# Zener Diode Voltage and Curve Equation

I am trying to figure out the zener voltage of 1n4742a zener diode. I constructed the following circuit: I measured the voltage across the diode and the current through it, and I stopped at the point where the current going through it was 67.5 mA and the voltage was 13.453 V. The data sheet states that the zener voltage is 12 v however here I have about 12% discrepancy. Is that usual? or is there something wrong with the way I am doing it. I did not further increase the voltage source, because I am afraid it will destroy the diode, so is there a better way to measure the zener voltage?

• The data sheet says for 12 volt zener , the test current is 21 mA. Feb 17 '18 at 4:02
• could you explain what test current is? I am new to this. Feb 17 '18 at 4:04
• You tested at a zener current of 67.5 mA, instead of 21 mA Feb 17 '18 at 4:06
• one of my data points is (-12.446,-20.33) which is within range of the uncertainty reported. However, I still don't understand what so special about 21 mA to be the test current. Feb 17 '18 at 4:10
• What is so special is that the data sheet says what the specification is : 21 mA. Feb 17 '18 at 4:12 