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Input Buffer - Power Clamp characteristics in AHC1GU04 IBIS File

Hw47343
Intellectual 260 points

Hi,

          I have a doubt regarding IBIS Input - Output behavior of the AHC1GU04 IC. The power clamp table of this IC shows quite weak current (as opposed to many other vendor's existing device's input Buffer). Can anyone please tell whether it is normal to have weak current in a power clamp table and it would be still be able to provide a clamp to power supply (Since many other single ended, 3.3V device has the strong current in a power clamp table).

Regards

  • 0
    TI__Intellectual 2140 points

    Hi Hw47343,

    Typically, very weak current on the power clmap table implies the buffer is fail-safe (no ESD structure between pin and power supply). This is absolutely normal from IBIS standpoint of view.

    If you can provide your info (company) and design opportunity for this particular device, it would be easier for us to contact an appropriate product group that support this device in case you have a furhter question regarding the device.

    Thanks for your interest in Texas Instruments products and services.

    Regards,

    -Eric

  • 0 in reply to Eric Kim- DSS
    Intellectual 260 points

    Hi Eric,

                        Thank you for the reply. I still could not get.

    "very weak current on the power clmap table implies the buffer is fail-safe (no ESD structure between pin and power supply). This is absolutely normal from IBIS standpoint of view." - Does it mean that there is no diode (at all) between input pin and Vcc (which clamps an overshoot at input pin to Vcc)? Or Is ESD structure separate from Clamp diode? What does a Fail-safe mode mean (if there is no connection /structure from Input pin to Vcc supply pin).

    Since after simulating the Hspice model (for IC AHC1GU04) and IBIS model (for IC AHC1GU04) under Hspice tool, it shows a Power clamping behavior. I am trying to develop IBIS software for PCB simulation.

    Regards

  • 0 in reply to Eric Kim- DSS
    Intellectual 260 points

    Hi Eric,

                       Can you please also suggest any inverter IC (Logic gates) with strong power clamp current.

    Kind regards

  • 0 in reply to Hw47343
    TI__Intellectual 2140 points

    Hi HW47343,

    Thansk for your inquiries/update.

    We are in the process of identifying a right product line contact to furhter assist you. 

    Can you please provide your company info and design opportunity with this product?

    Thanks,

    -Eric 

  • 0 in reply to Eric Kim- DSS
    Intellectual 260 points

    Hi Eric,

                          Thanks. The product is being used for some research applications at Univ. of Nottingham.

    Kind regards

  • 0 in reply to Hw47343
    TI__Mastermind 46480 points

    We do not have any little logic parts with power clamp diodes.

    The SN74HC04 will have clamp diodes on the inputs and outputs. they are specd at 20ma.  If you have something that can force more current than that then you will need current limiting series resistors. You will need to limit the current to less than 20ma. The related sped are Iik and Iok.

  • 0 in reply to Chris Cockrill
    Intellectual 260 points

    Hi Chris,

                         Thank you for the reply and suggestion. As I have stated previously, I am doing a research project (with AHC1GU04 in different packages for its input behavior). I am trying to compare the IBIS - Input Buffer Power clamp (as suggested in "AHC1GU04.ibs" file) response with some in-house developed software and it does not match the response of its HSpice library model and physical IC (on a PCB). Hence I wanted to know whether IBIS model of this IC (AHC1GU04) is equivalent to its HSpice model and physical IC.

    Kind regards