LED Component Technical Documentation - Lifecycle Phase Revision 2 - Release Date 2014-12-03 - English

1. Product Overview

This technical document pertains to a specific revision of an LED component. The primary information provided indicates the component's lifecycle phase, revision number, and release date. The lifecycle phase is designated as "Revision," which signifies that this document represents an updated version of the component's specifications or related technical data. The revision number is 2, and the official release date for this revision was December 3rd, 2014, at 19:32:43. The document states an "Expired Period" of "Forever," which typically implies that this version of the document does not have a predefined expiration date and remains valid until superseded by a newer revision. This core information forms the basis for understanding the version control and validity of the technical parameters detailed in subsequent sections.

2. In-Depth Technical Parameter Interpretation

While the provided excerpt focuses on document metadata, a complete technical datasheet for an LED component would typically include several key parameter categories. These parameters are critical for design engineers to properly integrate the component into a circuit or system.

2.1 Photometric and Color Characteristics

Photometric characteristics define the light output of the LED. Key parameters include luminous flux, measured in lumens (lm), which quantifies the perceived power of light. Another crucial parameter is luminous efficacy, measured in lumens per watt (lm/W), indicating the efficiency of converting electrical power into visible light. Color characteristics are defined by metrics such as correlated color temperature (CCT) for white LEDs, measured in Kelvin (K), which describes the warmth or coolness of white light. For colored LEDs, the dominant wavelength and color purity are specified. Chromaticity coordinates (e.g., on the CIE 1931 diagram) provide a precise, numerical description of the color point. Understanding these parameters is essential for applications requiring specific brightness levels and color quality.

2.2 Electrical Parameters

Electrical parameters govern the safe and efficient operation of the LED. The forward voltage (Vf) is the voltage drop across the LED when it is conducting current. It is typically specified at a particular test current (If). The forward current (If) is the recommended operating current, and exceeding the maximum rated forward current can lead to premature failure. Reverse voltage (Vr) is the maximum voltage the LED can withstand when biased in the non-conducting direction. These parameters are vital for selecting appropriate current-limiting resistors or designing constant-current driver circuits to ensure stable performance and long lifespan.

2.3 Thermal Characteristics

LED performance and longevity are heavily influenced by temperature. The junction temperature (Tj) is the temperature at the semiconductor chip itself. A key thermal parameter is the thermal resistance from the junction to the ambient air (RθJA) or to the solder point (RθJS). This value, measured in degrees Celsius per watt (°C/W), indicates how effectively heat is dissipated from the chip. Maintaining a low junction temperature is critical, as high temperatures accelerate lumen depreciation (light output decrease over time) and can drastically shorten the LED's operational life. Proper heat sinking and PCB thermal design are directly informed by these thermal characteristics.

3. Binning System Explanation

Due to inherent manufacturing variations, LEDs are sorted into performance bins. A binning system ensures consistency within a batch.

3.1 Wavelength/Color Temperature Binning

For colored LEDs, bins are defined by ranges of dominant wavelength. For white LEDs, bins are defined by ranges of correlated color temperature (CCT) and sometimes by distance from the black-body locus (Duv). This ensures color uniformity in applications using multiple LEDs.

3.2 Luminous Flux Binning

LEDs are binned according to their luminous flux output at a standard test current. This allows designers to select components that meet specific brightness requirements and to predict the total light output of an array.

3.3 Forward Voltage Binning

Forward voltage (Vf) is also binned. Using LEDs from the same or similar Vf bins can simplify driver design, improve current matching in parallel strings, and enhance overall system efficiency.

4. Performance Curve Analysis

Graphical data provides deeper insight into LED behavior under varying conditions.

4.1 Current-Voltage (I-V) Characteristic Curve

The I-V curve shows the relationship between the forward voltage and the current through the LED. It is non-linear, exhibiting a turn-on voltage below which very little current flows. The slope of the curve in the operating region relates to the dynamic resistance of the LED. This curve is fundamental for driver design.

4.2 Temperature Dependency Characteristics

Graphs typically show how forward voltage decreases with increasing junction temperature (for a constant current) and how luminous flux depreciates as temperature rises. These curves are essential for designing systems that operate reliably across their intended temperature range.

4.3 Spectral Power Distribution

The spectral distribution plot shows the relative intensity of light emitted at each wavelength. For white LEDs, this reveals the blend of the blue pump LED and the phosphor emission. It is used to calculate color rendering index (CRI) and other color quality metrics.

5. Mechanical and Packaging Information

Physical specifications ensure proper mounting and assembly.

5.1 Dimensional Outline Drawing

A detailed drawing provides all critical dimensions: length, width, height, lead spacing, and component tolerances. This is necessary for PCB footprint design and ensuring fit within the final assembly.

5.2 Pad Layout Design

The recommended PCB land pattern (pad geometry and size) is provided to ensure reliable solder joint formation during reflow soldering and to facilitate heat transfer away from the LED.

