*RoHS Directive 2002/95/EC Jan 27 2003 including Annex.
Specifications are subject to change without notice.
Customers should verify actual device performance in their specific applications.
4B04B-50X-RC - Surge Line Protection Modules
4B04B-501 (Pair of Matched Resistors)
Product Characteristics
Resistance Values........................................20 ohms - 100 ohms
Resistance Tolerance ...........................................................±1 %
TCR............................................................................100 ppm/°C
Ratio Tolerance.......................................>34 ohms...........±0.5 %
<34 ohms..............±1 %
Power Dissipation (per resistor) @ 25 ºC ................................2 W
Temperature Range ..........................................-55 ºC to +125 ºC
Environmental Characteristics
TESTS PER MIL-STD-202 ..............................................∆R MAX.
Resistance to Solvents .........................No Marking Deterioration
Resistance to Solder Heat ...........................±0.5 % or 0.5 ohms,
whichever is greater
Solderability .......................................................>95 % Coverage
Insulation Resistance ................10 megohms min. (isolated pins)
Bias Humidity Test .......................................50 V/85 % RH/85 °C
Functional Characteristics
Lightning Surge Test
Bellcore Spec GR-1089 10 x 1000 µsec .................1 kV
2 x 10 µsec ....................2.5 kV
ITU-T K.20 10 x 700 µsec ...................2 kV
Power Cross Test.............................................Per Bellcore spec.
(Vrms applied vary with resistance values)
Physical Characteristics
Body Style ..........................................................Open Frame SIP
Body Material..........................................................96 % Alumina
Lead Frame Material..................................Copper, solder coated
Standard Parts Available Off the Shelf..........50 ohms, 100 ohms
4B04B-502 (Resistor with Thermal Fuse)
Product Characteristics
Resistance Values.......................................5.6 ohms - 100 ohms
Resistance Tolerance....................1 % (optional), 5 % (standard)
TCR ..................................................................800 ±200 ppm/°C
Power Dissipation @ 25 ºC.....................................................2 W
Temperature Range..........................................-55 ºC to +125 ºC
Functional Characteristics
Lightning Surge Test
Bellcore Spec GR-1089 10 x 1000 µsec ..................1 kV
2 x 10 µsec .....................2.5 kV
Power Cross Test ............................................Per Bellcore spec.
(Vrms applied vary with resistance values)
Physical Characteristics
Body Style..........................................................Open Frame SIP
Body Material .........................................................96 % Alumina
Lead Frame Material .................................Copper, solder coated
Standard Parts Available Off the Shelf
.....................................................5.6 ohms, 10 ohms, 34 ohms
17
13 19
50.80
(2.000)
15.24
(0.600)
15.24
(0.600)
15.24
(0.600)
15.24
(0.600) TYP. 0.36 Max.
(.014 Max.)
2.29 Max.
(.090 Max.)
12.70
(0.500) MAX.
How To Order
4B 04 B - 50X - XXX LF
Model
(4B = Open Frame)
Number of Pins
Physical Configuration
Electrical Configuration
• 501 = Pair of Matched Resistors
Resistance Code
• First 2 digits are significant
• Third digit represents the
number of zeros to follow
Lead Free Option
Blank = Standard Product
LF = Lead Free / RoHS Compliant Product
How To Order
4B 04 B - 50X - XXX J LF
Model
(4B = Open Frame)
Number of Pins
Physical Configuration
Electrical Configuration
• 502 = Resistor with Thermal Fuse
Resistance Code
• First 2 digits are significant
• Third digit represents the
number of zeros to follow
5% Tolerance
Lead Free Option
Blank = Standard Product
LF = Lead Free / RoHS Compliant Product
Features
■Lead free versions available
(RoHS compliant*)
■Overvoltage/lightning protection to
Bellcore GR-1089 & ITU-T K.20
■Standard “off the shelf” designs
■Typical application is secondary
protection on telecom line cards
■Custom versions available, including
SMD solutions and fuse technology
(contact factory)
User must short pins 3 & 4 on the circuit board
Governing dimensions are in mm.
