LTW-482DS5 SMD LED Datasheet - White InGaN Chip, Yellow Lens, Detailed Electrical and Optical Parameters

1. Product Overview

LTW-482DS5 is a surface-mount device (SMD) LED lamp specifically designed for automated printed circuit board (PCB) assembly. It belongs to a component series designed for space-constrained application scenarios. This device combines an ultra-high-brightness white indium gallium nitride (InGaN) semiconductor chip with a yellow lens to produce a specific light color output. The construction of this LED makes it compatible with the standard infrared (IR) reflow soldering processes commonly used in large-scale electronics manufacturing.

The core advantages of this component lie in its miniaturized form factor and good adaptability to automated pick-and-place equipment, which helps simplify the production process. It is classified as an EIA (Electronic Industries Alliance) standard package, ensuring broad compatibility with industry assembly lines. The device is also specified as integrated circuit (I.C.) compatible, meaning that in many cases, it can be driven directly by typical logic-level voltages from microcontrollers or other digital circuits without the need for complex intermediate driver stages.

The target market for this LED encompasses a wide range of consumer electronics and industrial electronics. Primary applications include status indication, keyboard and keypad backlighting, and integration into miniature displays. It is also commonly found in communication equipment, office automation devices, various household appliances, and indoor signage or symbol lighting requiring a compact and reliable light source.

2. Detailed Technical Specifications

2.1 Absolute Maximum Ratings

Absolute Maximum Ratings define the limits beyond which permanent damage to the LED may occur. These values are specified at an ambient temperature (Ta) of 25°C. The maximum continuous DC forward current (IF) is 20 mA. A higher peak forward current of 100 mA is permitted, but only under strict pulse conditions of a 1/10 duty cycle and a pulse width not exceeding 0.1 ms. The maximum power dissipation is 72 milliwatts (mW). The operating temperature range for this device is rated from -20°C to +80°C, and the storage temperature range is from -40°C to +85°C. A critical rating during assembly is the infrared soldering condition, where the temperature must not exceed 260°C for a duration not exceeding 10 seconds during reflow soldering.

2.2 Electrical and Optical Characteristics

Typical operating characteristics are measured at Ta=25°C and a forward current (IF) of 5 mA (a common test condition). The forward voltage (VF) ranges from a minimum of 2.55 volts to a maximum of 3.15 volts, with the typical value implied within this range. The luminous intensity (Iv), a measure of perceived brightness, spans a wide range from 71.0 millicandelas (mcd) to 280.0 mcd. This variation is managed through a binning system. The viewing angle (2θ1/2), defined as the angle at which the luminous intensity drops to half its axial value, is 130 degrees, indicating a very wide beam pattern. The chromaticity coordinates, used to define the color point in the CIE 1931 color space, are specified under test conditions as x=0.304 and y=0.301. The reverse current (IR) is guaranteed to be less than 10 microamperes at a reverse voltage (VR) of 5V, although the device is not designed for reverse operation.

3. Binning System Description

To ensure consistency in mass production, LEDs are binned according to their performance. The LTW-482DS5 employs a three-dimensional binning system based on forward voltage (VF), luminous intensity (Iv), and hue (chromaticity point).

3.1 Forward Voltage (VF) Binning

VF is binned in 0.1V steps, ranging from V1 (2.55V - 2.65V) to V6 (3.05V - 3.15V). A tolerance of ±0.1V is applied to each bin. This allows designers to select LEDs with a narrower voltage range for applications requiring uniform brightness under constant voltage source drive, or to better match the calculation of current-limiting resistors.

3.2 Luminous Intensity (Iv) Binning

Luminous intensity is divided into three main code grades: Q (71.0 - 112.0 mcd), R (112.0 - 180.0 mcd), and S (180.0 - 280.0 mcd). A tolerance of ±15% is applied to each grade range. This grading is crucial for applications where perceived brightness consistency among multiple LEDs is critical, such as backlight arrays or status indicator groups.

3.3 Hue (Color) Binning

Chromaticity coordinates (x, y) are divided into six zones, labeled S1 through S6. Each bin defines a quadrilateral area on the CIE 1931 chromaticity diagram. The arrangement of these bins aims to group LEDs with similar white color temperature and hue. A tolerance of ±0.01 is applied to each coordinate within its bin. This ensures color uniformity when multiple LEDs are used side by side. The provided chart visually marks these S1-S6 zones on the chromaticity diagram.

