Fairchild CD4051BC Mux/Demux

Forum 2005-2010 (read only) Hardware Interfacing
1

Here's the pinout for the chip I'm using:

I'm wondering if, by convention, V_DD, V_EE, and V_SS mean anything to anyone. The datasheet is available here: Intelligent Power and Sensing Technologies | onsemi

From what I've read, V_DD seems to be the DC supply voltage.

Also, the recommended operating conditions on page 5 say that V_IN (which I take to be the various data inputs) should be "0V to V_DD V_DC" which doesn't mean much to me. I've never accomplished much using 0V.

Basically, I'm wondering if anyone can clarify what all these voltages mean, and how I might go about hooking this chip up to my board.

I plan to use the chip as a Demux to control 8 LEDs from a single digital I/O pin (and 3 more for the select bits).

I know how these chips work on a logic level, but the actual electrical wiring of the device is a bit beyond me.

2

This little page barley explains some of it, but in the case of a 4052 mux

Vdd = logic high / V+
Vss = logic low / gnd

Vee is interesting tho, since a 4050 can pass digital or analog signals, and when dealing with analog your dealing with AC a bunch Vee is used to split the voltages up, kinda like a dual voltage op amp

If your just passing digital signals, connect Vee to gnd

check out page 7 of this datasheet for more info on that topic

(edited)

3

another question that has come to mind:

Do I have to do anything to switch between multiplexing and demultiplexing? Or do the select bits simply route the in/out pins to the master in/out, with current direction determining function?

4

You don't have to do anything.

Did you see the example in the playground ?

5

I did, but I found it left a number of questions in my mind. There are also multiple manufacturers of 4051s and the one in the example didn't quite match mine. Thanks for clarifying :slight_smile:

I managed to get a 4051 all wired up on a breadboard (lots of wires, the in/out pins seem to be in some kind of random order). Hoping to get it all wired up to the Arduino tomorrow.

I've seen that some people have issues with the 4051s when they get them on the board (noise generated by IC switching). Hoping this simple project will get me comfortable with using muxes. I have some 45uF caps for low frequency filtering, but the 0.1uF caps I got from digikey are microscopic (in my defense, they looked huge in the product photos). Might have to make another order if high frequency noise is an issue. Hard to find through-hole caps at such a low capacitance though.

6

nah its not hard, any ceramic type cap is going to be that small or smaller

7

I have surface mounts for the 0.1uF caps though. I couldn't find them in through hole. I wouldn't mind it being small so long as it had leads.

8

they have the code 104 marked on them

9

brrrrrilliant! A thousand thanks.