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TPS63810: VOut> VIN, Bypassing for lowest power consumption

Chris Schramm
Intellectual 590 points
Part Number: TPS63810
Other Parts Discussed in Thread: LM66100,

Dear TI-Team,

In an application where a battery delivers the necessary power most of the time, the 11uA lowest Iq will still be a significant number.

What happens if VIN=EN=0V and Vout, eg, 3.7V? In the d/s reverse current is only mentioned for PWM operation.

If some sort of ideal diode is required, could a simple addition of LM66100 in series with Vout do the job?

If it is added closely to TPS63810, will there be caps required? Output capacitance is high (LTE-M cellular modem with about 800uF)

  • 0
    TI__Expert 7925 points

    Hi Chris,

    Thanks for reaching out.

    If you disable the device (EN=0), the output will be in high-impedance state, it will float. If you apply a voltage to the output there will be some small leakage current, as long as the applied voltage is within the recommended operating conditions. We do not characterize this leakage current in details, but if you apply 3.3 V at VOUT while VIN=EN=0, this reverse leakage current is typically 0.1 μA at room temperature, and maximum 1 μA over the whole recommended range. At VOUT = 3.7 V, it should be just a bit higher.

    Therefore, you do not need to use a diode for reverse current protection.

    Best regards,
    Milos



  • 0 in reply to Milos
    Intellectual 590 points

    Awesome, Milos, thank you. I guess this IC is the perfect fit for our use case then.

    For our high output capacitance and given that the modem and its caps are on an external board, is 1x 22uF Cin and 1x 22uF okay?

  • 0 in reply to Chris Schramm
    TI__Expert 7925 points

    Hi Chris,

    The minimum recommended input effective capacitance is 5 μF. The 22-μF capacitor for the input side should probably be fine, but please check the voltage derating for the capacitor you are using. 

    As for the output, we recommend minimum 13 μF effective low-ESR capacitance as close as possible to VOUT. Could you please tell me what do you have downstream the 3.7-V rail? What type of capacitors (ceramic/elko/tantalum), nominal values, and how far away they are?

    Best regards,
    Milos