SMD LED 19-21/G6C-FM1N2B/3T Datasheet - Size 2.0x1.25x0.8mm - Voltage 1.75-2.35V - Color Brilliant Yellow-Green - English Technical Document

1. Product Overview

The 19-21 SMD LED is a compact, surface-mount device designed for modern electronic applications requiring high-density component placement and reliable performance. This LED utilizes AlGaInP chip technology to produce a brilliant yellow-green light output. Its primary advantages include a significantly reduced footprint compared to traditional lead-frame LEDs, enabling smaller PCB designs and more compact end products. The lightweight construction further makes it ideal for miniature and portable applications where space and weight are critical constraints.

This component is fully compliant with RoHS, EU REACH, and halogen-free directives, ensuring its suitability for global markets with stringent environmental regulations. It is packaged on 8mm tape wound on 7-inch diameter reels, making it fully compatible with high-speed automated pick-and-place assembly equipment, thereby streamlining the manufacturing process.

1.1 Core Features and Advantages

• Miniaturized Package: The SMD format allows for a much smaller board size and higher packing density than leaded components.
• Automation Friendly: Supplied in tape-and-reel packaging compatible with standard automatic placement machinery.
• Robust Soldering: Compatible with both infrared and vapor phase reflow soldering processes.
• Environmental Compliance: The product is Pb-free, RoHS compliant, REACH compliant, and halogen-free (Br <900 ppm, Cl <900 ppm, Br+Cl < 1500 ppm).
• Mono-color Type: Emits a single, consistent brilliant yellow-green color.

1.2 Target Applications

This LED is versatile and finds use in various illumination and indication roles, including:

• Backlighting for automotive dashboards, switches, and control panels.
• Status indicators and keypad backlighting in telecommunication devices such as telephones and fax machines.
• Flat backlighting units for LCD displays, switch panels, and symbols.
• General-purpose indicator lights in consumer electronics, industrial controls, and instrumentation.

2. Technical Specifications and Objective Interpretation

2.1 Absolute Maximum Ratings

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

Interpretation: The 5V reverse voltage rating is relatively low, emphasizing that this LED is not designed for reverse-bias operation and requires protection in circuits where reverse voltage is possible. The forward current rating of 25mA is standard for small SMD LEDs. The ESD rating of 2000V (HBM) indicates standard handling precautions should be observed. The wide operating temperature range of -40°C to +85°C makes it suitable for automotive and industrial environments.

2.2 Electro-Optical Characteristics

These parameters are measured at a forward current (IF) of 20mA and an ambient temperature (Ta) of 25°C, representing typical operating conditions.

Interpretation: The luminous intensity range is broad (18-45 mcd), which is managed through a binning system (detailed later). The typical 100-degree viewing angle provides a wide emission pattern suitable for backlighting and diffuse indication. The dominant wavelength of 570-574.5 nm places the output firmly in the yellow-green region of the visible spectrum. The forward voltage range of 1.75V to 2.35V is relatively low, typical for AlGaInP technology, which helps minimize power consumption. The note explicitly states the device is not designed for reverse operation; the VR rating is for IR testing only.

3. Binning System Explanation

To ensure consistency in mass production, LEDs are sorted into performance bins. This allows designers to select parts that meet specific criteria for brightness, color, and electrical characteristics.

3.1 Luminous Intensity Binning

Analysis: The CAT code on the packaging label corresponds to this bin. Selecting a higher bin (e.g., N2) guarantees higher minimum brightness, which is crucial for applications requiring uniform panel brightness or long-distance visibility.

3.2 Dominant Wavelength Binning

Analysis: The HUE code on the label refers to this chromaticity/wavelength bin. Tighter wavelength control (smaller bin ranges) is essential for applications where color consistency across multiple LEDs is critical, such as in multi-segment displays or color-matched indicator arrays.

3.3 Forward Voltage Binning

Analysis: The REF code indicates the voltage bin. Using LEDs from the same voltage bin can help ensure more uniform current distribution when multiple LEDs are connected in parallel, preventing some LEDs from being overdriven.

4. Performance Curve Analysis

The datasheet provides several typical characteristic curves that illustrate the device's behavior under varying conditions.

4.1 Relative Luminous Intensity vs. Forward Current

This curve shows that light output increases with forward current but in a non-linear relationship. Driving the LED above the recommended 20mA may yield diminishing returns in brightness while significantly increasing power dissipation and junction temperature, potentially reducing lifespan.

4.2 Relative Luminous Intensity vs. Ambient Temperature

The curve demonstrates the negative temperature coefficient of luminous intensity. As ambient temperature rises, light output decreases. This is a critical consideration for designs operating in high-temperature environments; derating or thermal management may be necessary to maintain required brightness levels.

