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SN74LVTH240 - IV specification of Input pin

Ryuji
Guru 20090 points

Other Parts Discussed in Thread: SN74LVTH240

Hello,

Could you please let me know the IV specification of SN74LVTH240?

Currently , the open drain output is connected to the input of SN74LVTH240.
The Open drain output is connected to the 5V via 10kohm pull up.
Also, the open drain output is connected to the 0.7V via 2.7kohm pull down.

In this case, the voltage of open drain output should be 1.6V.
However the voltage is about 1.2V.
If we disconnect the SN74LVTH240, the voltage is 1.6V correctly.
Also if we change the pull up resister from 10kohm to 5kohm, the voltage is 1.6V correctly.
Thus I would like to know the input IV specification of the device.

Best Regards,
Ryuji Asaka 

  • 0
    TI__Mastermind 29905 points

    Hey Ryuji,

    From what you describe it is likely the SN74LVTH240 is pulling current through it's input from your pull up resistor. This would cause that lower than expected voltage on the input since the drop across your pull up resistor would be larger than expected. Note that the  II(hold) current is much larger than the II current. If SN74LVTH240 is in high impedance state on the output and the input still has the 1.2~1.6 V across it it will be drawing a higher than average current from your Vcc.

    Below is a diagram of what is happening if the device is in High Z:

    Thanks,

    Daniel

  • 0 in reply to Daniel Hartung
    Guru 20090 points
    Hello Daniel,

    Thank you for your support.
    Could you please let me know typ and max value of Il(hold) at Vcc=3V?
    There is only min value as +/-75uA.

    Our customer use the device as Vcc=3V.
    They measured the Il(hold) at the Vcc=3V, and the result is about +/-200uA.

    Best Regards,
    Ryuji Asaka
  • 0 in reply to Ryuji
    TI__Mastermind 29905 points
    Hey Ryuji,

    200uA is around the typical we expect on the device. I see that there is a max of 500uA for 3.6 Volts so we suggest you design around that value as your max. I cannot guarantee this max value however.

    Thanks,
    Daniel