LTLMR4YW2DA LED Lamp Datasheet - 4.2x4.2x6.9mm - 2.4V Max - 120mW - Yellow 590nm - English Technical Document

1. Product Overview

The LTLMR4YW2DA is a high-brightness surface mount LED lamp designed for demanding lighting applications. It utilizes a Yellow AllnGaP (Aluminum Indium Gallium Phosphide) semiconductor material to produce light with a peak wavelength of 594nm. The device is packaged in a diffused yellow epoxy lens package, which is engineered to provide a controlled, narrow radiation pattern without the need for additional secondary optics. This makes it particularly suitable for applications requiring precise light direction and high on-axis intensity.

The core advantages of this LED include its high luminous intensity output, reaching up to 16,000 mcd at a standard 20mA drive current, and its low power consumption leading to high efficacy. The package is constructed using advanced epoxy molding compound technology, which provides superior moisture resistance and UV protection, enhancing long-term reliability in various environments. The product is fully compliant with RoHS directives, being both lead-free and halogen-free.

The target market for this component includes manufacturers of professional signage and display systems. Its primary applications are in video message signs, traffic signs, and other forms of message signage where high visibility, color consistency, and reliability are critical. The narrow 25° typical viewing angle ensures that light is concentrated forward, maximizing perceived brightness for viewers directly in front of the sign.

2. Technical Parameter Analysis

2.1 Absolute Maximum Ratings

The device is specified for operation within strict limits to ensure reliability. The maximum power dissipation is 120 mW at an ambient temperature (TA) of 25°C. The DC forward current should not exceed 50 mA. For pulsed operation, a peak forward current of 120 mA is permissible under specific conditions: a duty cycle of 1/10 or less and a pulse width not exceeding 10ms. The operating temperature range is from -40°C to +85°C, and the storage temperature range extends from -40°C to +100°C. A critical rating for assembly is the reflow soldering condition, which allows a maximum peak temperature of 260°C for 10 seconds, compatible with standard lead-free reflow profiles.

2.2 Electrical and Optical Characteristics

Key performance parameters are measured at TA=25°C and IF=20mA. The luminous intensity (Iv) has a typical range from 7,200 to 16,000 millicandelas (mcd), with specific values determined by the binning process. The viewing angle (2θ1/2), defined as the full angle at which intensity drops to half its on-axis value, is typically 25° with a tolerance of ±2°. The dominant wavelength (λd) for the yellow color is specified between 583.5 nm and 593.5 nm, with a typical peak emission wavelength (λP) of 594 nm and a spectral half-width (Δλ) of 15 nm. The forward voltage (VF) ranges from a minimum of 1.8V to a maximum of 2.4V at the test current. The reverse current (IR) is limited to a maximum of 10 μA at a reverse voltage (VR) of 5V, noting that the device is not designed for operation in reverse bias.

3. Binning System Specification

The LEDs are classified into bins to ensure color and brightness consistency within a production lot. This allows designers to select components that meet specific application requirements for uniformity.

3.1 Luminous Intensity (Iv) Binning

LEDs are sorted based on their luminous intensity measured at 20mA. The bin codes are: Code X (7,200 - 9,300 mcd), Code Y (9,300 - 12,000 mcd), and Code Z (12,000 - 16,000 mcd). A tolerance of ±15% applies to each bin limit.

3.2 Dominant Wavelength (Wd) Binning

To control color consistency, LEDs are binned by dominant wavelength. The bins are: Y1 (583.5 - 586.0 nm), Y2 (586.0 - 588.5 nm), Y3 (588.5 - 591.0 nm), and Y4 (591.0 - 593.5 nm). A tolerance of ±1nm is applied to each bin limit.

3.3 Forward Voltage (Vf) Binning

Forward voltage is also binned to aid in circuit design for current regulation. The bins are: 1A (1.8 - 2.0V), 2A (2.0 - 2.2V), and 3A (2.2 - 2.4V). A tolerance of ±0.1V applies to each limit.

4. Mechanical and Package Information

4.1 Outline Dimensions

The package has a square body footprint of 4.2mm ±0.2mm on each side. The total height, including the lens, is 6.9mm ±0.5mm. The leads protrude from the bottom of the package, with a lead spacing (where leads emerge) of 3.65mm ±0.2mm. A maximum resin protrusion of 1.0mm under the flange is allowed. All dimensions include a general tolerance of ±0.25mm unless otherwise specified.

