Technical Information
Type Designation in Accordance with Pro Electron
Data Book 1 2000-09-01
1 Type Designation in Accordance with Pro Electron
This type designation applies to small-signal semiconductor components – in contrast to
integrated circuits, multiples of these components and semiconductor chips.
The number of the basic type consists of: two letters and a three-digit code.
First Letter
gives information about the material.
A. Germanium or other material with a band gap of 0.6 …1.0 eV
B. Silicon or other material with a band gap of 1.0 …1.3 eV
C. Gallium-arsenide or other material with a band gap of 1.3 eV
R. Compound material, e.g. cadmium-sulfide
Second Letter
Indicates the function for which the device is primarily designed.
A. Diode: signal, low power
B. Diode: variable capacitance
C. Transistor: low power, audio frequency
D. Transistor: power, audio frequency
E. Diode: tunnel diode
F. Transistor: low power, high frequency
G. Multiple of dissimilar devices; miscellaneous devices (e.g. oscillator)
H. Diode: magnetic sensitive
L. Transistor: power, high frequency
N. Optocoupler
P. Radiation-sensitive semiconductor component
Q. Radiation-emitting semiconductor component
R. Control or switching device: low power (e.g. thyristor)
S. Transistor: low power, switching
T. Control or switching device: power (e.g. thyristor)
U. Transistor: power switching
X. Diode: multiplier, e.g. varactor, step recovery
Y. Diode: rectifier, booster
Z. Diode: voltage reference or regulator; transient voltage suppressor diode
The three-digit code of the type designation consists of:
– a three-digit number, running from 100 to 999, for devices primarily intended for
consumer equipment etc.
– one letter and a two-digit number for devices primarily intended for industrial/
professional equipment. This letter has no fixed meaning.
Technical Information
Notation of the Symbols and Terms Used (DIN 41 785)
Data Book 2 2000-09-01
2 Notation of the Symbols and Terms Used (DIN 41 785)
The current, voltage, power (AC, DC, or average values) and resistance types (AC or
DC values) are indicated by using capital and small letters for the symbols.
Symbols
The instantaneous data of values varying with time are indicated by small letters.
Examples: i, v, p
Capital letters are used for DC, average, rms, and peak values of periodical functions of
the current, the voltage, and the power – i.e. for constant quantities.
Examples: I, V, P
Subscripts for the Symbols
The following subscripts are used:
E, e Emitter
B, b Base
C, c Collector
F, f Forward direction (diode operated in forward direction)
R, r Reverse direction (diode operated in reverse direction)
M, m Peak value
av Average value
The subscripts for peak and average values may be omitted provided that a confusion
with other values is impossible.
Total values (instantaneous values, DC values, average, rms, and peak values) referred
to a zero point are indicated by subscripts with capital letters.
Examples: iC,IC,vBE,VBE,pC,PC
Subscripts with small letters are used for the values of variable components (e.g. for
instantaneous values, peak, and rms values referred to an average value).
Examples: ic,Ic,vbe,Vbe,pc,Pc
To distinguish between peak, average, and rms values, further subscripts may be
added. The following abbreviations are recommended:
Peak values M, m
Average values Av, av
Examples: ICM,ICAV,Icm,Icav
Peak values may also be indicated by placing the symbol “Λ” over the letter.
Examples: ÎC,Îc
Technical Information
Maximum Ratings
Data Book 3 2000-09-01
3 Maximum Ratings
The maximum ratings specified are absolute ratings which, if exceeded, may result in
the destruction or permanent functional impairment of the component. When testing the
component, as for example in respect to breakdown voltages, or during application,
protection is to be provided in order to reliably ensure that maximum ratings are not
exceeded.