4. Performance Curve Analysis

The datasheet references typical performance curves, which graphically represent the relationship between key parameters. Although the provided text does not detail specific charts, standard curves for such LEDs typically include:

• Forward Current vs. Forward Voltage (I-V Curve):This nonlinear curve shows how voltage increases with current. This is crucial for designing drive circuits, especially when using constant voltage power supplies with series resistors.
• Luminous Intensity vs. Forward Current:This curve shows how light output increases with drive current. It is typically linear within a certain range but saturates at higher currents.
• Luminous Intensity vs. Ambient Temperature:This curve illustrates the thermal derating characteristics of light output. As the LED junction temperature increases, its luminous efficacy decreases. Understanding this is crucial for thermal management in applications.
• Relative Spectral Power Distribution:For white LEDs, this graph shows the emitted light intensity at each wavelength. White LEDs like the InGaN type typically have a blue emission peak from the chip itself, combined with a broader yellow emission from the phosphor coating, resulting in perceived white light.

5. Mechanical and Packaging Information

5.1 Package Dimensions

This LED conforms to the standard SMD package outline. All critical dimensions (such as length, width, height, and lead pitch) are provided in millimeters, with a standard tolerance of ±0.1 mm unless otherwise specified. The lens color is yellow, and the light source (chip) color is white. The datasheet includes detailed dimensioning diagrams for PCB pad design.

5.2 Polarity Identification and Pad Design

Kayan na ƙunshi alama ko siffofi na tsari (kamar yankewar kusurwa ko ɗigo) don nuna ƙafar cathode (korau). An ba da shawarar shimfidar kushin PCB, don tabbatar da ingantaccen haɗin guntun, amintaccen haɗin lantarki da mafi kyawun kwanciyar hankali na injiniya yayin aikin sake yin guntun baya da bayansa. Hakanan ana iya ƙayyadaddun alkiblar guntun dangane da alkiblar kullin, don hana faruwar tasirin "tsattsarkan dutse" (wato ɗayan ƙarshen ya tashi daga kushin).

6. Soldering and Assembly Guide

6.1 Infrared Reflow Soldering Temperature Profile

It provides a recommended reflow soldering temperature profile for lead-free (Pb-free) soldering processes. Key parameters include the preheat phase, time above liquidus, a peak temperature not exceeding 260°C, and a time limit at that peak temperature of a maximum of 10 seconds. This profile aims to minimize thermal stress on the LED package while ensuring reliable solder joints. It must be emphasized that the optimal profile may vary depending on the specific PCB design, solder paste, and oven characteristics.

6.2 Storage and Handling

These LEDs are Moisture Sensitive Devices (MSL Level 3). When sealed with desiccant in the original moisture barrier bag, they have a shelf life of one year under storage conditions of ≤30°C and ≤90% relative humidity (RH). Once the bag is opened, the components should be stored at ≤30°C and ≤60% RH. It is recommended to complete the infrared reflow soldering process within one week after opening. For storage outside the original packaging for more than one week, baking at approximately 60°C for at least 20 hours is required prior to soldering to remove absorbed moisture and prevent "popcorn" damage during reflow.

6.3 Cleaning

If cleaning is required after soldering, only specified solvents should be used. It is recommended to immerse the LED in ethanol or isopropyl alcohol at room temperature for no more than one minute. Unspecified chemical cleaners may damage the plastic lens or encapsulant material.

6.4 ESD (Electrostatic Discharge) Precautions

LEDs are susceptible to damage from electrostatic discharge and voltage surges. Proper ESD control measures must be implemented during handling and assembly. This includes using grounded wrist straps, anti-static gloves, and ensuring all equipment and work surfaces are properly grounded.

7. Packaging and Ordering Information

LTW-482DS5 is provided in packaging suitable for automated assembly. The components are placed in an 8mm wide embossed carrier tape. This tape is wound onto a standard 7-inch (approximately 178mm) diameter reel. Each full reel contains 3000 pieces. For quantities less than a full reel, the minimum packaging quantity for remaining stock is 500 pieces. The carrier tape and reel packaging comply with the ANSI/EIA-481 specification. The carrier tape has a cover seal to protect the components, and there is a limit on the maximum number of consecutively missing components in the tape.

