LED Component Datasheet - Revision 2 - Lifecycle Information - English Technical Document

1. Product Overview

This technical document provides comprehensive specifications and application guidelines for a light-emitting diode (LED) component. The primary function of this device is to convert electrical energy into visible light with high efficiency and reliability. LEDs are fundamental building blocks in modern lighting and display technologies, offering advantages such as long operational life, low power consumption, and robust performance across various environmental conditions. This datasheet covers the essential parameters required for engineers and designers to successfully integrate this component into their systems.

The core advantages of this LED include its standardized form factor, consistent optical output, and stable electrical characteristics. It is designed for mass production applications where reliability and cost-effectiveness are paramount. The target market encompasses a wide range of industries, including general illumination, automotive lighting, consumer electronics, signage, and backlighting for displays.

2. In-Depth Technical Parameter Analysis

A thorough understanding of the technical parameters is crucial for optimal design and performance.

2.1 Photometric and Colorimetric Characteristics

The photometric properties define the light output of the LED. Key parameters include luminous flux, which measures the perceived power of light emitted, typically specified in lumens (lm) under defined test conditions. The correlated color temperature (CCT) for white LEDs indicates the hue of the white light, ranging from warm white (e.g., 2700K-3000K) to cool white (e.g., 5000K-6500K). For colored LEDs, the dominant wavelength is the primary metric, defining the perceived color. Chromaticity coordinates (e.g., CIE x, y) provide a precise color point on the standard color space diagram. The viewing angle, or beam angle, specifies the angular distribution of the light intensity, usually defined as the angle where intensity drops to 50% of its peak value.

2.2 Electrical Parameters

The electrical characteristics govern the operating conditions of the LED. The forward voltage (Vf) is the voltage drop across the LED when a specified forward current (If) is applied. This parameter has a typical value and a maximum rating. The absolute maximum ratings define the limits beyond which permanent damage may occur, including maximum forward current, peak pulse current, and reverse voltage. Power dissipation is calculated as the product of forward voltage and current, and it must be managed to prevent overheating.

2.3 Thermal Characteristics

Thermal management is critical for LED performance and longevity. The junction temperature (Tj) is the temperature at the semiconductor chip itself. The thermal resistance from junction to solder point (Rth j-sp) or ambient (Rth j-a) quantifies how effectively heat is transferred away from the chip. A lower thermal resistance indicates better heat dissipation. Operating and storage temperature ranges define the environmental limits for reliable function and non-operational storage.

3. Binning System Explanation

Due to manufacturing variations, LEDs are sorted into performance bins to ensure consistency in end products.

3.1 Wavelength / Color Temperature Binning

LEDs are grouped based on their dominant wavelength (for monochromatic LEDs) or correlated color temperature and chromaticity coordinates (for white LEDs). Bins are defined on the CIE chromaticity diagram, often following standards like ANSI C78.377. This ensures color uniformity within a single application.

3.2 Luminous Flux Binning

LEDs are sorted according to their light output at a specified test current. Bins are typically defined in minimum lumen ranges (e.g., 20-22 lm, 22-24 lm). This allows designers to select components that meet specific brightness requirements.

3.3 Forward Voltage Binning

Components are categorized by their forward voltage drop at a given test current. Common bins might have ranges like 2.8V - 3.0V, 3.0V - 3.2V. Consistent voltage bins help in designing stable driver circuits and managing power distribution in arrays.

4. Performance Curve Analysis

4.1 Current-Voltage (I-V) Characteristic Curve

The I-V curve is fundamental, showing the relationship between the forward current through the LED and the voltage across it. It is non-linear, with a threshold voltage below which very little current flows. The curve's slope in the operating region determines the dynamic resistance. This graph is essential for selecting appropriate current-limiting circuitry.

4.2 Temperature Dependency Characteristics

Several key parameters vary with temperature. Luminous flux typically decreases as junction temperature increases. Forward voltage generally decreases with rising temperature for most LED types. These relationships are plotted to help designers understand performance under real-world thermal conditions and implement necessary compensation or cooling strategies.

4.3 Spectral Power Distribution (SPD)

The SPD graph plots the relative intensity of light emitted across the electromagnetic spectrum. For white LEDs (often using a blue chip with a phosphor coating), it shows the blue pump peak and the broader phosphor-converted emission. For colored LEDs, it shows a narrow peak at the dominant wavelength. The SPD determines the color rendering properties and color quality of the light.

5. Mechanical and Package Information

5.1 Outline Dimensions and Drawing

A detailed mechanical drawing provides the exact physical dimensions of the LED package, including length, width, height, and any curvature. Critical tolerances are specified. This information is vital for PCB footprint design and ensuring proper fit within the final assembly.

5.2 Pad Layout and Solder Pad Design

The recommended PCB land pattern (footprint) is provided, showing the size, shape, and spacing of the copper pads. This ensures reliable solder joint formation during reflow soldering. The design often includes thermal pads for heat sinking.

5.3 Polarity Identification

The method for identifying the anode (+) and cathode (-) terminals is clearly indicated. This is typically done via a marking on the package (such as a notch, dot, or cut corner), different lead lengths, or an internal visual cue. Correct polarity is essential for circuit operation.

6. Soldering and Assembly Guidelines

6.1 Reflow Soldering Profile

A recommended reflow temperature profile is specified, including preheat, soak, reflow (peak temperature), and cooling stages. Key parameters are peak temperature (typically not exceeding 260°C for a short duration), time above liquidus, and maximum ramp rates. Adhering to this profile prevents thermal damage to the LED package and solder joints.

