Surface Mount LED Lamp LTWMR4DX3KY Datasheet - Size 4.2x4.2x6.9mm - Voltage 2.5-3.3V - Color Yellow - Power 100mW - English Technical Document

1. Product Overview

The LTWMR4DX3KY is a high-brightness, yellow-emitting surface mount LED lamp designed for demanding lighting applications. It utilizes an InGaN chip combined with phosphor technology to produce its characteristic yellow light output through a water-clear lens. The device is engineered for compatibility with standard Surface Mount Technology (SMT) assembly lines, including industrial reflow soldering processes.

Its primary design advantage lies in its package, which features a lens shape (round or oval) engineered to provide a smooth radiation pattern and precise viewing angle control. This eliminates the need for additional secondary optics in many applications, offering a cost-effective and compact solution. The package employs advanced epoxy materials that provide excellent moisture resistance and UV protection, enhancing long-term reliability in various environments.

1.1 Core Advantages and Target Market

The LED offers several key benefits that make it suitable for professional lighting solutions. It delivers high luminous intensity output while maintaining low power consumption and high electrical-to-optical efficiency. The device is compliant with environmental standards, being lead-free, halogen-free, and RoHS compliant.

The primary target applications are in the signage and information display sector. Its high brightness and controlled beam angle make it ideal for video message signs, various traffic signs, and general message boards, both for indoor and outdoor use. The product is classified as Moisture Sensitivity Level (MSL) 3, which is a critical consideration for storage and handling prior to assembly.

2. In-Depth Technical Parameter Analysis

A thorough understanding of the device's limits and operating characteristics is essential for reliable system design.

2.1 Absolute Maximum Ratings

These ratings define the stress limits beyond which permanent damage to the device may occur. Operation under or at these limits is not guaranteed.

• Power Dissipation (Pd): 100 mW maximum. This is the total power the package can dissipate as heat.
• Forward Current: A DC forward current (IF) of 30 mA must not be exceeded for continuous operation. For pulsed operation, a peak forward current of 100 mA is allowed under specific conditions (duty cycle ≤ 1/10, pulse width ≤ 10ms).
• Thermal Derating: The maximum allowable DC forward current must be linearly derated from its value at 25°C at a rate of 0.54 mA per degree Celsius for ambient temperatures (TA) above 55°C.
• Temperature Ranges: The device is rated for an operating temperature range of -30°C to +85°C and a storage temperature range of -40°C to +100°C.
• Soldering: The LED can withstand reflow soldering with a peak temperature of 260°C for a maximum of 10 seconds.

2.2 Electrical and Optical Characteristics

These parameters are typically measured at an ambient temperature (TA) of 25°C and define the device's performance under normal operating conditions.

• Luminous Intensity (Iv): Ranges from a minimum of 5500 mcd to a maximum of 12000 mcd at a test current (IF) of 20 mA. The actual value is binned (see Section 4). The guarantee includes a ±15% testing tolerance.
• Viewing Angle (2θ_1/2): Defined as the full angle at which the luminous intensity is half the axial (on-center) intensity. It has a minimum of 30°, typical of 35°, with a measurement tolerance of ±2 degrees. This relatively narrow angle is beneficial for directing light efficiently in signage.
• Chromaticity Coordinates (x, y): The typical color point is specified at x=0.57, y=0.42 on the CIE 1931 chromaticity diagram. This defines the specific shade of yellow.
• Forward Voltage (VF): Ranges from 2.5V to 3.3V at IF=20mA. This variation must be accounted for in driver design to ensure consistent current.
• Reverse Current (IR): Maximum of 10 µA when a reverse voltage (VR) of 5V is applied. It is crucial to note that this device is not designed for reverse-bias operation; this test condition is for characterization only.

3. Binning System Specification

To ensure consistency in production, LEDs are sorted into bins based on key performance parameters.

3.1 Luminous Intensity Binning

The luminous output is classified into three primary bins, identified by the code marked on the packing bag.

