SMD LED LTST-E142KRKFKT Datasheet - Dual Color Red/Orange - 30mA - 75mW - English Technical Document

1. Product Overview

This document details the specifications for a dual-color, surface-mount LED (Light Emitting Diode) designed for automated printed circuit board (PCB) assembly. The device is engineered for space-constrained applications and offers a combination of red and orange light emission from a single package. Its miniature size and compatibility with standard assembly processes make it suitable for integration into a wide array of modern electronic equipment.

1.1 Core Advantages and Target Market

The primary advantages of this component include its compliance with RoHS (Restriction of Hazardous Substances) directives, packaging in industry-standard 8mm tape on 7-inch reels for automated pick-and-place machines, and full compatibility with infrared (IR) reflow soldering processes. It is preconditioned to JEDEC Level 3 moisture sensitivity standards, ensuring reliability during assembly.

The target applications span several sectors, including telecommunications (e.g., status indicators in routers, modems), office automation (e.g., backlighting for control panels on printers, scanners), home appliances, and various industrial equipment. It is commonly used for status indication, symbolic illumination, and front panel backlighting where clear, reliable visual feedback is required.

2. Technical Parameters: In-Depth Objective Interpretation

This section provides a detailed, objective analysis of the device's key performance characteristics as defined by its absolute maximum ratings and typical operating parameters.

2.1 Absolute Maximum Ratings and Thermal Characteristics

The device is rated for a maximum continuous forward current (DC) of 30mA for both the red and orange chips. Under pulsed conditions (1/10 duty cycle, 0.1ms pulse width), it can handle a peak forward current of 80mA. The maximum power dissipation is 75mW. The operational and storage temperature range is specified from -40°C to +100°C, indicating suitability for harsh environments.

Thermal management is critical for LED longevity. The typical thermal resistance from the junction to ambient (Rθja) is 155°C/W for both colors. With a maximum junction temperature (Tj) of 115°C, this thermal resistance value dictates the maximum allowable power dissipation under given ambient conditions to prevent overheating and premature failure.

2.2 Electrical and Optical Characteristics

The electrical and optical performance is measured at a standard test condition of 20mA forward current and 25°C ambient temperature.

• Luminous Intensity (Iv): For the red LED, the luminous intensity ranges from a minimum of 90 mcd to a maximum of 280 mcd. The orange LED offers a higher output, ranging from 140 mcd to 450 mcd. The typical viewing angle (2θ1/2), where intensity is half the axial value, is 120 degrees for both, providing a wide beam pattern.
• Spectral Characteristics: The red LED has a typical peak emission wavelength (λp) of 639 nm and a dominant wavelength (λd) range of 623-638 nm. The orange LED has a λp of 609 nm and a λd range of 598-610 nm. The spectral line half-width (Δλ) is typically 15 nm for both, defining the color purity.
• Electrical Parameters: The forward voltage (Vf) for both colors ranges from 1.7V (min) to 2.5V (max) at 20mA. The maximum reverse current (Ir) is 10 μA at a reverse voltage (Vr) of 5V. It is crucial to note that the device is not designed for reverse bias operation; this parameter is for infrared testing reference only.

3. Binning System Explanation

To ensure color and brightness consistency in production, the LEDs are sorted into bins based on key parameters.

3.1 Luminous Intensity (Iv) Binning

The luminous output is categorized into specific bins with defined minimum and maximum values. Each bin has a tolerance of ±11%.

• Red LED Bins: Codes include Q2 (90.0-112.0 mcd), R1 (112.0-140.0 mcd), R2 (140.0-180.0 mcd), S1 (180.0-224.0 mcd), and S2 (224.0-280.0 mcd).
• Orange LED Bins: Codes include T2 (140-180 mcd), U1 (180-224 mcd), U2 (224-280 mcd), V1 (280-355 mcd), and V2 (355-450 mcd).

3.2 Dominant Wavelength (Wd) Binning

For the orange LED specifically, dominant wavelength bins ensure precise color control. The bins are F1 (598-602 nm), F2 (602-606 nm), and F3 (606-610 nm), each with a tight tolerance of ±1 nm. This precise binning is essential for applications requiring specific color points, such as traffic signals or consistent panel backlighting.

4. Performance Curve Analysis

While the PDF references typical performance curves, their specific graphical data is not provided in the text. Based on standard LED behavior, these curves would typically illustrate the relationship between forward current and luminous intensity (I-V curve), the effect of ambient temperature on light output, and the spectral power distribution. Designers use these curves to understand performance under non-standard conditions (e.g., different drive currents or temperatures) and to optimize circuit design for desired brightness and efficiency.

5. Mechanical and Package Information

5.1 Package Dimensions and Pin Assignment

The device conforms to an EIA standard package outline. All dimensions are in millimeters with a general tolerance of ±0.2 mm unless otherwise noted. The component features a diffused lens. The pin assignment is specific: pins 2 and 3 are assigned to the red LED chip, while pins 1 and 4 are assigned to the orange LED chip. Correct polarity identification during PCB layout and assembly is critical for proper function.

5.2 Recommended PCB Attachment Pad

A recommended land pattern (footprint) for the PCB is provided to ensure reliable soldering and proper mechanical alignment. Adhering to this recommended pattern helps achieve good solder fillets, thermal relief, and prevents tombstoning or misalignment during reflow.

6. Soldering and Assembly Guidelines

6.1 IR Reflow Soldering Profile

The device is compatible with lead-free (Pb-free) soldering processes. A suggested IR reflow profile is referenced, compliant with the J-STD-020B standard. Key parameters include a maximum peak temperature of 260°C and a pre-heat stage up to 200°C for a maximum of 120 seconds. The profile is designed to minimize thermal stress on the LED package while ensuring a reliable solder joint.