8. Application Notes and Design Considerations

8.1 LED Driver

LED is a current-driven device. The most common and stable method of operation is to use a constant current source. If a constant voltage source (such as a microcontroller GPIO pin or a regulated power supply rail) is used, a current-limiting resistor must be connected in series with the LED. The resistor value (R) can be calculated using Ohm's law: R = (Supply Voltage - LED Forward Voltage) / Desired Current. For example, assuming VF is 2.8V, to drive an LED from a 5V supply at a typical test current of 5mA: R = (5V - 2.8V) / 0.005A = 440 ohms. A standard 470-ohm resistor would be a suitable choice. The resistor's power rating should also be checked: P = I²R = (0.005)² * 470 = 0.01175W, so a standard 1/8W (0.125W) resistor is more than sufficient.

8.2 Thermal Management

Although power consumption is low (maximum 72 mW), effective thermal management remains important for extending lifespan and maintaining light output. LED performance degrades as junction temperature increases. The PCB itself acts as a heat sink. Ensuring sufficient copper foil area connected to the LED thermal pad or pins, and providing ventilation in enclosed cases, aids in heat dissipation. Avoid operating the LED at both absolute maximum current and temperature simultaneously for extended periods.

8.3 Optical Design

A 130-degree viewing angle produces a very wide, diffuse beam. This is ideal for area lighting or status indicators that need to be visible from wide angles. For applications requiring a more focused beam, external secondary optics (such as lenses or light guides) must be added. A yellow lens filters the emitted white light, shifting the final output color towards a warmer tone.

9. Technical Comparison and Differentiation

The LTW-482DS5 differentiates itself through the specific combination of its white InGaN chip and yellow lens. Compared to standard white LEDs using clear lenses, this product offers a unique, warmer-toned light output, which may meet specific aesthetic or functional requirements (e.g., mimicking incandescent indicator lights). Its wide viewing angle is a key feature compared to narrow-angle LEDs used for spotlighting. A comprehensive binning system for voltage, intensity, and color provides consistency guarantees for multi-LED applications, which may not be as strictly defined in low-cost or generic LED products. Its compliance with standards for automatic placement and infrared reflow soldering makes it a reliable choice for modern automated electronics manufacturing.

10. Frequently Asked Questions (FAQ)

Q: Can I drive this LED directly from a 3.3V microcontroller pin?
A: It is possible, but it depends on the LED's forward voltage (VF). If the LED's VF is at the low end of its range (e.g., 2.6V), there is a 0.7V voltage drop. At the desired 5mA current, this requires a resistor of R = 0.7V / 0.005A = 140 ohms. This is feasible. However, if the LED's VF is 3.1V, the voltage drop is only 0.2V, requiring a 40-ohm resistor. At 5mA, the voltage drop across the MCU's internal driver may become significant, potentially causing the LED to fail to light up properly or exhibit inconsistent brightness. For achieving consistent performance across all VF bins, a driver circuit (such as a transistor) is more reliable.

Q: What is the difference between "lens color" and "light source color"?
A: "Light source color" refers to the light emitted by the semiconductor chip itself before it passes through the package lens. Here, it is a white InGaN chip. "Lens color" is the color of the plastic packaging material that forms the LED dome. The yellow lens acts as a filter, absorbing certain wavelengths (such as blue) and transmitting others (yellow, red), causing the final emitted light to appear warmer (more yellow/amber) than the output of the original white chip.

Q: Why is the reverse current (IR) specification important if the device is not used for reverse operation?
A: IR test is primarily a quality and reliability test. High reverse leakage current may indicate defects in the semiconductor junction. Furthermore, in circuit designs where LEDs may be exposed to reverse voltage transients (even brief ones), understanding the maximum leakage current helps in designing protection circuits to prevent damage or unexpected circuit behavior.

Q: How to interpret the binning code on the packaging?
A: The packaging label should contain codes for VF, Iv, and chromaticity binning (e.g., V3R-S4). This allows you to understand the specific performance range of that LED batch. For critical applications requiring strict consistency, you can specify the exact binning code when ordering.

11. Practical Application Examples

Example 1: Keyboard Backlight
In laptop keyboards, multiple LTW-482DS5 LEDs can be placed beneath the transparent keycap layer. Their 130-degree wide viewing angle ensures uniform illumination across the entire keyboard. The yellow lens provides a warm white backlight, often considered softer than cool white, especially in low-light environments. Designers select LEDs from the same luminous intensity (Iv) and tint (Sx) bins to ensure consistent color and brightness across the keyboard.

Example 2: Industrial Status Indicator Panel
On the control panels of industrial equipment, these LEDs can serve as status indicators, such as for "Power On".