I would like to use the FXL4245 to level shift both 3.3v and 1.8v signals to 1.2v.

I was thinking of supplying VCCB from 1.8v, VCCA from 1.2v and setting the direction to translate from B to A. Most of the signals in port B are indeed 1.8v except one which is at 3.3v.

While the datasheet doesn't specifically state the inputs are tolerant to 3.3v, the following table form the datasheet implies it should be ok: Table

The fact that the control inputs are limited and refferenced to VCCA while PORT A/B inputs can go as high as 3.6v suggests that it's ok for the inputs to go that high even though VCCB might be 1.8v for example. Another clue is the fact that the outputs are guaranteed to be high-z when either VCC A or B are at 0v.

Is this assumption correct ?

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    \$\begingroup\$ I think you have your answer right in front of you. Are you confused by what a data sheet says? \$\endgroup\$ – Sparky256 Jan 8 '18 at 17:46
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    \$\begingroup\$ Just want to double check that I'm not reading it wrong \$\endgroup\$ – Mike Jan 8 '18 at 18:17

Yes, you are reading it correct. 3.3V from B side will not damage the IC.

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