LED Component Datasheet - Revision 3 - Lifecycle Information - English Technical Document

1. Product Overview

This technical datasheet provides comprehensive information for a specific LED (Light Emitting Diode) component. The document is currently in its third revision, indicating a mature and stable product specification. The lifecycle phase is designated as "Revision," and the release date for this specific version is November 27, 2014. The expired period is marked as "Forever," suggesting this document remains the valid reference for the product's specifications unless superseded by a new revision. The core advantage of this component lies in its well-defined and finalized technical parameters, providing reliability and consistency for design engineers. The target market includes applications in general lighting, backlighting units, automotive lighting, and consumer electronics where stable performance is critical.

2. In-Depth Technical Parameter Analysis

While the provided excerpt focuses on document metadata, a complete datasheet for an LED component would contain detailed technical parameters. These are essential for proper circuit design and thermal management.

2.1 Photometric and Color Characteristics

The photometric characteristics define the light output. Key parameters include luminous flux (measured in lumens, lm), which indicates the total perceived power of light. The luminous intensity (measured in candela, cd) describes the light output in a specific direction. The dominant wavelength or correlated color temperature (CCT, measured in Kelvin, K) specifies the color of the emitted light, ranging from warm white (e.g., 2700K) to cool white (e.g., 6500K). The color rendering index (CRI, Ra) is a measure of how accurately the light source reveals the colors of objects compared to a natural light source, with higher values (closer to 100) being better for color-critical applications.

2.2 Electrical Parameters

Electrical parameters are crucial for driving the LED safely and efficiently. The forward voltage (Vf) is the voltage drop across the LED when it is operating at its specified current. It typically ranges from 2.8V to 3.6V for standard white LEDs. The forward current (If) is the recommended operating current, often 20mA, 60mA, 150mA, or higher depending on the power rating. The reverse voltage (Vr) is the maximum voltage the LED can withstand in the non-conducting direction without damage, usually around 5V. Exceeding the maximum ratings for current or voltage can lead to permanent degradation or failure.

2.3 Thermal Characteristics

LED performance and lifespan are heavily dependent on temperature. The junction temperature (Tj) is the temperature at the semiconductor chip itself. The thermal resistance (Rth j-a, measured in °C/W) indicates how effectively heat is transferred from the junction to the ambient environment. A lower thermal resistance is better, as it means the junction stays cooler for a given power dissipation. The maximum allowable junction temperature (Tj max) must not be exceeded to ensure long-term reliability. Proper heat sinking is essential to maintain Tj within safe limits.

3. Binning System Explanation

Due to manufacturing variations, LEDs are sorted into bins based on key parameters to ensure consistency within a production batch.

3.1 Wavelength / Color Temperature Binning

LEDs are binned according to their dominant wavelength (for colored LEDs) or correlated color temperature (for white LEDs). This ensures that all LEDs in an assembly have a nearly identical color appearance, preventing visible color shifts or uneven lighting. Bins are typically defined by a small range on the CIE chromaticity diagram.

3.2 Luminous Flux Binning

Luminous flux output is also binned. This allows designers to select LEDs that meet a specific minimum brightness requirement or to group LEDs of similar output for uniform illumination. Flux bins are usually defined as a percentage range (e.g., 100-110% of nominal flux).

3.3 Forward Voltage Binning

Forward voltage is binned to simplify driver design and improve efficiency in series/parallel configurations. Grouping LEDs with similar Vf values helps ensure even current distribution, especially when multiple LEDs are connected in parallel.

4. Performance Curve Analysis

Graphical data provides deeper insight into LED behavior under different operating conditions.

4.1 Current-Voltage (I-V) Characteristic Curve

The I-V curve shows the relationship between the forward current and the forward voltage. It is non-linear, exhibiting a threshold voltage below which very little current flows. Above this threshold, the current increases rapidly with a small increase in voltage. This characteristic necessitates the use of constant-current drivers rather than constant-voltage sources for stable operation.

4.2 Temperature Dependency

Several key parameters change with temperature. Typically, the forward voltage (Vf) decreases as the junction temperature increases. Conversely, the luminous flux output generally decreases with rising temperature. Understanding these relationships is vital for designing systems that maintain consistent performance across their operating temperature range.

4.3 Spectral Power Distribution (SPD)

The SPD graph plots the relative intensity of light emitted at each wavelength. For white LEDs, this typically shows a blue peak from the LED chip and a broader yellow/red peak from the phosphor coating. The shape of the SPD directly determines the CCT and CRI of the LED.

5. Mechanical and Package Information

The physical package protects the semiconductor die and provides electrical connections and thermal paths.

5.1 Dimensional Outline Drawing

A detailed drawing provides all critical dimensions of the LED package, including length, width, height, and any lens curvature. Tolerances are specified for each dimension. This information is essential for PCB (Printed Circuit Board) layout and mechanical integration into the final product.

