BR Series
Bare Element Current Sense Resistor
Features:
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Stackpole Electronics, Inc.
Resistive Product Solutions
1, 3 and 5 watts
±1%, ±2% or ±5% tolerance
Resistance wire TCR ±20ppm/ºC
Low inductance versions available for high frequency applications
All welded construction
Flameproof
Non-inductive (10 nH max)
Solderable copper leads (60/40)
High current handling to 70 amps
RoHS compliant / lead-free
Current sensing
Feedback
Low inductance
Surge and pulse
Applications:
Electrical Specifications
Type / Code
BR 1
BR 3
BR 5
Power Rating
(Watts) at 85ºC
1W
3W
5W
Resistance Temperature
Coefficient (1)
±100ppm/ºC - ±20ppm/ºC
±100ppm/ºC - ±20ppm/ºC
±100ppm/ºC - ±20ppm/ºC
Ohmic Range (Ω) and Tolerance (1)
1%
0.005 - 0.1
0.005 - 0.1
0.005 - 0.05
2%, 5%
0.005 - 0.1
0.005 - 0.1
0.005 - 0.05
(1) Contact factory for resistance values below 0.005Ω
Please refer to the High Power Resistor Application Note (page 3) for more information on designing and implementing
high power resistor types.
Mechanical Specifications
Type / Code
BR 1
BR 3
BR 5
A
0.45 + 0.04/-0.02
11.43 + 1.02/-0.508
0.6 + 0.04/-0.02
15.3 + 1.02/-0.508
0.8 + 0.04/-0.02
20.32 + 1.02/-0.508
B
0.2 ± 0.1
5.08 ± 2.54
0.6 Typ - 1 Max
15.3 Typ - 25.4 Max
0.6 Typ - 1 Max
15.3 Typ - 25.4 Max
C
0.125 ± 0.03
3.18 ± 0.762
0.125 ± 0.03
3.18 ± 0.762
0.125 ± 0.03
3.18 ± 0.762
D
0.065 ± 0.01/-0.005
1.65 ± 0.254/-0.127
0.065 ± 0.01/-0.005
1.65 ± 0.254/-0.127
0.065 ± 0.01/-0.005
1.65 ± 0.254/-0.127
E
0.04 ± 0.002
1.02 ± 0.051
0.04 ± 0.002
1.02 ± 0.051
0.04 ± 0.002
1.02 ± 0.051
Units
inches
mm
inches
mm
inches
mm
Rev Date: 12/22/2010
This specification may be changed at any time without prior notice
Please confirm technical specifications before you order and/or use.
1
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marketing@seielect.com
BR Series
Bare Element Current Sense Resistor
Stackpole Electronics, Inc.
Resistive Product Solutions
Mechanical Specifications
Test
Moisture Resistance
Load Life @ 25ºC - 1,000 hrs.
Short Time Overload
Temperature Cycle @ -40ºC & +125ºC (1,000 cyc)
Test Results
± 1%
± 1%
± 0.5%
± 1%
How to Order
SEI Type
Code
Nominal
Resistance
Tolerance
Packaging
BR
Type
BR
Description
Current Sense
Code
1
3
5
1
Wattage
1W
3W
5W
0.01
1%
Tolerance
1%
2%
5%
Code
B
B
Description
bulk
Pkg Qty
1,000
New part number format starting January 3
rd
, 2011:
How to Order
1
2
3
4
5
6
7
8
9
B
R
1
F
B
1
0
L
0
Product Series
BR
Current Sense
Size
1
3
5
Power
1W
3W
5W
Tolerance
Code Tol
1%
F
2%
G
5%
J
Code
B
Packaging
Description
Size
bulk
all sizes
Resistance Value
Quantity
1,000
Four characters with
"L" used as multiplier
of 10
-3
for any value
under 0.1 ohm.
0.1 ohm = R100
0.05 ohm = 50L0
0.005 ohm - 5L00
Rev Date: 12/22/2010
This specification may be changed at any time without prior notice
Please confirm technical specifications before you order and/or use.
2
www.seielect.com
marketing@seielect.com
BR Series
Bare Element Current Sense Resistor
Stackpole Electronics, Inc.
Resistive Product Solutions
High Power Chip Resistors and Thermal Management
Stackpole has developed several surface mount resistor series in addition to our current sense resistors,
which have had higher power ratings than standard resistor chips. This has caused some uncertainty and
even confusion by users as to how to reliably use these resistors at the higher power ratings in their designs.
The data sheets for the RHC, RMCP, RNCP, CSR, CSRN, CSRF, CSS, and CSSH state that the rated
power assumes an ambient temperature of no more than 100 degrees C for the CSS / CSSH series and 70
degrees C for all other high power resistor series. In addition, IPC and UL best practices dictate that the
combined temperature on any resistor due to power dissipated and ambient air shall be no more than 105C.
At first glance this wouldn’t seem too difficult, however the graph below shows typical heat rise for the CSR
½ 100 milliohm at full rated power. The heat rise for the RMCP and RNCP would be similar. The RHC with
its unique materials, design, and processes would have less heat rise and therefore would be easier to
implement for any given customer.
CSR 1/2 100m Surface Temp Rise
120
Test equipment:
Chroma Programmable DC Power supply
YF-162 TYPE--K thermometer
100
102
80
72
℃ 60
36
41
50
35
40
20
0
0.10
0.13
0.17
Power Rating
0.25
0.50
0.75
The 102 degrees C heat rise shown here would indicate there will be additional thermal reduction techniques
needed to keep this part under 105C total hot spot temperature if this part is to be used at 0.75 watts of
power. However, this same part at the usual power rating for this size would have a heat rise of around 72
degrees C. This additional heat rise may be dealt with using wider conductor traces, larger solder pads and
land patterns under the solder mask, heavier copper in the conductors, vias through PCB, air movement, and
heat sinks, among many other techniques. Because of the variety of methods customers can use to lower
the effective heat rise of the circuit, resistor manufacturers simply specify power ratings with the limitations
on ambient air temperature and total hot spot temperatures and leave the details of how to best accomplish
this to the design engineers. Design guidelines for products in various market segments can vary widely so it
would be unnecessarily constraining for a resistor manufacturer to recommend the use of any of these
methods over another.
Note:
The final resistance value can be affected by the board layout and assembly process, especially the size of the
mounting pads and the amount of solder used. This is especially notable for resistance values
≤
50 mΩ.
This should be taken into account when designing.
Rev Date: 12/22/2010
This specification may be changed at any time without prior notice
Please confirm technical specifications before you order and/or use.
3
www.seielect.com
marketing@seielect.com
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