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TPS27081A: Leakage voltage issue

JH Shin
Mastermind 7115 points
Part Number: TPS27081A
Other Parts Discussed in Thread: TPS22918

Hello,

My customer encountered the leakage voltage issue on the VOUT of  the TPS27081A load switch.

Turn on +3.3V_RTC and even TPM_EN is 0V, the leakage voltage of about 0.8V is continuously output on the VOUT(TPM_PWR).

The customer changes TPM_EN to high, +3.3V is output to the VOUT. But, Changing TPM_EN to low again, about 2V is continuously output on the VOUT.

Please help us solve the issue.

Regards,

JH

  • 0
    TI__Mastermind 32650 points

    Hi JH,

    In this load switch, because it is only a PMOS + NMOS, it will be susceptible to the output coming up when the input is applied. The reason is because the capacitor that controls the timing also slows down the charge and discharge of the PMOS gate. Therefore, when the input is applied, it takes time for the PMOS gate to be pulled high (OFF), and during this time, the PMOS allows current to flow from IN to OUT.

    When EN is pulled low, what is the output load resistance? If there is no discharge path, the output voltage will be held at a higher value for a long period of time.

    If this behavior is not acceptable for your system, I recommend using our newer device like TPS22918. This device is easier to use and has same functionality.

  • 0 in reply to Shreyas Dmello
    Intellectual 450 points

    Hello, do you have any others suggestions that could be pin compatible if we want 0V at the output when off?

    Does adding a pulldown at Vout could be an acceptable patch for now while looking to another pin compatible part?

    Thanks

    David

  • 0 in reply to David Lacasse
    TI__Mastermind 32650 points

    Hi David,

    A pull down resistor could be added to the output of the device. If the continual discharge path is acceptable for your design, a discharge resistor can be added.

    Note with a larger pull down resistor, leakage from Vout to GND will be less but the discharge rate will be slower.

    We do not have an pin to pin replacement for this device as we have integrated a lot of the features into our newer devices.