4.3 Forward Current Derating Curve

This graph defines the maximum allowable forward current as a function of ambient temperature. To prevent overheating and ensure reliability, the forward current must be reduced when operating at high ambient temperatures. Adherence to this curve is essential for long-term reliability.

4.4 Forward Voltage vs. Forward Current

The IV curve shows the exponential relationship typical of a diode. The forward voltage increases with current. The curve's slope in the operating region informs the necessary drive voltage and helps in calculating series resistor values for current limiting.

4.5 Spectrum Distribution and Radiation Pattern

The spectrum plot confirms the monochromatic nature with a peak around 575nm and a typical bandwidth of 20nm. The radiation pattern diagram illustrates the Lambertian-like emission profile with the 100-degree viewing angle, showing how intensity varies with angle from the central axis.

5. Mechanical and Package Information

5.1 Package Dimensions

The 19-21 package has nominal dimensions of 2.0mm (length) x 1.25mm (width) x 0.8mm (height). The drawing specifies tolerances of ±0.1mm unless otherwise noted. A clear cathode mark is indicated on the package, which is vital for correct orientation during assembly. The recommended land pattern (footprint) on the PCB should be designed according to these dimensions to ensure proper soldering and mechanical stability.

5.2 Polarity Identification

Correct polarity is essential for LED operation. The package features a distinct marking (typically a notch, dot, or chamfered corner) to identify the cathode terminal. Designers must ensure the PCB silkscreen and assembly documentation clearly reflect this orientation to prevent reverse installation.

6. Soldering and Assembly Guidelines

Proper handling and soldering are critical to maintaining LED performance and reliability.

6.1 Storage and Moisture Sensitivity

• Before Use: Do not open the moisture-proof barrier bag until ready for assembly.
• After Opening: Use within 168 hours (7 days). Store unused parts at ≤30°C and ≤60% RH.
• Rebaking: If the storage time is exceeded or the desiccant indicates moisture ingress, bake at 60±5°C for 24 hours before use.

6.2 Reflow Soldering Profile (Pb-free)

The recommended profile is crucial for forming reliable solder joints without damaging the LED.

• Pre-heating: 150-200°C for 60-120 seconds.
• Time Above Liquidus (217°C): 60-150 seconds.
• Peak Temperature: 260°C maximum, held for no more than 10 seconds.
• Heating Rate: Maximum 6°C/sec up to 255°C.
• Cooling Rate: Maximum 3°C/sec.
• Limit: Reflow soldering should not be performed more than two times.

6.3 Hand Soldering Precautions

If hand soldering is unavoidable, extreme care is needed:

• Use a soldering iron with a tip temperature <350°C.
• Limit contact time to ≤3 seconds per terminal.
• Use an iron with power ≤25W.
• Allow a minimum 2-second interval between soldering each terminal.

6.4 Current Protection and Repair

Current Limiting: An external series resistor is mandatory. The LED's exponential IV characteristic means a small voltage increase can cause a large current surge, leading to immediate failure. The resistor value must be calculated based on the supply voltage and the LED's forward voltage at the desired operating current.
Repair: Repair after soldering is not recommended. If absolutely necessary, use a dual-head soldering iron to simultaneously heat both terminals and avoid mechanical stress. Always verify post-repair functionality.

7. Packaging and Ordering Information

7.1 Packaging Specifications

The LEDs are supplied in moisture-resistant packaging:

• Carrier Tape: 8mm width.
• Reel: 7-inch (178mm) diameter.
• Quantity per Reel: 3000 pieces.
• Packaging: Components are sealed in an aluminum moisture-proof bag with a desiccant and humidity indicator card.

7.2 Label Explanation

The reel label contains codes that define the specific bin of the contained LEDs:

• P/N: Product Number (e.g., 19-21/G6C-FM1N2B/3T).
• CAT: Luminous Intensity Rank (e.g., M1, N2).
• HUE: Chromaticity Coordinates & Dominant Wavelength Rank (e.g., CC3).
• REF: Forward Voltage Rank (e.g., 1).
• LOT No: Traceable manufacturing lot number.

8. Application Suggestions and Design Considerations

8.1 Typical Application Circuits

The most common drive method is a constant current source or a voltage source with a series current-limiting resistor. For a supply voltage V_supply, the resistor value R is calculated as: R = (V_supply - V_F) / I_F, where V_F is the forward voltage of the LED at the desired current I_F (typically 20mA). Always use the maximum V_F from the datasheet or bin to ensure current does not exceed limits under worst-case conditions.

