Hi,
i have a 3.3v signal,that connected to a 5v input .
the requierment is VIH = 0.8VCC.
How can i simply rase up the signal to this level?
(the 3.3 output is not open drain or open collector)
how to do it for bidirectional pins?
please help,
John
IanP, reread his question. 3.3V into 5V won't work.
You could pass the 3.3V signal through a 74HCTxx chip that's powered by 5V.
Or maybe you could use a resistor pullup-divider gimmick, but you haven't told us VIL or the required speed.
For bidirectional, those Fairchild LVX parts look fine.
If you wanna go on the cheap side, you can use a diode and a pull-up resistor. This design will be a bit slower though, and you must verify that the ViL condition will be respected. Using a schottky diode with a low voltage drop would probably do...
You must connect the diode between the 3.3V output (cathode) and the 5V input (anode) and you use a pull-up resistor on the 5V side.