SN74AHC04: C_COMP mentioned in IBIS file seems to lower than what I'm measuring

Supreeth L Y

Part Number: SN74AHC04

HI, I checked that the C_COMP mentioned in the IBIS file is only 0.56pF. I am measuring around 2.3pF using TDR. Could this extra capacitance be from the ESD diodes at the input buffer or have they been factored into the C_COMP before it is added into the datasheet? Please let me know.

thanks,

Supreeth

3 months ago

0 Clemens Ladisch 3 months ago

Guru 262920 points

There also are C_pin and C_pkg.

(from An Introduction to IBIS Modeling)

0 Supreeth L Y 3 months ago

Prodigy 10 points

Does not answer my question. Does C_COMP include the capacitance added by the ESD diodes in the particular part I mentioned? or is C-pkg included in the C_COMP value mentioned in the IBIS file?

+1 Clemens Ladisch 3 months ago in reply to Supreeth L Y

Guru 262920 points

C_comp describes everything on the die, including the ESD protection. C_pkg essentially describes the bond wires; C_pin, the leads.

0 Supreeth L Y 3 months ago in reply to Clemens Ladisch

Prodigy 10 points

Thank you! that clears it up for me :)

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SN74AHC04: C_COMP mentioned in IBIS file seems to lower than what I'm measuring