high voltage analog pulse measurement

Using Arduino Sensors
1

Hi,

What happens when more than 5V appea on an Analog input pin?

does the ADC saturate at 1023?
does it wat around?
give me garbage?
or blow the arduino?

thanks

2

The ADC saturates at 1023. If you put more than about 5.6 V on the ADC pin, you may burn out the input pin, and perhaps the entire Arduino.

3

Thanks. that's my issue.

it's a given that that will happen. To simplify. I would have
one signal applied onto two Analog pins.

The first would have a divide by 4 and the second a divide by 16.

So the first would measure V between 0 and 20V, the second
between 0 and 80V.

But when 80V show up, the first ADC sees 20V. so would the
part burn out even if I put a large Resistor divider in it to stay
below the 20mA I read on this site the ADC can sink?

Is it good/ok/safe practice to put a diode in parallel to the lower
(dividing) Resistor to guarantee (sort of) that the voltage will
never be higher than 5? or 5.6 or even 4.7?

I need to measure and detect impulses and need as much of the
10 bit resolution the ADC can provide but also a higher dynamic range.

thanks a lot.