Oscillator at 3.3V, I/O at 2.6V

[gavin23]

Hello:

I have a 25MHz Oscillator @ 3.3V. I have an IC with I/Os operating at 2.6V. The 25M clock at 3.3V needs to be converted to 2.6V before being fed to the clock input on the IC.

What's the best method for doing this conversion?

Note that the oscillator will be less than 1 cm away from the IC clock input.

1/ Resistor divider? Has anyone done this already? Any SI issues I should be aware of?
2/ Clock Buffer (ie a clock buffer I could power at 2.6V but is 3.3V tolerant)
3/ Gate Buffer (eg 74LVC126 powered at 2.6V with 3.3V tolerant inputs). This doesn't seem like a good idea because the rise/fall times specs won't likely meet the clock input on the IC.

Thanks
Gavin

 

[lw1ecp]

Another possibility: what is the supply voltage tolerance for your oscillator?. Suppose it is happy with 3.0V. Then, even if its high output level is 3.0V, this won't bother your 2.6V I/O, no internal junction will be significantly forward biased.
Otherwise I would vote for 1: resistor divider, with a C across the series R. Use the same criterion as for 10x scope probes compensation: the added C will compensate the input C of the I/O. Choose as low Rs as possible consistent with output driving capability of your oscillator, especially in case the I/O has an important DC component (e.g. if it's a TTL gate).