LTL2V3YUJS Yellow LED Datasheet - Through Hole Lamp - 5mm Diameter - 2.1V Typ - 20mA - English Technical Document

1. Product Overview

This document details the specifications for a high-efficiency, yellow through-hole LED lamp. The device is designed for general-purpose indicator and illumination applications where reliable performance and clear visibility are required. Its core advantages include high luminous intensity output, low power consumption, and a uniform light pattern, making it suitable for a wide range of electronic equipment.

1.1 Core Features and Target Market

The LED is characterized by its lead-free, RoHS-compliant construction. It offers high luminous efficiency, which translates to bright output with relatively low current draw. The typical viewing angle of 36 degrees provides a consistent and wide light distribution. This device is I.C. compatible, meaning it can be driven directly by many logic circuits without requiring complex driver stages. Its primary target markets include consumer electronics, industrial control panels, automotive interior lighting, and various appliance indicators where through-hole mounting is preferred for durability or prototyping.

2. Technical Parameter Analysis

The following sections provide a detailed, objective interpretation of the key electrical, optical, and thermal parameters specified for the device.

2.1 Absolute Maximum Ratings

These ratings define the limits beyond which permanent damage to the device may occur. They are not intended for normal operation.

• Power Dissipation: 120 mW maximum. This is the total power (Vf * If) the package can safely handle.
• Forward Current: 50 mA continuous, 150 mA peak (under pulsed conditions: 1/10 duty cycle, 1ms pulse width). Exceeding the continuous current will overheat the semiconductor junction.
• Reverse Voltage: 5 V maximum. LEDs have low reverse breakdown voltage; applying a higher reverse voltage can cause immediate failure.
• Temperature Ranges: Operating: -40°C to +100°C; Storage: -55°C to +100°C. The device is suitable for harsh environments.
• Derating: The continuous forward current must be linearly derated by 0.67 mA for every degree Celsius above 60°C ambient temperature (Ta).

2.2 Electrical & Optical Characteristics

These are the typical and guaranteed performance parameters measured at an ambient temperature (Ta) of 25°C.

• Luminous Intensity (Iv): 2500-4200 mcd (millicandela) typical at a forward current (If) of 20 mA. The actual bin code (T, U, V, W) on the packing bag indicates the guaranteed minimum and maximum range for a specific batch, with a ±15% tolerance on the bin limits.
• Viewing Angle (2θ1/2): 32-36 degrees. This is the full angle at which the light intensity drops to half of its peak axial value.
• Wavelength: The light source is AlInGaP (Aluminum Indium Gallium Phosphide). Peak Emission Wavelength (λP) is typically 590 nm. The Dominant Wavelength (λd), which defines the perceived color, is binned between 584.5 nm and 592 nm (bins A, B, C). The spectral line half-width (Δλ) is typically 17 nm, indicating a relatively pure yellow color.
• Forward Voltage (Vf): 1.8-2.5 V at If=20mA, with a typical value of 2.1V. This parameter is also binned (codes 1 through 7) to aid in circuit design for consistent brightness in parallel strings.
• Reverse Current (Ir): Maximum 10 μA at a reverse voltage (Vr) of 5V.
• Capacitance (C): Typically 40 pF measured at zero bias and 1 MHz. This is relevant for high-speed switching applications.

3. Binning System Explanation

The product is classified into bins based on key performance parameters to ensure consistency within a production lot and for specific application needs.

3.1 Luminous Intensity Binning

Bin codes T, U, V, W categorize LEDs based on their minimum luminous intensity at 20mA. For example, bin 'U' guarantees an intensity between 3200 and 4200 mcd (with ±15% tolerance on these limits). This allows designers to select a brightness grade for their application.

3.2 Dominant Wavelength Binning

Bin codes A, B, C sort the LEDs by their dominant wavelength (color). Bin 'A' covers 584.5-587 nm (a more greenish-yellow), 'B' covers 587-589.5 nm, and 'C' covers 589.5-592 nm (a more orange-yellow). The tolerance for each bin limit is ±1 nm.

3.3 Forward Voltage Binning

Bin codes 1 through 7 group LEDs by their forward voltage drop at 20mA, in 0.1V steps from 1.8V to 2.5V. Using LEDs from the same Vf bin in a parallel circuit helps prevent current hogging, where LEDs with lower Vf draw more current and appear brighter or fail prematurely.

4. Mechanical & Packaging Information

4.1 Package Dimensions and Polarity

The device is a standard 5mm (T-1 3/4) round through-hole LED package with a water-clear lens. The cathode lead is typically identified as the shorter lead or the lead adjacent to a flat spot on the lens rim. The leads emerge from the package with a specified spacing, and all dimensional tolerances are ±0.25mm unless otherwise noted. Lead forming must be done at least 3mm from the base of the lens to avoid damaging the internal wire bonds.

4.2 Packaging Specifications

The LEDs are packed in anti-static bags. Standard packing quantities are 1000, 500, or 250 pieces per bag. Eight bags are placed in an inner carton (total 8000 pcs), and eight inner cartons are packed into an outer shipping carton (total 64,000 pcs). For shipping lots, only the final pack may contain a non-full quantity.

5. Assembly, Soldering & Handling Guidelines

5.1 Storage and Cleaning

For long-term storage outside the original packaging, LEDs should be kept in an environment not exceeding 30°C and 70% relative humidity. It is recommended to use them within three months or store them in a sealed container with desiccant. Cleaning, if necessary, should be done with alcohol-based solvents like isopropyl alcohol.

