what is the reliable IO level for 2.5V power supply

david sun77114 said:

how to estimate the IO level?

I was going to tell you to read the DC characteristics in the datasheet, but, the datasheet doesn't specify V_IL and V_IH numbers.

In the absence of the data from TI, I would recommend using the more restrictive values of 0.8 * V_CC.

Hi Brian

thank you very much for your prompt reply, 0.8Vcc for both ViH and Voh.

David Sun

Using the two values for 1.8 and 3V as points on a straight line (as this is usually the case for CMOS), it comes down to 0.35V + 0.5833*Vcc, so 1.88V for 2.5V supply.
However, assuming 0.8*Vcc is above the line for 1.8V and even more for 3V, so it will for sure be good for 2.5V :)