4.2 Polarity Identification

The device has three leads (P1, P2, P3). P1 and P3 are designated as the Anode (+), and P2 is designated as the Cathode (-). Correct polarity must be observed during PCB layout and assembly.

5. Soldering and Assembly Guidelines

5.1 Reflow Soldering Profile

The LED is rated for lead-free reflow soldering processes. The recommended profile parameters are: Preheat/Soak temperature from 150°C to 200°C for a maximum of 120 seconds. The time above liquidous temperature (T_L = 217°C) should be between 60 and 150 seconds. The peak package body temperature (T_P) must not exceed 260°C, and the time within 5°C of the specified classification temperature (T_C = 255°C) should be a maximum of 30 seconds. The total time from 25°C to peak temperature should not exceed 5 minutes.

5.2 Hand Soldering

If hand soldering is necessary, use a soldering iron with a tip temperature not exceeding 315°C. The soldering time per lead should be limited to a maximum of 3 seconds, and this should be performed only once per joint to prevent thermal damage to the LED.

5.3 Cleaning

If post-solder cleaning is required, use only alcohol-based solvents such as isopropyl alcohol. Harsh or aggressive chemical cleaners should be avoided as they may damage the epoxy lens or package markings.

6. Storage and Handling

6.1 Moisture Sensitivity

This component is classified as Moisture Sensitivity Level 3 (MSL3) per JEDEC standard J-STD-020. LEDs are supplied in a sealed moisture barrier bag (MBB) with a desiccant and a humidity indicator card. When stored in the unopened MBB at conditions of <30°C and <90% Relative Humidity (RH), the shelf life is 12 months.

6.2 Floor Life and Baking

After the moisture barrier bag is opened, the \"floor life\" begins. The LEDs must be stored at <30°C and <60% RH, and all soldering or high-temperature processes must be completed within 168 hours (7 days). Baking is required if: the humidity indicator card shows >10% RH, the floor life exceeds 168 hours, or the components have been exposed to >30°C and >60% RH. The recommended baking condition is 60°C ±5°C for 20 hours, and baking should be performed only once. Prolonged exposure to ambient air can oxidize the silver plating on the leads, affecting solderability. Unused LEDs should be resealed with desiccant in a moisture barrier bag.

7. Packaging Specification

The LEDs are supplied on embossed carrier tape for automated pick-and-place assembly. The tape dimensions are standardized: pocket pitch is 8.0mm ±0.1mm, tape width is 16.0mm ±0.3mm. Each reel contains 1,000 pieces of LEDs. The reels are then packaged with protective materials: one reel is placed in a moisture barrier bag with a desiccant and humidity indicator card. Three such moisture barrier bags are packed into one inner carton, totaling 3,000 pieces. Finally, ten inner cartons are packed into one outer shipping carton, resulting in a total of 30,000 pieces per outer carton. The packaging is clearly marked with electrostatic discharge (ESD) warnings, indicating that the devices are sensitive and require safe handling procedures.

8. Application Notes and Design Considerations

8.1 Typical Application Circuits

To ensure stable operation and longevity, the LED must be driven with a constant current source, not a constant voltage. A simple series resistor can be used for basic current limiting, calculated as R = (V_supply - V_F) / I_F. However, for applications requiring stable brightness over temperature or supply voltage variations, a dedicated LED driver IC or a transistor-based constant current circuit is recommended. The maximum DC current should not exceed 50 mA. For designs pushing the limits of power dissipation, careful attention must be paid to the derating curve, which specifies a linear derating of 0.75 mA per degree Celsius above 45°C ambient temperature.

8.2 Thermal Management

Although the package is not primarily designed as a power LED, effective thermal management on the PCB is still important for maintaining performance and lifetime. The PCB pad design should follow the recommended footprint to ensure good solder joint formation and thermal conduction away from the LED. Using a PCB with thermal vias under the LED's thermal pad (if applicable) or ensuring adequate copper pour connected to the cathode/anode pads can help dissipate heat. Operating the LED at or near its maximum ratings in high ambient temperatures will reduce its effective lifetime and may cause color shift or intensity drop.