4 Characteristics
Typical characteristics describe the component behavior at defined operating
conditions. The numerical values and diagrams pertain to the component type and shall
not be considered as characteristics of an individual component. The minimum and
maximum ratings stated for reasons of essential quality and application requirements
describe the actual spread of the characteristics, whereas spread curves in diagrams
usually specify the spread range which is to be expected. Electrical values are grouped
into “static” DC values and “dynamic” AC values. The thermal resistance is closely
related to the maximum ratings and, constituting the upper spread value, comes
immediately after the maximum ratings. The component's case data is defined by
reference to standard sheets and dimensional drawings.
Figure 1
ICDC value, no signal
ICAV Average value of the total current (referred to zero)
ICM,ÎCPeak value of the total current (referred to zero)
ICRMS RMS value of the total current (referred to zero)
Technical Information
Characteristics
Data Book 4 2000-09-01
Icav Average value of the variable component superimposed on the closed-circuit
direct current IC (referred to the DC no-signal value IC)
Ic, Icrms RMS value of the variable component (referred to the average value ICAV)
Icm,ÎcPeak value of the variable component (referred to the average value ICAV)
iCInstantaneous total value (referred to zero)
icInstantaneous value of the variable component (referred to the average value
ICAV)
The following relations apply to the values indicated in the above-mentioned diagram:
Basic Symbol Chart
The following chart illustrates the application of capital and small letter symbols.
Table 1 Symbols
i,v,p I,V,P
Subscripts
e
b
c
f
r
m
av
Instantaneous value of the
variable component RMS, average, and peak value of
the variable component
E
B
C
F
R
M
AV
Instantaneous total value
(as referred to zero) DC value, average, rms, and peak
value (as referred to zero)
ICRMS ICAV
2Icrms
2
+=
ICAV =IC+Icav
IC=ICAV +iC
ÎCM =IC=ICAV +Icm
Technical Information
Characteristics
Data Book 5 2000-09-01
Instructions for the Subscript Sequence
Voltages
As a rule, two subscripts are used to indicate the points between which the voltage is
measured.
Positive numerical values of the voltages correspond to positive potentials on the point
indicated by the first subscript as referred to the point indicated by the second subscript
(point of reference).
The second subscript may be omitted if this cannot lead to confusion or
misunderstandings.
A supply voltage may be indicated by repeating the subscript of the terminal concerned.
Examples: VEEB,VBBC,VCCE
Currents
As a rule, at least one subscript is used. Positive numerical values of the current
correspond to positive currents entering the component at the terminal indicated by the
first subscript.
Subscripts for Terminals
In the case of components having more than one terminal of the same type, the
subscripts for the terminals may be modified by suffixing a number to them. Subscript
and suffix must be written on the same line.
Example: VB2-E (voltage between second base terminal and emitter)
If several components form an assembly, the subscripts for the terminals may be
modified by prefixing a number to them, subscript and prefix having to be written on the
same line.
Example: V1B-2B (voltage between the base of the first component and the base of the
second component)
Admittances, Resistances, Four-Pole Network Coefficients, etc.
Symbols
Small letters with appropriate subscripts are used for four-pole network coefficients, as
well as resistances, admittances, capacitances, inductances, etc., which describe the
features of the component.
Examples: h11b,h11e,z21b,y22c
Technical Information
Characteristics
Data Book 6 2000-09-01
Capital letters with appropriate subscripts are used for four-pole network coefficients, as
well as resistances, admittances, capacitances, inductances, etc. of external network or
of networks in which the component forms just a part.
Examples: H11b,H11e,Z21b, Y22c
Capital-letter subscripts are used for DC values (including large-signal values) of four-
pole network coefficients, as well as, of resistances, admittances, etc.
The DC value is the slope of the straight line from the origin of the coordinate system to
the operating point on the characteristic of the component.
Examples: rB,h11B,hFE
Small-letter subscripts are used for AC values (small-signal values) of four-pole network
coefficients, as well as of resistances, admittances, capacitances, inductances, etc.
Examples: rbb,h11b,hfe
The first subscript or the first pair of subscripts written in the manner customary for matrix
elements is used for determining the elements of a four-pole network matrix.