• Bin Code W: 5500 mcd (Min) to 7200 mcd (Max)
• Bin Code X: 7200 mcd (Min) to 9300 mcd (Max)
• Bin Code Y: 9300 mcd (Min) to 12000 mcd (Max)

A tolerance of ±15% applies to the limits of each bin.

3.2 Hue (Color) Binning

The chromaticity coordinates are also binned into four groups (Y1, Y2, Y3, Y4) to control color consistency. Each bin defines a small quadrilateral area on the CIE chromaticity diagram with specific corner coordinates for x and y. The measurement allowance for color coordinates is ±0.01. This tight control is vital for applications where uniform color appearance across multiple LEDs is required.

4. Mechanical and Package Information

4.1 Outline Dimensions

The device has a compact surface-mount footprint. Key dimensions include a body size of approximately 4.2mm x 4.2mm, with an overall height of 6.9mm ±0.5mm. The leads have a spacing where they emerge from the package. A detailed dimensional drawing is provided in the datasheet, including notes on tolerances (typically ±0.25mm) and the maximum protrusion of resin under the flange (1.0mm max).

4.2 Polarity Identification and Pad Design

The LED features three pads (P1, P2, P3). P1 and P3 are designated as the Anode (+), while P2 is the Cathode (-). A recommended soldering pad pattern is provided to ensure proper electrical connection and thermal management. A specific note highlights that the pad connected to P3 is recommended to be linked to a heat sink or cooling mechanism, as it is designed to help distribute heat generated during operation, which is critical for maintaining performance and longevity.

5. Soldering, Assembly, and Handling Guidelines

Proper handling is required to maintain device integrity and solderability.

5.1 Storage and Moisture Sensitivity

As an MSL3 device, it has a finite floor life after the moisture barrier bag is opened. When sealed, it can be stored for up to 12 months at <30°C and 90% RH. After opening, the LEDs must be kept under <30°C and 60% RH and must complete soldering within 168 hours (7 days). Baking at 60°C ±5°C for 20 hours is required if the humidity indicator card shows >10% RH, the floor life is exceeded, or the devices are exposed to higher humidity. Baking should be performed only once.

5.2 Soldering Recommendations

The device is designed for reflow soldering, not dip soldering.

• Reflow Soldering: A maximum peak temperature of 260°C for 10 seconds is allowed. The recommended profile includes a pre-heat stage at 150-200°C for up to 120 seconds. Reflow should not be performed more than two times.
• Hand Soldering: If necessary, a soldering iron at a maximum temperature of 315°C can be used for no more than 3 seconds, and this should be done only once.

Critical cautions include avoiding external stress on the LED during soldering while it is hot and preventing rapid cooling from peak temperature, as thermal shock can damage the package or die.

5.3 Cleaning and Drive Method

If cleaning is required, alcohol-based solvents like isopropyl alcohol should be used. Importantly, LEDs are current-operated devices. To ensure intensity uniformity and prevent damage, they must be driven by a constant current source, not a constant voltage source. The forward current must be limited according to the Absolute Maximum Ratings and the application's thermal conditions.

6. Packaging Specification

The LEDs are supplied on embossed carrier tape for automated placement. The tape dimensions are specified, including pocket size, pitch, and cover tape details. A standard reel contains 1,000 pieces. The packaging is clearly marked as containing Electrostatic Sensitive Devices (ESD), requiring safe handling procedures to prevent damage from static discharge.

7. Application Suggestions and Design Considerations

7.1 Typical Application Scenarios

This LED is well-suited for applications requiring high visibility and directed light.

• Information Displays: Video message signs, scrolling text boards, and large-format informational displays benefit from the high brightness and narrow viewing angle, which increases on-axis intensity for better readability.
• Traffic and Safety Signage: Traffic signs, warning signs, and guidance signs where a specific yellow color (e.g., for caution) and high output are regulatory or functional requirements.
• Commercial Signage: Channel letters, illuminated logos, and backlit signs where efficient, compact light sources are needed.

