LTLMR4YVX3DA Yellow LED Lamp Datasheet - Size 4.2x4.2x6.9mm - Voltage 1.8-2.4V - Power 120mW - English Technical Document

1. Product Overview

The LTLMR4YVX3DA is a high-brightness, surface-mount LED lamp designed for demanding signage applications. It utilizes a yellow AllnGaP chip encapsulated in a diffused package, delivering intense luminous output with a controlled viewing angle. Its primary design philosophy centers on reliability and compatibility with standard industrial surface-mount technology (SMT) assembly processes, including lead-free reflow soldering.

1.1 Core Advantages and Target Market

This device offers several key advantages that differentiate it from standard SMD or PLCC packages. Its primary feature is a smooth radiation pattern and a narrow, well-defined viewing angle of typically 35 degrees. This optical characteristic is achieved through its specific lens design, eliminating the need for additional external optical lenses in many applications, thereby simplifying design and reducing system cost. The package employs advanced epoxy technology, providing superior moisture resistance and UV protection, which is critical for outdoor and long-term reliability.

The target markets are applications requiring high visibility and reliability, such as video message signs, traffic signs, and various indoor/outdoor message displays. Its construction is lead-free, halogen-free, and fully compliant with RoHS environmental directives.

2. Technical Parameter Analysis

A detailed, objective analysis of the electrical and optical characteristics is essential for proper circuit design and performance prediction.

2.1 Absolute Maximum Ratings

These ratings define the stress limits beyond which permanent damage to the device may occur. The maximum power dissipation is 120mW at an ambient temperature (TA) of 25°C. The DC forward current should not exceed 50mA. For pulsed operation, a peak forward current of 120mA is permissible under specific conditions (duty cycle ≤1/10, pulse width ≤10µs). A critical parameter is the derating factor for forward current: above 45°C, the maximum allowable DC current decreases linearly at a rate of 0.75mA per degree Celsius. The operating temperature range is from -40°C to +85°C, and storage can be from -40°C to +100°C. The device can withstand a reflow soldering peak temperature of 260°C for a maximum of 10 seconds.

2.2 Electrical and Optical Characteristics

Measured at TA=25°C and a standard test current (IF) of 20mA, the key parameters are:

• Luminous Intensity (Iv): Ranges from a minimum of 5500 mcd to a maximum of 12000 mcd. The typical value falls within this range. A ±15% testing tolerance is applied to the bin limits.
• Viewing Angle (2θ1/2): Defined as the full angle at which intensity is half the peak value. The typical value is 35 degrees (minimum 30 degrees), with a measurement tolerance of ±2 degrees.
• Peak Emission Wavelength (λP): Typically 594 nm.
• Dominant Wavelength (λd): Ranges from 584.5 nm to 594.5 nm, defining the perceived yellow color.
• Spectral Line Half-Width (Δλ): Typically 15 nm, indicating the spectral purity of the yellow light.
• Forward Voltage (VF): Ranges from 1.8V to 2.4V at 20mA.
• Reverse Current (IR): Maximum of 10 µA at a reverse voltage (VR) of 5V. It is crucial to note that the device is not designed for reverse bias operation; this test is for characterization only.

3. Binning System Specification

To ensure color and brightness consistency in production, LEDs are sorted into bins. The LTLMR4YVX3DA uses a three-dimensional binning system.

