Re: MOSFET Analog Switch Question

On 20/04/2025 2:46 pm, john larkin wrote:

On Sat, 19 Apr 2025 12:48:23 -0800, Christopher Howard
<christopher@librehacker.com> wrote:
 

Hi, I have some DG212BDJ Quad SPST CMOS Analog Switches. I am wondering
if there is some significance, for each switch, to how the source and
drain pins are used/fed. The data sheet says Analog Signal Range
(V_Analog) is +/- 15 V, so it doesn't matter which way the current is
moving across source and drain pins, right?

 It should be symmetric, happy conducting in either direction.

Only in the sense of conducting both ways. N-MOSFets tend to be more conductive than P-MOSFets. If they make the P-MOSFets bigger than the N-MOSFets they can can balance the channel resistances, but not the channel capacitances.

Don't let the signals go beyond the rails.

That would reverse bias the isolation diodes and feed current into the rails, and elsewhere if you are unlucky. The effects can  be unfortunate.
--
Bill Sloman, Sydney