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TPS22915BEVM-078: Maximum current carrying capacity of Quick output Discharge (QoD) MOSFET/resistor

Akshay Yembarwar
Prodigy 50 points
Part Number: TPS22915BEVM-078

Hi,

I am planning to use TPS22915B to enter into ship mode for my device. While entering into ship mode (commands sent over USB), I have a condition where the switch is turned off but because I have a USB connected, VOUT pin of TPS22915B still sees a voltage (approx 4.5V). I then remove the USB to go into actual ship mode.

I want to know the maximum current handling capacity of the MOSFET connected between VOUT and GND. Currently I can measure upto 30 mA flowing through it. 

  • 0
    TI__Mastermind 32650 points

    Hi Akshay,

    The current through the quick output discharge is limited by the internal pulldown resistor. The typical specification of 143Ohms was tested at 3.3V but the device is rated up to 5.5V.

    At 5.5V, the current through the QOD is typically 5.5V/143Ohms = 38.4mA.

    In your situation, if 30mA is the maximum current seen, the internal QOD should be fine.

    Thank you for choosing TI Power Switches in your designs.

  • 0 in reply to Shreyas Dmello
    Prodigy 50 points

    Thank you Shreyas!

    I had one more question, the datasheet does not specify the minimum resistance on the internal pulldown resistor. So is there a maximum current that can safely flow through it?

    Example: If internal pulldown resistor is 100 ohms,

    Current through QoD = 5.5/100 = 55 mA

    Is this still within typical operating conditions?

  • 0 in reply to Akshay Yembarwar
    TI__Mastermind 32650 points

    Akshay,

    TI does not spec a minimum pull down resistance value so I cannot guarantee a "maximum" pull down current value. 

    What I can say for sure is that if the voltage on the pins are within the operating spec listed in the datasheet, the device will behave as expected.