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High power and excellent heat dissipation
shunt resistor (metal current sensor) –
PU series, 3921 & 5931
The Yageo shunt resistor - PU series is a perfect
solution for current sensing applications with a high
power rating (up to 10W) requirement. Welding
technology is introduced to combine the center metal
alloy and copper (Cu) together at the terminations.
The central open air design is the key for achieving
good heat dissipation (Fig.1). The selection of metal
alloy provides a very low thermal EMF which can help
to minimize the current sensing error.
Thermal EMF is a source of signal noise and it is a negligible
factor for low ohmic resistors. For current sensing applications,
a low ohmic resistor is used to monitor current alteration and
the voltage is usually at minivolt (mV) level. As a result, the
thermal EMF might be large enough to impact the measurement
and become a sensing error. However, precision is the most
important requirement in current sensing, so a low thermal
EMF is an essential characteristic of a current sensor.
A simple experiment was implemented in order to establish
the real thermal EMF level of a shunt resistor and a thick film
current sensor. The testing resistor samples were mounted on
a PCB and powered under room temperature. Then a finger
was placed on the copper termination to simulate a slight rise
in the temperature condition. Figure 2 shows the thermal EMF
test results of a shunt resistor and a thick film current sensor.
The thermal EMF of the shunt resistor is visibly lower than the
thick film current sensor.
Yageo provides high power metal current sensor - shunt resistor
PU series in sizes 3921 and 5931. The advantages of good heat
dissipation, low thermal EMF, and wide operational temperature
range (-65°C~275°C) are ideal for precise current sensing
applications under a high temperature environment such as E
car battery management systems or power supply module.
Low Thermal EMF for Shunt Resistors - PU Series
Fig. 1 The structure of a shunt resistor. The central portion
does not have contact with the PCB after mounting.
Thermal EMF is an abbreviation of thermal electromotive
force. When two dissimilar metals contact with each
other and are heated, a voltage is generated at the
intermetallic junction due to the temperature change
which causes different molecular activity in the two
different metals. Thermal EMF is expressed in the
voltage change rate with temperature and is usually
measured in microvolt per degree Celsius (µV/℃). In
fact, thermal EMF exists in all resistors. For resistors,
since they are soldered on the PCB, the terminations
of resistors are connected to the copper circuit trace
and form metallic junctions which induce thermal EMF.
Fig. 2 Thermal EMF of a shunt resistor and a thick film current sensor. The
thermal EMF (DC voltage) of the shunt resistor is obviously lower
than the value of the thick film current sensor.
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5
10
15
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25
0
5
10
15
20
Thermal EMF of Shunt Resistor & Thick Film Current Sensor
DC Voltage (uV)
Shunt resistor
Thick film current sensor
Times (s)
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Yageo’s PU Series Application Map
Low Thermal EMF for Shunt Resistors - PU Series
▪ High rated power (3 ~ 10W)
▪ Resistance down to 0.2mR
▪ Sulfur resistant due to no Ag in the structure
▪ Low thermal EMF
▪ Excellent heat dissipation
▪ AEC-Q200 qualified
▪ Power supply
▪ Industrial equipments
▪ Telecommunication base station
▪ HID lights
▪ Battery management system
▪ ABS/ESP system
Applications
Features
HID lights
Telecommunication base station
Power supply
Industrial equipments
ABS/ESP system
Battery management system
Benefits
▪ Open-Air design provides good heat dissipation which is able to work under high ambient temperature
▪ Perfect for current sensing applications with a high power rating requirement
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Established in 1977, the Yageo Corporation has become the world's leading total service provider of passive
components with capabilities on a global scale, including production and sales facilities in Asia, Europe and the
Americas. Yageo’s broad product offerings are targeting at key vertical markets,
including applications for consumer electronics, computer & peripherals, industrial/
power, alternative energy, and automotive.