T-1 3/4 White LED Lamp Datasheet - 5mm Diameter - 3.6V Forward Voltage - 120mW Power Dissipation - English Technical Document

1. Product Overview

This document details the specifications for a high-brightness, white light-emitting diode (LED) designed for through-hole mounting on printed circuit boards (PCBs) or panels. The device utilizes InGaN (Indium Gallium Nitride) technology to produce white light and is encapsulated in a popular T-1 3/4 (5mm) diameter package with a water-clear lens. It is engineered for low power consumption and high efficiency, making it suitable for a wide range of indicator and illumination applications where reliable performance is required.

The core advantages of this LED include its compliance with RoHS (Restriction of Hazardous Substances) directives, meaning it is lead-free. Its design is compatible with integrated circuits due to low current requirements. The versatile mounting capability allows for flexible integration into various electronic assemblies.

2. In-Depth Technical Parameter Analysis

2.1 Absolute Maximum Ratings

The device must not be operated beyond these limits, as doing so may cause permanent damage.

• Power Dissipation (Pd): 120 mW. This is the maximum total power the LED can dissipate as heat.
• Peak Forward Current (I_FP): 100 mA. This is the maximum allowable pulsed current, specified under a 1/10 duty cycle with a 0.1ms pulse width. It is significantly higher than the DC rating to accommodate brief, high-intensity pulses.
• DC Forward Current (I_F): 30 mA. This is the maximum continuous forward current recommended for reliable long-term operation.
• Operating Temperature Range (T_opr): -25°C to +80°C. The LED is designed to function within this ambient temperature range.
• Storage Temperature Range (T_stg): -30°C to +100°C.
• Lead Soldering Temperature: 260°C for 5 seconds, measured 1.6mm (0.063") from the LED body. This defines the thermal profile the leads can withstand during manual or wave soldering.

2.2 Electrical & Optical Characteristics

These parameters are measured at an ambient temperature (T_a) of 25°C and define the typical performance of the device.

• Luminous Intensity (I_v): 10000 - 16000 mcd (millicandela) at a forward current (I_F) of 20mA. This is a measure of the perceived power of light emitted in a specific direction. The actual value is subject to a ±15% tolerance and is classified into bins (see Section 3). Measurement follows the CIE eye-response curve.
• Viewing Angle (2θ_1/2): 15 degrees (typical). This is the full angle at which the luminous intensity drops to half of its peak axial value. A narrow viewing angle like this indicates a more focused, spotlight-like beam.
• Chromaticity Coordinates (x, y): Approximately 0.30, 0.30 at I_F = 20mA. These coordinates define the color point of the white light on the CIE 1931 chromaticity diagram. Specific bins are defined for tighter color control (see Section 3).
• Forward Voltage (V_F): 3.3V (min) / 3.6V (max) at I_F = 20mA. This is the voltage drop across the LED when operating. It is also binned for consistency.
• Reverse Current (I_R): 100 µA (max) at a Reverse Voltage (V_R) of 5V. Critical Note: This parameter is for test purposes only. The LED is not designed for reverse-bias operation, and applying a reverse voltage in an actual circuit can damage the device.

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 requirements for brightness, voltage, and color.

3.1 Luminous Intensity (I_v) Bins

Based on minimum and maximum luminous intensity values at I_F=20mA:

• Y1: 10000 - 13000 mcd
• Z1: 13000 - 17000 mcd
• Z2: 17000 - 22000 mcd

A 15% measurement allowance applies.

3.2 Forward Voltage (V_F) Bins

Based on forward voltage at I_F=20mA:

• 3H: 2.75V - 3.00V
• 4H: 3.00V - 3.25V
• 5H: 3.25V - 3.50V
• 6H: 3.50V - 3.60V

A 15% measurement allowance applies.

3.3 Hue (Chromaticity) Bins

Defined by quadrilaterals of (x,y) coordinates on the CIE 1931 diagram, such as:

• Bin 40: Coordinates forming a quadrilateral around a specific white point.
• Bin 50, 60, 70: Subsequent bins with progressively different color coordinates, allowing selection from cooler to potentially warmer white tones (specific interpretation requires the diagram).

A color coordinate measurement allowance of ±0.01 applies.