6.2 Storage and Handling

Proper storage is essential to maintain solderability. When the moisture-proof bag is sealed, LEDs should be stored at ≤30°C and ≤70% RH, with a recommended shelf life of one year. Once the bag is opened, the storage environment should not exceed 30°C and 60% RH. Components exposed beyond 168 hours (Level 3) should be baked at approximately 60°C for at least 48 hours before soldering to remove absorbed moisture and prevent "popcorning" during reflow.

6.3 Cleaning

If cleaning after soldering is necessary, only specified solvents should be used. Immersing the LED in ethyl alcohol or isopropyl alcohol at normal temperature for less than one minute is recommended. Unspecified chemicals may damage the LED package or lens.

7. Packaging and Ordering Information

The standard packaging is 8mm wide embossed carrier tape wound on 7-inch (178mm) diameter reels. Each reel contains 4000 pieces. For quantities less than a full reel, a minimum packing quantity of 500 pieces is available. The packaging follows ANSI/EIA 481 specifications. The tape is sealed with a cover tape to protect components, and the maximum number of consecutive missing components ("missing lamps") in a reel is two.

8. Application Suggestions

8.1 Typical Application Scenarios

This dual-color LED is ideal for applications requiring multi-state indication. For example, in a network switch, the red LED could indicate a fault or error state, while the orange LED could indicate activity or a warning condition. In consumer electronics, it can be used for dual-color backlighting of buttons or for creating amber/red status symbols. Its wide viewing angle makes it suitable for indicators that need to be visible from various angles.

8.2 Design Considerations

• Current Limiting: Always use a series current-limiting resistor (or a constant-current driver) for each LED color. The resistor value should be calculated based on the supply voltage, the LED's forward voltage (use max Vf for a conservative design), and the desired operating current (≤30mA DC).
• Thermal Management: Consider the power dissipation (P = Vf * If) and the thermal resistance. In high ambient temperatures or when driven at high currents, ensure adequate PCB copper area or other heatsinking methods are used to keep the junction temperature below 115°C.
• ESD Protection: While not explicitly stated, handling LEDs with appropriate ESD (Electrostatic Discharge) precautions is always recommended during assembly.

9. Technical Comparison and Differentiation

The key differentiator of this component is its dual-color capability in a single, compact SMD package. Compared to using two separate single-color LEDs, this saves PCB space, reduces component count, and simplifies assembly. The wide 120-degree viewing angle is another advantage over narrower-beam LEDs for panel indication. The precise binning for both intensity and wavelength offers designers predictable performance and color consistency in volume production.

10. Frequently Asked Questions (Based on Technical Parameters)

Q: Can I drive the red and orange LEDs simultaneously at 20mA each?
A: No. The absolute maximum power dissipation is 75mW. If both LEDs are on with Vf=2.5V and If=20mA, the total power would be 100mW (2.5V*20mA*2), exceeding the rating. Simultaneous operation requires derating the current for each LED or ensuring only one is on at a time.

Q: What is the difference between peak wavelength and dominant wavelength?
A> Peak wavelength (λp) is the wavelength at which the emitted optical power is maximum. Dominant wavelength (λd) is the single wavelength perceived by the human eye that matches the color of the light. λd is more relevant for color specification in visual applications.

Q: The reverse current is 10μA at 5V. Can I use this LED in an AC circuit?
A: No. The datasheet explicitly states the device is not designed for reverse operation. Applying reverse voltage, especially in an AC circuit, can damage the LED. External circuitry (like a rectifier) must be used to protect the LED if used with AC.

11. Practical Design and Usage Case

Case: Dual-Status Indicator for a Power Supply Unit
A designer is creating a PCB for a desktop power supply. They need one indicator to show when AC power is present (standby) and another to show when the DC output is active. Using this dual-color LED simplifies the design: the orange LED (pins 1 & 4) is connected to the standby voltage rail via a current-limiting resistor. The red LED (pins 2 & 3) is connected to the main DC output rail via another resistor. The PCB footprint requires only one component location. The wide viewing angle ensures the status is visible from the front of the chassis. The designer selects bins R2 for red and U1 for orange to ensure sufficient brightness. They follow the recommended reflow profile and storage guidelines during assembly to ensure reliability.

12. Principle Introduction

Light Emitting Diodes (LEDs) are semiconductor devices that emit light when an electric current passes through them. This phenomenon is called electroluminescence. In this specific device, the red light is produced by an Aluminum Indium Gallium Phosphide (AlInGaP) semiconductor material, which is efficient at producing red and orange wavelengths. The diffused lens over the chip scatters the light, creating the wide 120-degree viewing angle instead of a narrow beam. The dual-color function is achieved by housing two separate semiconductor chips (one red, one orange) within the same package, with independent electrical connections (anodes and cathodes) for each.

13. Development Trends

The general trend in SMD LED technology continues toward higher efficiency (more lumens per watt), allowing for brighter output at lower currents and reduced power consumption. There is also a drive for increased miniaturization while maintaining or improving optical performance. Color consistency and tighter binning tolerances are becoming standard as automated optical inspection in manufacturing improves. Furthermore, integration of control electronics (like constant-current drivers or PWM controllers) directly into the LED package is an emerging trend, simplifying circuit design for the end user. The principles of RoHS compliance and compatibility with lead-free, high-temperature reflow processes are now fundamental requirements in the industry.