LED Component Datasheet - Lifecycle Revision 1 - Release Date 2013-11-14 - English Technical Document

1. Product Overview

This technical document provides comprehensive specifications and application guidelines for a light-emitting diode (LED) component. The primary focus of this datasheet is to detail the lifecycle management and revision history of the product, ensuring users have access to the most current and accurate technical information. The component is designed for general illumination and indicator applications, offering a balance of performance, reliability, and efficiency. Its core advantages include stable performance over its lifecycle, clear revision tracking, and adherence to standardized technical documentation practices. The target market encompasses a wide range of industries, including consumer electronics, automotive lighting, industrial controls, and general signage, where consistent component performance and traceability are critical.

2. Technical Parameters Deep Objective Interpretation

While the provided PDF excerpt focuses on lifecycle data, a complete LED datasheet typically includes detailed technical parameters. The following sections outline the standard categories of information essential for design-in and application.

2.1 Photometric and Color Characteristics

Photometric characteristics define the light output and quality of the LED. Key parameters include luminous flux, measured in lumens (lm), which indicates the total perceived power of light emitted. The dominant wavelength or correlated color temperature (CCT) specifies the color of the light, ranging from warm white (e.g., 2700K) to cool white (e.g., 6500K) for white LEDs, or specific nanometer (nm) values for colored LEDs (e.g., 630nm for red). Chromaticity coordinates (e.g., CIE x, y) provide a precise color point on the color space diagram. The viewing angle, typically defined as the angle where luminous intensity drops to half of its maximum value, determines the beam pattern. For high-color-rendering applications, the Color Rendering Index (CRI) is a crucial metric, with values above 80 considered good for general lighting.

2.2 Electrical Parameters

Electrical parameters are fundamental for circuit design. The forward voltage (Vf) is the voltage drop across the LED when operating at its specified forward current (If). This value is temperature-dependent and typically provided at a standard test current (e.g., 20mA, 150mA, 350mA) and junction temperature (e.g., 25°C). The forward current rating is the maximum continuous current the LED can handle without damage. Reverse voltage (Vr) specifies the maximum voltage that can be applied in the reverse-biased direction before breakdown occurs. Dynamic resistance, derived from the IV curve slope, is important for driver stability analysis.

2.3 Thermal Characteristics

LED performance and lifetime are heavily influenced by thermal management. The junction temperature (Tj) is the temperature at the semiconductor chip itself. The thermal resistance from junction to solder point (Rth j-sp) or junction to ambient (Rth j-a) quantifies how effectively heat is transferred away from the chip. A lower thermal resistance indicates better heat dissipation. Maximum allowable junction temperature (Tj max) is the absolute limit for reliable operation. Exceeding this temperature accelerates lumen depreciation and can lead to catastrophic failure. Proper heatsinking is essential to maintain Tj within safe limits.

3. Binning System Explanation

Due to manufacturing variations, LEDs are sorted into performance bins to ensure consistency within a production lot and across orders.

3.1 Wavelength / Color Temperature Binning

LEDs are binned according to their dominant wavelength (for monochromatic LEDs) or correlated color temperature and chromaticity coordinates (for white LEDs). Bins are defined by small ranges on the CIE color chart (e.g., MacAdam ellipses). Tighter binning (smaller ellipses) ensures minimal color variation in an array but may increase cost.

3.2 Luminous Flux Binning

Luminous flux output is also binned. A typical binning scheme might categorize LEDs based on their minimum luminous flux at a specified test current. For example, bins may be labeled with codes representing a percentage range of the typical flux value.

3.3 Forward Voltage Binning

Forward voltage is binned to aid in driver design and to ensure consistent brightness in parallel configurations. Bins specify a range of Vf values (e.g., 2.8V - 3.0V, 3.0V - 3.2V). Selecting LEDs from the same Vf bin can improve current matching in arrays.

