LTW-2S3D8 White LED Datasheet - T-1 3/4 Package - 3.1V Max - 93mW - English Technical Document

1. Product Overview

This document details the specifications for a through-hole white LED, identified by part number LTW-2S3D8. The device is designed as a status indicator component suitable for a wide range of electronic applications. It features a popular T-1 3/4 (approximately 5mm) diameter package with a water-clear lens, constructed using InGaN technology to produce white light.

1.1 Core Advantages and Features

The LED offers several key benefits for design engineers:

• Environmental Compliance: The product is lead (Pb) free and compliant with RoHS directives.
• High Efficiency: It provides high luminous output with low power consumption, contributing to energy-efficient designs.
• Design Flexibility: The through-hole form factor allows for versatile mounting on printed circuit boards (PCBs) or panels.
• Ease of Use: It is compatible with integrated circuits (ICs) due to its low current requirement.
• Reliability: The device is designed for high reliability in various operating conditions.

1.2 Target Applications and Markets

This LED is targeted at multiple industries requiring reliable status indication. Primary application areas include:

• Computer peripherals and internal components
• Communication equipment
• Consumer electronics
• Home appliances
• Industrial control systems and instrumentation

2. In-Depth Technical Parameter Analysis

The following sections provide a detailed breakdown of the device's operational limits and performance characteristics.

2.1 Absolute Maximum Ratings

These ratings define the stress limits beyond which permanent damage to the device may occur. All values are specified at an ambient temperature (TA) of 25°C.

• Power Dissipation (Pd): 93 mW maximum.
• Forward Current:
  • Continuous DC Forward Current (IF): 30 mA maximum.
  • Peak Forward Current: 100 mA maximum, permissible only under pulsed conditions (duty cycle ≤ 1/10, pulse width ≤ 10ms).
• Thermal Derating: The maximum DC forward current must be linearly derated by 0.45 mA for every degree Celsius above 30°C ambient temperature.
• Temperature Ranges:
  • Operating Temperature: -40°C to +85°C.
  • Storage Temperature: -40°C to +100°C.
• Soldering Temperature: Leads can withstand 260°C for a maximum of 5 seconds, provided the soldering point is at least 2.0mm (0.079\") from the LED body.

2.2 Electrical and Optical Characteristics

These are the typical performance parameters measured at TA=25°C under standard test conditions.

• Luminous Intensity (Iv): Ranges from 13,000 to 29,000 millicandelas (mcd) at a forward current (IF) of 20mA. The typical value is 23,000 mcd. A ±15% testing tolerance is applied to the bin limits.
• Viewing Angle (2θ1/2): 15 degrees. This is the full angle at which the luminous intensity drops to half of its axial (on-center) value, indicating a relatively focused beam.
• Forward Voltage (VF): Ranges from 2.5V to 3.1V at IF=20mA, with a typical value of 2.8V.
• Reverse Current (IR): 10 μA maximum when a reverse voltage (VR) of 5V is applied. Important Note: The device is not designed for operation under reverse bias; this test condition is for characterization only.
• Chromaticity Coordinates (x, y): Derived from the CIE 1931 chromaticity diagram. Specific coordinate bins are defined in a separate table.

3. Bin Table Specification System

The LEDs are sorted into bins based on key performance parameters to ensure consistency within a production lot. This allows designers to select parts matching specific requirements.

3.1 Luminous Intensity (Iv) Binning

LEDs are classified into three intensity bins (Z1, Z2, Z3) measured at IF=20mA. A ±15% tolerance applies to each bin limit.

• Bin Z1: 13,000 mcd (Min) to 17,000 mcd (Max)
• Bin Z2: 17,000 mcd (Min) to 22,000 mcd (Max)
• Bin Z3: 22,000 mcd (Min) to 29,000 mcd (Max)

The Iv classification code is marked on each packing bag for traceability.

3.2 Forward Voltage (VF) Binning

LEDs are also binned according to their forward voltage drop at IF=20mA, with six bins (0F to 5F) covering the range from 2.5V to 3.1V. A measurement allowance of ±0.1V is permitted.

• Bin 0F: 2.50V to 2.60V
• Bin 1F: 2.60V to 2.70V
• ... continues to Bin 5F: 3.00V to 3.10V

3.3 Chromaticity (Hue) Binning

The white light color is defined by chromaticity coordinates (x, y) on the CIE 1931 diagram. The datasheet provides a table of hue ranks (e.g., C0, B4, B6, B3, B5, A0) with specific coordinate quadrilaterals. A measurement allowance of ±0.01 is applied to the coordinates. A visual reference is provided via the CIE 1931 Chromaticity Diagram graphic.

4. Mechanical and Packaging Information

4.1 Outline Dimensions and Tolerances

The LED uses a standard T-1 3/4 radial leaded package. Key dimensional notes include:

• All dimensions are in millimeters (inches provided in parenthesis).
• Standard tolerance is ±0.25mm (0.010\") unless otherwise specified.
• The maximum protrusion of resin under the flange is 1.0mm (0.04\").
• Lead spacing is measured at the point where leads emerge from the package body.

