CSM Series
Bulk Metal
®
Technology High Precision, Current Sensing, Power
Surface Mount, Metal Strip Resistor with Resistance Value from 1 m
,
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 m to 200 m
Bulk Metal
®
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 m vs. 2 m)
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
Quick prototype quantities available, please contact
foil@vpgsensors.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.
The Vishay Foil Resistors (VFR) application engineering
department is available to advise and make
recommendations.
For non-standard technical requirements and special
applications, please contact
foil@vpgsensors.com.
B
I
A
Zin
R
C
I
D
~
=
∞
V
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
(2)
Tolerance
1 W
(1)
31 A
± 0.5 % (1 m to < 3 m)
± 0.1 % (3 m to 200 m)
± 50 ppm/°C (1 m to < 3 m)
± 15 ppm/°C (3 m to 200 m)
± 10 ppm/°C (3 m to 10 m) is available on request
(3)
CSM2512
1 m to 200 m
3 W ( 1 m to 10 m)
2 W (> 10 m to 200 m)
54 A
± 0.5 % (1 m to < 2 m)
± 0.1 % (2 m to 200 m)
± 25 ppm/°C (1 m to < 3 m)
± 15 ppm/°C (3 m to 200 m)
± 10 ppm/°C (1 m to 10 m) is available on request
(3)
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
0.29 g
Notes
(1)
For values above 0.1
derate linearly to 80 % rated power at 0.5
(2)
Maximum current for a given resistance value is calculated using I
=
P
R
(3)
Please contact application engineering:
foil@vpgsensors.com
* This datasheet provides information about parts that are RoHS-compliant and/or parts that are non-RoHS-compliant. For example, parts with
lead (Pb) terminations are not RoHS compliant. Please see the information/tables in this datasheet for details.
Document Number: 63089
Revision: 17-Aug-15
For any questions, contact
foil@vpgsensors.com
www.vishayfoilresistors.com
1
CSM Series
ABOUT CSM
(Low Ohm Value 1 m to 200 m)
New high-precision Bulk Metal
®
surface-mount Power Metal
Strip
®
resistor of 1 m to 200 m 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@vpgsensors.com
Document Number: 63089
Revision: 17-Aug-15
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
Switching Power Supply Study Group
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