[sdiy] Question about CMOS switches

[Donald Tillman]

On Jan 15, 2011, at 11:20 PM, David G. Dixon wrote:

> Here's a quick question for any digital gurus out there:

(Analog, actually.   :-) )


> Is there any problem driving analog switches in the DG series with switching
> signals that swing to (or near) the rails (provided, of course, that the
> switches are powered from the rails)?

Yeah, there is...  

On devices like the DG409, the switch still works, but it injects a significant amount of charge into the analog lines.   So if you care about charge injection you'll need to limit the control voltage swing.

That's not mentioned in the data sheets; I discovered it the hard way.

  -- Don

--
Don Tillman
Palo Alto, California
don at till.com
http://www.till.com