Basic Definitions. 03Jan Datasheet 


VISHAY
Basic Definitions
Vishay Semiconductors
Basic Sinterglass Diode Parameters
The major parameters for the selection of the appro
priate sinterglass diodes are the maximum reverse
voltage (VRRM), the average forward current (IFAV)
and for switching application the reverse recovery
characteristic (trr), too. Additional parameters may be
for example the reverse avalanche energy capability
(ER) and forward surge capability (IFSM) etc.
VR
VRRM
V(BR)R
IR
IF
VF
IFAV
Reverse voltage
Repetitive peak reverse voltage, including all repeated reverse transient voltages
Reverse breakdown voltage
Reverse (leakage) current, at a specified reverse voltage VR and temperature TJ
Forward current
Forward voltage drop, at a specified forward current IF and temperature TJ
Average forward output current, at a specified current waveform (normally 10ms/50Hz halfsine
wave, sometimes 8.3ms/60Hz halfsinewave), a specified reverse voltage and a specified mounting
condition (e.g. leadlength = 10mm or PCB mounted with certain pads and distance)
IFSM
Peak forward surge current, with a specified current waveform (normally 10ms/50Hz halfsinewave,
sometimes 8.3ms/60Hz halfsinewave),
trr Reverse recovery time, at a specified forward current (normally 0.5A), a specified reverse current
(normally 1.0A) and specified measurement conditions (normally from 0 to 0.25A)
ER Reverse avalanche energy, nonrepetitive
Polarity Conventions
The voltage direction is given
• by an arrow which points from the measuring point
to the reference point
or
• by a two letter subscript, where the first letter is the
measuring point and the second letter is the refer
ence point.
In the case of alternating voltages, once the voltage
direction is selected it is maintained throughout. The
alternating character of the quantity is given with the
time dependent change in sign of its numerical values
.
A I1 B
A I2 = –I1
B
AA A
94 9316
V1 VAB
V2=–V1=VBA=–VAB
Figure 2.
B B B 94 9315
Figure 1.
The numerical value of the voltage is positive if the
potential at the arrow tail is higher than at the arrow
head; i.e., the potential difference from the measuring
point (A) to the reference point (B) is positive.
The numerical value of the voltage is negative if the
potential at the arrow head is higher than the tail; i.e.,
the potential difference from the measuring point to
the reference point is negative.
The numerical value of the current is positive if the
charge of the carriers moving in the direction of the
arrow is positive (conventional current direction), or if
the charge of the carriers moving against this direc
tion is negative. The numerical value of the current is
negative if the charge of the carriers moving in the
direction of the arrow is negative, or if the charge of
the carriers moving against this direction is positive.
The general rules stated above are also valid for alter
nating quantities. Once the direction is selected, it is
maintained throughout. The alternating character of
the quantity is given with the timedependent change
in sign of its numerical values.
Document Number 84067
Rev. 7, 07Jan03
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Vishay Semiconductors
VISHAY
Polarity conventions for diodes
Here, the direction of arrows is selected in such a way
that the numerical values of currents and voltages are
positive both for forward (F or f) and reverse (R or r)
directions.
A IF
K
VF
A IR K
VR
Figure 3.
Arrangement of Symbols
Letter symbols for current, voltage and power
(according to DIN 41 785, sheet 1)
To represent current, voltage and power, a system of
basic letter symbols is used. Capital letters are used
for the representation of peak, mean, DC or root
meansquare values. Lower case letters are used for
the representation of instantaneous values which
vary with time.
Capital letters are used as subscripts to represent
continuous or total values, while lower case letters are
used to represent varying values.
The following table summarizes the rules given above
.
Basic letter
Uppercase
Uppercase
Instantaneous values which
vary with time
Maximum (peak) average
(mean) continuous (DC) or
rootmeansquare (RMS)
values
Subscript(s)
Uppercase
Uppercase
Varying component alone, i.e.,
instantaneous,
rootmeansquare, maximum
or average values
Continuous (without signal) or
total (instantaneous, average or
maximum) values
Letter symbols for impedance, admittances, two
port parameters etc.
For impedance, admittance, twoport parameters,
etc. capital letters are used for the representation of
external circuits of which the device is only a part.
Lower case letters are used for the representation of
electrical parameters inherent in the device.
