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TPS4H000-Q1: Off-State Output Sink Current Definition

Shinichi Yokota
Genius 9715 points
Part Number: TPS4H000-Q1

Hello,

I'd like to confirm the direction of current of the parameter I(ol,off) - Off-state output sink current of TPS4H000-Q1. The data sheet has the negative value -75 µA as its Min, but since it's a negative value, does it mean a current flowing out from the OUTx pin? As the parameter name says "output sink current," I wonder if it may suggest a sink current that flows into the OUTx pin. Which is correct?

Best regards,
Shinichi Yokota

  • 0
    TI__Mastermind 28270 points

    Hello,

    in off state the FET is OFF,  means there is no current flowing from VS to VOUT.

    VS = VOUT means there is no current flowing from VOUT to VS through the body diode

    This is a sinking current flowing into the device by applying a voltage source on VOUT. It is due to internal circuitry connected to VOUT

    Regards

  • 0 in reply to Mahmoud Harmouch
    TI__Genius 9715 points

    Hi,

    Thank you for your quick reply. I understood the OUTx pin pulls a current of 75 µA at the maximum in off state when the OUTx pin is connected to 13.5 V.

    Please let me ask a next question. How much will the Max I(ol,off) current be reduced if both the VS and the OUTx voltages are down to 6 V? In my application, an off-state open-load condition must be detected, but the resistance of pull-up resistor R(PU) needed for open-load detection must be much bigger than the recommended 20 kΩ. I'm wondering if it can be because the supply voltage of the TPS4000-Q1 is 6 V in my design. I hope 100 kΩ or larger can be used with 6-V supply.

    Best regards,
    Shinichi Yokota

  • 0 in reply to Shinichi Yokota
    TI__Mastermind 28270 points
    Hello Yokota-san,

    The I(ol,off) sinking current is lower at lower output voltage. It is not characterized at 6V but my estimation is around half the value mentioned in the datasheet. That means 37.5uA. It may work with 100K by to be conservative, I suggest to use pull up resistor Rpu = V(ol,off) min/37.5uA = 42.6K.

    Regards, Mahmoud
  • 0 in reply to Mahmoud Harmouch
    TI__Genius 9715 points

    Mahmoud-san,

    Thank you for your comment. But I need more accurate estimate on the I(ol,off) value at VVS = 6 V. You assumed the I(ol,off) value will change linearly with VVS. Is it based on the device's internal architecture? If not, could you somehow confirm it or collect data on I(ol,off) vs. VVS with a few samples?

    Best regards,
    Shinichi Yokota