How to Build a Programmable Zener Circuit Diagram. The ICL8212 is connected as a programmable zener diode. Zener voltages from 2 V up to 30 V can be programmed by mostly suitable selecting R2. The zener voltage is: Because of the absence of internal compensation in the ICL8212, CI is necessary to ensure stability.
Two points worthy of note are the extremely low-knee current (less than 300 ) and the low dynamic impedance (typically 4 to 7 ohms) over the operating current range of 300 to 12 mA.