CAPITAL letters are used as subscripts for the desig
nation of static (DC) values, while lower case letters
are used for the designation of smallsignal values.
If more than one subscript is used (hFE, hfe), the letter
symbols are either all capital or all lower case.
If the subscript has numeric (single, double, etc.) as
well as letter symbol(s) (such as h21E or h21e'), the dif
ferentiation between static and smallsignal value is
made only by a subscript letter symbol.
Other quantities (values) which deviate from the
above rules are given in the list of letter symbols.
The following table summarizes the rules given above
.
Basic letter
Uppercase
Uppercase
Electrical parameters inherent
in the semiconductor devices
except inductances and
capacitances
Electrical parameters of
external circuits and of circuits
in which the semiconductor
device forms only a part; all
inductances and capacitances
Uppercase
Smallsignal values
Subscript(s)
Uppercase
Static (dc) values
Examples:
GP Power gain
ZS Source impedance
fT Transition frequency
IF Forward current
Example for the use of symbols
according to 41785 and IEC 148
VF
VFSM
VFRM
VFWM
0
VRWM
VRRM
VRSM
VR
t
93 7796
Figure 4.
VF Forward voltage
VR Reverse voltage
VFSM Surge forward voltage (nonrepetitive)
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Document Number 84067
Rev. 7, 07Jan03

VISHAY
Vishay Semiconductors
VRSM Surge reverse voltage (nonrepetitive)
VFRM Repetitive peak forward voltage
VRRM Repetitive peak reverse voltage
VFWM Crest working forward voltage
VRWM Crest working reverse voltage
List of Symbols
A Anode
a Distance (in mm)
bpn Normalized power factor
C Capacitance, general
Ccase Case capacitance
CD Diode capacitance
Ci Junction capacitance
CL Load capacitance
CP Parallel capacitance
ER Reverse avalanche energy, nonrepetitive
F Noise figure
f Frequency
fg Cutofffrequency
g Conductance
K Kelvin, absolute temperature
IF Forward current
iF Forward current, instantaneous total value
IFAV Average forward current, rectified current
IFRM Repetitive peak forward current
IFSM Surge forward current, nonrepetitive
IFWM Crest working forward current
IR Reverse current
IRM Maximum reverse current
iR Reverse current, instantaneous total value
IRAV Average reverse current
IRRM Repetitive peak reverse current
IRSM Nonrepetitive peak reverse current
IRWM Crest working reverse current
IS Supply current
IZ Zoperating current
IZM Zmaximum current
l Length (in mm), (caseholder/soldering point)
LOCEP (local epitaxy)
A registrated trade mark of TEMIC for a pro
cess of epitaxial deposition on silicon. Applica
tions occur in planer Zdiodes. It has an
advantage compared to the normal process,
with improved reverse current.
P Power
PR Reverse Power
Ptot Total power dissipation
PV Power dissipation, general
Pvp Pulsepower dissipation
Q Quality
Qrr Reverse recovery charge
RF Forward resistance
rf Differential forward resistance
RL Load resistor
rP Parallel resistance, damping resistance
RR Reverse resistance
rr Differential reverse resistance
rs Series resistance
RthJA Thermal resistance between junction and
ambient
RthJC Thermal resistance between junction and case
RthJL Thermal resistance junction lead
rz Differential Zresistance in breakdown region
(range) rz = rzj + rzth
rzj Zresistance at constant junction temperature,
inherent Zresistance
rzth Thermal part of the Zresistance
T Temperature, measured in centigrade
T Absolute temperature, Kelvin temperature
T Period duration
Tamb Ambient temperature (range)
tav Integration time
Tcase Case temperature
tfr Forward recovery time
Tj Junction temperature
TK Temperature coefficient
TL Connecting lead temperature in the holder (sol
dering point) at the distance/(mm) from case
ttTPp
Pulse duration (time)
Duty cycle
tr Rise time
trr Reverse recovery time
ts Storage time
Tsd Soldering temperature
Tstg Storage temperature (range)
V(BR) Breakdown voltage
VF Forward voltage
VF Forward voltage, instantaneous total value
VFAV Average forward voltage
Vo Rectified voltage
VFP Turn on transient peak voltage
Document Number 84067
Rev. 7, 07Jan03
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