VCS101, VCS103, VCS401
Vishay Foil Resistors
High Precision Bulk Metal
®
Foil Power Current Sense Resistors
with TCR of ± 15 ppm/° from 0.005
Ω
C
FEATURES
NEW
•
Temperature coefficient of resistance (TCR):
± 20 ppm/° (available to ± 15 ppm/°
C
C)
•
Resistive tolerance: to ± 0.1 %
•
Resistance range: 0.005
Ω
to 0.2
Ω
(for higher or
lower values, please contact us)
•
Power rating: to 1.5 W at + 25 ° (free air)
C
•
Maximum operating temperature: + 175 °
C
•
Load life stability: ± 0.5 % at 25 ° 2000 h at rated power
C,
•
Vishay Foil resistors are not restricted to standard values;
specific “as required” values can be supplied at no extra cost or
delivery (e.g. 0R123 vs. 0R1)
•
Non-inductive, non-capacitive design
•
4 leads for Kelvin connection
•
Rise time: 1.0 ns effectively no ringing
•
Thermal EMF: 0.05 µV/° typical
C
•
Voltage coefficient: < 0.1 ppm/V
•
Non-inductive: 0.08 µH
•
Pattern design minimizing hot spots
•
Terminal finish: lead (Pb)-free or tin/lead alloy*
•
Prototype quantities available in just 5 working days or sooner.
For more information, please contact
foil@vishaypg.com
•
For better performances, see VCS201, VCS202 and VCS301,
VCS302 datasheets or contact application engineering
INTRODUCTION
Model VCS101, VCS103 and VCS401 resistors are available in 2
configurations. This Bulk Metal
®
resistor can serve as a low ohm,
high power resistive shunt or as a medium power current sensing
resistor. Resistors are non-insulated.
The art of current sensing calls for a variety of solutions based on
application requirements. Current sensing is best achieved with a
Kelvin connection, which removes the unwanted influences of lead
resistance and lead sensitivity to temperature. Other requirements
such as high stability and short thermal stabilization time when the
power changes may dictate a special resistor design.
High-precision resistors used for current sensing are usually low
ohmic value devices suitable for four terminal connections. Two
terminals, called “current terminals”, are connected to conduct
electrical current through the resistor, while voltage drop VS is
measured on the other two terminals, called “sense” or “voltage
drop” terminals. According to Ohm’s law, the sensed voltage drop
VS divided by the known resistance RS gives the sensed current
IS. The accuracy of measurement depends on the stability of ohmic
resistance RS between the nodes, i.e. the points of connection of
the sense leads. Since the voltage leads feed into an "infinite"
resistance circuit, there is no current flowing through the voltage
terminals and, therefore, no IR drop in the voltage sense leads.
Thus, the four-terminal system eliminates the voltage drop errors
originated in the leads when the voltage terminations are
connected close to the resistance element (excluding significant
portions of the leads that carry the current).
This arrangement, called a “Kelvin connection”, reduces, especially
for low ohmic resistance values, a measurement error due to the
resistance of the lead wires and the solder joints as the sensing is
performed inside the resistor, in or close to the active resistive bulk
metal foil element. Of the commonly used methods of measuring the
magnitude of electrical current, this current sensing resistor method
provides the most precise measurement. According to Ohm’s law,
V = IR, the voltage drop measured across a resistor is proportional to
the current flowing through the resistor. With the known value of the
resistance R, the voltage drop sensed on the resistor indicates the
intensity of the current flowing through it.
Assuming an ideal current sense resistor that doesn’t change
its resistance value when there is a change in the magnitude
of the current or a change in environmental conditions, like
the ambient temperature or self heating, the measured voltage
drop will yield a precise value of the current: I = V/R. But with
a real-life resistor, such as a metal film resistor or a manganin
bar, a change in current intensity (and in the dissipated power)
will cause a change in the resistor's value which will involve a
thermal transient period taking a few seconds or longer to
stabilize. Therefore, the key to a fast and precise measurement
of current is the use of a real life current sensing resistor
which approaches, as closely as possible, an ideal resistor.
That is, a resistor that is not influenced by changes in the
magnitude of the current flowing through it nor by changes in
ambient temperature or any other environmental condition.
* Pb containing terminations are not RoHS compliant.
Document Number: 63016
Revision: 04-May-10
Real life resistors exhibit two temporary changes from their
room-temperature values:
1. When they are cooled or heated by a changing ambient
temperature, and
2. By self-heating due to the power they have to dissipate (Joule
effect).
When a high precision is required, these two effects induce a change
in the resistive element's temperature,
∆T
a
due to ambient and
∆T
sh
due to self heating, both of which must be considered.
The ambient temperature changes slowly, and all parts of a resistor
follow uniformly the change of the ambient temperature, but the effect
of the dissipated power is different. The temperature of the resistive
element - the active part of the resistor - will change rapidly with the
change of the intensity of current. The power it has to dissipate will
change proportionally to the square of the current and a rapid increase
in current will cause a sudden increase in the temperature of the
resistive element and in the heat that must be dissipated to the
ambient air. A rapid decrease in current will take longer to register the
current change because the heat build-up takes longer to dissipate
through the physical encapsulants. These two effects of resistance
changes are quantified by TCR - Temperature Coefficient of
Resistance and by PCR - Power Coefficient of Resistance (called also
“Power TCR”).