7.2 Critical Design Considerations

• Thermal Management: The 100mW power dissipation limit and thermal derating curve necessitate effective PCB layout for heat dissipation. Using the recommended pad pattern to connect to thermal planes or heatsinks is crucial for maintaining performance and reliability, especially at high ambient temperatures or drive currents.
• Current Drive: Always use a constant current driver circuit. The forward voltage can vary from 2.5V to 3.3V; a constant voltage supply would cause large variations in current and thus light output, and could easily exceed the maximum current rating.
• Optical Design: The built-in lens provides a ~35-degree viewing angle. For applications requiring different beam patterns, secondary optics must be designed considering the LED's primary radiation pattern.
• ESD Protection: Implement appropriate ESD protection measures during handling, assembly, and in the end circuit, as LEDs are generally sensitive to electrostatic discharge.

8. Technical Comparison and Differentiation

Compared to standard SMD or PLCC (Plastic Leaded Chip Carrier) package LEDs, this device offers distinct advantages for signage applications. The primary differentiator is its integrated lens design, which provides superior control over the viewing angle and a smoother radiation pattern without the need for additional external lenses. This integration reduces part count, simplifies assembly, and can lower the total system cost and size. The use of advanced epoxy also offers better environmental resistance (moisture, UV) than some standard packages, making it more robust for outdoor applications.

9. Frequently Asked Questions (Based on Technical Parameters)

Q: What is the main advantage of the narrow viewing angle?

A: A narrow viewing angle concentrates the light output into a smaller cone, resulting in higher axial luminous intensity (candelas). This makes the sign or display appear brighter when viewed straight on, which is often the primary viewing direction, improving visibility and efficiency.

Q: Why is the device rated MSL3, and what does it mean for my production?

A: MSL3 indicates the plastic package can absorb moisture from the air. During reflow soldering, this trapped moisture can vaporize rapidly, causing internal damage (\"popcorning\"). It mandates controlled storage and a limited \"floor life\" after the bag is opened (168 hours under specified conditions), after which baking is required before soldering.

Q: Can I drive this LED directly from a 3.3V or 5V power supply?

A: No. The forward voltage varies, and an LED is a diode whose current increases exponentially with voltage. Connecting it directly to a voltage source, even 3.3V, would likely cause excessive current, overheating, and rapid failure. A series current-limiting resistor or, preferably, a dedicated constant-current LED driver circuit must be used.

Q: How do I interpret the bin codes (W, X, Y, Y1, Y2, etc.)?

A: The letter (W/X/Y) indicates the luminous intensity range of the LED. The number following \"Y\" (Y1/Y2/Y3/Y4) indicates its color (hue) bin. For consistent appearance in a product, it is advisable to specify and use LEDs from the same intensity and color bin.

10. Practical Application Case Study

Scenario: Designing an Outdoor Bus Stop Information Panel

An engineer is designing a solar-powered, outdoor bus stop display that shows route and schedule information. The display must be readable in direct sunlight and operate reliably in varying weather conditions (-10°C to 50°C ambient).

Design Choices:

1. The LTWMR4DX3KY is selected for its high brightness (up to 12,000 mcd) to overcome ambient light.

2. Its narrow viewing angle (30-35°) is ideal as passengers typically view the sign from a limited range of positions directly in front.

3. The moisture-resistant and UV-protected package is critical for long-term outdoor durability.

4. The MSL3 rating requires the manufacturing partner to follow strict moisture control procedures during PCB assembly.

5. The PCB layout incorporates the recommended pad pattern, with the P3 pad connected to a large copper pour acting as a heatsink to manage the ~60mW of heat generated per LED at 20mA.

6. A constant-current driver IC is used to power a matrix of these LEDs, ensuring uniform brightness despite forward voltage variations and providing dimming capability for night-time operation to save power.

This case highlights how the device's specific parameters directly inform and enable a robust, real-world design.