Mark_R
Member
Hi,
Setting up an input for a 4-20mA Circuit to a 5V ADC, Looking at the standard 250 ohm resistor to create the 5V signal at 20mA but I'm concerned with blowing the ADC if someone crosses the field wiring and sticks the excitation voltage (likely 24V) to the input.
I was fiddling with a zener / fuse setup (see attached) but the ADC lists 5.3v absolute max, and I can't come up with a combination of values that would work across the tolerance window. I ether get into the zener range too early or over voltage the input of the ADC.
How is this normally dealt with? (full isolation would be awesome!)
Setting up an input for a 4-20mA Circuit to a 5V ADC, Looking at the standard 250 ohm resistor to create the 5V signal at 20mA but I'm concerned with blowing the ADC if someone crosses the field wiring and sticks the excitation voltage (likely 24V) to the input.
I was fiddling with a zener / fuse setup (see attached) but the ADC lists 5.3v absolute max, and I can't come up with a combination of values that would work across the tolerance window. I ether get into the zener range too early or over voltage the input of the ADC.
How is this normally dealt with? (full isolation would be awesome!)
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