4. Performance Curve Analysis

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

4.1 Current-Voltage (I-V) Characteristic Curve

The I-V curve shows the relationship between forward current and forward voltage. It is non-linear, exhibiting a turn-on voltage (the "knee" of the curve) beyond which current increases rapidly with small increases in voltage. This curve is essential for designing constant-current drivers, as it highlights the need for current regulation rather than voltage regulation to control light output.

4.2 Temperature Characteristics

Key graphs illustrate the dependency of parameters on temperature. Luminous flux vs. junction temperature typically shows a decrease in output as temperature rises. Forward voltage vs. temperature shows a negative temperature coefficient (Vf decreases as Tj increases). Understanding these relationships is critical for thermal design and predicting performance in the application environment.

4.3 Spectral Power Distribution

The spectral power distribution (SPD) graph plots relative radiant power against wavelength. For white LEDs based on a blue chip and phosphor, it shows the blue emission peak and the broader phosphor-converted yellow/green/red spectrum. The SPD determines the color quality metrics like CRI and color temperature.

5. Mechanical and Packaging Information

Physical specifications ensure proper PCB layout and assembly.

5.1 Dimension Drawing

A detailed dimensioned drawing provides all critical measurements: overall length, width, and height, lens dimensions, and lead spacing (for through-hole) or pad dimensions (for SMD). Tolerances are specified for each dimension.

5.2 Pad Layout Design

For surface-mount devices (SMDs), the recommended land pattern (footprint) for the PCB is provided. This includes pad size, shape, and spacing, which are crucial for achieving a reliable solder joint and proper thermal connection.

5.3 Polarity Identification

The method for identifying the anode and cathode is clearly indicated. For SMD LEDs, this is often a marking on the package (e.g., a green dot, a notch, or a chamfered corner) or a different pad size/shape on the underside. For through-hole LEDs, the cathode is typically indicated by a flat edge on the lens or a shorter lead.

6. Soldering and Assembly Guidelines

Proper handling and assembly are vital for reliability.

6.1 Reflow Soldering Profile

A recommended reflow soldering temperature profile is provided for SMD components. This includes preheat, soak, reflow (peak temperature), and cooling ramp rates and durations. The maximum peak temperature and time above liquidus are specified to prevent damage to the LED package and internal materials.

6.2 Precautions and Handling

General precautions include avoiding mechanical stress on the lens, preventing electrostatic discharge (ESD) during handling (LEDs are often ESD-sensitive), and not touching the lens with bare hands to avoid contamination. Recommendations for cleaning agents compatible with the package material may also be included.

6.3 Storage Conditions

Ideal storage conditions to maintain solderability and prevent moisture absorption (for moisture-sensitive packages) are specified. This typically involves storage in a dry environment (low humidity) at a moderate temperature, often in sealed, moisture-barrier bags with desiccant.

7. Packaging and Ordering Information

Information for procurement and logistics.

7.1 Packaging Specifications

The unit packaging is described (e.g., tape and reel for SMDs, tubes, or trays). Key reel specifications include tape width, pocket spacing (pitch), reel diameter, and quantity per reel. Anti-static properties of the packaging material are noted.

7.2 Labeling Information

The information printed on the packaging label is explained, which may include part number, quantity, lot/batch code, date code, and binning codes for luminous flux and color.

7.3 Part Numbering / Model Naming Rules

The structure of the part number is decoded. It typically includes fields representing the product series, color, flux bin, color bin, voltage bin, packaging type, and sometimes special features. This allows users to specify the exact performance characteristics required.

8. Application Suggestions

Guidance for implementing the LED in end products.

8.1 Typical Application Circuits

Schematics for basic drive circuits are often provided. The most common is a series resistor with a constant voltage source, suitable for low-current indicators. For illumination applications, constant-current driver circuits (using dedicated ICs or transistors) are recommended to ensure stable light output regardless of forward voltage variations.

8.2 Design Considerations

Critical design factors are highlighted: thermal management (PCB copper area, thermal vias, possible external heatsink), optical design (lens selection for desired beam pattern), electrical design (driver selection based on current/voltage requirements, protection against reverse polarity and transients), and dimming compatibility (PWM vs. analog).