11 (or i) = input
22 (or o) = output
21 (or f) = forward transfer
12 (or r) = reverse transfer
Examples: V1 = h11 ×I1 + h12 ×V2
I2 = h21 ×I1 + h22 ×V2
Note
When written in matrix representation (or as elements of matrixes) the voltage and
current symbols are supplemented by a subscript consisting of a single numeral.
Subscript 1 = input
Subscript 2 = output
The second subscript or the subscript following the pair of numerals indicates the basic
circuit. If the common terminal is self-evident, the second subscript may be omitted
e = common emitter configuration
b = common base configuration
c = common collector configuration
Examples: (common base configuration)
I1 = y11b ×V1b + y12b ×V1b
I2 = y21b ×V1b + y22b ×V2b
If the transistor is described with a four-pole characteristic, it is recommended to fix the
direction arrows for the input and output currents in the direction of the four-pole network.
Technical Information
Alphanumerical List of the Symbols Used
Data Book 7 2000-09-01
5 Alphanumerical List of the Symbols Used
aOn-off base current ratio
A Anode
AStatic current gain in common base configuration
αDynamic short-circuit current gain in common base configuration
bImaginary part of y-parameters
b11 Imaginary part of the short-circuit input admittance (of parameter y11)
b12 Imaginary part of the short-circuit reverse transfer admittance
(of parameter y12)
b21 Imaginary part of the short-circuit forward transfer admittance
(of parameter y21)
b22 Imaginary part of the short-circuit output admittance (of parameter y22)
B, b Base terminal
C, c Collector terminal
CCapacitance
Cb'c Intrinsic base collector capacitance
Cb'e Intrinsic base emitter capacitance
CcCollector junction capacitance (in general)
Ccase Case capacitance (in general)
Ccb Collector base capacitance
CCBO Collector base capacitance (including case capacitance) with open emitter
(IE=0)
Cc'b Intrinsic collector base capacitance
Cce Collector-emitter capacitance
Cdg1 Reverse transfer capacitance
Cdss Output capacitance
Ceb Emitter-base capacitance
CEBO Emitter-base capacitance (including case capacitance) with collector open
(IC=0)
Ce'b Intrinsic emitter base capacitance
Cg1ss Gate1 input capacitance
Cg2ss Gate2 input capacitance
Cib Input capacitance
CLLoad capacitance
Cob Output capacitance
Cth Thermal capacity (disregarding of heat dissipation to the environment)
CTDiode capacitance
CT1
/
CT28 Capacitance ratio (CT (VR = 1 V) / CT (VR = 28 V))
∆CT
/
CTCapacitance matching
C11 Capacitance of the short-circuit input admittance (of parameter y11)
Technical Information
Alphanumerical List of the Symbols Used
Data Book 8 2000-09-01
C12 Capacitance of the short-circuit reverse transfer admittance
(of parameter y12)
C21 Capacitance of the short-circuit forward transfer admittance
(of parameter y21)
C22 Capacitance of the short-circuit output admittance (of parameter y22)
DDuty cycle D = tp/T
E, e Emitter terminal
∆fFrequency difference
fFrequency
fCCutoff frequency
fhfb Cutoff frequency of the short-circuit small signal current gain in common
base configuration
fhfe Cutoff frequency of the short-circuit small signal current gain in common
emitter configuration
fhfe1 Frequency at which hfe = 1
fmax Maximum frequency of oscillation
fTTransition frequency (Current gain-bandwidth product)
F Noise figure
gReal part of the y-parameters
gConductance (instantaneous value)
gb'c Intrinsic base collector conductance
gb'e Intrinsic base emitter conductance
gce Collector emitter conductance
gm; gfs Transconductance
gth Coefficient of thermal conductivity (instantaneous total value)
gthJC Coefficient of thermal conductivity (total instantaneous value) between heat
source and case, with infinitely good heat dissipation from the case
(Tcase =Tamb)
g11 Real component of the short-circuit input admittance (of parameter y11)
g12 Real component of the short-circuit reverse transconductance
(of parameter y12)
g21 Real component of the short-circuit forward transconductance
(of parameter y21)
g22 Real component of the short-circuit output admittance (of parameter y22)
GConductance (DC or average value)
∆GGain flatness
GaAssociated gain
GgInternal conductance of generator
GLLoad conductance
Technical Information
Alphanumerical List of the Symbols Used
Data Book 9 2000-09-01
Gma Power gain (Maximum available gain)
Gms Power gain (Maximum stable gain)
∆GpGain control range
GpPower gain
Gpb Power gain in common base configuration
Gpe Power gain in common emitter configuration
Gpopt Power gain, optimum
Gpbinv Reverse power loss (feedback damping)
Gpbopt Power gain in common base configuration, optimum
Gpeopt Power gain in common emitter configuration, optimum
Gth Coefficient of thermal conductivity (thermal conduction constant)
GthA Coefficient of thermal conductivity (thermal conduction constant) between
heat source and static ambient air when using a cooling plate of defined size
GthJA Coefficient of thermal conductivity (thermal conduction constant) between
heat source and static ambient air.
