I/O Line Protectors

Posted on Dec 2, 2012

A 5.1-V zener diode clamps positive-going transients, and a Schottky rectifier clamps negative-going transients. Th

I/O Line Protectors
Click here to download the full size of the above Circuit.

e Schottky rectifier has problems at both ends of the temperature scale. At 125°C (257°F), its leakage current can reach 50 when the input line is at 5 V. This leakage is not a big deal unless the input resistor has a value of 100 kfi or more. More troubling, at temperatures below -40°C (-40°F), the Schottky rectifier"s forward voltage rises to about 0.47 V, which is perilously close to the -0.50-V max spec that most HCMOS-type /iP"s inputs can tolerate. The third circuit, Fig. 20-3(c), uses two regular silicon rectifiers. One rectifier is connected in series with the input line, thereby isolating the " inputs from negative-going voltage spikes. The other rectifier is in series with a 5.1-V zener, which clamps positive-going transients.

Leave Comment

characters left:

New Circuits



Popular Circuits

1.5V Battery FM transmitter
Cat / Dog Detector
Low frequency divider
Proximity alarm
Multi Channel Remote Control System
Mains operated LED night lamp
Switch De-Bouncer Circuit
Ion Ray Gun
SR63 holiday lights ASIC