Zener Diode Project
Zener Diode Project
Zener Diode Project
Outlines
Application of Zener
Diode Numerical of Zener
Diode
Introduction
The zener diode is a silicon pn junction devices that
differs from rectifier diodes because it is designed for
operation in the reverse -breakdown region. The
breakdown voltage of a zener diode is set by carefully
controlling the level during manufacture. The basic
function of zener diode is to maintain a specific voltage
across it’s terminals within given limits of line or load
change. Typically it is used for providing a stable
reference voltage for use in power supplies and other
equipment.
Construction of Zener
Zener diodes are designed to operate in reverse breakdown. Two types
of reverse breakdown in a zener diode are avalanche and zener. The
avalanche break down occurs in both rectifier and zener diodes at a
sufficiently high reverse voltage. Zener breakdown occurs in a zener
diode at low reverse voltages.
A zener diode is heavily doped to reduced the breakdown
voltage.
This causes a very thin depletion region.
The zener diodes breakdown characteristics are
determined by the doping process
Zeners are commercially available with voltage
breakdowns of 1.8 V to 200 V.
Working of Zener
A zener diode is much like a normal diode. The
exception being is that it is placed in the circuit in reverse
bias and operates in reverse breakdown. This typical
characteristic curve illustrates the operating range for a
zener. Note that it’s forward characteristics are just like a
normal diode
Breakdown Characteristics
Figure shows the reverse portion of a zener diode’s
characteristic curve. As the reverse voltage (VR) is
increased, the reverse current (IR)
remains extremely small up to the “knee” of the curve.
The reverse current is also called the zener current, IZ. At
this point, the breakdown
effect begins; the internal zener resistance, also called
zener impedance (ZZ), begins to decrease as reverse
current increases rapidly
ZENER BREAKDOWN
.
Practical Model & Ideal Characteristic Curve of Zener
Diode
Zener Diode Applications –
Zener Regulation with a Varying Input
Voltage
Zener Limiting
Zener Diode Voltages
• As well as producing a single
stabilised voltage output, zener
diodes can also be connected
together in series along with normal
silicon signal diodes to produce a
variety of different reference voltage
output values
• The values of the individual Zener
diodes can be chosen to suit the
application while the silicon diode will
always drop about 0.6 - 0.7V in the
forward bias condition.