LTLMH4YRADA LED Lamp Datasheet - Dimensions 4.2x4.2x2.0mm - Voltage 1.8-2.4V - Yellow 590nm - 120mW Power - English Technical Document

1. Product Overview

The LTLMH4YRADA is a high-brightness, surface-mount LED lamp designed for modern electronic assembly. It utilizes a yellow diffused package with an AllnGaP chip emitting at a peak wavelength of 590nm. This device is engineered to deliver superior luminous intensity while maintaining low power consumption, making it an efficient choice for illumination applications. Its primary design philosophy centers on compatibility with standard Surface Mount Technology (SMT) processes, allowing for seamless integration into automated production lines using common industrial reflow soldering profiles. The package is constructed with advanced epoxy materials that provide excellent moisture resistance and UV protection, enhancing its durability and lifespan in demanding environments.

The core advantages of this LED include its high luminous output, which enables bright and clear visual signals, and its specifically engineered radiation pattern. The lamp features a typical viewing angle of 100/40°, offering a controlled, narrow beam without the need for additional secondary optics. This characteristic is particularly beneficial for applications requiring directed light or sharp visual demarcation. Furthermore, the product is fully compliant with environmental regulations, being lead-free, halogen-free, and RoHS compliant, aligning with global sustainability initiatives.

The target market for this component is broad, encompassing both commercial and industrial sectors. Its key applications are found in areas requiring reliable and vivid visual indicators, such as indoor and outdoor message signs, video message displays, and various types of traffic signage. The combination of its rugged construction, optical performance, and ease of assembly makes it a versatile solution for designers and engineers.

2. In-Depth Technical Parameter Analysis

2.1 Absolute Maximum Ratings

Understanding the absolute maximum ratings is critical for ensuring device reliability and preventing premature failure. The LTLMH4YRADA has a maximum power dissipation of 120mW at an ambient temperature (TA) of 25°C. The DC forward current is rated at 50mA, while a higher peak forward current of 120mA is permissible under pulsed conditions (duty cycle ≤ 1/10, pulse width ≤ 10ms). A key parameter for thermal management is the derating factor; the maximum forward current must be linearly reduced by 0.75 mA for every degree Celsius the ambient temperature rises above 45°C. The device is rated for operation within a temperature range of -40°C to +85°C and can be stored between -40°C to +100°C. Crucially, it can withstand reflow soldering at a peak temperature of 260°C for a maximum of 10 seconds, which is standard for lead-free solder processes.

2.2 Electrical and Optical Characteristics

The performance of the LED is defined under standard test conditions at TA=25°C. The luminous intensity (Iv) ranges from a minimum of 1500 mcd to a maximum of 4200 mcd at a forward current (IF) of 20mA. It is important to note that the Iv guarantee includes a ±15% testing tolerance. The dominant wavelength (λd) specification is between 584.5 nm and 594.5 nm, categorizing it firmly in the yellow spectrum, with a typical peak emission wavelength (λP) of 594 nm. The spectral half-width (Δλ) is typically 15 nm, indicating a relatively pure color emission. The forward voltage (VF) at 20mA ranges from 1.8V to 2.4V, which is a critical parameter for driving circuit design. The reverse current (IR) is specified at a maximum of 10 μA when a reverse voltage (VR) of 5V is applied, though the device is not designed for operation in reverse bias.

3. Binning System Specification

To ensure consistency in application, the LEDs are sorted into bins based on key performance parameters. This allows designers to select components that match their specific requirements for brightness, color, and voltage.

3.1 Luminous Intensity Binning

The luminous intensity is classified into four bins (R, S, T, U) when measured at IF=20mA. Each bin has defined minimum and maximum values: R (1500-1900 mcd), S (1900-2500 mcd), T (2500-3200 mcd), and U (3200-4200 mcd). A tolerance of ±15% applies to each bin limit.

3.2 Dominant Wavelength Binning

The color consistency is managed through dominant wavelength binning. Four bins (Y1, Y2, Y3, Y4) are defined: Y1 (584.5-587.0 nm), Y2 (587.5-589.5 nm), Y3 (589.5-592.0 nm), and Y4 (592.0-594.5 nm). The tolerance for each bin limit is ±1 nm.

3.3 Forward Voltage Binning

Forward voltage is binned to aid in current matching for LEDs connected in parallel. Three bins (1A, 2A, 3A) are specified at IF=20mA: 1A (1.8-2.0V), 2A (2.0-2.2V), and 3A (2.2-2.4V). The tolerance for each bin limit is ±0.1V.