4. Performance Curve Analysis

While specific graphs are referenced in the datasheet, typical curves for such LEDs would include:

• Relative Luminous Intensity vs. Forward Current (I_v vs. I_F): Shows how light output increases with current, typically in a sub-linear fashion, emphasizing the importance of current regulation over voltage regulation.
• Forward Voltage vs. Forward Current (V_F vs. I_F): Demonstrates the exponential I-V characteristic of a diode. The voltage rises sharply once the turn-on threshold is passed.
• Relative Luminous Intensity vs. Ambient Temperature (I_v vs. T_a): Illustrates the decrease in light output as the junction temperature increases, a key consideration for thermal management in high-power or high-ambient-temperature applications.

These curves are essential for understanding the device's behavior under non-standard conditions (different currents or temperatures) and for accurate circuit design.

5. Mechanical & Package Information

5.1 Package Dimensions

The LED uses a standard T-1 3/4 (5mm) round through-hole package. Key dimensional notes include:

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

5.2 Polarity Identification & Lead Forming

Typically, the longer lead denotes the anode (positive), and the shorter lead or a flat spot on the package rim denotes the cathode (negative). The datasheet emphasizes critical handling rules:

• Lead forming must be done before soldering and at normal room temperature.
• Bends should be made at least 3mm from the base of the LED lens. Using the package body as a fulcrum is prohibited.
• Leads should be cut at normal temperature.

6. Soldering & Assembly Guidelines

6.1 Soldering Parameters

Hand Soldering (Iron):

• Temperature: 300°C maximum.
• Time: 3 seconds maximum per lead (one time only).

Wave Soldering:

• Pre-heat Temperature: 100°C maximum.
• Pre-heat Time: 60 seconds maximum.
• Solder Wave Temperature: 260°C maximum.
• Contact Time: 5 seconds maximum.

Critical Rule: Maintain a minimum clearance of 2mm between the base of the LED lens and the solder point. The lens must never be dipped into solder.

6.2 Storage & Cleaning

• Storage: Recommended storage conditions are ≤30°C and ≤70% relative humidity. LEDs removed from their original moisture-barrier bags should be used within three months. For longer storage, use a sealed container with desiccant or a nitrogen atmosphere.
• Cleaning: Use alcohol-based solvents like isopropyl alcohol if cleaning is necessary.

6.3 Electrostatic Discharge (ESD) Precautions

LEDs are sensitive to static electricity. Handling precautions include using wrist straps, anti-static gloves, and ensuring all equipment is properly grounded.

7. Packaging & Ordering Information

The standard packaging flow is as follows:

• Basic Unit: 500 or 250 pieces per anti-static moisture-barrier bag.
• Inner Carton: Contains 10 bags, totaling 5,000 pieces.
• Outer Carton: Contains 8 inner cartons, totaling 40,000 pieces.

The specific part number (e.g., LTW-2S3D7) identifies the product. The luminous intensity bin code is marked on each packing bag.

8. Application Recommendations

8.1 Typical Application Scenarios

This LED is suitable for general-purpose indicator lights, status displays, backlighting for small panels, and decorative lighting in consumer electronics, appliances, industrial control panels, and automotive interior applications (where environmental specs are met). It is intended for ordinary electronic equipment.

8.2 Circuit Design Considerations

Drive Method: LEDs are current-driven devices. To ensure uniform brightness, especially when connecting multiple LEDs in parallel, it is strongly recommended to use a series current-limiting resistor for each LED (Circuit Model A). Driving multiple LEDs in parallel directly from a voltage source (Circuit Model B) is discouraged due to variations in forward voltage (V_F) between individual LEDs, which can cause significant differences in current and, consequently, brightness.

The series resistor value can be calculated using Ohm's Law: R = (V_supply - V_F) / I_F, where V_F and I_F are the desired operating points for the LED.

8.3 Thermal Management

While this is a low-power device, adhering to the maximum power dissipation and operating temperature ratings is crucial for longevity. In applications with high ambient temperatures or enclosed spaces, ensure adequate airflow or consider derating the operating current.