8.3 Optical Design Considerations

The built-in diffused lens and narrow viewing angle eliminate the need for secondary optics in many signage applications, simplifying assembly and reducing cost. The radiation pattern is relatively smooth. Designers should consider the angular intensity distribution when planning the spacing between LEDs in an array to achieve uniform illumination without dark spots. The diffused nature of the lens helps to minimize pixelation or individual LED hotspots, creating a more seamless visual appearance in message boards.

9. Technical Comparison and Differentiation

Compared to standard SMD (Surface Mount Device) or PLCC (Plastic Leaded Chip Carrier) package LEDs, this lamp-style package offers distinct advantages for directional lighting. Standard SMD LEDs often have a wider viewing angle (e.g., 120°), spreading light over a larger area, which is inefficient for applications requiring light to be seen from a specific direction. The LTLMR4YW2DA's 25° viewing angle concentrates the luminous flux, resulting in significantly higher axial luminous intensity (candelas) for the same amount of total light output (lumens). This makes it more efficient for applications like traffic signs, where the viewer is typically within a narrow cone in front of the sign. The integrated lens and robust through-hole style leads in an SMD body provide a good balance of optical control, mechanical strength, and compatibility with automated assembly.

10. Frequently Asked Questions (FAQ)

Q: What is the difference between peak wavelength and dominant wavelength?
A: Peak wavelength (λP) is the single wavelength at which the emission spectrum has its maximum intensity. Dominant wavelength (λd) is derived from the CIE chromaticity diagram and represents the single wavelength of the monochromatic light that would appear to have the same color as the LED to a human observer. For a narrow-spectrum LED like this yellow AllnGaP type, they are typically very close, but λd is the more relevant parameter for color specification.

Q: Can I drive this LED with a voltage source?
A: It is strongly discouraged. LEDs are current-driven devices. Their forward voltage has a tolerance and varies with temperature. Connecting directly to a voltage source, even with a series resistor calculated for a typical V_F, can result in excessive current if the actual V_F is at the low end of its range, potentially damaging the LED. Always use a current-limiting mechanism.

Q: Why is the MSL3 rating and baking process important?
A: Moisture absorbed into the plastic package can vaporize rapidly during the high-temperature reflow soldering process, causing internal delamination, cracking, or \"popcorning,\" which leads to immediate or latent failure. Adhering to the MSL3 handling procedures (168-hour floor life, proper storage, and baking when required) is critical for ensuring assembly yield and long-term field reliability.

Q: How do I interpret the bin codes when ordering?
A> The bin codes (e.g., Iv=Z, Wd=Y3, Vf=2A) allow you to specify the performance range you require for your application. For a sign requiring very high and uniform brightness, you might specify Iv=Z. For critical color-matching between multiple signs or within a large array, you would specify a tight Wd bin like Y2 or Y3. Consult with the supplier for available bin combinations.

11. Operational Principle

The LTLMR4YW2DA is based on AllnGaP (Aluminum Indium Gallium Phosphide) semiconductor technology. When a forward voltage exceeding the diode's turn-on threshold is applied, electrons from the n-type region and holes from the p-type region are injected into the active region. Here, they recombine, releasing energy in the form of photons. The specific bandgap energy of the AllnGaP alloy in the active region determines the wavelength of the emitted light, which in this case is in the yellow region of the visible spectrum (~590nm). The diffused epoxy lens surrounding the semiconductor die serves to extract the light from the high-index material, shape the radiation pattern into a narrow beam, and protect the delicate semiconductor structure from mechanical and environmental damage.

12. Industry Context and Trends

Surface mount LED lamps like the LTLMR4YW2DA represent a mature and optimized segment of the LED market, bridging the gap between low-power indicator LEDs and high-power illumination LEDs. The trend in this segment continues to be towards higher efficiency (more lumens or candelas per watt), improved color consistency through tighter binning, and enhanced reliability metrics such as longer lifetime (L70, L90) under various operating conditions. There is also a sustained drive for miniaturization while maintaining or increasing optical output, allowing for finer pixel pitches in high-resolution displays and signs. Furthermore, compatibility with increasingly stringent environmental regulations (beyond RoHS, considering substances like REACH) and the ability to withstand higher temperature reflow profiles for advanced PCB assemblies remain key development drivers.