Electronics > Beginners
Drive a 12V analog switch from logic level input
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Benta:
Almost all analog switches have separate digital and analog supply pins with internal level shifting. The 4066 is an exception. Check out the DG6xx or the DG4xx series from Vishay, for instance.
hermitengineer:
For more background, this is a vintage game console, the Colecovision.  It has an expansion port that I'm connecting to.  The pin in question switches video output from its internal chip to the expansion port's video input.  Commercial expansion modules just shorted +12V to the video enable, but I'd like to be selective.

Anyway, I'd like to treat the CV itself as a black box, though I at least know its internal circuitry.  So that means no mods to the 4066 or removal of its 10K pull-down.
Zero999:
Why not simply use a logic level translator IC such as the CD4504 or CD40109? It's non-inverting and doesn't require any other components.
http://www.ti.com/lit/ds/symlink/cd4504b.pdf
http://www.ti.com/lit/ds/symlink/cd40109b.pdf

Oh and if you do want to go discrete, a BJT can be used in non-inverting configuration by connecting the input to the emitter, rather than the base.
vk6zgo:
Of course, you do realise that +12v is a legitimate logic level in its own right?
hermitengineer:

--- Quote from: Zero999 on November 22, 2019, 11:42:02 pm ---Why not simply use a logic level translator IC such as the CD4504 or CD40109? It's non-inverting and doesn't require any other components.
http://www.ti.com/lit/ds/symlink/cd4504b.pdf
http://www.ti.com/lit/ds/symlink/cd40109b.pdf

Oh and if you do want to go discrete, a BJT can be used in non-inverting configuration by connecting the input to the emitter, rather than the base.


--- End quote ---
A 4504 may indeed be the most robust and simple solution.  I just turn up my nose at the number of unused gates  >:D  Why don't they make a single-gate version that can take 12V+?

As mentioned above, the existing circuit within the "black box" that I'm interfacing to uses a 10K pull-down, so a resistive supply would not be a good match.  So unfortunately, that level shifter circuit has the same problem as the MOSFET ones.
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