Delta ICC and ICC - Which one to use

I am reading TI’s datasheet for the SN74LV1T126DCKR buffer to get the total current consumed in my application. I am having trouble understanding what parameters I need to use. More specifically what parameter to use, ICC or Delta ICC. I have one input at a different voltage level (1.8V) other than 0V and 3.3V ( this is VCC).

1.8V enables the input to pass through to the output. The chip is powered using 3.3V.

What I understand:
ICC = basically the current used from VCC with no load on the outputs.
Delta ICC = Is the change in ICC current due to the fact that one or more input voltages Vi is not at a 0V or VCC Level.

What I’ve read:
PDF: Understanding and Interpreting Standard-Logic Data Sheets
Per the PDF “ICC will increase by the number of inputs, n, not at 0V or VCC” basically n*ICC.

The datasheet (attached is a screen shot of what I am looking at if you don’t want to use the whole datasheet):
I understand that the test conditions are different than what I have but for a VCC at 5.5V and an input at 03V or 3.4V, no load and all other inputs at 0V or VCC, the Delta ICC is 1.35mA. The second test condition, for a VCC at 1.8V and an input at 03V or 1.1V, no load and all other inputs at 0V or VCC, the Delta ICC is 1.35mA.

Now, I can’t seem to figure out which test condition to use or how to use that information. Using the “n*ICC” method doesn’t seem to match with what the datasheet says as well.

If you could help me understand this I would greatly appreciate this!

Thanks in advance!

SN74lV1T126.pdf (1.1 MB)

The two test conditions offered suggest an exponential/logarithmic relationship between Delta Icc and Vcc; increasing Vcc by a factor of roughly 3 adds on two decimal places to the quoted Delta Icc figure.

Using some (very) rough guesstimation I’d throw my dart at Delta Icc being around 0.1mA @ 3.3v Vcc. Over-safe route would be to design using the Delta Icc figure given for 5v. Characterizing the device yourself under the anticipated use conditions would give better-informed results.