9. Technical Comparison

An objective comparison with other LED technologies or previous generations can contextualize the product's position. This may involve comparing efficacy (lumens per watt), color rendering index (CRI), lifetime (L70/B50 ratings), package size, and thermal performance against alternatives like incandescent bulbs, CFLs, or other LED packages. The differentiation might be in a specific area like higher efficacy at a given current, better color uniformity, or a more compact form factor enabling new design possibilities.

10. Frequently Asked Questions (FAQ)

Answers to common technical queries based on the parameters.

• Q: Can I drive this LED with a constant voltage source? A: It is not recommended for stable operation. LEDs are current-driven devices. A small change in forward voltage causes a large change in current. A constant-current driver is essential for consistent brightness and longevity, especially for power LEDs.
• Q: How do I calculate the series resistor value for a simple indicator circuit? A: Use Ohm's Law: R = (Vsupply - Vf_led) / If_desired. Ensure the resistor's power rating is sufficient: P_resistor = (If_desired)^2 * R.
• Q: Why is the luminous flux in my application lower than the datasheet value? A: Datasheet values are typically measured at 25°C junction temperature. In your application, the junction temperature is likely higher due to less-than-ideal heatsinking, causing flux droop. Also, ensure you are driving the LED at the exact specified test current.
• Q: Can I connect multiple LEDs in parallel directly? A: Direct parallel connection is generally discouraged due to variations in forward voltage. LEDs with a slightly lower Vf will draw disproportionately more current, leading to uneven brightness and potential overstress. Use separate current-limiting resistors for each parallel branch or a dedicated multi-channel driver.

11. Practical Use Cases

Examples of how the LED's specific parameters translate into real-world designs.

• Case 1: Architectural Cove Lighting: Using LEDs binned for tight color consistency (e.g., within a 3-step MacAdam ellipse) to ensure uniform white light along a long cove without visible color shifts. The design uses a constant-current driver with PWM dimming for smooth brightness control, and the PCB incorporates large thermal pads to manage heat.
• Case 2: Automotive Interior Switch Backlighting: Selecting a specific dominant wavelength (e.g., 625nm red) for compliance with automotive color standards. The design accounts for the high ambient temperature environment by derating the drive current to keep the junction temperature below the maximum rated value, ensuring long-term reliability.
• Case 3: Portable Device Status Indicator: Utilizing the low forward voltage and current capability of the LED to minimize power draw from a battery. A simple series resistor circuit is sufficient here due to the low power level. The wide viewing angle ensures the indicator is visible from various angles.

12. 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 bandgap energy 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. More advanced white LEDs use multiple phosphors to achieve higher color rendering.

13. Development Trends

The LED industry continues to evolve with several clear objective trends. Efficacy (lumens per watt) is steadily increasing through improvements in internal quantum efficiency, light extraction, and phosphor technology. Color quality is improving, with high-CRI (Ra>90) and full-spectrum LEDs becoming more common for applications requiring accurate color rendering. Miniaturization continues, enabling higher pixel density in direct-view displays and finer-pitch video walls. There is a strong focus on reliability and lifetime prediction under various stress conditions. Integration is another trend, with LED packages incorporating drivers, sensors, and control electronics to form "smart" light engines. Finally, the expansion of spectral output beyond visible light is significant, with UV-C LEDs for disinfection and IR LEDs for sensing seeing rapid development.

14. Lifecycle and Revision Management

As indicated in the provided PDF content, this document is identified as Revision 1. The lifecycle phase is marked as Revision, signifying an active, current version of the product specification. The release date for this revision is documented as 2013-11-14 15:59:23.0. The expired period is noted as Forever, which typically indicates that this revision does not have a planned obsolescence date and remains valid until superseded by a newer revision. This structured approach to documentation ensures that engineers and procurement specialists can accurately reference the specific version of the component's specifications used in their designs, which is critical for quality control, repeatability, and troubleshooting. Changes between revisions are usually summarized in a revision history section, detailing what parameters, text, or drawings were modified, added, or removed.