[sdiy] Using the VEE pin on a 405x Multiplexer

[David G. Dixon]

> I'm trying to understand how to use VEE (Pin 7) on a 4053 Multiplexer.
> 
> My understanding is that I can apply a negative voltage bias to this pin
> which will allow an AC signal to pass through (I'm hoping for approx. 10V
> PP @ +/-5V) - all while powering it with +12V @ VDD Pin 16.
> 
> Can anyone confirm a) if this understanding is right, b) what the maximum
> negative voltage is (is -12V OK?) that I can apply to VEE and c) is it
> just one in, one out or is there some equation balance between VDD & VEE.
> 
> The data sheet for the HCF4053 shows it getting 0V, -5V, -7.5V and -10V
> but the text talks about -13.5V (with VDD @ 5V)

The CD405x datasheet says it can handle signals up to 15Vp-p, and mentions
specifically that VDD = 5V and VEE = -5V allows +/-5V signals to pass.
However, under the Absolute Maximum Ratings section, it says the minimum
input voltage is 0.5VDC.  These statements would appear to be mutually
exclusive!

I've used CD405x in a few circuits without problems, but only for positive
voltages.  Indeed, I redesigned the CGS ASR on the basis that the 4052
couldn't (or shouldn't) pass bipolar signals, opting instead for the DG409,
which is made specifically to do so.  The idea that 4052 was unsuitable for
bipolar signals was built specifically into Ken Stone's original design,
with a buffer at the input attenuating and biasing the signal to make it
strictly positive, and buffers at the output to do just the opposite.  None
of this is necessary with DG409.