SMD LED Yellow 1206 Package Datasheet - Dimensions 3.2x1.6x1.1mm - Forward Voltage 2.0V - Power 75mW - English Technical Documentation

1. Product Overview

This document provides the complete technical specifications for a high-performance, surface-mount yellow LED. The device utilizes an advanced AlInGaP (Aluminum Indium Gallium Phosphide) semiconductor chip, which is renowned for delivering high luminous efficiency and excellent color purity. The LED is housed in a standard 1206 package, making it compatible with automated pick-and-place assembly lines and common infrared or vapor phase reflow soldering processes. It is designed as a RoHS-compliant green product, suitable for a wide range of applications requiring a reliable and bright yellow indicator.

1.1 Core Advantages and Target Market

The primary advantages of this LED include its ultra-high brightness, consistent performance within specified bins, and compatibility with industry-standard assembly techniques. Its typical luminous intensity reaches up to 180 millicandelas (mcd) at a standard drive current of 20mA. The target markets for this component are broad, encompassing consumer electronics, industrial control panels, automotive interior lighting, signage, and general-purpose indicator applications where a clear, vibrant yellow signal is required.

2. In-Depth Technical Parameter Analysis

2.1 Absolute Maximum Ratings

Operating the device beyond these limits may cause permanent damage. The absolute maximum ratings are specified at an ambient temperature (Ta) of 25°C.

• Power Dissipation (Pd): 75 mW. This is the maximum amount of power the LED package can safely dissipate as heat.
• Peak Forward Current (I_FP): 80 mA. This is the maximum allowable instantaneous current, typically under pulsed conditions (1/10 duty cycle, 0.1ms pulse width). It should not be used for continuous DC operation.
• DC Forward Current (I_F): 30 mA. This is the maximum recommended continuous forward current for reliable long-term operation.
• Reverse Voltage (V_R): 5 V. Applying a reverse voltage exceeding this value can break down the LED's PN junction.
• Operating & Storage Temperature Range: -55°C to +85°C. The device can function and be stored within this wide temperature range.
• Infrared Soldering Condition: Withstands 260°C for 5 seconds, which is a standard condition for lead-free (Pb-free) reflow soldering processes.

2.2 Electro-Optical Characteristics

The following parameters are measured at Ta=25°C and a forward current (I_F) of 20mA, unless otherwise stated. These define the core performance of the LED.

• Luminous Intensity (I_V): 18.0 (Min) to 180.0 (Max) mcd. The actual intensity for a specific unit is determined by its bin code (see Section 3). Measurement is performed with a filter approximating the CIE photopic eye-response curve.
• Viewing Angle (2θ_1/2): 130 degrees (Typical). This is the full angle at which the luminous intensity drops to half of its value at the central axis (0°). A wide viewing angle like this provides a broad, diffuse light pattern suitable for panel indicators.
• Peak Emission Wavelength (λ_P): 595 nm (Typical). This is the wavelength at which the spectral power distribution of the emitted light is at its maximum.
• Dominant Wavelength (λ_d): 587 to 602 nm. This is derived from the CIE chromaticity diagram and represents the perceived color of the light. The tolerance is ±1 nm.
• Spectral Line Half-Width (Δλ): 16 nm (Typical). This indicates the spectral purity; a smaller value means a more monochromatic color.
• Forward Voltage (V_F): 1.8V (Min), 2.0V (Typ), 2.4V (Max) at I_F=20mA. The tolerance is ±0.1V. This parameter is crucial for designing the current-limiting circuitry.
• Reverse Current (I_R): 10 µA (Max) at V_R=5V.
• Capacitance (C): 40 pF (Typ) at V_F=0V, f=1MHz. This is relevant for high-frequency switching applications.

3. Binning System Explanation

To ensure color and brightness consistency in production, LEDs are sorted into bins. This product uses a binning system primarily for luminous intensity.

3.1 Luminous Intensity Binning

The intensity is measured at I_F=20mA. The bin code is marked on the packaging reel. The tolerance within each bin is ±15%.

• Bin Code M: 18.0 – 28.0 mcd
• Bin Code N: 28.0 – 45.0 mcd
• Bin Code P: 45.0 – 71.0 mcd
• Bin Code Q: 71.0 – 112.0 mcd
• Bin Code R: 112.0 – 180.0 mcd

Designers should specify the required bin code when ordering to guarantee the necessary brightness level for their application. For applications not requiring tight brightness matching, a wider bin range may be acceptable to reduce cost.

4. Performance Curve Analysis

While specific graphical curves are referenced in the datasheet (Fig.1, Fig.5), their typical behavior can be described based on semiconductor physics and standard LED characteristics.

