CDCM61004 ibis model OUT_LVCMOS seems to have the wrong output impedence

Hi Paul,

You are correct. Per IBIS model of CDCM61004 for LVCMOS output, the P and N channel impedance is ~51 ohms. There would not be a need to add a 22 ohm external series resistor to match a 50 ohm transmission line. I would recommend keeping a pad for an external series termination resistor and populate it with 0 ohms initially. In the meantime, I will dig up characterization data on this device.

Regards

Arvind

Hi Arvind,

Thanks for your quick response.

The data sheet specs a 30 ohm drive impedance with the need for an external 22 ohm series terminator.

Do i imply from your answer that the data sheet is incorrect?

regards

Paul

Hi Paul,

It is hard to conclude if the datasheet or IBIS model is incorrect until we can dig the characterization data for this device. The recommended approach would be to layout the board with provision to add in a series termination resistor at the device output as necessary.

Regards

Arvind

Hi Arvid,

Thanks you for your time and help.

Let me know what you conclude when you find the relevant data.

Regards

Paul