GthJC Coefficient of thermal conductivity (thermal conduction constant) between
heat source and case, with infinitely good heat dissipation from the case
(Tcase =Tamb)
GVVoltage gain
Γopt Reflection coefficient for minimum noise
hParameter of the hybrid-matrix (h-matrix)
h11 Short-circuit input impedance
h12 Open-circuit reverse voltage transfer ratio (voltage feedback ratio hre)
h21 Short-circuit forward current transfer ratio (small signal current gain)
h22 Open-circuit output admittance
hFE DC current gain in common emitter configuration (static forward current
transfer ratio)
hfe Small-signal current gain in common emitter configuration (β=h21 e)
hfeo Small-signal current gain in common emitter configuration at f= 1 kHz
(Dynamic short-circuit forward current transfer ratio in common emitter
configuration)
i1Input AC current
i2Output AC current (in general)
IBBase current (DC or average value)
IB1 Control current, base-one current (UJT)
IB2 Turn-off base current, on-off base current (UJT)
IBM Peak base current
ICCollector current (DC or average value)
ICBO Collector cutoff current with open emitter (IE = 0)
ICEO Collector cutoff current with open base (IB = 0)
Technical Information
Alphanumerical List of the Symbols Used
Data Book 10 2000-09-01
ICER Collector cutoff current with RBE =R(with a resistance RBE between base and
emitter)
ICES Collector cutoff current with short-circulated emitter diode (VBE = 0)
ICEV Collector cutoff current with reverse emitter diode
ICM Peak collector current
IDDrain current
IDSS Drain source saturation current
IEEmitter current (DC or average value)
IEBO Emitter cutoff current with open collector (IC = 0)
IEM Peak emitter current
IFForward current
IFM Peak forward current
IFS Surge current, maximum 1 sec
IGGate leakage current
±IG1SS Gate1-source leakage current
±IG2SS Gate2-source leakage current
IKShort-circuit current
IoRectified current
IRReverse current
IP3Third order intercept point
kStability factor
K Cathode
LInductance
LsSeries inductance
m In a subscript: maximum (peak value)
mDegree of modulation
max In a subscript: maximum (e.g. upper scattering limit)
min in a subscript: minimum (e.g. Iower scattering limit)
M in a subscript: maximum (peak value)
NF, F Noise figure
NFmin,Fmin Minimum noise figure
NF50Ω,F50ΩNoise figure 50 Ω−System
P; p Power dissipation
PAE Power added efficiency
PpPulse power dissipation
Ptot Total power dissipation
P– 1dB RF output power at 1 dB compression point
Technical Information
Alphanumerical List of the Symbols Used
Data Book 11 2000-09-01
ϕPhase of y-parameters
ϕ11 Phase of the short-circuit input admittance (of parameter y11)
ϕ12 Phase of the short-circuit reverse transfer admittance (of parameter y12)
ϕ21 Phase of the short-circuit forward transfer admittance (of parameter y21)
ϕ22 Phase of the short-circuit output admittance (of parameter y22)
QQ factor (Quality factor)
rResistance (instantaneous value)
rbb' Base intrinsic resistance
rbb' Cb'c Feedback time constant
rcc Collector intrinsic resistance
reb Emitter intrinsic resistance
rfForward resistance of diodes
RResistance (DC or average value)
RBE Resistance between base and emitter
RgInternal resistance of generator
RLLoad resistance
RNEquivalent noise resistance
rNNormalized equivalent noise resistance
RsSeries resistance
Rth Thermal resistance