8.2 Thermal Management

While the package is small, power dissipation (up to 60mW) can still cause a temperature rise. For applications running at high ambient temperatures or high currents, ensure adequate PCB copper area (thermal pads) around the LED's solder pads to act as a heat sink and conduct heat away from the junction.

8.3 Optical Design

The 100-degree viewing angle provides wide, diffuse light. For focused or directed light, external lenses or light guides may be required. The water-clear resin of the LED package is suitable for use with light pipes.

9. Technical Comparison and Differentiation

The 19-21 LED, based on AlGaInP technology, offers distinct advantages for yellow-green emission:

• vs. Traditional Leaded LEDs: The primary advantage is the SMD format, enabling automated assembly, reduced size, and weight.
• vs. Other SMD Colors: AlGaInP LEDs typically have higher luminous efficacy in the yellow/amber/green spectrum compared to older technologies, resulting in brighter output at the same current.
• vs. White LEDs: For pure color indication (e.g., status lights), monochromatic LEDs like this one are more efficient and color-saturated than phosphor-converted white LEDs.

10. Frequently Asked Questions (FAQ)

10.1 Why is a series resistor absolutely necessary?

LEDs are current-driven devices. Their forward voltage has a negative temperature coefficient and production tolerance. A voltage source without a current limit would allow runaway current as the LED heats up, leading to rapid failure. The series resistor provides a simple, linear current limit.

10.2 Can I drive this LED with a PWM signal for dimming?

Yes, pulse-width modulation (PWM) is an effective method for dimming LEDs. It works by rapidly switching the LED on and off. The perceived brightness is proportional to the duty cycle. This method avoids the color shift that can occur with analog (current reduction) dimming. Ensure the PWM frequency is high enough (typically >100Hz) to avoid visible flicker.

10.3 What do the bin codes mean, and how do I select them?

Bin codes categorize LEDs by performance. For example, if your design requires uniform brightness across a panel, you should specify a tight luminous intensity bin (e.g., only N1). If color consistency is paramount, specify a tight wavelength bin (e.g., only CC3). Consult with your supplier to ensure availability of specific bin combinations.

10.4 How many times can I reflow solder this LED?

The datasheet specifies a maximum of two reflow soldering cycles. Each thermal cycle induces stress on the internal die attach and wire bonds. Exceeding two cycles significantly increases the risk of latent failures or performance degradation.

11. Practical Design and Usage Examples

11.1 Dashboard Switch Backlighting

In an automotive dashboard, multiple 19-21 LEDs can be placed behind translucent switch caps. Their small size allows them to fit into tight spaces. Using LEDs from the same luminous intensity and wavelength bins ensures all switches have uniform color and brightness. The wide viewing angle provides even illumination across the switch surface. The operating temperature range comfortably covers the automotive interior environment.

11.2 PCB Status Indicator Array

On a network router or industrial controller, a row of these LEDs can indicate power, network activity, and system faults. Their low forward voltage minimizes power consumption from the system's logic rail (e.g., 3.3V). By placing them in a grid and specifying a consistent voltage bin, designers can use a single current-limiting resistor value for multiple LEDs in parallel, simplifying the bill of materials.

12. Technology Principle Introduction

The 19-21 LED is based on AlGaInP (Aluminum Gallium Indium Phosphide) semiconductor material. This material system is particularly efficient at producing light in the yellow, orange, red, and green regions of the spectrum. When a forward voltage is applied across the p-n junction, electrons and holes recombine, releasing energy in the form of photons. The specific composition of the AlGaInP layers determines the wavelength (color) of the emitted light. In this device, the composition is tuned to produce photons with a dominant wavelength between 570nm and 574.5nm, which the human eye perceives as a brilliant yellow-green. The water-clear epoxy resin encapsulant protects the semiconductor chip and acts as a primary lens, shaping the light output beam.

13. Industry Trends and Developments

The trend in indicator and backlight LEDs continues toward higher efficiency, smaller packages, and greater integration. While the 19-21 represents a mature and reliable package size, newer packages like 1.6x0.8mm or even smaller are becoming common for space-constrained applications. There is also a growing emphasis on improving color consistency and reducing bin spread at the manufacturing level through advanced epitaxial growth and sorting technologies. Furthermore, the drive for higher reliability in automotive and industrial applications pushes for improved performance under high-temperature and high-humidity conditions. The underlying AlGaInP technology remains a workhorse for saturated colors, though advancements in phosphor-converted and direct-emission green LEDs using other material systems (like InGaN) continue to evolve for specific performance targets.