LTW-020ZDCG White LED Datasheet - SMD Package - 3.2V Typical - 20mA - 1000-1720mcd - English Technical Document

1. Product Overview

The component is a white surface-mount LED (Light Emitting Diode) designed as an energy-efficient and compact light source. It combines the long lifetime and reliability inherent to LED technology with competitive brightness levels, aiming to provide design flexibility for solid-state lighting applications intended to replace conventional lighting solutions.

1.1 Core Advantages and Target Market

Key features of this LED include compatibility with automatic placement equipment, suitability for infrared and vapor phase reflow soldering processes, and compliance with green product standards (Pb-free and RoHS). It is packaged in 12mm tape on 7-inch diameter reels.

Primary Application Areas:

• Reading lights for automotive, bus, and aircraft interiors.
• Portable lighting such as flashlights and bicycle lights.
• Architectural and decorative lighting: downlighters, cove lighting, undershelf lighting, task lighting.
• Outdoor and security lighting: bollards, garden lights.
• Signage: edge-lit signs for exit or point-of-sale displays.
• Signal lighting: traffic signals, beacons, rail crossing lights.

2. Technical Parameters: In-Depth Objective Interpretation

2.1 Absolute Maximum Ratings

These ratings define the limits beyond which permanent damage to the device may occur. Operation under reverse bias is specifically cautioned against.

• Power Dissipation: 120 mW
• Peak Forward Current: 100 mA (at 1/10 duty cycle, 0.1ms pulse width)
• DC Forward Current: 30 mA
• Reverse Voltage: 5 V
• Operating Temperature Range: -30°C to +85°C
• Storage Temperature Range: -40°C to +100°C
• Reflow Soldering Condition: 260°C peak temperature for 10 seconds maximum (lead-free process).

2.2 Electro-Optical Characteristics

Measured at an ambient temperature (Ta) of 25°C and a forward current (IF) of 20 mA, unless otherwise stated.

• Luminous Intensity (IV): Minimum 1000 mcd, Typical 1720 mcd. This parameter is measured using a sensor filtered to match the CIE photopic eye-response curve.
• Viewing Angle (2θ1/2): 110 degrees. This defines the angular spread where the luminous intensity is at least half of the peak intensity.
• Chromaticity Coordinates (x, y): Based on the CIE 1931 chromaticity diagram. The typical values provided are x=0.300, y=0.290. A tolerance of ±0.01 should be applied to these coordinates. The test standard referenced is CAS140B.
• Forward Voltage (VF): Minimum 2.9 V, Maximum 3.6 V at IF=20mA.
• ESD Withstand Voltage: 2 kV (Human Body Model). Proper ESD handling precautions are strongly recommended, including the use of grounded wrist straps and equipment.

3. Binning System Explanation

The product is classified into bins based on key parameters to ensure consistency within a production batch. Designers must consider these bins for color and brightness matching in their applications.

3.1 Forward Voltage (VF) Binning

LEDs are sorted into bins (V0 to V6) based on their forward voltage drop at 20mA. Each bin has a range of 0.1V, with an additional tolerance of ±0.1V on each bin.

• Example: Bin V0 covers 2.9V to 3.0V.

3.2 Luminous Intensity (IV) Binning

LEDs are sorted into bins (T, A, B, C, D) based on their luminous intensity at 20mA. A tolerance of ±10% applies to each bin's range.

• Example: Bin D covers 1580 mcd to 1720 mcd.

3.3 Color Ranks (Chromaticity Binning)

A detailed table defines specific color ranks (e.g., A52, A53, BE1, BG3). Each rank is defined by a quadrilateral or triangle on the CIE 1931 chromaticity diagram, specified by three or four (x, y) coordinate points. This allows for precise color selection and matching for applications requiring specific white point coordinates.

4. Performance Curve Analysis

The datasheet references typical electrical and optical characteristic curves measured at 25°C ambient temperature. While the specific graphs are not detailed in the provided text, such curves typically include:

• Relative Luminous Intensity vs. Forward Current: Shows how light output increases with current, typically in a non-linear fashion, eventually saturating.
• Forward Voltage vs. Forward Current: The IV curve, showing the exponential relationship characteristic of a diode.
• Relative Luminous Intensity vs. Ambient Temperature: Illustrates the decrease in light output as the junction temperature rises, a critical factor for thermal management.
• Spectral Power Distribution: For a white LED (likely a blue die with phosphor), this would show the blue peak and the broader phosphor-converted yellow spectrum.