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

The AlInGaP material has a typical forward voltage in the range of 1.8V to 2.4V. The I-V curve is exponential. A small increase in voltage beyond the turn-on threshold (around 1.6V-1.7V) causes a large, non-linear increase in current. This underscores the critical need for a current-limiting resistor or constant-current driver, as connecting the LED directly to a voltage source slightly above its V_F would result in excessive current and immediate failure.

4.2 Luminous Intensity vs. Forward Current

The light output (luminous intensity) is approximately proportional to the forward current in the normal operating range (up to the maximum DC current). Driving the LED at a current lower than 20mA will proportionally reduce brightness, while driving it above 20mA (up to 30mA) will increase brightness but also generate more heat, potentially reducing lifespan and causing color shift.

4.3 Temperature Characteristics

Like all LEDs, the performance of this device is temperature-dependent. As the junction temperature increases:

• Luminous Intensity decreases. The output can drop significantly at high temperatures.
• Forward Voltage decreases. The V_F has a negative temperature coefficient.
• Dominant Wavelength may shift slightly, potentially affecting the perceived color.

Proper thermal management in the application design is essential to maintain consistent performance and longevity.

4.4 Spectral Distribution

The spectral output curve for this yellow AlInGaP LED is characterized by a single, dominant peak around 595 nm with a relatively narrow half-width of 16 nm. This results in a saturated, pure yellow color without significant emission in the red or green spectral regions.

5. Mechanical and Package Information

5.1 Package Dimensions

The LED is housed in an industry-standard 1206 surface-mount device (SMD) package. Key dimensions include a body length of approximately 3.2 mm, a width of 1.6 mm, and a height of 1.1 mm. The package features a water-clear lens which does not diffuse the light, allowing the inherent chip brightness and color to be fully realized. Detailed mechanical drawings with tolerances (±0.10 mm typically) are provided in the datasheet for PCB footprint design.

5.2 Polarity Identification and Pad Design

The cathode (negative terminal) is typically identified by a green marking on the package or a notch in the lens. It is crucial to orient the LED correctly on the PCB. Recommended solder pad dimensions are provided to ensure a reliable solder joint and proper alignment during reflow. The pad design accounts for thermal relief and prevents tombstoning (one end lifting during soldering).

6. Soldering and Assembly Guidelines

6.1 Reflow Soldering Profile

A suggested infrared (IR) reflow profile for lead-free processes is included. Key parameters include:

• Preheat: Ramp-up to 120-150°C.
• Soak/Preheat Time: Maximum 120 seconds.
• Peak Temperature: Maximum 260°C.
• Time Above Liquidus: 5 seconds maximum at peak temperature.

Adhering to this profile prevents thermal shock and damage to the LED's epoxy lens and internal wire bonds.

6.2 Cleaning and Storage

Cleaning: If cleaning after soldering is necessary, only use specified solvents. Immersing the LED in ethyl alcohol or isopropyl alcohol at room temperature for less than one minute is recommended. Harsh or unspecified chemicals can damage the plastic lens, causing clouding or cracking.

Storage: LEDs should be stored in their original moisture-barrier packaging at conditions not exceeding 30°C and 70% relative humidity. Once removed from the packaging, they should be reflow-soldered within one week. For longer storage outside the original bag, they must be kept in a sealed container with desiccant or in a nitrogen ambient. If stored for more than a week outside the bag, a bake-out at approximately 60°C for at least 24 hours is required before soldering to remove absorbed moisture and prevent \"popcorning\" during reflow.

7. Packaging and Ordering Information

The LEDs are supplied on 8mm wide embossed carrier tape wound onto 7-inch (178 mm) diameter reels. Each reel contains 4000 pieces. The tape pockets are sealed with a top cover tape to protect components. The packaging conforms to ANSI/EIA-481-1-A standards. For smaller quantities, a minimum packing of 500 pieces is available for remainder lots. The part number LTST-C190KYKT uniquely identifies this product variant (water clear lens, AlInGaP chip, yellow color).

8. Application Notes and Design Considerations

8.1 Drive Circuit Design

LEDs are current-driven devices. The most critical design rule is to always use a series current-limiting resistor when driving from a voltage source. The resistor value (R) can be calculated using Ohm's Law: R = (V_supply - V_F) / I_F. For example, to drive the LED at 20mA from a 5V supply with a typical V_F of 2.0V: R = (5V - 2.0V) / 0.020A = 150 Ω. A resistor must be used for each LED when connecting multiple LEDs in parallel (Circuit Model A). Connecting LEDs directly in parallel without individual resistors (Circuit Model B) is not recommended due to variances in individual V_F characteristics, which cause uneven current distribution and differing brightness levels.