Rthc Thermal resistance of a chassis plate (cooling plate, no heat sink)
RthJA Thermal resistance between junction (heat source) and static ambient air
RthJS Thermal resistance between junction and soldering point
RthJT Thermal resistance between junction and Chip base
(Chip thermal resistance)
RthTS Thermal resistance between chip base and soldering point
(package / alloy layer)
RthSA Thermal resistance between soldering point and ambient
(substrate thermal resistance)
RthJC Thermal resistance between junction (heat source) and case at infinitely
good heat dissipation from the case (Tcase =Tamb)
RODifferential resistance
S212Power gain in 50 Ω-system
S11 Input reflection coefficient in 50 Ω-system
S21 Forward transmission coefficient in 50 Ω-system
S12 Reverse transmission coefficient in 50 Ω-system
S22 Output reflection coefficient in 50 Ω-system
Technical Information
Alphanumerical List of the Symbols Used
Data Book 12 2000-09-01
tTime
tdDelay time
tfFall time
tgt Gate controlled turn-on time
tgq Gate controlled turn-off time
th In a subscript: thermal
toff Turn-off time (toff = tS + tf)
ton Turn-on time (ton = td + tr)
tpPulse duration
tqCircuit commutated turn-off time
trRise time
trr Reverse recovery time
tsStorage time
TTemperature
TPeriod duration
Tamb Ambient temperature
Tcase Case temperature
TCh Channel temperature
TjJunction temperature
Tr Abbreviation for “transistor”
TSSoldering point temperature
Tstg Storage temperature
τCharge carrier life time
vVoltage (instantaneous value)
vFM Peak forward voltage
vRF Input RF voltage
vRM Peak reverse voltage
vRS Maximum surge voltage, 1 sec
v1Input AC voltage
v2Output AC voltage
VVoltage
Vbatt Battery voltage
VBB Base supply voltage
VBE Base emitter voltage
V(BR) …Breakdown voltage
V(BR) DS Drain-Source-breakdown voltage
±V(BR) G1SS Gate1-Source-breakdown voltage
±V(BR) G2SS Gate2-Source-breakdown voltage
– VG1S(P) Gate1-Source Pinch-off voltage
– VG2S(P) Gate2-Source Pinch-off voltage
VCB Collector base voltage
VCBO Collector-base voltage with open emitter (IE = 0)
Technical Information
Alphanumerical List of the Symbols Used
Data Book 13 2000-09-01
VCC Collector supply voltage
VDS Drain-source voltage
VDG Drain-gate voltage
VGS Gate-source voltage
VCE Collector emitter voltage
VCEO Collector-emitter (reverse) voltage base open (IB = 0)
VCER Collector-emitter (reverse) voltage with a resistor between base and emitter
VCES Collector-emitter voltage with short-circulated emitter diode (VBE =0)
VCEsat Collector-emitter saturation voltage
VCEV Collector-emitter (reverse) voltage with reverse base emitter diode
VlN Input voltage
VEBO Emitter-base voltage with open collector (IC = 0)
VFForward voltage
VGS(P),VPPinch-off voltage
VOOpen-circuit voltage
VOUT Output voltage
VtTuning voltage
YParameter of the admittance matrix (y-matrix)
Y11 Short-circuit input admittance
Y12 Short-circuit reverse transfer admittance
Y21 Short-circuit forward transfer admittance
Y22 Short-circuit output admittance
z12 Reverse impedance with open input
Z1Input impedance (general)
Z2Output impedance (general)
νCollector or drain efficiency
ωAngular frequency ω = 2 ×π×f
Technical Information
Explanation of the Symbols and Terms Used
Data Book 14 2000-09-01
6 Explanation of the Symbols and Terms Used
This section contains brief explanations of the symbols and terms used in the data
sheets for transistors.
