 1MΩ, the A voltage does not drop.
    If the pull-down resistor is made too small, it will result in a steady-state loss, so is there any countermeasure other than a pull-down resistor?

    Regards.

  • 0 in reply to ?? ??
    TI__Mastermind 30730 points

    Hi,

    Bleeder resistor is the only countermeasure. The leakage can not be stopped.

    Regards,

    Shiven Dhir