5. Mechanical and Package Information

5.1 Outline Dimensions

All dimensions are in millimeters with a standard tolerance of ±0.1 mm unless otherwise specified. The package is an industry-standard SMD format. The anode terminal is clearly marked in the diagram for correct polarity orientation during assembly.

5.2 Recommended PCB Attachment Pad Layout

A land pattern design is provided for the printed circuit board to ensure reliable soldering during the infrared or vapor phase reflow process. Adhering to this recommended footprint is crucial for achieving proper solder joint formation and mechanical stability.

6. Soldering and Assembly Guidelines

6.1 Reflow Soldering Parameters

The component is rated for lead-free reflow soldering with a peak temperature of 260°C for a maximum of 10 seconds. A reflow profile compliant with J-STD-020D is suggested. The profile should include appropriate preheat, soak, reflow, and cooling stages to minimize thermal shock and ensure reliable solder joints.

6.2 Storage and Handling Conditions

The LED is classified as Moisture Sensitivity Level (MSL) 3 per JEDEC J-STD-020.

• Sealed Package: Store at ≤30°C and ≤90% RH. Shelf life is one year in the moisture-proof bag with desiccant.
• Opened Package: Store at ≤30°C and ≤60% RH. The components must be subjected to soldering within 168 hours (7 days) of exposure. If the humidity indicator card turns pink (≥10% RH) or the exposure time is exceeded, baking at 60°C for at least 48 hours is recommended before use. Reseal any unused parts with desiccant.

6.3 Cleaning

If cleaning is necessary after soldering, only use specified solvents. Immersing the LED in ethyl alcohol or isopropyl alcohol at normal temperature for less than one minute is acceptable. The use of unspecified chemical cleaners is prohibited as they may damage the LED package or optics.

7. Packaging and Ordering Information

7.1 Tape and Reel Specifications

The components are supplied in embossed carrier tape with a width of 12mm, wound onto 7-inch (178mm) diameter reels.

• Reel Capacity: Maximum of 2000 pieces per reel.
• Cover Tape: Empty pockets are sealed with a top cover tape.
• Missing Components: A maximum of two consecutive missing components ("lamps") is allowed per the specification.
• Standard: Packaging complies with EIA-481-1-B specifications.

Detailed dimensional drawings for both the carrier tape pockets and the reel are provided in the datasheet.

8. Application Suggestions and Design Considerations

8.1 Design Considerations

• Current Limiting: Always drive the LED with a constant current source or a current-limiting resistor. The absolute maximum DC current is 30mA; typical operation is at 20mA.
• Thermal Management: Although power dissipation is low (120mW max), ensuring adequate PCB copper area or thermal vias helps maintain lower junction temperature, which preserves luminous output and longevity.
• ESD Protection: Implement ESD protection measures in the circuit and during handling, as the device is rated for only 2kV HBM.
• Optics: The 110-degree viewing angle is suitable for wide-area illumination. For focused beams, secondary optics (lenses) would be required.

8.2 Application Limitations and Cautions

The datasheet contains a critical caution regarding application scope. These LEDs are intended for standard commercial and industrial electronics. They are not designed or qualified for applications where failure could directly jeopardize life or health, such as:

• Aviation control systems
• Medical life-support equipment
• Transportation safety-critical signals (without additional qualification)
• Other high-reliability/safety-critical systems

Consultation with the manufacturer is required for such applications.

9. Technical Comparison and Differentiation

While a direct comparison with other part numbers is not provided in this single datasheet, key differentiators of this component can be inferred:

• Brightness Range: Offers a relatively high luminous intensity (up to 1720 mcd at 20mA) for its package size, targeting applications requiring good point-source brightness.
• Color Binning: The extensive color rank table allows for precise color selection, which is advantageous for applications requiring consistent white color appearance across multiple LEDs.
• Compatibility: Full compatibility with standard SMD assembly processes (auto-placement, IR/vapor phase reflow) makes it a drop-in solution for high-volume manufacturing.

10. Frequently Asked Questions Based on Technical Parameters

10.1 What is the typical operating current and voltage?

The standard test condition and typical operating point is 20mA forward current. At this current, the forward voltage typically falls between 2.9V and 3.6V, depending on the specific VF bin. The power consumption is approximately 60-70mW.

10.2 How do I interpret the color binning codes?

The alphanumeric codes (e.g., A52, BE3) correspond to specific regions on the CIE 1931 chromaticity diagram defined in the Color Ranks Table. To ensure color uniformity in your design, specify and use LEDs from the same color rank. The first letter/number often groups similar color temperatures or hues.