5.3 Polarity Identification

The method for identifying the anode and cathode (e.g., a notch, a cut corner, or a marked lead) is clearly indicated to prevent incorrect orientation during assembly.

6. Soldering and Assembly Guidelines

Proper handling and soldering are critical for reliability.

6.1 Reflow Soldering Profile

A recommended reflow temperature profile is provided, including preheat, soak, reflow peak temperature, and cooling rates. Adhering to this profile prevents thermal shock and damage to the LED package or internal die.

6.2 Precautions and Handling

Guidelines cover protection from electrostatic discharge (ESD), avoidance of mechanical stress on the lens, and recommendations against cleaning with certain solvents that may damage the silicone or epoxy lens material.

6.3 Storage Conditions

Ideal storage conditions (temperature and humidity ranges) are specified to prevent degradation of the component before use, particularly for the packaging and internal materials.

7. Packaging and Ordering Information

Information for procurement and logistics.

7.1 Packaging Specifications

Details on reel size, tape width, pocket dimensions, and quantity per reel are provided for automated pick-and-place assembly equipment.

7.2 Labeling Information

The format and content of labels on reels or boxes, which typically include part number, quantity, lot number, and bin codes.

7.3 Part Number Nomenclature

An explanation of the part number coding system, which may encode information such as color, flux bin, voltage bin, package type, and special features.

8. Application Recommendations

Guidance for implementing the component effectively.

8.1 Typical Application Circuits

Schematics for basic driving circuits, such as using a series resistor with a constant voltage source or employing a dedicated constant-current LED driver IC. Considerations for parallel and series configurations are discussed.

8.2 Design Considerations

Key points include thermal management on the PCB (using thermal vias, copper pours), optical design for desired beam pattern, and electrical design to minimize ripple current and ensure stable operation.

9. Technical Comparison

While specific competitor names are omitted, the document might highlight this component's key differentiators. These could include higher luminous efficacy leading to better energy efficiency, a wider operating temperature range for harsh environments, superior color consistency (tighter binning), or a more robust package design for improved reliability under thermal cycling. Such advantages are derived from its specific technical parameters as listed in previous sections.

10. Frequently Asked Questions (FAQ)

Answers to common technical queries based on the parameters.

Q: What driver current should I use?
A: Always refer to the absolute maximum ratings and recommended operating conditions. Operate at or below the specified forward current (If) to ensure longevity. Using a constant-current driver is highly recommended for stable performance.

Q: How do I calculate the required series resistor?
A: Use Ohm's Law: R = (Vsupply - Vf) / If. Use the typical or maximum Vf from the datasheet for your calculation, and ensure the resistor's power rating is sufficient (P = (If)^2 * R).

Q: Why is thermal management so important?
A: High junction temperature directly causes lumen depreciation and reduces operational life. Exceeding the maximum junction temperature can cause immediate failure. Proper heat sinking maintains Tj within safe limits.

Q: Can I connect multiple LEDs in parallel directly?
A: It is generally not recommended due to Vf variation between LEDs. Small differences can cause significant current imbalance, leading to uneven brightness and potential overstress of one LED. Use separate current limits or series connections with a higher voltage supply.

11. Practical Use Cases

Based on the implied technical parameters of a standard LED, here are generalized application examples.

Case 1: Indicator Light on a Consumer Device: A low-current LED is used with a simple series resistor. Key considerations are the required brightness (viewing angle and luminous intensity), color, and the available supply voltage on the device's PCB.

Case 2: Architectural Linear Lighting: Multiple high-efficacy LEDs are mounted on a long, narrow PCB strip. Design focuses on achieving uniform color and brightness along the length (requiring tight binning), efficient thermal management via an aluminum channel, and using a constant-current driver capable of dimming for ambiance control.

Case 3: Automotive Interior Lighting: LEDs must operate reliably across a wide temperature range (-40°C to +85°C or higher). The design must account for potential voltage transients in the vehicle's electrical system and ensure the light output and color remain consistent at all temperatures.

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 recombine with holes, 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 or ultraviolet LED chip with a phosphor material. The phosphor absorbs some of the blue/UV light and re-emits it as a broader spectrum of longer wavelengths (yellow, red), mixing with the remaining blue light to produce white light.

13. Technology Trends

The LED industry continues to evolve. Key trends include the ongoing improvement of luminous efficacy, pushing the theoretical limits of electrical-to-optical conversion. There is a strong focus on enhancing color quality, such as achieving higher Color Rendering Index (CRI) values and more consistent color points. Miniaturization of packages while maintaining or increasing light output is another trend, enabling new design possibilities. The development of novel phosphor materials aims to create more efficient and stable white light spectra. Furthermore, the integration of control electronics directly with the LED chip (e.g., IC-on-board) is simplifying driver design and enabling smarter, addressable lighting systems. These advancements are driven by demands for greater energy savings, improved light quality, and expanded functionality in lighting applications.