TOKEN
Current
Sensing
Resistors
Chip Current Sense / Open-Air Current Shunts /
Axial Current Sense Resistors
Token Electronics Industry Co., Ltd
.
Taiwan:
No. 137, Sec. 1, Chung Shin Rd., Wu Ku Hsiang, Taipei Hsien, Taiwan, R.O.C
TEL: 886-2-2981 0109; FAX: 886-2-2988 7487
China:
12F, Zhongxing Industry Bld., Chuangye Rd., Nanshan District, Shenzhen, Guangdong
TEL: 86-755-2605 5363, 2605 5364; FAX: 86-755-2605 5365
http://www.token.com.tw
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Product Index
Information
General Information ----------------------------------------------------------------------------- 01
Design & Selection ------------------------------------------------------------------------------ 03
Terminology & Glossary ----------------------------------------------------------------------- 05
Chip Current Sense Resistors
LRC Series - Current Sense Metal Strip Chip Resistors ---------------------------- 08
CS Series - Surface Mount Current Detecting Resistors ---------------------------- 13
TCS Series - Thin Film Current Sensing Chips ----------------------------------------- 21
Open-Air Current Shunts
LRA Series - Open Air Low Ohmic Resistors ------------------------------------------- 26
LRB Series - Open Air Low Inductance ---------------------------------------------------- 29
OAR Series - Open-Air Metal Element Current Sense -------------------------------- 32
FL Series - Current Shunt Resistors ------------------------------------------------------- 35
LSQ Series - Kelvin Four Terminal Resistors -------------------------------------------- 42
LRD Series - Open-Air Four Leads Resistors ------------------------------------------- 46
LPS Series - Low Ohm Current Sense for Shunts ------------------------------------- 49
Open-Air Current Shunts
BWL Series - Power Low Resistance Resistors ---------------------------------------- 52
NE Series - Low Ohmic Extra Precision Resistors ------------------------------------ 54
Notice:
Specification Changed or Version Updated will be posted at irregular intervals.
All Updated and Final Specifications, Please Confirm with TOKEN ELECTRONICS
REPRESENITIVES.
:
:
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Information of Current Sensing Resistors
Information of
Current Sensing
Resistors
You Current Options - Token Current Sense
As the world becomes more and more technology-driven, the uses for current sensing resistors will
continue to increase. The need for even lower resistance value ranges is already becoming evident,
as is the need for these resistors to handle more power. The industry-wide trend is the emergence of
smaller and smaller products.
Token Electronics offers a wide variety of current sensing products from the industry to military
standards, such as current sense in Thin-Film / Thick-Film Technology, Bare Element Resistors,
and Open Air Shunts. This enables Token to present an astounding number of possible solutions
for any circuit design needs.
Applications of Current Detecting Resistors
Token’s TCS and CS Series unique form factor provides automotive designers with several
advantages. Both TCS and CS Series are ideal for applications involving window lift motors,
fuel pump systems, seat belt pretensioners, and pulsewidth modulator feedback.
The wider resistive element and lower resistance enables higher current to pass through the device.
Token’s LRC ultra low ohmic metal strip chip series provides the inherent ability to flex slightly and
offers stress relief during extreme temperature cycling on typical or metal substrates. This LRC series
is suitable for switch power supply applications (DC-DC Converter, Charger, Adaptor) and power
management of monitor.
The open air design of bare element resistor LRA and LRB Series provide a far cooler operation by
allowing more air flow under the resistive element to keep excess heat from being transmitted to the
PC board. They are suitable for high power AC/DC detection of power supply circuit.
Token axial moulded BWL series provides power rating up to 10 watts and lower resistance 0.005Ω,
is ideal for all types of current sensing applications including switching and linear power supplies,
instruments and power amplifiers.
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TOKEN
Information of Current Sensing Resistors
PDF Catalogue Download
Token standard current sensing resistors can be replacement for Vishay, IRC, Ohmite, KOA, Yageo devices
with fast delivery and more competitive price. Contact us with your specific needs. Download Low Ohmic
Current Sense Catalogue in PDF file (367KB).
Generally, a resistor manufacturer will offer their most popular devices as standards creating a
reference for Engineers to design from. Typically, and especially true in the Current Sensing category,
a standard device is available for most common applications. However, for applications requiring
parameters that are not currently considered industry standards, Token is uniquely equipped to offer
design and development services at comparatively lower costs than our competitors. In this case, the
following information is required to effectively design a current sensing resistor:
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Design & Select Current Sense Resistors
Design & Select
Current Sense
Resistors
Point 1 - Power Rating
Calculate the power dissipation under operating conditions
Equation: Pavg = IRMS2 × R; where Power (P), Current (I), Root Mean Square (RMS),
Resistance (R).Allowing
for transient or fault conditions and high ambient temperature if applicable,
select the required power rating.For many current sense products, only the maximum temperature of
the solder joints limits the power rating.Power rating is thus a function of the PCB layout design as
well as of component selection (see point 4.).
Point 2 - Resistance Value
Determine the minimum suitable resistance value. This is the lowest value of peak sense voltage
consistent with an acceptable signal to noise ratio, divided by the peak current to be measured.
Point 3 - Temperature Coefficient of Resistance (TCR)
Establish the accuracy needed in terms of a tolerance on the value and of sensitivity to temperature.
The latter factor is quoted as Temperature Coefficient of Resistance (TCR), defined as the value
change in parts per million for a 1°C temperature rise. It is generally higher for low value resistors
because the metallic leads or terminations, which have a very high TCR, make up a significant part of
the total resistance value.
To achieve acceptable accuracy it is normally necessary to make four-terminal (Kelvin) connections
to the resistor. This means connecting the current carrying tracks and the voltage sense tracks directly
to the component pads. Even when this is done, there is still some pad area and solder in series with
the resistor, which may compromise the actual tolerance and TCR of the soldered part. For very high
accuracy or very low values, a four-terminal resistor type is the best choice.
Point 4 - PCB Layout
Care must be taken when laying out a PCB if the stated performance of a sense resistor is to be
achieved. The current carrying tracks should be as wide as possible, using multiple layers connected
by many vias near the component pad. This also improves the heatsinking of the joints.
The best way to make four-terminal connections to a two-terminal through-hole resistor is to use
different sides of the PCB for the current and voltage connections. Failing this, current and voltage
tracks should connect to opposite sides of the component pad.
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