In order to distinguish between the different voltages and currents of the transistor, suffix
letters are used.
The letters provide information on the connection mode of the transistor terminals. The
order on which they are indicated together with the sign (+ or –) indicates the direction
of the voltage or current. The technical concept of current flow applies (current flow from
+ to –).
The three transistor terminals are denoted as follows:
Emitter E
Base B
Collector C
In order to characterize the cutoff currents and reverse voltages a third suffix letter is
used. This letter provides information on the connection mode of the third terminal which
is otherwise not mentioned.
Following abbreviations are used:
O The third, unmentioned terminal is open.
R Ohmic resistance between the terminal mentioned in the second place and the
unmentioned terminal.
S Short circuit between the terminal mentioned in the second place and the
unmentioned terminal.
V Reverse bias voltage between the terminal mentioned in the second place and the
unmentioned terminal.
7 Technical Explanations
7.1 Basic Transistor Configurations
Figure 2 Common Emitter Configuration
Technical Information
Technical Explanations
Data Book 15 2000-09-01
Figure 3 Common Base Configuration
Figure 4 Common Collector Configuration
Table 2 Characteristics of the Basic Configurations
Common Emitter
Configuration Common Base
Configuration Common Collector
Configuration
Input impedance
Z1
medium
Z1e
low high
Output impedance
Z2
high
Z2e
very high low
Small-signal current gain high
hfe
< 1 high
Voltage gain high high < 1
Power gain very high high medium
Cutoff frequency low
fhfe
high low
Technical Information
Technical Explanations
Data Book 16 2000-09-01
7.2 Explanations of Important Electrical Characteristics
7.2.1 DC Parameters
Figure 5 VCER (ICER)
Collector-emitter reverse voltage (collector-emitter cutoff current) with a resistor
between base and emitter. The maximum permissible resistance value RBE is specified
in the data sheets. The reverse voltage VCEO applies to higher values of RBE.
Figure 6 VCBO (ICBO)
Collector-base reverse voltage (collector-base cutoff current) with emitter open: IE=0.
Technical Information
Technical Explanations
Data Book 17 2000-09-01
Figure 7 VEBO (IEBO)
Emitter-base reverse voltage (emitter-base cutoff current) with collector open: IC=0.
Figure 8 VCEO (ICEO)
Collector-emitter reverse voltage (collector-emitter cutoff current) with base open: IB=0.
The state IB= 0 may also occur for a short while, e.g. in operation as a switch, with a
resistance interposed between base and emitter.
Figure 9 VCEV (ICEV)
Collector-emitter reverse voltage (collector emitter cutoff current) with blocked emitter
diode, i.e., reverse bias voltage between base and emitter.
Technical Information
Technical Explanations
Data Book 18 2000-09-01
Figure 10 VCES (ICES)
Collector-emitter reverse voltage (collector-emitter cutoff current) with shorted emitter
diode: VBE = 0.
7.2.2 RF Parameters
Gma,Gms
Maximum available gain if k≥ 1
Maximum stable gain if k < 1
kStability factor
S212
Insertion power gain in a 50 Ω system without matching at input and output.
