Rating at 25℃ ambient temperature unless otherwise specified. Resistive or
Inductive load, 60Hz.
For Capacitive load derate by 20 %.
|Max. instantaneous forward voltage drop per leg at 1.0A||VF||1.0||V|
Max. DC reverse current at rated TA=25℃
DC blocking voltage per element TA=25℃
Types of Diodes
• Normal Diodes
Standard signal diodes are among the most basic, average, no-frills
members of the diode family. They usually have a medium-high
forward voltage drop and a low maximum current rating. A common
example of a signal diode is the 1N4148. Very general purpose, it’s
got a typical forward voltage drop of 0.72V and a 300mA maximum
forward current rating.
A rectifier or power diode is a standard diode with a much higher
maximum current rating. This higher current rating usually comes at
the cost of a larger forward voltage. The 1N4001, for example, has
a current rating of 1A and a forward voltage of 1.1V.
And, of course, most diode types come in surface-mount varieties as
well. You’ll notice that every diode has some way (no matter how
tiny or hard to see) to indicate which of the two pins is the
• Schottky Diodes
Another very common diode is the Schottky diode. The semiconductor
composition of a Schottky diode is slightly different from a normal
diode, and this results in a much smaller forward voltage drop,
which is usually between 0.15V and 0.45V. They’ll still have a very
large breakdown voltage though.
Schottky diodes are especially useful in limiting losses, when
every last bit of voltage must be spared. They’re unique enough to
get a circuit symbol of their own, with a couple bends on the end
of the cathode-line.
• Zener Diodes
Zener diodes are the weird outcast of the diode family. They’re
usually used to intentionally conduct reverse current. Zener’s are
designed to have a very precise breakdown voltage, called the zener
breakdown or zener voltage. When enough current runs in reverse
through the zener, the voltage drop across it will hold steady at
the breakdown voltage.
Taking advantage of their breakdown property, Zener diodes are
often used to create a known reference voltage at exactly their
Zener voltage. They can be used as a voltage regulator for small
loads, but they’re not really made to regulate voltage to circuits
that will pull significant amounts of current.
Zeners are special enough to get their own circuit symbol, with
wavy ends on the cathode-line. The symbol might even define what,
exactly, the diode’s zener voltage is.