Side-Looking SMD LED Green 530nm - EIA Package - 20mA - 76mW - English Datasheet

1. Product Overview

This document details the specifications for a high-brightness, side-looking surface-mount device (SMD) LED. The component utilizes an InGaN (Indium Gallium Nitride) semiconductor chip to produce green light. It is designed for automated assembly processes and is compatible with infrared reflow soldering, making it suitable for high-volume manufacturing. The LED is packaged on 8mm tape wound onto 7-inch diameter reels, adhering to EIA (Electronic Industries Alliance) standard packaging for consistent handling and placement.

1.1 Core Features and Advantages

• High Brightness: Utilizes an ultra-bright InGaN chip technology.
• Side-Viewing Emission: The package is designed to emit light from the side, which is ideal for backlighting applications in thin-profile devices.
• Automation Friendly: Fully compatible with automatic pick-and-place equipment and standard infrared reflow solder profiles.
• Lead-Free and RoHS Compliant: The device meets Restriction of Hazardous Substances (RoHS) directives.
• IC Compatible: Can be driven directly by standard integrated circuit outputs.

1.2 Target Applications

This LED is intended for general-purpose indicator and backlighting applications in consumer electronics, office equipment, communication devices, and household appliances. Its side-emitting characteristic makes it particularly useful for edge-lighting panels, status indicators on PCBs, and backlighting for LCD displays in portable devices.

2. Technical Specifications and In-Depth Analysis

2.1 Absolute Maximum Ratings

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

• Power Dissipation (Pd): 76 mW. This is the maximum power the LED package can dissipate as heat at an ambient temperature (Ta) of 25°C.
• Continuous Forward Current (IF): 20 mA DC. The recommended steady-state operating current.
• Peak Forward Current: 100 mA, permissible only under pulsed conditions (1/10 duty cycle, 0.1ms pulse width). This allows for brief, high-intensity flashes.
• Operating Temperature Range: -20°C to +80°C. The ambient temperature range for reliable operation.
• Storage Temperature Range: -30°C to +100°C.
• Soldering Temperature: Withstands 260°C for 10 seconds, which is typical for lead-free (Pb-free) reflow processes.

2.2 Electro-Optical Characteristics

These parameters are measured at Ta=25°C and IF=20mA, unless otherwise specified. They define the performance under normal operating conditions.

• Luminous Intensity (Iv): Ranges from a minimum of 71.0 mcd to a typical maximum of 450.0 mcd. Intensity is measured using a sensor filtered to match the human eye's photopic response (CIE curve).
• Viewing Angle (2θ_1/2): 130 degrees. This is the full angle at which the light intensity drops to half of its peak (on-axis) value, indicating a very wide emission pattern suitable for side illumination.
• Peak Wavelength (λ_P): 530 nm. The wavelength at which the spectral power output is maximum.
• Dominant Wavelength (λ_d): 525 nm. This is the single wavelength perceived by the human eye that defines the color of the LED, derived from the CIE chromaticity diagram.
• Spectral Bandwidth (Δλ): 35 nm. The width of the emission spectrum at half the maximum intensity (Full Width at Half Maximum - FWHM).
• Forward Voltage (V_F): Typically 3.2V, with a range from 2.8V to 3.6V at 20mA. This is the voltage drop across the LED when conducting current.
• Reverse Current (I_R): Maximum 10 μA at a reverse voltage (V_R) of 5V. Important: This device is not designed for reverse bias operation; this parameter is for leakage test purposes only.

3. Binning System Explanation

To ensure consistency in production, LEDs are sorted into performance bins. This allows designers to select parts that meet specific voltage, brightness, and color requirements.

3.1 Forward Voltage Binning

Units are binned based on their forward voltage (V_F) at 20mA. Each bin has a tolerance of ±0.1V.

• D7: 2.80V – 3.00V
• D8: 3.00V – 3.20V
• D9: 3.20V – 3.40V
• D10: 3.40V – 3.60V

3.2 Luminous Intensity Binning

Units are binned based on their luminous intensity (I_v) at 20mA. Each bin has a tolerance of ±15%.

