CSM Series
Vishay Foil Resistors
Bulk Metal
®
Technology High Precision, Current Sensing, Power
Surface Mount, Metal Strip Resistor with Resistance Value from 1 m
Ω
,
Rated Power up to 3 W and TCR to 0 ± 15 ppm/°C Maximum
FEATURES
•
Temperature coefficient of resistance:
± 15 ppm/°C max. (- 55 °C to + 125 °C, + 25 °C
ref.); ± 10 ppm/°C max. (- 55 °C to + 125 °C,
+ 25 °C ref.) is available on request (see table 1)
•
Power rating: 1 W to 3 W
•
Resistance tolerance: ± 0.1 %
•
Resistance range: 1 mΩ to 200 mΩ
(1)
•
Vishay Foil resistors are not restricted to standard values,
specific “as required” values can be supplied at no extra
cost or delivery (e.g. 2.3456 mΩ vs. 2 mΩ)
•
Load life stability to ± 0.2 % (70 °C, 2000 h at rated power)
•
Short time overload: ± 0.1 % typical
•
Thermal EMF: 3 µV/°C (DC offset error, significant for low
values)
•
Maximum current: up to 54 A
•
Proprietary processing techniques produce low TCR, tight
tolerance and improve stability
•
Low inductance < 5 nH
•
Solderable terminations
•
Excellent frequency response to 50 MHz
•
Matched sets are available on request
•
Screening in accordance with EEE-INST002 available
(per MIL-PRF-55342 and MIL-PRF-49465; see 303144
and 303145 datasheets)
•
Terminal finishes available: lead (Pb)-free, tin/lead alloy
•
Prototype quantities available in just 5 working days
or sooner. For more information, please contact
foil@vishaypg.com
•
For better performance please contact Application
Engineering
•
Compliant to RoHS directive 2002/95/EC
No minimum order quantity and any value at any
tolerance available within resistance range.
Vishay Foil Resistors’ application engineering department is
available to advise and make recommendations.
For non-standard technical requirements and special
applications, please contact
foil@vishaypg.com.
B
I
A
Zin
~
∞
=
V
R
C
I
D
Four terminal (Kelvin) design: allows for precise and
accurate measurements.
FIGURE 1 - POWER DERATING CURVE
100
+ 70 °C
Rated Power (%)
80
60
40
20
0
- 65 - 50
- 25
0
25
50
75
100
125
150
170
Ambient Temperature (°C)
TABLE 1 - SPECIFICATIONS
PARAMETER
Resistance Range
Power Rating at 70 °C
Maximum Current
(3)
Tolerance
1 W
(2)
31 A
± 0.5 % (1 mΩ to < 3 mΩ)
± 0.1 % (3 mΩ to 200 mΩ)
± 50 ppm/°C (1 mΩ to < 3 mΩ)
± 15 ppm/°C (3 mΩ to 200 mΩ)
± 10 ppm/°C (3 mΩ to 10 mΩ) is available on request
(4)
CSM2512
1 mΩ to 200 mΩ
(1)
3 W ( 1 mΩ to 10 mΩ)
2 W (> 10 mΩ to 200 mΩ)
54 A
± 0.5 % (1 mΩ to < 2 mΩ)
± 0.1 % (2 mΩ to 200 mΩ)
± 25 ppm/°C (1 mΩ to < 3 mΩ)
± 15 ppm/°C (3 mΩ to 200 mΩ)
± 10 ppm/°C (1 mΩ to 10 mΩ) is available on request
(4)
CSM3637
Temperature Coefficient
Max. (- 55 °C to + 125 °C,
+ 25 °C Ref.)
Operating Temperature
- 65 °C to + 170 °C
Range
Maximum Working Voltage
(P x
R)
1/2
Weight (Maximum)
0.09 g
Notes
(1)
For CSM2512 up to 500 mΩ please contact application engineering:
foil@vishaypg.com
(2)
For values above 0.1
Ω
derate linearly to 80 % rated power at 0.5
Ω
(3)
Maximum current for a given resistance value is calculated using I
=
P
⁄
R
(4)
Please contact application engineering:
foil@vishaypg.com
* Pb containing terminations are not RoHS compliant, exemptions may apply
Document Number: 63089
Revision: 3-May-11
For any questions, contact:
foil@vishaypg.com
0.29 g
www.vishayfoilresistors.com
1
CSM Series
Vishay Foil Resistors
ABOUT CSM
(Low Ohm Value 1 mΩ to 200 mΩ)
New high-precision Bulk Metal
®
surface-mount Power Metal
Strip
®
resistor of 1 mΩ to 200 mΩ that features an improved
load-life stability of ± 0.2 % at + 70 °C for 2000 h at rated
power, an absolute TCR of ± 15 ppm/°C maximum from
- 55 °C to + 125 °C, + 25 °C ref., and a tolerance of ± 0.1 %.
