At 02:44 AM 4/16/2008, you wrote:
>Hi all. I'm a little bit confused about the CD4052 4 channel
>multiplexer. I'm just unsure about the Vee pin. I'm considering using
>it to switch some audio signals (consumer line level) and I'm really
>not quite sure what voltage Vee wants to see. There is a datasheet
>here if anyone wants to have a look:
>http://focus.ti.com/lit/ds/symlink/cd4051b.pdf
>
>I guess what I'm trying to figure out is if I can run this all off a
>single ended 12V supply or if I need both positive and negative
>supplies.
>
>Thanks!
>
>Josh

For audio, since it is bipolar wrt ground, you probably want to
make Vdd the same as your uC Vdd, Vss = 0V, and Vee something like -Vdd.
You have to make sure your signal range does not go much outside the range
of Vee <= Vin <= Vdd, or if it does, that not much current flows, the usual.

Note that, depending on the crest factor you're assuming, a 0dBu signal
could be as much as ~8V peak (20dB) or ~3V (12dB).

If you're pushing the limits of Vdd - Vee, note that not all manufacturers
have as much as 20V abs max, and 15 or 16 is a lot better choice in most
cases, or go to a "real" analog mux, which will have better Ron, more
constant Ron with Vin(eg. lower audio distortion).

Best regardes,

Spehro Pefhany --"it's the network..."            "The Journey is the reward"
speff@interlog.com             Info for manufacturers: http://www.trexon.com
Embedded software/hardware/analog  Info for designers:  http://www.speff.com



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