• Q: 71.0 mcd – 112.0 mcd
• R: 112.0 mcd – 180.0 mcd
• S: 180.0 mcd – 280.0 mcd
• T: 280.0 mcd – 450.0 mcd

3.3 Dominant Wavelength Binning

Units are binned based on their dominant wavelength (λ_d) at 20mA. Each bin has a tolerance of ±1nm.

• AP: 520.0 nm – 525.0 nm
• AQ: 525.0 nm – 530.0 nm
• AR: 530.0 nm – 535.0 nm

4. Performance Curve Analysis

While specific graphs are referenced in the datasheet, typical performance trends can be described:

4.1 Forward Current vs. Forward Voltage (I-V Curve)

The LED exhibits a non-linear I-V characteristic typical of a diode. The forward voltage increases logarithmically with current. Operating significantly above the recommended 20mA will cause a disproportionate increase in V_F and power dissipation (heat).

4.2 Luminous Intensity vs. Forward Current

The light output (luminous intensity) is approximately proportional to the forward current within the recommended operating range. However, efficiency may drop at very high currents due to increased junction temperature.

4.3 Temperature Dependence

LED performance is temperature-sensitive. As the junction temperature increases:

• Forward Voltage (V_F): Decreases slightly.
• Luminous Intensity (I_v): Decreases. The rate of this decrease is a key factor in thermal management design.
• Wavelength (λ_d): May shift slightly, typically towards longer wavelengths (red shift).

5. Mechanical and Packaging Information

5.1 Package Dimensions and Polarity

The LED comes in a standard EIA-compliant SMD package. The datasheet includes a detailed dimensional drawing. The cathode is typically marked, often by a notch, a green dot, or a different lead length/shape. Correct polarity is essential for operation.

5.2 Recommended PCB Land Pattern

A suggested soldering pad layout is provided to ensure reliable solder joints and proper alignment during reflow. Adhering to this pattern helps prevent tombstoning (component standing up on one end) and ensures good thermal and electrical connection.

6. Assembly, Soldering, and Handling Guidelines

6.1 Reflow Soldering Profile

A suggested infrared reflow profile for lead-free processes is provided, compliant with JEDEC standards. Key parameters include:

• Preheat: 150–200°C for up to 120 seconds to gradually heat the board and activate flux.
• Peak Temperature: Maximum 260°C.
• Time Above Liquidus: The profile should limit the time the LED's leads are above the solder melting point to a maximum of 10 seconds, and reflow should not be performed more than twice.

Note: The optimal profile depends on the specific PCB design, solder paste, and oven. The provided profile serves as a starting point.

6.2 Hand Soldering

If hand soldering is necessary, use a temperature-controlled iron set to a maximum of 300°C. Limit the soldering time to 3 seconds per lead, and solder only once.

6.3 Cleaning

If cleaning is required after soldering, use only specified solvents. Immerse the LED in ethyl alcohol or isopropyl alcohol at room temperature for less than one minute. Do not use ultrasonic cleaning or unspecified chemicals, as they may damage the plastic lens or package.

6.4 Storage and Moisture Sensitivity

The LEDs are moisture-sensitive. If the original sealed moisture-proof bag (with desiccant) is unopened, they should be stored at ≤30°C and ≤90% RH and used within one year. Once the bag is opened, the storage environment must not exceed 30°C and 60% RH. Components removed from the original packaging should be reflow-soldered within one week. For longer storage outside the original bag, store in a sealed container with desiccant or in a nitrogen desiccator. If stored open for more than a week, a bake-out at approximately 60°C for at least 20 hours is recommended before assembly to remove absorbed moisture and prevent "popcorning" during reflow.

6.5 Electrostatic Discharge (ESD) Precautions

LEDs are sensitive to electrostatic discharge. Always handle them in an ESD-protected area using grounded wrist straps, anti-static mats, and conductive containers. All equipment must be properly grounded.

7. Packaging and Ordering Information

7.1 Tape and Reel Specifications

The LEDs are supplied on 8mm wide embossed carrier tape, sealed with a top cover tape. The tape is wound onto standard 7-inch (178mm) diameter reels. Each reel contains 4000 pieces. For quantities less than a full reel, a minimum packing quantity of 500 pieces applies for remainder lots.