3.1 Luminous Intensity Binning

Binned at IF=20mA. The bin code (W, X, Y) defines a min-max range for luminous intensity in millicandelas (mcd). Each bin limit has a ±15% tolerance.
W: 5500 - 7200 mcd
X: 7200 - 9300 mcd
Y: 9300 - 12000 mcd

3.2 Dominant Wavelength Binning

Binned at IF=20mA. The bin code (Y1, Y2, Y3, Y4) defines a min-max range for dominant wavelength in nanometers (nm). Each bin limit has a ±1nm tolerance.
Y1: 584.5 - 587.0 nm
Y2: 587.0 - 589.5 nm
Y3: 589.5 - 592.0 nm
Y4: 592.0 - 594.5 nm

3.3 Forward Voltage Binning

Binned at IF=20mA. The bin code (1A, 2A, 3A) defines a min-max range for forward voltage in volts (V). Each bin limit has a ±0.1V tolerance.
1A: 1.8 - 2.0 V
2A: 2.0 - 2.2 V
3A: 2.2 - 2.4 V

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 a total height of 6.9mm ±0.5mm. The lead spacing (where leads emerge from the package) is 2.0mm ±0.5mm. All dimensions are in millimeters, with a general tolerance of ±0.25mm unless otherwise specified. A small protrusion of resin under the flange is allowed, with a maximum height of 1.0mm.

4.2 Polarity Identification and Pad Design

The component has three leads (P1, P2, P3). P1 and P3 are the anode connections, while P2 is the cathode. This configuration must be carefully observed during PCB layout. A recommended soldering pad pattern is provided to ensure proper solder joint formation and mechanical stability during reflow. The pad design includes rounded corners (R0.5) to prevent solder bridging and ensure reliable connections.

5. Soldering and Assembly Guidelines

Proper handling is critical for reliability. This device is Moisture Sensitive Level 3 (MSL3) per JEDEC J-STD-020.

5.1 Storage and Handling

LEDs in an unopened moisture barrier bag (with desiccant) can be stored at <30°C and 90% RH for up to 12 months. After opening the bag, components 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 exceeds 168 hours, or the components are exposed to >30°C and 60% RH. Baking should be performed only once.

5.2 Reflow Soldering Profile

A lead-free reflow profile is recommended. Key parameters include: a preheat/soak stage from 150°C to 200°C for a maximum of 120 seconds; a time above liquidus (217°C) between 60 and 150 seconds; a peak temperature (Tp) of 260°C maximum; and a time within 5°C of the specified classification temperature (255°C) for a maximum of 30 seconds. The total time from 25°C to peak temperature should not exceed 5 minutes.

5.3 Cleaning

If cleaning is necessary after soldering, only alcohol-based solvents such as isopropyl alcohol should be used.

6. Packaging Specification

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. Standard packing includes 1,000 pieces per reel. For bulk shipment: one reel is placed in a moisture barrier bag with a desiccant and humidity indicator card; three such bags are packed into an inner carton (3,000 pcs total); and ten inner cartons are packed into an outer shipping carton (30,000 pcs total). The last pack in a shipping lot may not be full.

7. Application Notes and Design Considerations

7.1 Typical Application Scenarios

This LED is ideally suited for applications requiring high brightness and good visibility in various lighting conditions. Primary uses include:
- Video Message Signs: For large-scale displays where consistent color and brightness across many pixels is crucial.
- Traffic Signs: Leveraging its high intensity and reliability for safety-critical signaling.
- General Message Signs: Both indoor and outdoor, benefiting from its moisture resistance and controlled viewing angle.

7.2 Design Considerations

Current Driving: A constant current driver is strongly recommended over a constant voltage source to ensure stable luminous output and prevent thermal runaway. The design should operate well below the absolute maximum DC current of 50mA, typically at or near the test current of 20mA for guaranteed specifications.
Thermal Management: Although power dissipation is relatively low (120mW max), proper PCB layout with adequate thermal relief and, if necessary, a small copper pad for heat sinking will enhance longevity and maintain performance, especially in high ambient temperature environments or when driven at higher currents.
Optical Integration: The built-in 35-degree viewing angle may be sufficient for many applications. For different beam patterns, secondary optics can be used, but the initial lens design provides a smooth radiation pattern as a starting point.
ESD Protection: While not explicitly stated in the datasheet, standard ESD precautions should be observed during handling and assembly of all LED components.