5.2 Pad Layout and Solder Pad Design

The recommended PCB land pattern (solder pad geometry and size) is provided to ensure reliable solder joint formation during reflow soldering. This includes the pad dimensions, spacing between pads, and any thermal relief patterns for pads connected to large copper areas for heat dissipation.

5.3 Polarity Identification

Clear markings indicate the anode (+) and cathode (-) terminals. This is often done via a notch, a dot, a beveled corner, or different lead lengths. Correct polarity is mandatory for the LED to function.

6. Soldering and Assembly Guidelines

Proper handling and assembly are critical to prevent damage to the LED.

6.1 Reflow Soldering Profile

A recommended reflow soldering temperature profile is provided. This graph shows temperature versus time, specifying key zones: preheat, soak, reflow (with peak temperature), and cooling. The maximum allowable body temperature and the duration at peak temperature are critical limits that must not be exceeded to avoid damaging the plastic package or the internal wire bonds.

6.2 Precautions and Handling

LEDs are sensitive to electrostatic discharge (ESD). Handling should be performed at ESD-protected workstations using grounded wrist straps. Avoid applying mechanical stress to the lens. Do not touch the lens with bare fingers, as contaminants can affect light output and cause discoloration over time.

6.3 Storage Conditions

LEDs should be stored in a cool, dry environment within specified temperature and humidity ranges. They are typically supplied in moisture-sensitive bags with a humidity indicator card. If the bag has been opened or the humidity level exceeds a certain threshold, the components may require baking before reflow to prevent "popcorning" (package cracking due to rapid vapor expansion during soldering).

7. Packaging and Ordering Information

This section details how the product is supplied and how to specify it when ordering.

7.1 Packaging Specifications

The LEDs are supplied on tape and reel for automated assembly. The specifications include reel diameter, tape width, pocket spacing, and the number of components per reel.

7.2 Label Information

The reel label contains vital information such as part number, quantity, lot/batch number, date code, and bin codes for luminous flux and color.

7.3 Part Numbering System

The part number is a code that encapsulates the key attributes of the LED, such as package size, color, flux bin, voltage bin, and sometimes viewing angle. Understanding this nomenclature is essential for correct procurement.

8. Application Recommendations

Guidance on how to best utilize the LED in real-world designs.

8.1 Typical Application Circuits

Schematics for basic constant-current driver circuits are often provided. These may include simple resistor-based drivers for low-current LEDs or more complex circuits using dedicated LED driver ICs for higher power or multiple LEDs.

8.2 Design Considerations

Key design points include thermal management (calculating required heat sink performance), optical design (lens selection for desired beam pattern), and electrical design (ensuring the driver can deliver stable current over the expected input voltage range and ambient temperature). Derating curves, which show the maximum allowable forward current as a function of ambient temperature, are crucial for reliable design.

9. Technical Comparison

While this datasheet describes a single product, designers often compare it to alternatives. Potential points of comparison could include higher luminous efficacy (lumens per watt), better color rendering (higher CRI), a wider operating temperature range, or a more compact package size compared to previous generations or competitor products. The "Revision 3" status implies incremental improvements over earlier versions, likely in areas like efficiency, reliability, or color consistency.

10. Frequently Asked Questions (FAQ)

Common questions based on technical parameters include: "What driver current should I use?" (Answer: The specified typical forward current, If). "Why is my LED dimmer than expected?" (Possible answers: Junction temperature too high, driving current below specification, or incorrect flux bin selected). "Can I connect multiple LEDs in parallel?" (Answer: Not recommended without individual current balancing, due to Vf variation; series connection with a constant-current driver is preferred). "What is the expected lifetime?" (Answer: Typically defined as the time until luminous flux degrades to 70% or 50% of its initial value when operated at specified conditions, often 50,000 hours).

11. Practical Use Cases

Based on common specifications for a component with a finalized datasheet, practical applications include: Architectural Lighting: Used in linear fixtures or downlights where consistent color and long life are paramount. Consumer Electronics: Serving as status indicators or keyboard backlights in devices requiring reliable, low-power illumination. Automotive Interior Lighting: Providing map lights, dome lights, or accent lighting, benefiting from stable performance across a wide temperature range.

12. Operating Principle Introduction

An LED is a semiconductor diode. When a forward voltage is applied, electrons from the n-type semiconductor and holes from the p-type semiconductor are injected into the active region. When electrons and holes 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 materials used in the active region. 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

The LED industry continuously evolves. General trends include increasing luminous efficacy, allowing more light output for less electrical power and heat. There is a push for higher color rendering indices (CRI >90, even >95) for applications like retail lighting and museums. Miniaturization continues, enabling new applications in ultra-thin displays. Furthermore, the development of LEDs on non-traditional substrates and new phosphor systems aims to improve performance and reduce costs. The existence of a "Revision 3" datasheet reflects this iterative process of product improvement and refinement.