Atmega328p CLKOUT @16MHz 5V to 3.3V I²C device ... Buffer or Shifter?

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1

Dear Forum,
I'd like to use the CLKOUT functionality of the 328P to supply a 3.3V I²C device (AFE 4404). I'll use level shifters (BSSS138) for the I²C and some other digital control lines to the AFE but what should I do with the CLKOUT signal? The I²C device is specified for MAX 3.6V on all digital inputs.
Using the same standard level shifter seems kind of wrong as I do not need bi-directionality and the BSS138-based solutions might be to slow?

I was wondering if anybody else came across a similar problem?

I probably will use an appropriate voltage divider and a good buffer amp (e.g. LT6220) but definitely will try to use the BSS138 level shifter when they arrive tomorrow just to verify the "general" assumption that these are to slow for HF.

What do you think?
Best,
G.

2

Use a logic gate powered from the 3V3 supply. Some are 5V tolerant (such as LVC family), others tolerate quite large input current (i.e. "normal" HC family). For the latter just use some (1k-10k) between Arduino output and gate input. Only concern is the 3V3 circuit must be able to consume this extra current.

3

Oh darn! Thank you so much! This happens when you are a self-tought electronics tinker guy
So I guess a SN74LVC1G34 should just be fine?
Best,
G.

4

It should be OK. Or 1G58 (or 59) multifunction gate.

5

Hey,
thanks a lot!
Best,
G.