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SN65HVD485E / Calculation of IIH

Ryuji
Guru 20090 points

Hello,

Could you please let me know the calculation method of IIH and IIL?

If Vcc=5V and VIH=2V, Is IIH (5V-2V)/(200kΩ+500Ω) = 15uA ?
I think that this calculation is wrong due to the datasheet specification is -30uA(typ).



Best Regards,
Ryuji Asaka

  • 0
    TI__Mastermind 20820 points
    Hi Ryuji,

    I need to double check with the designer that the equivalent circuit in the data sheet is a good representation for this calculation. I will follow up with you when I have a suitable answer.
  • 0 in reply to Michael Peffers
    Guru 20090 points

    Hello Micael san,

    I'm looking forward to your reply.
    Thank you.

    Best Regards,
    Ryuji Asaka

  • 0 in reply to Ryuji
    TI__Mastermind 20820 points
    Hi Ryuji,

    The typical circuits that are shown in the data sheet cannot be used to calculate IIH and IIL values as they are not 100% true to the design of the circuit. These circuits are used to give a general description of the circuit functionality that is being implemented on die.

    I did pull the ATE data from the most recent lot of wafers that ran through the fab and the IIH/IIL values are within data the data sheet specification as expected. Thanks and please let me know if you have any other questions?
  • 0 in reply to Michael Peffers
    Guru 20090 points

    Hello

    Thank you for the reply.
    Could you please let me know the difference between Equivalent Schematic and actual Schematic ?

    Are there the variation in the resistance ?
    Or are there any protection circuit which adding the IIH/IIL?

    Best Regard,
    Ryuji Asaka

  • 0 in reply to Ryuji
    TI__Mastermind 20820 points
    HI Ryuji,

    This information proprietary to our process and cannot be disclosed for obvious reasons.

    Of course there will be variations in resistance over process and temperature but we meet the IIH and IIL spec that is outlined in the data sheet. This empirical data was collected across worst case conditions and many devices during the characterization process before the IC was released to market and it is verified time and time again during the fabrication process.

    There is an ESD protection circuit on the input and it can be seen in the "equivalent" circuit diagram in the data sheet. The ESD structure would be a source of additional leakage current adding to the 15uA that you have already calculated.

    I hope this was helpful, please let me know if you have any additional questions.
  • 0 in reply to Michael Peffers
    Guru 20090 points

    Hello Michael san,

    Thank you for the information.
    Our customer add the pulldown resistor to DE, RE pins.
    Thus I checked the internal resistor variation.
    Then, our customer calculate the internal resistor by IIH,IIL and they determine the pulldown resistor value.

    If this pulldown resistor has problem, please let me know.

    Best Regards,
    Ryuji Asaka