Multiplexer-High and low voltage levels

[Murugesh_89]

Hi,
What is the range of voltages for a multiplexer to detect as LOW. Similarly HIGH?

Previously i thought 0 to 1.8V as LOW, above which as HIGH.

When i viewed in scope i found that i am wrong and i cant able to exactly note the value.

Can anyone pls tell me the exact range. I am using the 74HC151. In datasheet i can't able to find the data.

Regards,
Murugesh

 

[kripacharya]

Here is the data sheet, in case you don't have it ... **broken link removed**

The specs you need to look at are VIL and VIH

Note that these values are dependent on the Vcc supplied to the IC.

 

[chuckey]

its a shame that on page 9, the Vi have their typ and max/min data is swopped around. i.e. for a Vcc of 2V, H in typ = 1.2 and the min is 1.5
( But their heart is in the right place !)
Frank

 

[kripacharya]

Actually Vih always will be specified with a Min higher than the Typ. Here "Min" has to be interpreted as "worst case". Its placed under Min because its the minimum below the Vcc at which HIGH will be sensed.

A little convoluted, but i guess it does make sense.