Tài liệu ZENER DIODES ppt

3.1 ZENER DIODES
VOLTAGE REGULATION
aA voltage regulator circuit automatically
maintains the output voltage of a power
supply constant, regardless of
-a change in the load
- a change in the source voltage
ZENER DIODES
aThe simplest of all voltage regulators
is the zener diode voltage regulator.
aA zener diode is a s
pecial diode that p
is optimized for operation in the
breakdown re
gion.g
ZENER DIODE CIRCUITZENER DIODE CIRCUIT
a
The zener diode is typically connected
a
The zener diode is typically connected
reverse biased, in parallel with the load.
a Resistor Rs limits current to zenera Resistor Rs limits current to zener.
ZENER DIODE CHARACTERISTICS
aIn the forward
region, the zener
diode acts like a
regular siliconregular silicon
diode, with a 0.7
volt drop when itvolt drop when it
conducts.
ZENER DIODE CHARACTERISTICS

aIn the reverse bias
region a reverseregion, a reverse
leakage current
flows until theflows until the
breakdown voltage
is reached.
aAt this point, the
reverse current,
called zener
current Iz,
increases sharplyincreases sharply.
ZENER DIODE CHARACTERISTICS
aVoltage after
bkd ilbreakdown is also
called zener
voltage Vzvoltage Vz.
aVz remains nearly
a constant evena constant, even
though current Iz
varies
considerably.