4.2 Packaging Specifications

The LEDs are supplied in industry-standard packaging:

• Basic Unit: 500, 200, or 100 pieces per anti-static packing bag.
• Inner Carton: Contains 10 packing bags (e.g., 5,000 pieces if using 500pc bags).
• Outer Carton (Standard): Contains 8 inner cartons, totaling 40,000 pieces. It is noted that in every shipping lot, only the final pack may be a non-full pack.

5. Application Guidelines and Cautions

Proper handling and application are critical for reliability and performance.

5.1 Storage and Handling

• Storage Environment: Should not exceed 30°C or 70% relative humidity.
• Shelf Life: LEDs removed from original packaging should be used within three months. For longer storage, they should be kept in a sealed container with desiccant or in a nitrogen ambient.
• Cleaning: Use alcohol-based solvents like isopropyl alcohol if necessary.

5.2 Assembly and Soldering

• Lead Forming: Must be done before soldering at normal temperature. Bend leads at a point at least 3mm from the base of the LED lens. Do not use the package base as a fulcrum.
• PCB Assembly: Apply minimum clinch force to avoid mechanical stress.
• Soldering:
  • Maintain a minimum 2mm clearance from the lens base to the solder point. Do not immerse the lens in solder.
  • Soldering Iron: Max 350°C for max 3 seconds (one time only).
  • Wave Soldering: Pre-heat to max 100°C for max 60 seconds. Solder wave at max 260°C for max 5 seconds.
  • Critical Warning: Excessive temperature or time can deform the lens or cause catastrophic failure. IR reflow soldering is NOT suitable for this through-hole LED.

5.3 Drive Circuit Design

LEDs are current-operated devices. To ensure uniform brightness when using multiple LEDs:

• Recommended Circuit (Circuit A): Incorporate an individual current-limiting resistor in series with each LED when connecting them in parallel. This compensates for natural variations in the forward voltage (I-V characteristic) of individual LEDs.
• Non-Recommended Practice (Circuit B): Connecting multiple LEDs directly in parallel without individual series resistors is discouraged, as it can lead to significant brightness differences and uneven current sharing.

5.4 Electrostatic Discharge (ESD) Protection

The LED is susceptible to damage from static electricity or power surges. Standard ESD handling precautions must be observed during assembly and handling.

6. Performance Curve Analysis and Design Considerations

While specific graphical curves are referenced in the datasheet (Typical Electrical/Optical Characteristics Curves), their implications are critical for design.

6.1 Interpretation of Typical Curves

Designers should expect curves depicting:

• Relative Luminous Intensity vs. Forward Current: Shows how light output increases with current, typically in a non-linear fashion. Operating above the absolute maximum current rating is prohibited.
• Forward Voltage vs. Forward Current: Illustrates the diode's I-V characteristic. The voltage binning system helps predict this curve's position for a given lot of parts.
• Relative Luminous Intensity vs. Ambient Temperature: Demonstrates the decrease in light output as junction temperature rises, emphasizing the importance of thermal management and current derating.

6.2 Thermal Management Considerations

With a maximum power dissipation of 93mW and a required derating of 0.45 mA/°C above 30°C, effective thermal design is essential for maintaining performance and longevity, especially in high ambient temperature environments or when driving the LED near its maximum current.

7. Technical Comparison and Application Notes

7.1 Product Differentiation

This LED's primary differentiators within the through-hole indicator market are its combination of a relatively high luminous intensity (up to 29,000 mcd) with a narrow 15-degree viewing angle, making it suitable for applications requiring a bright, directed beam. The comprehensive binning system for intensity, voltage, and chromaticity provides a high degree of consistency for batch production.

7.2 Typical Application Circuits and Calculations

For a standard 5V supply and targeting the typical forward current of 20mA with a typical VF of 2.8V, the series resistor value (R) can be calculated using Ohm's Law: R = (Vsupply - VF) / IF = (5V - 2.8V) / 0.020A = 110 Ohms. The nearest standard value (e.g., 100 or 120 Ohms) should be selected, and the resistor's power rating must be checked: P = (Vsupply - VF) * IF = 2.2V * 0.02A = 0.044W, so a standard 1/8W (0.125W) resistor is sufficient.

7.3 Frequently Asked Questions (FAQs) Based on Parameters

• Q: Can I drive this LED at 30mA continuously?
  A: Yes, but only if the ambient temperature is at or below 30°C. Above 30°C, the current must be derated per the specification (0.45 mA/°C). At 85°C, the maximum allowable continuous current would be significantly lower.
• Q: Why is a series resistor necessary even if my power supply voltage matches the LED's VF?
  A: The VF is a nominal value with a range (2.5V-3.1V) and is temperature-dependent. A resistor is required to regulate the current, preventing thermal runaway which could occur if a slight increase in temperature lowers VF, causing current to increase uncontrollably.
• Q: What does the \"Water Clear\" lens description imply?
  A: It indicates the lens is non-diffused, resulting in a more focused beam pattern as defined by the 15-degree viewing angle, compared to a diffused lens which would create a wider, softer light pattern.