ƒT
Transition frequency, determined by S-parameter measurement and calculation.
h21 Current gain
fMeasurement frequency
Gms S21
S12
--------
=Gma S21
S12
-------- kk
21––()×=
k1S11 2
–S22 2
–S11S22 S12S21
–2
+
2S12S21
-------------------------------------------------------------------------------------------------=
S21 2
()
dB 10 S21 2
log×=
fTh21 f×=
Technical Information
Thermal Resistance
Data Book 19 2000-09-01
PAE
Power Added Efficiency
ηEfficiency (collector- or drain-efficiency)
Ccb Collector-base capacitance
Cce Collector-emitter capacitance
Ceb Emitter-base capacitance
8 Thermal Resistance
The heat caused by the power loss Ptot in the active semiconductor region during
operation results in an increased temperature of the component. The heat is dissipated
from its source (junction J or channel Ch) via the chip, the case and the substrate (pc
board) to the heat sink (ambient A). The junction temperature TJat an ambient
temperature TAis determined by the thermal resistance RthJA and the power dissipation
Ptot:
(with RthJA in K/W or °C/W)
Figure 11
PAE PRF, OUT
PRF, IN PDC
+
----------------------------------=ηPRF, OUT
PDC
----------------------=
BCcb
Cce
Ceb
E
C
TJ=TA + Ptot ×RthJA
Technical Information
RF and AF Transistors and Diodes in SMD Packages
Data Book 20 2000-09-01
9 RF and AF Transistors and Diodes in SMD Packages
In SMD packages the heat is primarily dissipated via the pins. The total thermal
resistance in this case is made up of the following components:
RthJA thermal resistance between junction and ambient (total thermal resistance)
RthJS thermal resistance between junction and soldering point
RthJT thermal resistance between junction and chip base (chip thermal resistance)
RthTS thermal resistance between chip base and soldering point (package/alloy layer)
RthSA thermal resistance between soldering point and ambient (substrate thermal
resistance)
RthJS contains all type-dependent quantities. For a given power dissipation Ptot it is
possible to use it to precisely determine the component temperature if the temperature
TSof the warmest soldering point is measured (for bipolar transistors typically the
collector, for FETs the source lead).
The temperature of the soldering point TSis determined by the application, i.e. by the
substrate, heat produced by external components and the ambient temperature TA.
These components combine to form the substrate thermal resistance RthSA that is circuit-
dependent and can be influenced by heat dissipation measures.
If measurement of the temperature of the soldering point TSis not possible, or if
estimation of the junction temperature is sufficient, RthSA can be read from diagrams
below. Here we give an approximate value of the thermal resistance RthSA between the
soldering point on an epoxy or ceramic substrate and still air as a function of the area of
the collector mounting or ceramic. The parameter is the dissipated power, i.e. the heat
TS–TA of the pc board. So in this case for the operating temperature:
RthJA =RthJT + RthTS + RthSA
RthJS =RthJT + RthTS
TJ=TS + Ptot ×RthJS
TS=TA + Ptot ×RthSA
TJ=TA + Ptot × (RthJS + RthSA)
Technical Information
RF and AF Transistors and Diodes in SMD Packages
Data Book 21 2000-09-01
In the data sheets RthJS is stated as a thermal reference quantity of the heat dissipation.
The total thermal resistance RthJA is stated for comparison purposes. Depending on the
typical component application, substrates of the following kinds are used for reference:
• AF applications epoxy circuit board: collector mounting area in cm2Cu (see data
sheets), thickness 35 µm Cu.
• RF applications ceramic substrate: 15 mm ×16.7 mm ×0.7 mm (alumina) or epoxy
circuit board with collector mounting area corresponding to 80 K/W.
The two diagrams below show, to an approximation, the thermal resistance as a function
of the substrate area, assuming that the test device is located in the center of a virtually
square substrate.
