For my project I need a lot of analog inputs that are driven by 12V. Usually that would involve a voltage divider for each input.
I’ve come up with the idea to use a analog multiplexer to switch the input before stepping it down to 3v levels. But most multiplexer IC’s cannot cope with large analog voltages. I would be needing a multiplexer that handles 3.3v digital pins select drive the 12v analog input.
Unfortunatley Not! Minimum 5vdc supply with vdd+5vdc max analogue signal ie… on 5v supply + 5vdc = max vin of 10 volts analogue in, But even if you supply 15vdc you cant go above with your analogue… as it’s 15v max throughout
How much should I put on the chip (Vdd/Vcc versus Vss/Vee) to drive +12V inputs with a 3v digital pin? Sorry if this sounds stupid, but I am stil a new to this
It just means that you can only raise the analogue in voltage 5 volts above the power rail, but no more than 15 volts…
Just power the thing at 12 volts and use 12 volt signals and stick a voltage divider on the 4051 output and if you supply 0 - 3.3v from the FEZ to the multiplex signals you’ll be good to go.
[quote]Just power the thing at 12 volts and use 12 volt signals and stick a voltage divider on the 4051 output and if you supply 0 - 3.3v from the FEZ to the multiplex signals you’ll be good to go.
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Great,thanks. I just wanted to make sure the Fez supply would be enough to drive to signal selectors… Will any 4051 do this or do I need to select a specific supplier? Over here in the Netherlands there’s not much choice in shops/parts and i don’t want to spend $5 shipping on a $0.25 part.
Also, yes: I am really getting the hang on this voltage divider stuff.