Our applications engineering department is prepared to advise and
to make recommendations. For non-standard technical
requirements and special applications, please contact us.
For any questions, contact:
foil@vishaypg.com
www.foilresistors.com
1
VCS101, VCS103, VCS401
Vishay Foil Resistors
FIGURE 1 - DIMENSIONS AND SCHEMATIC
Model VCS101 Current Sensor
W
H
I
Leads
0.032 Diameter
Solder Coated
Copper
(#20 AWG)
0.500 Min.
I1
0.520 ± 0.020
0.200 ± 0.030
0.920 ± 0.020
0.040 Diameter Lead
Solder Coated Copper
(#18 AWG)
0.630
0.032 Diameter Lead
Solder Coated Copper
(#20 AWG)
Model VCS401 Current Shunt
0.520 ± 0.020
W
I
1
I
2
R
I
E2
I2
E1
V
H
0.500 Min.
Leads
0.040 x 0.005
Tin Plated
Copper
Leads
0.040 x 0.005
Tin Plated Copper
Model VCS103 Current Sensor
W
H
0.500 Min.
I
1
E
1
E
2
I
2
E
1
E
2
0.689 ± 0.020
0.200 ± 0.030
1.083 ± 0.020
TABLE 1 - CHARACTERISTICS AND DIMENSIONS
(1)
MODEL
NUMBER
VCS101
VCS401
VCS103
RESISTANCE
RANGE
(Ω)
0.005 to 0.01
Ω
0.01 to 0.05
Ω
0.05 to 0.2
Ω
0.005 to 0.01
Ω
0.01 to 0.05
Ω
0.05 to 0.25
Ω
TIGHTEST
RESISTANCE
TOLERANCE (%)
±1
± 0.5
± 0.1
±1
± 0.5
± 0.1
POWER RATING
at + 25 °C
1W
1W
1.5 W
MAXIMUM
CURRENT
15 A
3A
15 A
H
W
H
W
H
W
DIMENSIONS
INCHES
0.130
0.080
0.130
0.080
0.190
0.080
(mm)
(3.30)
(2.03)
(3.30)
(2.03)
(4.83)
(2.03)
Note
(1)
Tighter performances are available, please contact our application engineering department
TABLE 2 - VCS101, VCS103 AND VCS401 PERFORMANCE - MIL-PRF-49465
TEST OR CONDITION
Maximum Ambient Temperature at Rated Power
Maximum Ambient Temperature at Zero Power
Temperature Coefficient
Thermal Shock, 5 x (- 65 ° to + 125 °C)
C
Short Time Overload, 5 x P
nom
x 5 s
Terminal Strength
High Temperature Exposure, 2000 h at + 175 °
C
Moisture Resistance
Low Temperature Storage, 24 h at - 65 °
C
Shock (Specified Pulse)
Vibration (High Frequency)
Life (Rated Power, + 25 ° 2000 h)
C,
Resistance Tolerance
Note
∆R’s
plus additional 0.0005
Ω
for measurement error.
± 0.02 %
± 0.05 %
± 0.05 %
± 0.05 %
± 0.05 %
± 0.02 %
± 0.05 %
± 0.05 %
± 0.5 %
VCS101, VCS103 AND VCS401
TYPICAL
∆
LIMITS
+ 25 °
C
+ 175 °
C
See table 3
± 0.05 %
± 0.5 %
± 0.1 %
± 1.0 %
± 0.1 %
± 0.05 %
± 0.1 %
± 0.1 %
± 3.0 %
MAXIMUM
∆
LIMITS
± 0.1 %, ± 1 %, ± 3 %, ± 5 %, ± 10 %
TABLE 3 - TC SPECIFICATIONS
(- 55 °C to + 125 °C, + 25 °C Ref.)
VALUE
0.005
Ω
to 0.01
Ω
> 0.01
Ω
to 0.05
Ω
> 0.05
Ω
to 0.25
Ω
www.foilresistors.com
2
For any questions, contact:
foil@vishaypg.com
TC (ppm/°C)
± 90
± 30
± 20
Document Number: 63016
Revision: 04-May-10
Legal Disclaimer Notice
Vishay Precision Group
Disclaimer
All product specifications and data are subject to change without notice.
Vishay Precision Group, Inc., its affiliates, agents, and employees, and all persons acting on its or their behalf
(collectively, “Vishay Precision Group”), disclaim any and all liability for any errors, inaccuracies or incompleteness
contained herein or in any other disclosure relating to any product.
Vishay Precision Group disclaims any and all liability arising out of the use or application of any product described
herein or of any information provided herein to the maximum extent permitted by law. The product specifications do
not expand or otherwise modify Vishay Precision Group’s terms and conditions of purchase, including but not limited
to the warranty expressed therein, which apply to these products.
No license, express or implied, by estoppel or otherwise, to any intellectual property rights is granted by this
document or by any conduct of Vishay Precision Group.
The products shown herein are not designed for use in medical, life-saving, or life-sustaining applications unless
otherwise expressly indicated. Customers using or selling Vishay Precision Group products not expressly indicated
for use in such applications do so entirely at their own risk and agree to fully indemnify Vishay Precision Group for
any damages arising or resulting from such use or sale. Please contact authorized Vishay Precision Group
personnel to obtain written terms and conditions regarding products designed for such applications.
Product names and markings noted herein may be trademarks of their respective owners.
Document Number: 63999
Revision: 22-Feb-10
www.vishaypg.com
1
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