9. Technical Comparison & Differentiation

Compared to older technology like incandescent bulbs, this LED offers vastly superior efficiency, longer lifetime, and lower heat generation. Within the LED market, its key differentiators are its specific combination of high luminous intensity (10,000+ mcd) from a standard 5mm package, a narrow 15-degree viewing angle for directed light, and well-defined binning structure for brightness and color consistency. The RoHS compliance is a standard requirement but remains a critical feature for modern electronics manufacturing.

10. Frequently Asked Questions (FAQs)

Q: Can I drive this LED directly from a 5V supply without a resistor?
A: No. This would likely destroy the LED. The forward voltage is around 3.6V. Applying 5V would cause excessive current to flow, exceeding the maximum DC rating. Always use a series current-limiting resistor.

Q: What is the difference between the Peak Forward Current (100mA) and the DC Forward Current (30mA)?
A: The LED can handle short pulses of higher current (100mA) but only at a low duty cycle. For continuous operation, the current must not exceed 30mA. Exceeding the DC rating causes excessive heat and rapid degradation.

Q: Why is the viewing angle so narrow (15°)?
A: The water-clear lens and the internal die reflector are designed to collimate the light into a focused beam. This is ideal for applications where the light needs to be seen from a specific direction, like a panel indicator viewed head-on.

Q: How do I interpret the Hue Bins (40, 50, etc.)?
A: These bins represent different regions on the CIE chromaticity diagram. Lower numbers (e.g., Bin 40) typically correspond to white light with different correlated color temperatures (CCT). For precise color matching, consult the specific chromaticity diagram and coordinate ranges provided in the full datasheet.

11. Practical Design Case Study

Scenario: Designing a status indicator panel with 10 identical white LEDs. The available power supply is 12V DC. The goal is to achieve bright, uniform illumination.

Design Steps:

1. Circuit Topology: To ensure uniformity, connect the 10 LEDs in series, each with its own resistor (or use a single higher-wattage resistor for the whole string if V_F bins are tight). A parallel connection is riskier due to V_F variation.
2. Operating Point: Choose a forward current (I_F). A safe and bright point is 20mA, which is the test condition and within the 30mA max.
3. Voltage Calculation: Assume a worst-case V_F from Bin 6H: 3.6V. For 10 LEDs in series, total V_F = 36V. This exceeds the 12V supply, so a series connection of all 10 is impossible. Instead, use two parallel branches of 5 LEDs each in series.
4. Resistor Calculation for One Branch (5 LEDs):
   Total V_F (5 LEDs) = 5 * 3.6V = 18V. This is already above 12V, so this approach also fails. Re-evaluate: With a 12V supply, you can only have a few LEDs in series. For 3 LEDs in series: V_F = 10.8V. Resistor R = (12V - 10.8V) / 0.020A = 60 Ohms. Power in resistor P = I²R = (0.02^2)*60 = 0.024W, so a standard 1/4W resistor is fine. You would need 4 such strings (3+3+3+1) to make 10 LEDs, with appropriate resistors for each string.
5. Implementation: This design provides uniform brightness per string and protects each LED with its own current limit.

12. Operating Principle Introduction

This white LED is based on InGaN semiconductor technology. Unlike traditional white LEDs that use a blue die with a yellow phosphor, the datasheet specifies "InGaN White," which typically indicates a similar principle: a semiconductor chip emits blue light. This blue light then excites a layer of yellow (or yellow and red) phosphor coating inside the package. The combination of the blue light from the chip and the yellow/red light from the phosphor mixes to produce light that appears white to the human eye. The specific mix of phosphors determines the correlated color temperature (CCT) and color rendering index (CRI) of the white light. The water-clear lens allows the full mixed light to pass through with minimal diffusion, contributing to the narrow viewing angle.

13. Technology Trends

The development of white LED technology is driven by continuous improvements in efficiency (lumens per watt), color quality (CRI and CCT consistency), and cost reduction. While surface-mount device (SMD) LEDs dominate new designs due to smaller size and better suitability for automated assembly, through-hole LEDs like this T-1 3/4 package remain relevant for prototyping, hobbyist projects, repair work, and applications requiring robust mechanical mounting or higher single-point brightness from a discrete package. Trends in materials science focus on developing more efficient and stable phosphors, as well as exploring new semiconductor structures to improve light extraction and thermal performance. The underlying drive is towards more sustainable and energy-efficient lighting solutions across all sectors.