Programming instructions

Diodes
Multisim Component Reference Guide 3-6 ni.com
3.3 Zener Diode
A zener diode is designed to operate in the reverse breakdown, or Zener, region, beyond the
peak inverse voltage rating of normal diodes. This reverse breakdown voltage is called the
Zener test voltage (Vzt), which can range between 2.4 V and 200 V.
In the forward region, it starts conducting around 0.7 V, just like an ordinary silicon diode. In
the leakage region, between zero and breakdown, it has only a small reverse current. The
breakdown has a sharp knee, followed by an almost vertical increase in current.
Zener diodes are used primarily for voltage regulation because they maintain constant output
voltage despite changes in current.
3.3.1 DC Model
The DC characteristic of a real diode in Multisim is divided into the forward and reverse
characteristics.
DC forward characteristic:
DC reverse characteristic:
IIe VG V nV
DS
V
nV
DDT
D
T
=−








+∗ ≥−15
min
for
I
Ie VG
IVG
IBV
Ie
BV
V
D
S
V
nV
D
SD
S
BV V
V
T
D
T
D
T
=
−








+∗ − ≤ ≤
−+∗ − < <−
−=−
−−+








<−











−
+






1
1
min
min
5nV V 0
BV V 5nV
V BV
V BV
for
for
for
for
TD
DT
D
D
ComponentRef.book Page 6 Thursday, December 7, 2006 10:12 AM