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

[Ian Fritz]

The sequential switch circuit converts input voltage into current and feeds 
the virtual ground of an opamp inverting amplifier.  So the signal voltage 
at the 4051 is zero.  In addition the chip is run at Vdd--Vee = 15V, well 
within the 18V maximum rating.  This is generally the best way to use the 
mux chips if you want large input signals.

   Ian

At 11:26 AM 10/8/2010, Jason Proctor wrote:
>i think Ken's sequential switch module does something similar with a 4051. 
>there's a note at the end of the "how it works" section regarding it --
>
>http://cgs.synth.net/modules/cgs28_seq_switch.html
>
>must confess i still don't understand it! :-S
>
>
>
>>this is very exciting news
>>
>>i have always wondered this myself and i dont know why i didnt just go 
>>ahead and try it....but now YOU have done it for us
>>
>>thanks!
>>
>>>  Well, I got bored and impatient so I plugged VDD: +12V, VSS: 0V and 
>>> VEE: -12V and I'm now running an 11.5V PP AC sine wave through it with 
>>> no probs.
>>>
>>>  No smoke, no warmth on the chip (so far), as far as I can tell sine in 
>>> = sine out.
>>>
>>>  So there you go. If anyone has a reason why I shouldn't be doing this 
>>> - please chime in.
>>>
>>>  J
>>
>>
>>
>>
>>
>>
>>On Oct 8, 2010, at 12:25 PM, Justin Owen wrote:
>>
>>>  -----Original Message-----
>>>  From: David G. Dixon [dixon at interchange.ubc.ca]
>>>  Received: 08.10.2010 16:55:55
>>>  To: 'Justin Owen'; 'SDIY List'
>>>  Subject: RE: [sdiy] Using the VEE pin on a 405x Multiplexer
>>>
>>>>>  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 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!
>>>
>>>
>>>
>>>
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>>
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