Direct's open air 4-Lead kelvin connected resistors (LRD) tackle current sensing applications.
Open Air Four Terminal Resistors LRD Series

Always preferred in current sense applications, Direct's LRD Series range is available in the 1W, 3W, 5W, 7W and 10W packages, resistance values down to 0.001 ohm, with tolerances as tight as 0.50% and TCRs of 50ppm standard.

The 4 Lead Kelvin configuration enables current to be applied through two opposite terminals and a sensing voltage to be measured across the other two terminals, eliminating the resistance and temperature coefficient of the terminals for a more accurate current measurement.

With LRD, only a minimal shift in resistance value will occur during its entire lifetime. Most of this shift takes place during the first few hundred hours of operation, and virtually no change is noted thereafter.

The Open Air (LRD) Kelvin 4-terminal Resistor meet the RoHS requirements and can be manufactured to custom length/width for use as a current shunt. Direct will also produce outside these specifications to meet customer requirements. Contact us with your specific needs.

Features :
- Low inductance, 4 leads for Kelvin connection.
- Radial, self-supporting, design is ideal for PC board mounting.
- Decimal marked, silicone coated, Tinned copper terminal for easy soldering.

Applications :
- Surge/Pulse Applications, Current Sensing Application.
- Feed Back & Motor Control, High Precision Measurement Instrumentation.

Specification & Dimensions (Unit: mm) (LRD)
4-Terminal Current Sensing Open Air (LRD) Dimensions
Type Rating Wattage Resistance Range (mΩ) Tolerance (%) TCR (ppm/°C)
LRD-1 1W 1 ~ 10 mΩ D(±0.5%)
F(±1%)
G(±2%)
J(±5%)
±50 ppm/°C
±100 ppm/°C
LRD-3 3W 1 ~ 10 mΩ
LRD-5 5W 0.5 ~ 5 mΩ
LRD-7 7W 0.3 ~ 3 mΩ
LRD-10 10W 0.1 ~ 1 mΩ

Power Derating Curve (LRD)
(LRD) Power Derating Curve

Characteristic Specification & 4-Lead Kelvin Connections (LRD)
4-wire Sensing (LSQ-C) Dimensions
Test Items Test Method Specification
Operating Temperature Range   -55°C ~ 125°C
Maximum Working Voltage   (P40°C x R)1/2
Terminal Tensile Strength 50N, 10s ΔR≤±1.0%R
Withstand Voltage 1000V, 1 Min. No damage on the appearance.
Short Time Overload 5 times rated power, 5s ΔR≤±4.0%R
Thermal Shock -55°C~+125°C, 5 cycles, 30 min. ΔR≤±5.0%R
Load Life 70°C, 1000h 1.5 hours on, 0.5 hours off. ΔR≤±5.0%R

How to Order
LRD 5 R005 F P
Part Number
LRD
Rated Power
1 1 Watt
3 3 Watt
5 5 Watt
7 7 Watt
10 10 Watt
Resistance Value (Ω)
R005 0.005Ω
R05 0.05Ω
R1 0.1Ω
Tolerance %
D ±0.5%
F ±1%
G ±2%
J ±5%
Package-Code
P Bulk


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