Dimensions in parenthesis are inches
and are approximate.
12 34
25.40±.50
(1.000±.020)
2.54±.127
(.100±.005)
17.78±.254
(0.700±.010)
TYP.
MAX.
0.36 Max.
(.014 Max.)
1.40 Max.
(.055 Max.)
3.05 Max.
(.120 Max.)
11.30
(0.445)
3.43 ± 0.38
(0.135 ± 0.015)
2.54±.127
(.100±.005)
Functional Schematic
LEAD FREE
VERSIONS ARE
RoHS COMPLIANT*
Specifications are subject to change without notice.
Customers should verify actual device performance in their specific applications.
General Description
Surge is defined as a high-energy, short-duration pulse caused
by lightning or the switching of power loads. In short, a surge
can be a transient wave of voltage, current or power. Most of the
surge pulse waveforms are unidirectional impulses. Surge wave-
forms occur in many situations, including computer memory dri-
vers and telecommunication equipment. Standards for various
natural surge pulse waveforms in the telecommunication indus-
try are IEC 801-5, ANSI/IEEE C62.41 and Bellcore GR-NWT-
001089. Two consequences of inefficient surge protection in a
system are (1) permanent damage to internal components,
which will require component replacement and (2) temporary
instability to a system, resulting in volatile memory loss in a
computer or other disruptions.
A typical telecommunication application is shown in Figure 1.
There are various protection devices which guard against surge
overstresses. Typically, a crowbar is used for primary protection,
while current limiters and clamps are used as secondary protec-
tion.
There are several standard telecommunication waveforms - 10
x 1000 microsecond, 0.5 x 700 micro-second, 10 x 700
microsecond, etc. The definition of a 10 x 1000 microsecond is
shown in Figure 2. The first number refers to the voltage rise
time while the second numbers indicate the duration. All of
these surge pulse waveforms consist of energy levels from 10 to
100 Joules.
DURATION Td
100
90
30
50
0t90
t30t0 t50 TIME t
FRONT TIME: 1.67 x (t90-t30) (VOLTAGE)
DURATION: t50-t0
FOR EXAMPLE: 10X1000 µSEC WAVE FORM DEFINITION
OPEN-CIRCUIT VOLTAGE:
FRONT TIME: 10 µSEC
DURATION: 1000 µSEC
IMPULSE WAVE
(ANSI / IEEE C62.41 - 1991)
VOLTAGE IN PERCENT OF PEAK VALUE
Figure 2. Surge Waveform
Line Protection Networks
Line protection networks are used to dissipate high energy for
a short period of time. Figure 3 shows how the amount of ener-
gy is dependent on the pulse duration and value of the load
resistance. An equation used to determine the amount of energy
transferred to the load by the overstress test waveform can be
given as follows1:
Energy, W = ________ • ________ v2(t)dt
1 RL
(RS+ RL) (RS+ RL)
0 8
∫
where RS = source resistance (W)
RL = load resistance (W)
W = energy (Joules)
RS
RL
v(t)
Over
Voltage
Over
Voltage TELECOM
CIRCUIT
Fuse
Line Protection
Network
Ring
Tip
Clamp
(Diverter or Arrestor)
Current Limiter
(Suppression)
Secondary
Protection
Primary
Protection
Crowbar
(Diverter or Arrestor)
Building
Entrance on Equipment
4B04B-50X-RC - Surge Line Protection Modules
Figure 1. Typical Telecom Application
Surge protection is necessary in situations where smaller
device geometries and higher densities make circuits suscepti-
ble to electrical over stress. Applications include instances
where faster processing speeds having less inherent filtering
make circuits more susceptible to noise. Also, when vulnerable
ICs are used in less-controlled environments, circuits can be
exposed to extreme electrical conditions.
Common Surge Modes
There are two common surge modes: (1) metallic, i.e., normal,
transverse or differential (Figure 4) and (2) longitudinal, i.e., com-
mon (Figure 5). In the metallic surge mode, earth or ground is
not involved. Both conductors are metal. Surge current flows
from tip to ring or ring to tip. The longitudinal surge mode
involves a connection in which the wave is applied between one
or more lines and ground. The longitudinal surge current flows
from tip to ground and ring to ground.
