Precision Low Ohmic Resistors (LRA)

Precision Open-Air Low Ohmic Resistor (LRA) Introduction

Open Air Precision Low Ohmic Resistors (LRA) Feature Longer Thermal Path.

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  • Low Ohmic Open Air Resistors - LRA Series

Token's current sense LRA open air resistors are expected to gain wide acceptance in the worldwide market as a result of increased thermal management capabilities.

The LRA series is designed for applications requiring the transfer of heat away from circuits and solder joints. Available in 0.5W, 1W, and 1.5W rating, the resistor is being specified for current sensing, feedback, current detective, supper low inductance, as well as surge and pulse applications.

The hot spot on the LRA open-air resistor is approximately 0.2 degrees higher than on a typical metal strip chip resistor. This results in an increased thermal path for the LRA, reducing heat transfer into the solder joints and circuits.

The flameproof LRA low resistance value resistors are constructed of a wire resistive element with welded copper leads to prevent solder wicking, which can change the device's resistance value in the circuit by as much as 30%. Because of this, the device is ideal for thermally harsh environments, including automotive and aerospace applications, as well as enclosed, poorly ventilated circuits in applications such as laptop computers.

The LRA Open Air Series feature a reduced pitch, or spacing between the leads on the circuit board (with a corresponding increase in the board mounted profile), when compared to the standard Token LRB Series devices.

The LRA resistors are rated for 1W or 1.5W at 70°C, with resistance values from 0.1Ω to 0.003Ω and tolerances down to ±1%. Operating temperature range is -50°C to 300°C. The LRA Series is available in bulk packaging in 200 increments.

Token will also produce devices outside these specifications to meet customer requirements. A lead-free RoHS-compliant version is available, as is a non-inductive version for high frequency applications. Contact us with your specific needs.

Download PDF Specification Precision Low Ohmic Resistor.

Features :
  1. Radial leads.
  2. Non-inductance.
  3. Solderable Copper Leads.
  4. Lead (Pb)-free and RoHS compliant.
  5. ±1%, ±2%, ±5%, ±10% standard tolerance.
  6. High stability bare metal element open air style.
Applications :
  1. Automotive Current Sensing, Feedback System.
  2. CPU Drive Control, Power Tool Motor controls.
  3. Power Supply Shunt, Current Detective.
  4. Inverter and Switching Power Supplies
  5. Residual Battery Power Detection.
  6. High power AC/DC detection.

Dimensions (Unit: mm) (LRA)

Low Ohmic Open Air (LRA) DimensionsLow Ohmic Open Air (LRA) Dimensions
Type H Max. (Unit: mm) RM (Unit: mm)
LRA350-009 6.5 10
LRA351-009 10.5
LRA352-009 17.0
LRA351-010 8.0 15
LRA352-010 14.5
LRA352-010 16.1±1.0 14.5±1.0
LRA352-010 17.1±1.0 14.5±1.0
LRA352-011 12.0 20

Construction:

1. The resistive elements consist of a flat metal-band.
2. Spot welded Cu-terminals ensure high stability of contacts.
3. Thus, this construction results in a non inductive of both high stability and overload capacity.

Characteristic Specification (LRA)

Type LRA 350-009 351-009
351-010
352-009
352-010
352-011
Power rating P70 W 0.5 1.0 1.5
Resistance range Ω R003~R051 R004~R068 R006~R10
E-series   E24≥R010
Tolerances % ±1, ±2, ±5, ±10
Temperature coefficient PPM ±25~±100
Max. Cont. working voltage VRMS For all styles
Insulation voltage (1min.) VRMS Non insulated
Insulation resistance Ω Non insulated
Derating, linear °C 70~300(0W)
Climatic category   55/200/56
Temperature range °C -50~300
Thermal resistance KW-1 200 100 70
Failure rate (Total, max, 60% conf. lev.) 10-9 * h-1 Ca.10, Depends on value
Endurance (P70, 70,1000h) []% ±3.0
Damp heat, steady state(40°C,93% r.h.,56d) []% ±0.5
Climatic sequence []% ±0.5
Terminal strength []% ±0.5
Terminal tensile strength N 30
Resistance to soldering heat ( 260°C,10s ) []% ±0.2 typ.
Solder ability s 2.5 Flow time, solder globule test
IEC 60068-2-20-T
Making   Value imprinted

Packing Specification (LRA)

Type Package Pieces Pack.-Code
LRA350-009 Bulk 200pcs Bulk
LRA351-009
LRA351-010
Bulk 200pcs Bulk
LRA352-010
LRA352-011
Bulk 200pcs Bulk

Order Codes (LRA)

LRA351-009 R024 J P
Part Number
Resistance Value (Ω)
R020 0.020Ω
R022 0.022Ω
R024 0.024Ω
R100 0.100Ω
Tolerance
F ±1%
G ±2%
J ±5%
K ±10%
Pack. -Code
P Bulk