Typical current sensing resistors offer a load-life stability of
≥
1 % through a 2000 h workload. The improved resistance
stability of the CSM Series makes it ideal for
tightened-stability voltage division and precision current
sensing applications in switching linear power supplies,
power amplifiers, measurement instrumentation, bridge
networks, and medical and test equipment. In addition, the
CSM Series complies with EEE-INST-002 (MIL-PRF 55342
and MIL-PRF 49465) for military and space applications.
Traditional Passive current sensors and shunts generate
heat under power, which changes their resistance, and thus
their voltage output. The CSM’s low absolute TCR reduces
errors due to temperature gradients, thus reducing a major
source of uncertainty in current measurement. The CSM
can withstand unconventional environmental conditions,
including the extremely high temperatures and radiation-rich
environments of down-hole oil exploration and well logging,
or the deep-sea underwater repeaters in cross-ocean
communications.
The stability of the CSM can be further enhanced by
post-manufacturing operations (PMO), such as temperature
cycling, short-time overload, and accelerated load life which
are uniquely applicable to Bulk Metal
®
Foil resistors.
The device features a low thermal electromotive force (EMF)
that is critical in many precision applications. The CSM’s
all-welded construction is composed of a Bulk Metal
®
resistive element with welded copper terminations, plated for
soldering. The terminations make true ohmic contact with the
resistive layer along the entire side of the resistive element,
thereby minimizing temperature variations. Also, the resistor
element is designed to uniformly dissipate power without
creating hot spots, and the welded terminations material is
compatible with the element material.
These design factors result in a very low thermal-EMF
(3 µV/°C) resistor, because in addition to the low thermal
EMF compatibility of the metals, the uniformity and thermal
efficiency of the design minimizes the temperature
differential across the resistor, thereby assuring low thermal
EMF generation at the leads. This further reduces the
“battery effect” exhibited by most current-sensing or
voltage-reference resistors. Thus, the parasitic voltage
generated at the junction of two dissimilar metals, which is
especially important in low-value current-sensing resistors, is
minimized, while the pure current-to-voltage conversion is
protected from such interference in DC applications.
The stability problems associated with analog circuits are
very pervasive, but knowledgeable selection of a few
high-quality resistors, networks, or trimming potentiometers
www.vishayfoilresistors.com
2
For any questions, contact:
foil@vishaypg.com
Document Number: 63089
Revision: 3-May-11
in critical locations can greatly improve circuit performance,
long-term application-related performance, as well as the
designer’s peace-of-mind.
Additionally, the overall system cost is often reduced when a
knowledgeable designer concentrates costs in a few
exceptionally stable components whose proven minimal-
deviation load and environmental stability can often eliminate
the necessity of additional compensating circuitry or
temperature-controlling systems. The higher reliability and
better overall system performances also achieve excellent
product results in the field, enhancing market acceptance
and product reputation.
Designers often unnecessarily pay for tighter tolerances than
required simply to accommodate the resistance stability
shifts they know to be imminent in an application due to the
large application-related changes in the components they
selected. Selection of a high-stability component like the
CSM in these applications eliminates the need for shift
allowance due to “planned instability” and allows the use of
looser initial tolerances than would be necessary with
current-sensing resistors based on other technologies.
The Key Applications
Applications requiring accuracy and repeatability under
stress conditions such as the following:
•
Switching and linear power supplies
•
Precision current-sensing
•
Power management systems
•
Feedback circuits
•
Power amplifiers
•
Measurement instrumentation
•
Precision instrumentation amplifiers
•
Medical and automatic test equipment
•
Satellites and aerospace systems
•
Commercial and Military avionics
•
Test and measurement equipment
•
Electronic scales
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