LTL1DEGYHJ Through Hole LED Lamp Datasheet - T-1 Package - Voltage 2.0V - Power 78mW - Green/Yellow - English Technical Document

1. Product Overview

This document details the specifications for a through-hole LED lamp, designated LTL1DEGYHJ. This component is designed for status indication and low-power lighting applications across various electronic devices. It is offered in two distinct colors: green and yellow, both featuring a white diffused lens for a uniform, wide-angle light output. The device conforms to the popular T-1 (3mm) diameter package standard, making it compatible with a vast array of existing PCB designs and panel cutouts.

1.1 Core Features and Advantages

The primary advantages of this LED series include its low power consumption and high luminous efficiency, contributing to energy savings in end applications. It is constructed using lead-free materials and is fully compliant with RoHS (Restriction of Hazardous Substances) directives, ensuring environmental safety. The standard T-1 form factor provides designers with a familiar and widely available component for rapid prototyping and production.

1.2 Target Applications and Markets

This LED is suitable for a broad spectrum of applications requiring clear, reliable visual indicators. Key target markets include communication equipment (e.g., routers, modems), computer peripherals, consumer electronics, and home appliances. Its reliability and simple drive requirements make it an ideal choice for indicating power status, operational modes, or system alerts.

2. Technical Parameter Deep-Dive Analysis

This section provides an objective and detailed interpretation of the key electrical, optical, and thermal parameters specified for the LTL1DEGYHJ LED.

2.1 Absolute Maximum Ratings

The absolute maximum ratings define the stress limits beyond which permanent damage to the device may occur. For both green and yellow variants, the maximum continuous DC forward current is 30mA. The power dissipation is rated at 78mW. A peak forward current of 120mA is permissible under pulsed conditions (duty cycle ≤ 1/10, pulse width ≤ 10μs). The device is rated for operation within an ambient temperature range of -30°C to +85°C and can be stored in temperatures from -40°C to +100°C. During soldering, the leads can withstand 260°C for a maximum of 5 seconds, provided the soldering point is at least 2.0mm from the LED body.

2.2 Electrical and Optical Characteristics

The typical operating point for testing optical characteristics is at a forward current (IF) of 20mA. At this current, the typical forward voltage (VF) is 2.0V for both colors, with a range from 1.6V (min) to 2.5V (max). This variance necessitates the use of current-limiting resistors in series with each LED for stable operation. The luminous intensity (Iv) varies significantly between colors: the green LED has a typical intensity of 85 millicandelas (mcd), while the yellow LED is brighter with a typical intensity of 240 mcd. The viewing angle (2θ1/2) is a wide 80 degrees, providing a broad emission pattern suitable for panel-mounted indicators. The dominant wavelength (λd) defines the perceived color: green LEDs target 570nm, and yellow LEDs target 590nm. The spectral half-width (Δλ) is approximately 15nm for green and 20nm for yellow, indicating the spectral purity of the emitted light.

3. Binning System Specification

To ensure color and brightness consistency in production, the LEDs are sorted into bins based on key parameters. This allows designers to select components that meet specific application requirements for uniformity.

3.1 Luminous Intensity Binning

Luminous intensity is binned into distinct codes. For green LEDs, bin 'CD' covers 50-85 mcd, and bin 'EF' covers 85-140 mcd. For yellow LEDs, bin 'GH' covers 140-240 mcd, and bin 'JK' covers 240-400 mcd. A testing tolerance of ±30% is applied to these bin limits.

3.2 Dominant Wavelength Binning

The dominant wavelength is also tightly controlled through binning. Green LEDs are available in bins H06 (564-567nm), H07 (567-570nm), H08 (570-572nm), and H09 (572-574nm). Yellow LEDs are available in bins Y02 (584-589nm) and Y03 (589-594nm). The tolerance for each wavelength bin limit is ±1nm, ensuring precise color matching within a selected bin.

4. Performance Curve Analysis

While specific graphical curves are referenced in the datasheet (Fig.1, Fig.6), their implications are critical for design. The forward current vs. forward voltage (I-V) curve is non-linear, characteristic of a diode. The relationship between luminous intensity and forward current is generally linear within the operating range, but designers must not exceed the absolute maximum current rating. The angular intensity distribution (related to the viewing angle) shows how light output decreases off-axis, which is important for ensuring visibility from different angles. The spectral distribution plot shows the peak emission wavelength and the width of the spectrum, which correlates with the color saturation.

5. Mechanical and Packaging Information

5.1 Outline Dimensions and Tolerances

The LED conforms to the standard T-1 (3mm) round package dimensions. Key mechanical notes include: all dimensions are in millimeters, with a general tolerance of ±0.25mm unless specified otherwise. The maximum protrusion of resin under the flange is 1.0mm. Lead spacing is measured where the leads exit the package body, which is critical for PCB layout. The anode (positive) lead is typically identified as the longer lead, a standard industry practice for polarity identification.

5.2 Packing Specification

The LEDs are packaged for bulk handling and automated assembly. They are first packed in bags containing 500, 200, or 100 pieces. Ten of these bags are then placed into an inner carton, totaling 5,000 pieces. Finally, eight inner cartons are packed into an outer shipping carton, resulting in a total of 40,000 pieces per outer carton. The datasheet notes that in every shipping lot, only the final pack may not be a full pack.

6. Soldering and Assembly Guidelines

Proper handling is essential to maintain LED performance and reliability.

