[SOLVED] Difference between an ordinary diode and zener diode...

1.Can anybody comment on the difference between the forward characteristics of an ordinary diode and zener diode?
2. What is the meaning of breakdown? Does it mean the diode has been destroyed?

Breakdown mens the reverse voltage at which diode starts conducting heavily. See datasheets of diodes 1N4001 through 1N4007 and some zener diodes for forward characteristics.

Jayanth:......Cant an ordinary diode conduct heavily in breakdown region?

As indicate by JD in post #2, Ordinary diode does conduct heavily in the breakdown region but it can not recover back to attain its original characteristics whereas Zener diodes can. this is one of the majour difference in characteristics.

The main difference between an ordinary diode and zener is their REVERSE breakdown voltage.

Deliberately, the ordinary diode breakdown is made relatively high. And in normal operation, this breakdown voltage shouldn’t be reached otherwise some unexpected and/or undesired things may happen.

On the other side, zener diodes are made, deliberately, to have a rather known breakdown voltage (referred as zener voltage). In normal operation, the circuit takes advantage of it so that the voltage over the zener stays 'rather' constant independent of its current. But to use a zener properly, its maximum reverse current (Iz) that is allowed to flow in the zener diode should obey the formula:

Iz (in mA) < P_zener (in mW) / V_zener

where:
P_zener (in mW), power dissipation, is usually given on the zener datasheet.