zener
I am trying to use an LED array to indicate a voltage level. For example, if the voltage is 3V, then 1 LED is lightened up. If 4V, 2 are lightened up. If 5V, 3 are lightened up, etc.. My previous design is to use many simple analog comparators to achieve this.
I now somewhat feel that it is possible to achieve the same effect with some Zener diodes. It would greatly simplify my circuit. How may I do it with Zener diodes?
The reason the same symbol is sometimes used for TVS diodes (Transorbs) and Zeners, is a Transorb has a lot in common with a Zener. An ideal Zener and an Ideal TVS-diode would be indistinguishable in their characteristics. This leads to ... laziness in library management (or ignorance) and the same symbol is used.
Regulator Zeners and TVS-Zener diodes differ in aspects of their construction to facilitate either higher continuous rating or high pulse capability.
Zener TVS devices are constructed with large area silicon p-n junctions designed to operate in avalanche and handle much higher currents than their cousins, Zener voltage regulator diodes
Only uni-directional TVS diodes are created at wafer level. The bidirectional TVS diodes you can buy are just two such dies packaged in series.
Examples of symbols for some TVS devices:
From your images
http://www.onsemi.com/pub_link/Collateral/HBD854-D.PDF
Using a TVS diode instead of, or in addition to a MOV for AC line protection?
Three reasons:
First, operating in the forward orientation only allows operation at a single voltage, nominally about 0.7 volts for a silicon diode. Diode construction can be tailored to produce a wide range of breakdown voltages, with a consequent choice of different regulator outputs.
Second, your V-I curve overstates the sharpness of a forward-biased junction. There is no relatively flat portion other than in the vicinity of zero, and that's not very useful.
Third, with an exponential V-I curve, the forward-biased junction cannot be operated at useful current levels with good regulation.
Best Answer
Not trying to ruin the show, but the cheapest STM8 microcontroller would come for $0.5 and perform 10-bit A/D conversions for you. It will run without any external component and the programmer will come for another $3.5, which isn't bad at all.
Why not give it a shot??