Heat Dissipation from PC Board to Heat Dissipation from Al2O3-Substrate
Ambient Air (mounting pad Cu 35 µm/ to Ambient Air (substrate in still air,
substrate: epoxy 1.5 mm) vertical 0.6 mm thick)
Technical Information
RF and AF Transistors and Diodes in SMD Packages
Data Book 22 2000-09-01
9.1 Temperature Measuring of Components Leads
Measuring with temperature indicators (e.g. thermopaper)
Temperature indicators do not cause heat dissipation and thus allow an almost exact
determination of temperature. A certain degree of deviations can only result from rough-
grade indication of the temperature indicators. This method is quite easy and provides
sufficient accuracy. It is particularly suitable for measurement on pc boards.
Measuring with thermocouple elements
Measurement with thermocouple elements is not advisable because the functioning of
the circuit can be influenced by the electrical conduction and the heat dissipation by the
soldering point. This corrupts the results of the measurement, unless measurement is
carried out with appropriate effort.
9.2 Permissible Total Power Dissipation in DC Operation
The total power dissipation Ptot defines the maximum thermal gradient in the component.
As a result of the heating of components, the maximum total power dissipation Ptot max
stated in the data sheets is only permissible up to limits of TS max or TA max. These critical
temperatures describe the point at which the maximum permissible junction temperature
TJ max is reached. The maximum permissible ambient or soldering-point temperature is
calculated as follows:
In diodes the power dissipation is for the most part caused by internal resistance. So the
diagram has to be translated into the form IF=f(TS;TA), resulting in the bent shape of
the curve. For RthJA the appropriate standard substrate was taken in each case. The
diagrams shown here are intended as examples. For the application the curve given in
the data sheet is to be taken. Exceeding the thermal max. ratings is not permissible
because this could mean lasting degradation of the component’s characteristics or even
its destruction.
TS max = TJ max – Ptot max × RthJS
TA max = TJ max – Ptot max × RthJA
Technical Information
RF and AF Transistors and Diodes in SMD Packages
Data Book 23 2000-09-01
Total Power Dissipation Forward Current
Ptot = f (TS;TA1))IF = f (TS;TA1))
1) Al2O3-Substrate 15 mm ×16.7 mm ×0.7 mm / Package mounted on alumina 15 mm ×16.7 mm ×0.7 mm
9.3 Permissible Total Power Dissipation in Pulse Operation
In pulse operation, under certain circumstances, higher total power dissipation than in
DC operation can be permitted. This will be the case when the pulse duration tp, i.e. the
length of time that power is applied, is small compared to the thermal time constant of
the system. This time constant, i.e. the time until the final temperature is reached,
depends on the thermal capacitances and resistances of the components chip, case and
substrate. The thermal capacitance utilized in the component is a function of the pulse
duration.
Here we describe this through the transient thermal resistance. The pulse-load thermal
resistance, or the permissible increase in Ptot that can be derived from it, is shown by
way of examples in the following curves. For the application the particular data sheet
should be taken.
The duty factor tp/Tis given as a parameter for periodic pulse load with a period of T.
For long pulse durations the factor Ptot max/Ptot DC approaches a value of 1, i.e. Ptot in
pulsed operation can be equated with the DC value. At extremely short pulse widths, on
Ptot max / Ptot DC = f (tp)
Technical Information
ESD (Electrostatic Discharge Sensitive Device)
Data Book 24 2000-09-01
the other hand, the increase in temperature as a result of the pulse (residual ripple)
becomes negligible and a mean temperature is created in the system that corresponds
to DC operation with average pulse power.
Permissible Pulse Load Permissible Pulse Load
RthJS =f (tp)Ptot max / Ptot DC = f (tp)
10 ESD (Electrostatic Discharge Sensitive Device)
ESD-sensitive components are supplied in anti-static packaging. The attached warning
label calls your attention to the necessity of protecting the components against
electrostatic discharge, beginning with the opening of the package.
11 Standards
For detailed information please refer to the following DIN literature:
DIN 41 782: Diodes
DIN 41 785: Maximum Ratings
DIN 41 791: General Instructions
DIN 41 852: Semiconductor Technology
DIN 41 853: Terms Relating to Diodes
DIN 41 854: Terms Relating to Bipolar Transistors