6.2 Handling and Assembly Precautions

Precautions include avoiding mechanical stress on the LED lens, preventing contamination of the optical surface, using ESD (electrostatic discharge) protection during handling, and ensuring no solder flux residue remains on the lens. Manual soldering with an iron is generally not recommended.

6.3 Storage Conditions

LEDs should be stored in a dry, inert environment. Specific conditions include a temperature range (e.g., 5°C to 30°C), relative humidity below a certain threshold (e.g., 60% RH), and protection from direct sunlight and corrosive gases. Moisture sensitivity level (MSL) rating indicates if baking is required before use after exposure to ambient humidity.

7. Packaging and Ordering Information

7.1 Packaging Specifications

The component is supplied in industry-standard packaging. Common formats include tape-and-reel for automated assembly, with specifications for reel diameter, tape width, pocket spacing, and component orientation. Quantities per reel are specified (e.g., 2000 pieces per 13-inch reel).

7.2 Labeling and Marking

The packaging label includes information such as part number, quantity, date code, lot number, and bin codes for luminous flux, color, and voltage. The individual LED package is marked with a part number or a simplified code for identification.

7.3 Part Numbering System

The part number is a code that encapsulates key attributes. It typically includes fields representing the product series, package size, color/wavelength, flux bin, voltage bin, and sometimes special features. A decoding table is provided to translate the part number into its constituent specifications.

8. Application Recommendations

8.1 Typical Application Circuits

Basic application circuits are illustrated. The most common is a series resistor used to limit current when powered by a constant voltage source (like a battery or DC power supply). For more precise control, constant current driver circuits (linear or switching regulators) are recommended, especially for arrays or when brightness consistency is critical.

8.2 Design Considerations

Key design considerations include: thermal management through adequate PCB copper area or heatsinking; ensuring the driver can deliver the required current within the LED's voltage range; protecting against reverse polarity and voltage transients; considering optical design (lenses, diffusers) for the desired light distribution; and designing for manufacturability and reliability.

9. Technical Comparison and Differentiation

Compared to earlier generation LEDs or alternative technologies, this component may offer improvements in efficacy (lumens per watt), providing more light output for the same electrical input. It may feature a more compact package size, enabling higher density designs. Enhanced color consistency (tighter binning) improves uniformity in multi-LED applications. Superior reliability metrics, such as longer L70 lifetime (time to 70% of initial lumen output), reduce total cost of ownership. The package may also be designed for improved thermal performance, allowing higher drive currents or better sustained output.

10. Frequently Asked Questions (FAQ)

Q: What is the maximum continuous current I can drive this LED with?
A: Refer to the Absolute Maximum Ratings table. Exceeding the specified maximum forward current can cause immediate or gradual degradation of the LED, reducing its lifespan and light output.

Q: How do I select the correct current-limiting resistor?
A: Use Ohm's Law: R = (Vsupply - Vf_led) / If_desired. Use the typical Vf from the datasheet for initial calculation, but consider the binning range and temperature effects for robust design. Ensure the resistor's power rating is sufficient: P = (If_desired)^2 * R.

Q: Why is the light output of my LED decreasing over time?
A: Lumen depreciation is normal. The Lxx lifetime rating (e.g., L70) in the datasheet predicts the operating hours until output falls to a percentage (e.g., 70%) of initial value. Excessive drive current or high junction temperature accelerates this depreciation.

Q: Can I connect multiple LEDs in series or parallel?
A> Series connection is generally preferred when using a constant current driver, as it ensures identical current through each LED. Parallel connection requires careful matching of forward voltage bins to prevent current imbalance, which can lead to uneven brightness and potential overstress of individual LEDs.

11. Practical Application Examples

Example 1: Linear LED Light Fixture. Multiple LEDs are mounted on a long, narrow metal-core PCB (MCPCB). They are connected in a series-parallel combination powered by a single constant current driver. The metal core provides essential heat sinking. Optical elements like diffusers or reflectors are placed over the array to create uniform linear illumination for office or retail lighting.

Example 2: Automotive Interior Lighting. A small cluster of LEDs, possibly in different colors, is used for dome lights, map reading lights, or accent lighting. The design must account for the wide input voltage range of a vehicle's electrical system (e.g., 9V-16V) using an appropriate voltage regulator or buck converter. The LEDs must also meet automotive-grade reliability and temperature requirements.

12. Operating Principle Introduction

An LED is a semiconductor p-n junction diode. When a forward voltage is applied, electrons from the n-type region and holes from the p-type region are injected into the junction region. When these charge carriers recombine, energy is released in the form of photons (light). The wavelength (color) of the emitted light is determined by the energy bandgap of the semiconductor material used (e.g., InGaN for blue/green, AlInGaP for red/amber). White LEDs are typically created by coating a blue LED chip with a yellow phosphor; some of the blue light is converted to yellow, and the mixture of blue and yellow light is perceived as white.

13. Technology Trends and Development

The LED industry continues to evolve with several clear trends. Efficacy (lumens per watt) is steadily increasing, reducing energy consumption for a given light output. Color quality metrics, such as Color Rendering Index (CRI) and newer measures like TM-30, are improving, especially for high-CRI applications like museum and retail lighting. Miniaturization continues, enabling ever-smaller pixel pitches in direct-view displays. There is also significant development in specialized areas such as UV-C LEDs for disinfection, micro-LEDs for next-generation displays, and horticultural LEDs tailored for plant growth spectra. Reliability and lifetime under various operating conditions remain a key focus for industrial and automotive applications.