Hi again,
I forgot to mention, at this low voltage you can even try several series connected
SS diodes to act as a zener clamp.
Another way is to use a single SS diode from the divider to the +5v or +3.3v
supply. When the divider tries to go higher than say 5v the diode conducts
and limits it to 5.5v or so. A Schottky would work good here i think.
One catch though is you have to make sure the impedance of the network
is high enough and the 5v supply has enough load so that the network does
not overdrive the 5v supply and cause it to rise up above 5v. An extra 100
ohm resistor from +5v to ground helps here.
Willbe reminded me of something else i forgot to mention...
Since your basically detecting dc and it probably doesnt have to be
super fast, a small capacitor should also be used from the divider
output to ground. This will help block the steep spikes from
reaching the AD input.
I forgot to mention, at this low voltage you can even try several series connected
SS diodes to act as a zener clamp.
Another way is to use a single SS diode from the divider to the +5v or +3.3v
supply. When the divider tries to go higher than say 5v the diode conducts
and limits it to 5.5v or so. A Schottky would work good here i think.
One catch though is you have to make sure the impedance of the network
is high enough and the 5v supply has enough load so that the network does
not overdrive the 5v supply and cause it to rise up above 5v. An extra 100
ohm resistor from +5v to ground helps here.
Willbe reminded me of something else i forgot to mention...
Since your basically detecting dc and it probably doesnt have to be
super fast, a small capacitor should also be used from the divider
output to ground. This will help block the steep spikes from
reaching the AD input.