digital buffer/switch

[Simon]

I'm having trouble finding what I want probably because I don't know what to call it.

I'm looking for a digital buffer, preferably so that I can connect two outputs together so that the signal can come from one or the other input and of course the buffers need to have an enable pin. What do I need ? what is available ?

[onlooker]

Multiplexer, or input selector ic assuming you need only pass the current logic level, not  really buffering/storing  multi bit data stream.

[Simon]

ok, infact I suppose the 7400 range has something

[kizzap]

4051?

[TheGreatGooglyMoogly]

Couple ideas from things we use at my work:

CMOS Switch - PI3C3125 type - http://www.pericom.com/assets/Datasheets/PI3C3125.pdf
Prop delay is 0.25 ns and the enable is like 1.5 ns.

Tri-state buffers: http://www.nxp.com/documents/data_sheet/74HC_HCT125.pdf

We use the Pericom chip to switch a 27 MHz and a 74.25 MHz clock to a video chip. 

[jlmoon]

I'm having trouble finding what I want probably because I don't know what to call it.

I'm looking for a digital buffer, preferably so that I can connect two outputs together so that the signal can come from one or the other input and of course the buffers need to have an enable pin. What do I need ? what is available ?

I'm questioning your last part of your requirements.. "connect two outputs together so that the signal can come from one or the other input"?  Are you requesting a input multiplexer or a output mixer?
 if a switch or multiplexer .. how fast?

[rob77]

you need a buffer/line driver or transparent latch with high-impedance output.

for example :
74HC244 - buffer
74HC373 / 74HC573 - transparent latch

both examples are with high-Z outputs - you can wire the outputs of multiple drivers/latches together and activate the output enable on ONE driver/latch at a time.

[Simon]

I'm having trouble finding what I want probably because I don't know what to call it.

I'm looking for a digital buffer, preferably so that I can connect two outputs together so that the signal can come from one or the other input and of course the buffers need to have an enable pin. What do I need ? what is available ?

I'm questioning your last part of your requirements.. "connect two outputs together so that the signal can come from one or the other input"?  Are you requesting a input multiplexer or a output mixer?
 if a switch or multiplexer .. how fast?

Well i suppose I'm asking the things to do what they are meant to, connect more than one signal to the same "bus" but in my case I've only got one wire and two inputs to it and want to have one or the other pass so as long as they can tri-state I'm fine