MODEL BSR SERIES
Thick Film
2512 Surge Resistors
NEW PRODUCT
FEATURES
• 1.2/50 microsecond 250V pulse
• 10/700 microsecond 250V pulse
APPLICATIONS
• Nickel barrier terminations
• Double glass passivation
Telephone lines are often subject to a variety of voltage
disturbances which fall into two main categories -
short duration, high voltage transients caused by
lightning strikes and longer duration, over voltages
which may be caused by direct connection to main
power lines. The advent of electronic switching has
meant that sophisticated methods of protection against
these two fault conditions has to be incorporated to
ensure that potential damage is limited.
The two types of protection are:
primary,
which
attempts to deal with the bulk of the energy from a fast
transient, particularly lightning strikes and power
crosses and
secondary,
which provides a further level
of protection to prevent damage to sensitive electronic
circuits.
The possibility of disturbances in the line is dependent
on the environment of the equipment installation. In
the case of a PABX, where the telephone line, terminal
equipment and the line interface are all installed in the
same building, the possibility of induced lightning
transients is greatly reduced and the opportunity for
damage induced by direct connection to mains is low.
For these reasons the degree of protection is much less
than for equipment connected outside the building
where the risk increases dramatically.
BI Technologies is involved in secondary protection for
all types of environment. The BSR Series has been
specifically designed for PABX where cost is of
paramount importance. For central switches, the
tip
and ring
resistors are expected to perform identically to
maintain the correct resistance for a balanced line
system. Both resistors are therefore generally
produced on a common substrate, which may be
through hole or surface mount, and perform close to
one another under all foreseeable fault conditions in
both common and differential modes. For PABX,
tracking is not required because an individual resistor
is used which normally runs at low power yet has the
ability to withstand considerable power for long
periods and has good characteristics under high
voltage transient conditions.
The BSR Series is a surface mount chip resistor
in a standard 2512 package which utilizes special
resistor film to handle the high voltage with
Contact factory for custom surge resistors meeting
Bellcore testing conditions.
Continued . . .
5
Specifications subject to change without notice.
5-7
Model BSR Series
APPLICATIONS
sophisticated laser trimming to prevent flash over. In
the event of a very high voltage pulse the resistor will
go open-circuit preventing damage to surrounding
components or the printed circuit board. Two units are
required for each incoming line to protect both tip and
ring individually and collectively. The resistor is made
from nonflammable material.
ELECTRICAL
The BSR Series is manufactured in BI’s highly
automated production facility in Glenrothes, Scotland,
which also produces standard 2512 chip resistors and
a wide range of chip resistor networks, R/C networks
as well as gull wing 14 and 16 lead resistor networks,
all of which are used on the PABX line card and in
many other areas of electronics.
Surge Capability, Max.
Standard Resistance Range, Ohms
Standard Resistance Tolerances
Operating Temperature Range
Temperature Coefficient of Resistance, Max.
Power Ratings, Watts, at 70°C (See Note )
Operating Voltage, Max.
Note : For 2 watts limit part temperature to +155° C
ENVIRONMENTAL
1.2 / 50 µs, 250 V; 10 / 700 µs, 250 V (∆R ±5%+0.1Ω)
0.05 to 10000 Ohms
±5%, ±10%, ±20% Optional : ±1%, ±2%
-55°C to +125°C
±100ppm/°C above 10 Ohms
1 and 2
100 V dc or
√PR
whichever is less
Short Time Overload, Max.
Temperature Cycling
Moisture Resistance
Load Life
Resistance to Solder Heat
2.5 x rated voltage (∆R ±1%+0.1
Ω)
-55°C to +125°C, 5 cycles (∆R ±5%+0.1
Ω)
1,000 hours at 40°C, 95% RH (∆R ±3%+0.1
Ω)
1,000 hours at 70°C + Rated Voltage, Max. (∆R ±3%+0.1
Ω)
260°C for 10 sec. (∆R ±5%+0.1
Ω)
CONSTRUCTION
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Glass Passivation:
Glass Protective
Coating
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Substrate:
Alumina
Resistor:
Ruthenium Oxide
90/10 Tin-Lead
Solder Plating
Nickel Barrier
Thick Film Conductor
5-8
Model BSR Series
Microcontroller MCU
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