Auto-range input

Using a Teensy LC, will over-voltage damage a pin set to digital?

Current should not be an issue for a meter. The digital pins in this design could receive up to 18v. Just wanted to ask before before I blow up a chip.

Example attached: (logic would switch on/off voltage dividers)

AutoRange.jpg

(deleted)

I could not find any information specifically on a pin set to high (as if it was set to high or not). Teensy is not very popular yet.

Just trying to find the simplest solution to auto-range. Any links or examples are welcome.

plancette’s image

2e16ea569d7812579269162fb8c5ec4361e9ff79.jpg

(deleted)

Can you please explain how you see that circuit work.

As I see it you clamp the input signal to 3.6V with a zener so overvoltage should not reach the pin(s) of the Teensy. My electronics knowledge is very rusty though.

I appreciate your responses. But Digital is I/O. I am trying to find the simplest way to make an auto ranging analog input using a voltage divider controlled by digital outputs (if possible). If a digital pin can handle a high voltage low current situation, I have zero worries.

I have the datasheet. If you have anything useful I would appreciate it.

wawa and allanhurst helped me do the same in this thread.

Thank you so much JMeller. I ran across the post in my searches, but I missed Page 2! Exactly what I was looking for!

JMeller. Two questions after reading up and watching your video. Awesome display for the price and clean coding.

Did you ever test it to 36v?

What size resistor did you end up using on the analog pin?

plancette:
Did you ever test it to 36v?

I repurposed the design and have not tested it for 36v - despite purchasing a booster.

plancette:
What size resistor did you end up using on the analog pin?

39K

Wawa's reply in reply #8:

Current will be limited to about 1mA.
The internal pin protection will clamp this to VCC.