10.3 Can I drive this LED with a 5V supply?

Not directly. Connecting a 5V supply directly across the LED would cause excessive current flow, likely exceeding the absolute maximum rating and destroying the device. You must use a series current-limiting resistor or a constant-current driver. For example, with a 5V supply and a target of 20mA, assuming a VF of 3.2V, the required series resistor would be R = (5V - 3.2V) / 0.02A = 90 Ohms (a standard 91 Ohm resistor could be used).

10.4 What are the MSL 3 handling requirements?

MSL 3 means the package can withstand up to 168 hours (7 days) of factory floor conditions (≤30°C/60% RH) after the moisture-proof bag is opened. If the bag is opened, you have one week to complete the reflow soldering process. If this time is exceeded, the parts must be baked at 60°C for 48 hours to remove absorbed moisture and prevent "popcorning" (package cracking) during reflow.

11. Practical Design and Usage Examples

11.1 Example: Designing a PCB Mounted Indicator Light

Scenario: Creating a simple status indicator powered from a 3.3V microcontroller GPIO pin.
Design Steps:

1. Current Limit: The GPIO pin can source 20mA. This matches the LED's typical current. No external driver needed.
2. Resistor Calculation (for safety margin): Even though VCC (3.3V) is close to VF (~3.2V), a small series resistor is good practice to limit inrush current. R = (3.3V - 3.2V) / 0.02A = 5 Ohms. Use a 10 Ohm resistor for a safer limit.
3. PCB Layout: Use the recommended land pattern. Connect the cathode (identified in the outline drawing) to the resistor and then to the GPIO pin. Connect the anode to the 3.3V rail. Include a small copper pour under the LED pad for slight heat sinking.
4. Software: Drive the GPIO pin high to turn the LED on.

11.2 Example: Multi-LED Array for Task Lighting

Scenario: Designing an undershelf light using 10 LEDs for even illumination.
Design Considerations:

• Color Matching: Specify a single, tight color bin (e.g., BE2) from your supplier to avoid visible color differences between LEDs.
• Drive Method: Use a constant-current LED driver IC capable of delivering 200mA (10 LEDs * 20mA) for series or parallel-series configuration. A simple linear regulator would be inefficient due to the voltage drop.
• Thermal Management: Space the LEDs adequately on the metal-core PCB (MCPCB) to allow heat dissipation. The 120mW per LED translates to 1.2W total, requiring conscious thermal design.
• Optics: The native 110-degree beam may be sufficient. For a more focused or diffused look, consider adding a light guide or a diffuser panel.

12. Principle of Operation Introduction

White LEDs like the LTW-020ZDCG typically operate on the principle of phosphor conversion. The core of the device is a semiconductor chip, usually made from indium gallium nitride (InGaN), which emits blue light when forward biased (electrical current passes through it). This blue light-emitting chip is coated or covered with a layer of phosphor material—often based on yttrium aluminum garnet (YAG) doped with cerium.

When the blue photons from the chip strike the phosphor, a portion of them are absorbed. The phosphor then re-emits this energy as light across a broader spectrum, predominantly in the yellow region. The combination of the remaining unabsorbed blue light and the phosphor-emitted yellow light mixes to produce the perception of white light to the human eye. The exact proportions of blue and yellow, and the specific phosphor composition, determine the correlated color temperature (CCT) and chromaticity coordinates (x, y) of the white light produced, leading to the detailed binning system described in the datasheet.

13. Technology Trends and Developments

The field of solid-state lighting (SSL) continues to evolve. General trends observable in the industry, which provide context for components like this, include:

• Increased Efficiency (Lumens per Watt): Ongoing improvements in semiconductor epitaxy, chip design, and phosphor technology steadily increase the luminous efficacy of white LEDs, reducing energy consumption for the same light output.
• Improved Color Quality: Development of multi-phosphor blends and novel phosphor materials (e.g., quantum dots) aims to improve the Color Rendering Index (CRI), making colors appear more natural under LED illumination, and to offer a wider range of precise color temperatures.
• Miniaturization and Higher Density: Advancements in packaging allow for smaller LED footprints and higher power densities, enabling more compact and brighter lighting solutions.
• Smart and Connected Lighting: Integration of control electronics directly with LED packages or modules to enable dimming, color tuning, and connectivity (IoT) is a growing trend, moving beyond simple passive components.
• Reliability and Lifetime Predictions: Enhanced understanding of failure mechanisms and better testing methodologies lead to more accurate lifetime predictions (L70, L90 metrics) under various operating conditions, crucial for professional lighting design.

Components such as the one described in this datasheet represent a mature point in this technological progression, offering a reliable, standardized solution for a wide array of general lighting applications.