4. Performance Curve Analysis

While the PDF indicates typical characteristic curves are present, specific graphical data for IV curves, temperature dependence, and spectral distribution is referenced but not detailed in the provided text. These curves are essential for design engineers. Typically, they would illustrate the relationship between forward current and luminous intensity, showing how output increases with current before potential saturation or efficiency drop. Temperature characteristic curves would show the decrease in luminous intensity and the shift in forward voltage as junction temperature rises. The spectral distribution curve would visually confirm the peak wavelength and spectral half-width, providing insight into color purity. Designers should consult the full datasheet for these graphs to optimize thermal management, drive current, and optical system design.

5. Mechanical and Package Information

5.1 Outline Dimensions

The LED features a compact surface-mount package. Key dimensions include a body size of 4.2mm ±0.2mm in length and width, with a total height of 2.0mm ±0.5mm. The leads protrude from the package, and the lead spacing is measured at the point where they emerge. A notable mechanical feature is the potential for a protruded resin under the flange, with a maximum height of 1.0mm. All dimensions are provided in millimeters, with a general tolerance of ±0.25mm unless otherwise specified.

5.2 Pad Design and Polarity Identification

The recommended soldering pad pattern is provided to ensure proper electrical connection and thermal performance. The device has three pads: P1 (Anode), P2 (Cathode), and P3 (Anode). It is critically important to note that pad P3 is specifically recommended to be connected to a heat sink or other cooling mechanism within the PCB design. This pad is integral for distributing heat generated during operation, thereby improving reliability and maintaining optical performance. Correct polarity orientation during placement is essential to prevent device damage.

6. Soldering and Assembly Guidelines

6.1 Storage and Moisture Sensitivity

This component is classified as Moisture Sensitivity Level 3 (MSL3) per JEDEC J-STD-020. LEDs in an unopened moisture barrier bag can be stored for up to 12 months at <30°C and 90% RH. After opening the bag, the components must be kept in an environment of <30°C and <60% RH, and all soldering must be completed within 168 hours (7 days). If the humidity indicator card shows >10% RH, the floor life exceeds 168 hours, or the parts are exposed to >30°C and 60% RH, baking is required. The recommended bake condition is 60°C ±5°C for 20 hours, and this should be performed only once to avoid damaging the package.

6.2 Reflow Soldering Profile

A lead-free reflow soldering profile is recommended. Key parameters include: a preheat/soak stage between 150°C and 200°C for a maximum of 120 seconds, a time above liquidus (217°C) between 60 to 150 seconds, a peak temperature (Tp) of 260°C, and a time within 5°C of the specified classification temperature (255°C) of 30 seconds maximum. The total time from 25°C to peak temperature should not exceed 5 minutes. It is strictly advised that reflow soldering not be performed more than two times, and hand soldering not more than once. Rapid cooling from peak temperature should be avoided, and no external stress should be applied to the LED while it is at high temperature.

6.3 Cleaning and Handling

If cleaning is necessary after soldering, only alcohol-based solvents such as isopropyl alcohol should be used. The device is sensitive to electrostatic discharge (ESD), so appropriate ESD-safe handling procedures must be followed during all stages of assembly and installation.

7. Packaging and Ordering Information

The LEDs are supplied on embossed carrier tape for automated placement. The tape dimensions are specified, with pockets designed to securely hold the 4.2mm x 4.2mm body. The tape is wound onto a standard 13-inch (330mm) reel. Each full reel contains a total of 1,000 pieces. The reel is labeled with appropriate caution notices, including "Electrostatic Sensitive Devices" and "Safe Handling Required." The part number LTLMH4YRADA is the primary ordering code, and the revision history (P001 to P005) is tracked for engineering change control.

8. Application Recommendations

8.1 Typical Application Scenarios

This LED is well-suited for both indoor and outdoor signage applications due to its high brightness and environmental robustness. Primary uses include dynamic message signs for advertising or information displays, various types of traffic signs requiring high visibility and reliability, and general status or indicator lights in electronic equipment. The narrow viewing angle characteristic makes it ideal for applications where light needs to be directed specifically at a viewer or a surface without excessive spill.

8.2 Design Considerations and Drive Method

An LED is a current-operated device. To ensure uniform brightness when multiple LEDs are used in parallel within an application, it is strongly recommended to use a constant current drive circuit rather than a constant voltage source. This practice compensates for the natural variation in forward voltage (Vf) from one LED to another, which is detailed in the bin table. Connecting LEDs directly in parallel to a voltage source can lead to significant current imbalance, where LEDs with a lower Vf draw more current, potentially overdriving them while under-driving others, resulting in uneven brightness and reduced lifespan. Therefore, implementing individual current-limiting resistors or, preferably, a dedicated constant-current LED driver IC is essential for optimal performance and longevity.