7.2 Part Number Structure

The part number LTST-S220TGKT encodes key attributes:

• LTST: Likely denotes the product family (Lite-On SMD LED).
• S220: Likely indicates the package style/size (side-looking, 220 mil? - specific to manufacturer).
• TGKT: Likely denotes color (Green), bin codes for intensity/wavelength/voltage, and perhaps tape/reel packaging. The exact decoding is manufacturer-specific.

8. Application Notes and Design Considerations

8.1 Current Limiting

An LED is a current-driven device. Always use a series current-limiting resistor or a constant-current driver circuit. The resistor value can be calculated using Ohm's Law: R = (V_supply - V_F) / I_F. Use the maximum V_F from the datasheet (3.6V) to ensure sufficient current under all conditions.

8.2 Thermal Management

Although power dissipation is low (76mW), proper PCB layout is important for long-term reliability. Ensure adequate copper area around the LED pads to act as a heat sink, especially if operating at high ambient temperatures or near the maximum current.

8.3 Optical Design

The 130-degree side-viewing angle provides wide, diffuse illumination. For applications requiring more focused light, external lenses or light guides may be necessary. Consider the interaction of the LED's emission pattern with adjacent components and enclosures.

9. Technical Comparison and Differentiation

This LED's primary differentiators are its side-viewing package and InGaN chip technology. Compared to top-emitting LEDs, it is designed to direct light parallel to the PCB surface, saving vertical space. InGaN technology enables high brightness and efficiency in the green/blue spectrum regions compared to older technologies like AlGaAs.

10. Frequently Asked Questions (FAQ)

10.1 Can I drive this LED without a current-limiting resistor?

No. Connecting an LED directly to a voltage source will cause excessive current to flow, instantly destroying the device. A series resistor or active current regulator is mandatory.

10.2 What is the difference between Peak Wavelength and Dominant Wavelength?

Peak Wavelength is the physical peak of the light spectrum emitted. Dominant Wavelength is the perceived color point on the CIE chart. For a monochromatic source, they are similar. For LEDs with some spectral width, the dominant wavelength is what the human eye perceives as the color.

10.3 Why is there a storage and baking requirement?

The plastic packaging can absorb moisture from the air. During the high-temperature reflow soldering process, this trapped moisture can rapidly expand into steam, causing internal delamination or cracking ("popcorning"). Baking removes this moisture.

11. Practical Design Example

Scenario: Designing a side-lit status indicator on a 5V digital logic board.

1. Component Selection: Choose an LED from the appropriate intensity bin (e.g., 'R' for medium brightness).
2. Current Setting: Decide to operate at the typical 20mA.
3. Resistor Calculation: Using worst-case V_F = 3.6V. R = (5V - 3.6V) / 0.020A = 70 Ohms. The nearest standard value is 68 Ohms. Re-calculating current: I = (5V - 3.2V_typ) / 68Ω ≈ 26.5mA (safe, below absolute max DC current).
4. PCB Layout: Place the LED according to the recommended land pattern. Add small thermal relief spokes to the cathode pad connected to a ground plane for heat dissipation.
5. Assembly: Follow the lead-free reflow profile, ensuring the board is baked if moisture-sensitive handling time has been exceeded.

12. Operating Principle

An LED is a semiconductor p-n junction diode. When a forward voltage is applied, electrons from the n-type material recombine with holes from the p-type material in the active region (the InGaN chip). This recombination releases energy in the form of photons (light). The specific wavelength (color) of the light is determined by the energy bandgap of the semiconductor material used. InGaN has a bandgap suitable for producing green, blue, and white (with phosphor) light.

13. Technology Trends

The optoelectronics industry continues to advance in several key areas relevant to such components:

• Increased Efficiency (lm/W): Ongoing material science and chip design improvements yield more light output per unit of electrical input power.
• Miniaturization: Package sizes continue to shrink while maintaining or improving optical performance.
• Improved Color Consistency: Tighter binning tolerances and advanced manufacturing processes reduce color variation between production batches.
• Higher Reliability and Lifetime: Better packaging materials and thermal management designs extend operational lifespans, especially under high-temperature conditions.
• Integration: Trends include integrating multiple LED chips (RGB), drivers, or control logic into single packages for smarter lighting solutions.

This side-looking SMD LED represents a mature, reliable component built on established InGaN technology, optimized for automated assembly and consistent performance in a wide range of indicator and backlight applications.