Tip
Ring
TELECOM
CIRCUIT
G
Figure 4. Typical Metallic Application Mode
Tip
Ring
TELECOM
CIRCUIT
G
Figure 5. Typical Longitudinal Application Mode
CENTRAL OFFICE
Telephone
Line
Power Lines
Primary
Protection Secondary
Protection SLIC
Figure 6. Surge Causes
Bourns Line Protection Networks
The Bourns Line Protection Network provides current limiting
for telecommunication protection circuits and consists of two
high-power surge resistors, which are utilized in the sec-
ondary protection block of central office switch systems
(Figure 6). This device protects sensitive circuitry from light-
ning strikes and power cross-conditions by limiting irregular
currents through the system.
The line protection network features a resistance range
between 50 and 100 ohms, resistors that are able to withstand
lightning and power conditions per Bellcore specification GR-
NWT-001089, noise reduction through close-ratio matching (±
percent) between tip and ring resistor pairs and superior material
systems created especially for high-power, high-reliability prod-
ucts and applications.
Figure 3. Energy Comparison
2
3
4
5
6
7
8
9
10
11
12
1
ENERGY
(JOULES)
10 x 700 µSEC 1 kV
Rs = 40Ω
(IEC 801-5 SPEC)
10 x 1000 µSEC 1 kV
Rs = 10Ω
(BELLCORE GR-NWT-001089 SPEC)
3.4
10.0
(EXAMPLE: LOAD RESISTOR = 50Ω)
4B04B-50X-RC - Surge Line Protection Modules
Specifications are subject to change without notice.
Customers should verify actual device performance in their specific applications.
Thick Film Line Protection Network Construction And Benefits
Glaze (Environmental Passivation)
Thick Film Resistor (High Power Material)
Solder Attached (Excellent in Pullstrength)
Termination
(Heat Conductivity,
Good Solderability)
Ceramic Substrate
Lead Frame (Excellent Thermal Conductivity, Pull Strength)
CROSS-SECTION OF TYPICAL DESIGN
Customer Advantages
The Bourns Thick Film Line Protection Network provides cus-
tomers with tip and ring resistors on the same component for
single placement processing. Customer lead times are reduced
because parts are readily available. Bourns is an experienced
supplier of state-of-the-art thick film overcurrent protection
devices. Bourns also has global design and manufacturing cen-
ters for localized service.
Specialty devices are available like surge resistor and standard
resistors on the same package, fusible links which are “fail safe”
integrated with surge resistors and custom electrical configura-
tions and tolerances. The thick film line protection network also
has quick-turn sample times.
1REFERENCE: STANDLER, RONALD B., “PROTECTION OF ELECTRONIC CIRCUITS FROM
OVERVOLTAGES.” PP 89 - 102, 1989.
4B04B-50X-RC - Surge Line Protection Modules
Thick Film Line Protection Network Technology Comparison
ELEMENTS OLDER TECHNOLOGY STATE-OF-THE-ART TECHNOLOGY
Ceramic thickness
Seated height
Material and process
Temperature coefficient
of resistance (TCR)
Tip and ring resistors
ratio
Surge test waveforms
• 100 cycles
• 100 cycles
• 10 cycles
Bias humidity
temperature
1000 hr. ∆R
Greater than 0.040 in.
Greater than 0.5 in.
Standard thick film
material and process
Greater than
100ppm/°C
1%
10 x 700 µsec 1 kV
10 x 1000 µsec 1 kV
2% or greater
Less than or equal to
0.040 in.
Less than or equal to
0.5 in.
• New high power material
• Improved processing
Less than 100ppm/°C
0.5% or lower
10 x 700 µsec 1 kV
10 x 1000 µsec 1 kV
2 x 10 µsec 2.5 kV
0.25% or lower
Specifications are subject to change without notice.
Customers should verify actual device performance in their specific applications.
REV. 02/07