8.2 Electrostatic Discharge (ESD) Protection

This LED is sensitive to electrostatic discharge. ESD can cause latent damage, leading to increased reverse leakage current, reduced forward voltage, or complete failure (no light emission). Prevention measures are mandatory during handling and assembly:

• Use grounded wrist straps and anti-static mats.
• Ensure all equipment and workstations are properly grounded.
• Use ionizers to neutralize static charge that may accumulate on the plastic lens.

To test for potential ESD damage, check if the LED lights up at a very low current (e.g., 0.1mA). A healthy AlInGaP LED should have a V_F > 1.4V at this test condition.

8.3 Thermal Management

Although the power dissipation is relatively low (75mW max), effective heat sinking through the PCB copper pads is important for maintaining stable light output and long life, especially in high ambient temperature environments or when driving near the maximum current. Ensure the PCB layout provides adequate copper area connected to the LED's thermal pads.

9. Reliability and Testing

The product undergoes standard reliability tests per industry norms. These tests may include operational life testing at room temperature and elevated temperatures, thermal cycling, humidity testing, and solderability tests. The specific test conditions and standards are referenced in the datasheet to assure the component's robustness for commercial and industrial applications.

10. Frequently Asked Questions (FAQ)

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

Peak Wavelength (λ_P) is the physical wavelength where the light emission is strongest. Dominant Wavelength (λ_d) is a calculated value from color science (CIE diagram) that best represents the color perceived by the human eye. For a monochromatic source like this yellow LED, they are often close but not identical.

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

No. The forward voltage is not a fixed value but varies slightly from unit to unit and decreases with temperature. Connecting it directly to a voltage source will result in an uncontrolled and potentially destructive current flow. A series resistor or constant-current driver is always required.

10.3 Why is there a wide range in the Luminous Intensity specification (18-180 mcd)?

This is the total possible range across all production bins. Actual LEDs are sorted into tighter bins (M, N, P, Q, R) as described in Section 3. You must specify your required brightness bin when ordering to get consistent performance.

10.4 Is this LED suitable for outdoor use?

The operating temperature range (-55°C to +85°C) allows for use in many outdoor environments. However, prolonged exposure to direct UV sunlight may degrade the epoxy lens material over time, potentially causing discoloration or reduced light output. For harsh outdoor applications, LEDs with UV-resistant lenses should be considered.

11. Practical Application Example

Scenario: Designing a status indicator panel for an industrial controller. The panel requires 10 bright yellow LEDs to indicate \"system active\" or \"warning.\" The system power rail is 3.3V.

Design Steps:

1. Current Selection: Choose a drive current of 20mA for a good balance of brightness and longevity.
2. Resistor Calculation: Using the maximum V_F (2.4V) for a conservative design ensures the LED is never over-driven even with unit-to-unit variation. R = (3.3V - 2.4V) / 0.020A = 45 Ω. The nearest standard value is 47 Ω.
3. Power in Resistor: P = I² * R = (0.020)² * 47 = 0.0188W. A standard 1/8W (0.125W) resistor is more than sufficient.
4. Circuit Topology: Use 10 identical circuits, each with one LED and one 47Ω resistor connected to the 3.3V rail. Do not connect the 10 LEDs in parallel sharing a single resistor.
5. PCB Layout: Follow the recommended pad layout from the datasheet. Include a small copper pour connected to the cathode/anode pads for slight thermal relief.
6. Ordering: Specify Bin Code \"R\" (112-180 mcd) to ensure the indicators are uniformly bright and clearly visible.

12. Technology Introduction and Trends

12.1 AlInGaP Technology Principle

AlInGaP is a III-V compound semiconductor material where Aluminum (Al), Indium (In), Gallium (Ga), and Phosphorus (P) are combined in specific ratios. By adjusting these ratios, the bandgap of the material can be engineered, which directly determines the wavelength (color) of the emitted light when electrons and holes recombine. AlInGaP is particularly efficient in the red, orange, amber, and yellow spectral regions, offering higher efficiency and better temperature stability than older technologies like GaAsP.

12.2 Industry Trends

The general trend in SMD indicator LEDs is towards higher efficiency (more light output per unit of electrical power), improved color consistency through tighter binning, and increased reliability under higher temperature soldering profiles required for lead-free assembly. There is also a move towards miniaturization (smaller packages like 0402 and 0201) for space-constrained applications, though the 1206 package remains popular for its ease of handling, good solder joint visibility, and robust thermal performance. Another trend is the integration of onboard resistors or IC drivers within the LED package to simplify circuit design.