5.2 Soldering Process

Important: This is a through-hole device and is NOT suitable for Infrared (IR) reflow soldering processes. Only wave soldering or hand soldering should be used.

• Hand Soldering: Iron temperature should not exceed 300°C, and soldering time per lead should be 3 seconds maximum. A minimum clearance of 2mm must be maintained between the solder point and the base of the LED lens.
• Wave Soldering: Pre-heat temperature should not exceed 100°C for up to 60 seconds. The solder wave temperature should be a maximum of 260°C, with the leads exposed for no more than 5 seconds.

Excessive temperature or time can melt the lens or cause catastrophic failure of the LED die.

5.3 Electrostatic Discharge (ESD) Protection

Although not as sensitive as some ICs, LEDs can be damaged by electrostatic discharge. Recommended precautions include using grounded wrist straps and workstations, anti-static gloves, and ionizers to neutralize static charge on the LED surface during handling.

6. Application Design Recommendations

6.1 Drive Circuit Design

LEDs are current-operated devices. To ensure uniform brightness and longevity, they must be driven with a current-limiting mechanism. The simplest and most recommended method is to use a series resistor for each LED, as shown in Circuit Model A in the source document. This compensates for variations in the forward voltage (Vf) between individual LEDs. Connecting multiple LEDs directly in parallel (Circuit Model B) without individual resistors is not recommended, as differences in Vf will cause uneven current distribution and brightness.

The series resistor value (R) can be calculated using Ohm's Law: R = (Vsupply - Vf_LED) / If, where Vf_LED is the forward voltage of the LED at the desired current (If). Always use the maximum Vf from the datasheet for a conservative design that ensures the current does not exceed the limit even with a low-Vf LED.

6.2 Thermal Management Considerations

While the through-hole package dissipates heat through its leads, attention must be paid to the power dissipation and derating curve. Operating at high ambient temperatures (above 60°C) requires reducing the maximum continuous forward current as specified. Ensuring adequate spacing on the PCB and avoiding enclosing the LED in a sealed, unventilated space will help maintain junction temperature within safe limits.

6.3 Typical Application Scenarios

• Status Indicators: Power-on, standby, or fault indicators in consumer appliances, networking equipment, and industrial controls.
• Panel Illumination: Backlighting for switches, dials, or legends on instrument panels.
• Automotive Interior Lighting: Map lights, dashboard indicator backlighting (subject to specific automotive-grade qualifications).
• Signage & Displays: As individual pixels or segments in low-resolution informational displays.

7. Performance Curves and Characteristics

The datasheet references typical performance curves which are crucial for understanding device behavior under non-standard conditions. While the specific graphs are not reproduced in text, their implications are analyzed below.

7.1 Luminous Intensity vs. Forward Current (I-V Curve)

The light output (luminous intensity) is approximately proportional to the forward current over a certain range. However, efficiency may drop at very high currents due to increased heat. The curve helps designers choose an operating point that balances brightness with efficacy and device lifetime.

7.2 Forward Voltage vs. Temperature

The forward voltage of an LED has a negative temperature coefficient; it decreases as the junction temperature increases. This is an important consideration for constant-voltage drives, as a warmer LED will draw more current, potentially leading to thermal runaway if not properly current-limited.

7.3 Spectral Distribution

The spectral output curve shows the intensity of light emitted at each wavelength. It confirms the peak wavelength and the spectral half-width, defining the color purity. Shifts in this curve with temperature or drive current are typically minimal for AlInGaP LEDs compared to some other types.

8. Frequently Asked Questions (FAQ)

8.1 Can I drive this LED directly from a 5V logic output or microcontroller pin?

No, not directly. A typical microcontroller pin can only source or sink 20-40mA, which is within the LED's range, but the pin's output voltage is 5V (or 3.3V). The LED's forward voltage is only about 2.1V. Connecting it directly would attempt to pass a very high, uncontrolled current, damaging both the LED and possibly the microcontroller pin. You must always use a series current-limiting resistor.

8.2 Why is there a ±15% tolerance on the luminous intensity bin limits?

This tolerance accounts for measurement system variations and minor production fluctuations. It means an LED from bin U (3200-4200 mcd) could realistically measure as low as ~2720 mcd (3200 * 0.85) or as high as ~4830 mcd (4200 * 1.15) when measured on a different, calibrated system. Designers should account for this range in their optical requirements.

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

Peak Wavelength (λP) is the wavelength at which the spectral power distribution curve reaches its maximum intensity. Dominant Wavelength (λD) is a calculated value derived from the CIE chromaticity diagram; it represents the single wavelength of a pure monochromatic light that would appear to have the same color as the LED to a standard human observer. λD is more relevant for color specification in applications.

9. Technology Overview and Trends

9.1 AlInGaP Technology Principle

This LED utilizes an Aluminum Indium Gallium Phosphide (AlInGaP) semiconductor material for its active region. By precisely controlling the ratios of these elements during crystal growth, the bandgap of the material can be engineered to emit light in the yellow, orange, and red parts of the visible spectrum. AlInGaP is known for its high internal quantum efficiency and good performance at elevated temperatures compared to older technologies like Gallium Phosphide (GaP).

9.2 Industry Context and Evolution

Through-hole LEDs like this one represent a mature and highly reliable packaging technology. While surface-mount device (SMD) LEDs dominate new designs for their smaller size and suitability for automated assembly, through-hole LEDs remain vital for applications requiring higher mechanical robustness, easier manual prototyping, repair, or situations where heat dissipation through leads is beneficial. The ongoing development focuses on increasing luminous efficacy (more light per watt) and improving color consistency within production bins, even for these established package types.