6.1 Storage and Cleaning

LEDs should be stored in an environment not exceeding 30°C and 70% relative humidity. If removed from their original moisture-barrier packaging, they should be used within three months. For longer storage outside the original bag, they should be kept in a sealed container with desiccant. Cleaning, if necessary, should be done with alcohol-based solvents like isopropyl alcohol.

6.2 Lead Forming

If leads need to be bent, the bend must be made at a point at least 3mm from the base of the LED lens. The base of the lead frame should not be used as a fulcrum. Lead forming must always be performed before the soldering process and at room temperature to avoid stress on the epoxy lens.

6.3 Soldering Process

A minimum clearance of 2mm must be maintained between the base of the lens and the solder point. The lens must never be immersed in solder. For hand soldering with an iron, the maximum recommended temperature is 350°C for no more than 3 seconds (one time only). For wave soldering, pre-heat should not exceed 100°C for 60 seconds max, and the solder wave should be at 260°C max for 5 seconds max. Importantly, Infrared (IR) reflow soldering is explicitly stated as unsuitable for this through-hole type LED product. Excessive heat or time can cause lens deformation or catastrophic failure.

7. Application Design Recommendations

7.1 Drive Circuit Design

LEDs are current-operated devices. To ensure uniform brightness when multiple LEDs are used in parallel, it is strongly recommended to use a individual current-limiting resistor in series with each LED (Circuit A). Connecting LEDs directly in parallel without individual resistors (Circuit B) is discouraged, as slight variations in the forward voltage (Vf) characteristic between individual LEDs will cause significant differences in current sharing and, consequently, brightness. The series resistor value can be calculated using Ohm's Law: R = (Vsupply - Vf_LED) / I_desired, where Vf_LED is the typical forward voltage from the datasheet (e.g., 2.0V) and I_desired is the target operating current (e.g., 20mA).

7.2 Electrostatic Discharge (ESD) Protection

These LEDs are susceptible to damage from electrostatic discharge. Preventive measures must be implemented in the handling environment: personnel should use grounded wrist straps or anti-static gloves; all equipment, worktables, and storage racks must be properly grounded. An ion blower is recommended to neutralize static charges that may accumulate on the plastic lens due to friction during handling.

8. Technical Comparison and Design Considerations

Compared to surface-mount device (SMD) LEDs, through-hole LEDs like the LTL1DEGYHJ offer easier manual prototyping and repair, and can be more robust in high-vibration environments due to their mechanical connection. Their key differentiator is the wide viewing angle (80°) provided by the dome-shaped, diffused lens, which is ideal for applications where the indicator needs to be visible from a wide range of angles. Designers must account for the higher power dissipation on the PCB compared to modern SMD LEDs and ensure adequate clearance around the lens for light emission.

9. Frequently Asked Questions (Based on Technical Parameters)

9.1 Can I drive this LED at 30mA continuously?

While the absolute maximum DC forward current is 30mA, for optimal longevity and reliability, it is advisable to operate at or below the typical test condition of 20mA. Operating at the maximum rating may reduce lifespan and increase thermal stress.

9.2 Why is a series resistor necessary even if my power supply voltage matches the LED's forward voltage?

The forward voltage (Vf) is not a fixed value but has a range (e.g., 1.6V to 2.5V). A power supply set to a nominal 2.0V could deliver excessive current to an LED with a Vf at the lower end of its range, potentially damaging it. The series resistor acts as a simple, reliable current regulator.

9.3 What does the ±30% tolerance on luminous intensity bins mean for my design?

It means that an LED from the "EF" bin (85-140 mcd) could actually measure anywhere from approximately 60 mcd to 182 mcd when tested. For applications requiring very uniform brightness, you may need to select LEDs from a tighter bin or implement electrical calibration in your circuit.

10. Practical Application Examples

Example 1: Power Indicator on a Device: A single green LED from the EF bin, driven at 15mA via a series resistor from a 5V rail, provides a clear, bright "power on" indication. The wide viewing angle ensures visibility from the front and sides of the equipment.

Example 2: Dual-Status Indicator: Using one green and one yellow LED adjacent to each other. A microcontroller GPIO pin can sink current to light each LED independently, indicating different system states (e.g., green for "standby," yellow for "active," both off for "fault"). Individual resistors for each LED are mandatory.

11. Operating Principle Introduction

Light Emitting Diodes (LEDs) are semiconductor devices that emit light when an electric current passes through them. This phenomenon, called electroluminescence, occurs when electrons recombine with electron holes within the device, releasing energy in the form of photons. The color of the light is determined by the energy band gap of the semiconductor material used. In this component, specific semiconductor compounds are used to produce green and yellow light. The white diffused epoxy lens serves to protect the semiconductor chip, shape the light output beam, and diffuse the light to create a uniform, non-glaring appearance.

12. Technology Trends and Context

While surface-mount technology (SMT) dominates modern high-density electronics, through-hole LEDs remain relevant for applications requiring robustness, ease of manual assembly, or compatibility with existing designs. The trend in indicator LEDs is towards higher efficiency (more light output per mA of current) and tighter binning tolerances for improved color and brightness consistency. The RoHS compliance and lead-free construction of this component align with global environmental regulations and industry standards. The fundamental drive requirements and application principles outlined in this datasheet remain consistent across both through-hole and SMD LED technologies.