Tristate Buffer Output if Input is High-Z?
ard at p850ug1.demon.co.uk
Tue Sep 27 12:57:27 CDT 2005
> If a tristate buffer is enabled by its control line, but the input to
> the buffer is at high-Z is there a typical output?
No, the input will float. _Most_ TTL buffers have inputs that should
float high (so the output will be whatever you should get for a high
input), CMOS ones will pick up random noise. A very few buffers will
float low, I think.
If you require the output to be at a known state under such condtions,
you need to ensure the input is at a known state too, e.g. by adding a
One thing you can be sure of is that the output will not be
high-impedance if the buffer is enabled. The bit of your message that I
deleted seems to suggest you were hoping it would be.
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