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DS26LV32AT: Input impedance model

Luis Abril
Prodigy 20 points
Part Number: DS26LV32AT


I have to protect against lightning and interferences telecommand and data lines RS422 which uses a DS26LV32AT as receiver. Therefore I would like a model of the receiver inputs to carry out Spice Simulations attacking the receiver input with waveforms about 250 V and 10 A:

1- I have tried the Ibis model but the results don´t convince me because it doesn’t include the ESD clamping diodes. I´ve developed a model by advice of other designers that you can see in file Capture1_Zin, do you think is a proper model for the inputs, let´s say pins 1 &2? Can you provide me a model of the receiver input impedance?.

2-I have to apply waveforms that are mainly pulses or damped sinusoids, if the maximum ratings are exceed for a time let´s say 30 uS, how I could asses if the driver has survived the lightning/ interference?.

  • 0
    TI__Guru 53242 points

    Hi Luis,

    1.  The 5k pull-down to ground isn't present on the inputs for this device. Besides that the ibis Model looks okay - I'd double check the diode number to make sure it lines up with datasheet values - the diode data is in the ibis model listed under "PWR CLAMP" or "GND CLAMP". For this device we didn't directly spec input impedance. You can get a ball-park estimate with the VIH and IIH ratings - The max ratings are what is used based on available data in the datasheet:

    VIH = VCC = 3.3V ; IIH = 10uA --> 3.3V/10uA = 330K Ohms. For a VCC input on the input pin the max current is 10uA. It will be high impedance as this is just a simple logic input gate.

    2. The model will not give you a "Fail" code if the part would be damaged - if the parts max ratings are violated there could be major issues in terms of damage and we do not guarantee operation passed max ratings of the device. 

    Best,

    Parker Dodson

  • 0 in reply to Parker Dodson
    Prodigy 20 points

    Hi Parker,

    Thanks for your quick answer, for question 2, I was wondering if TI has a datasheet available to customer with maximum ratings in pulsed operation. Same for the DS26LV31T.

    Best regards,

  • 0 in reply to Luis Abril
    TI__Guru 53242 points

    Hi Luis,

    The datasheet we have available on the product page is the only datasheet that we have public facing for this part. This isn't something that is included in the datasheet specifications for this part.

    Best,

    Parker Dodson