8. Technical Comparison and Differentiation

Compared to standard 3528 or 5050 SMD LEDs, the LTLMR4YVX3DA package is designed specifically for high-intensity directional lighting in signage. Its key differentiator is the integrated lens that provides a controlled, narrow viewing angle without added optics, which is not a standard feature in generic SMD packages. The use of AllnGaP technology for yellow light offers higher efficiency and better temperature stability compared to older technologies like phosphor-converted white LEDs used for yellow filters. The package robustness (moisture and UV resistance) also positions it above many basic SMD LEDs intended primarily for indoor use.

9. Frequently Asked Questions (Based on Technical Parameters)

Q: What is the difference between peak wavelength and dominant wavelength?
A: Peak wavelength (λP=594nm) is the wavelength at which the emitted optical power is maximum. Dominant wavelength (λd=584.5-594.5nm) is derived from the color coordinates and represents the single wavelength of the pure spectral color that matches the perceived color of the LED. Dominant wavelength is more relevant for color specification.

Q: How do I interpret the binning codes when ordering?
A: You must specify codes for Intensity (e.g., Y), Wavelength (e.g., Y3), and Voltage (e.g., 2A) to get a consistent batch. The part number LTLMR4YVX3DA implies specific bin selections (Y for intensity, VX for wavelength/voltage combinations). Consult the supplier for the exact bin mapping to the part number suffix.

Q: Can I drive this LED with a 3.3V supply?
A: Directly connecting to a 3.3V source is not recommended and would likely destroy the LED due to excessive current. You must use a current-limiting resistor or, preferably, a constant-current driver circuit. The forward voltage is only 1.8-2.4V, so the excess voltage must be dropped across the series resistor or regulator.

Q: Why is the Moisture Sensitivity Level (MSL3) important?
A: During reflow soldering, trapped moisture inside the plastic package can vaporize rapidly, causing internal delamination or \"popcorning,\" which cracks the package and destroys the LED. Adhering to the 168-hour floor life after bag opening and following baking procedures when required is essential for high assembly yield.

10. Practical Design and Usage Case

Scenario: Designing a compact traffic warning sign.
A designer needs a highly visible, flashing yellow light. They select the LTLMR4YVX3DA for its high intensity (selecting bin Y for maximum brightness) and narrow viewing angle to ensure the light is directed at oncoming drivers. They design a PCB with the recommended pad layout. A simple circuit using a microcontroller PWM pin drives a MOSFET constant-current sink set to 20mA. The MSL3 requirements are communicated to the assembly house, who schedule the SMT line to run these parts within 48 hours of opening the moisture barrier bags. The final sign is tested for luminous intensity and color consistency across all units, meeting the regulatory standards for traffic equipment.

11. Operating Principle

This LED is based on Aluminum Indium Gallium Phosphide (AllnGaP) semiconductor technology. When a forward voltage exceeding the diode's threshold is applied, electrons and holes are injected into the active region from the n-type and p-type materials, respectively. They recombine radiatively, releasing energy in the form of photons. The specific composition of the AllnGaP layers determines the bandgap energy, which directly corresponds to the wavelength of the emitted light—in this case, in the yellow region (~590nm). The diffused epoxy encapsulant both protects the semiconductor die and acts as a primary lens, shaping the light output into the specified radiation pattern.

12. Technology Trends and Context

The development of high-brightness AllnGaP LEDs revolutionized colored indicator and signage lighting, offering superior efficiency, longevity, and reliability over incandescent and filtered light sources. Current trends in this application space include the push for even higher luminous efficacy (more light output per electrical watt) to reduce energy consumption in large installations. There is also a focus on improving color consistency and stability over temperature and lifetime. Furthermore, packaging technology continues to evolve to provide better thermal management, allowing for higher drive currents and consequently higher brightness from the same chip size, or enabling longer lifetime at standard currents. The integration of driver electronics and control interfaces (e.g., for addressable RGB signs) is another significant trend, though this particular component remains a discrete, high-performance light source designed for integration into larger systems.