9. Technical Comparison and Differentiation

Compared to standard SMD or PLCC (Plastic Leaded Chip Carrier) packages, this surface mount lamp offers distinct advantages for specific applications. The key differentiator is its integrated lens design, which provides a controlled radiation pattern (100/40° viewing angle) without the need for an additional external optical lens. This simplifies the mechanical design of the final product, reduces part count, and can lower overall assembly cost. The advanced epoxy package offers superior moisture and UV resistance compared to some standard packages, making it more reliable for outdoor or harsh environment applications. The high luminous intensity in a compact form factor also provides a competitive advantage in space-constrained designs where high brightness is required.

10. Frequently Asked Questions (FAQ)

10.1 What is the meaning of the 100/40° viewing angle?

The viewing angle is specified as 100/40°. This typically refers to two different angular measurements. The first value (100°) often represents the full width at half maximum (FWHM) in one plane (e.g., the horizontal plane), where the luminous intensity drops to 50% of its peak value. The second value (40°) likely represents the FWHM in the perpendicular plane (e.g., the vertical plane), resulting in a more elliptical or narrow beam pattern. This asymmetric pattern is designed for specific signage applications.

10.2 Can I use a constant voltage source to drive this LED?

It is not recommended. Due to the variation in forward voltage (Vf) as shown in the bin table, driving multiple LEDs directly from a constant voltage source will cause uneven current distribution. Always use a constant current driver or include a current-limiting resistor in series with each LED or each string of series-connected LEDs to ensure stable and uniform operation.

10.3 How many times can I reflow solder this component?

The datasheet explicitly states that reflow soldering must not be done more than two times. This limit is set to prevent excessive thermal stress on the epoxy package and the internal die attach, which could lead to delamination, increased thermal resistance, or outright failure.

10.4 What does MSL3 mean, and why is baking necessary?

MSL3 (Moisture Sensitivity Level 3) indicates that the plastic packaging of the LED can absorb moisture from the atmosphere. During the high-temperature reflow soldering process, this trapped moisture can rapidly turn to steam, creating internal pressure that may crack the package (a phenomenon known as "popcorning"). Baking removes this absorbed moisture, making the component safe for reflow. Adhering to the specified floor life (168 hours after bag opening) and baking requirements is critical for assembly yield and long-term reliability.

11. Practical Design and Usage Case

Consider designing a compact, outdoor pedestrian crossing signal. The design requires a bright, yellow warning light that is clearly visible in daylight. The LTLMH4YRADA is selected for its high luminous intensity (up to 4200 mcd) and yellow color. Its narrow 40° vertical viewing angle helps concentrate the light towards pedestrians at street level, reducing upward light pollution. The MSL3 rating necessitates careful planning of the PCB assembly schedule to ensure all LEDs are soldered within 168 hours of opening the moisture barrier bag. The three-pad footprint is used, with the P3 pad connected to a large copper pour on the PCB acting as a heat sink to manage the 120mW power dissipation, ensuring stable light output over the product's lifetime. A constant-current driver circuit is designed to provide a stable 20mA to each LED, ensuring consistent brightness across all units despite natural Vf variations.

12. Operational Principle

The LTLMH4YRADA is based on an Aluminum Indium Gallium Phosphide (AllnGaP) semiconductor material. When a forward voltage exceeding its threshold (approximately 1.8V) is applied, electrons and holes recombine in the active region of the semiconductor chip, releasing energy in the form of photons. The specific composition of the AllnGaP layers is engineered to produce photons primarily in the yellow region of the visible spectrum, with a dominant wavelength around 590nm. The diffused epoxy lens surrounding the chip serves to extract the light efficiently from the semiconductor and shape the radiation pattern into the specified 100/40° viewing angle, while also providing mechanical and environmental protection.

13. Technology Trends

The surface-mount LED technology represented by this component continues to evolve along several key trajectories. Efficiency improvements are a constant focus, aiming to deliver higher luminous output (lumens) per electrical watt input. This drives the development of more efficient semiconductor materials and advanced chip architectures. Package technology is also advancing, with trends towards higher thermal conductivity materials to better manage heat from increasingly powerful chips, allowing for higher drive currents and greater brightness from the same footprint. Furthermore, there is a growing emphasis on color consistency and tighter binning specifications to meet the demands of high-end display and lighting applications, as well as enhanced reliability features for automotive and industrial markets.