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TLV3401 open-drain pull-up voltage requirements

Eduardo Rey
Prodigy 80 points
Other Parts Discussed in Thread: TLV3401

I am using the TLV3401 comparator in a design where I currently have the open drain pull-up voltage set to +3.3V while powering the device with a single +5V supply.  This is working properly as it is now but I would like to change the pull-up voltage to +1.8V.  I could not find any pull-up voltage requirements on the datasheet for the comparator's output so I want to make sure that part will continue to work as intended with the +1.8V.  Thanks for your time.

  • 0
    Mastermind 7395 points

    I don't think that voltage is an issue, I would say that the issue is current. If the pullup resistor is very small, you will have a lot of current and the output voltage for low status will not be low enough, check the graphs at page 6 of the datasheet. On the other hand, if the pullup resistor is very high, the transition from low to high will take a lot of time.

    I would say that for 1.8V, you should plan for a sink current of less than 0.2mA at low level output. Actually it depends on the voltage level you want to ensure while output is low.

  • 0
    TI__Guru* 93105 points

    Hi Eduardo,

    I reviewed the TLV3401 internal schematic and the output is simply an open-drain, NMOS transistor, with its source at the VGND potential. There are no back connections form the drain to the Vcc rail via ESD cells, or anything.  Even though the NMOS device's gate will be swinging over a wider voltage range than its drain this should not be a problem for the device.

    Regards, Thomas

    PA - Linear Applications Engineering