3.1mm Blue LED LTL1CHTBK5 Datasheet - Dimensions 3.1mm Dia - Voltage 3.8V - Power 120mW - English Technical Document

1. Product Overview

This document details the technical specifications for a high-efficiency, low-power consumption blue light-emitting diode (LED) designed for through-hole mounting on printed circuit boards (PCBs) or panels. The device features a 3.1mm diameter package and utilizes InGaN (Indium Gallium Nitride) technology to produce blue light. Its core advantages include compatibility with integrated circuits due to low current requirements and versatile mounting options, making it suitable for a wide range of indicator and backlighting applications in consumer electronics, instrumentation, and general-purpose electronic equipment.

2. In-Depth Technical Parameter Analysis

2.1 Absolute Maximum Ratings

The device's operational limits are defined at an ambient temperature (T_A) of 25°C. Exceeding these ratings may cause permanent damage.

• Power Dissipation (P_D): 120 mW - The maximum total power the device can safely dissipate.
• Peak Forward Current (I_FP): 100 mA - Permissible under pulsed conditions (1/10 duty cycle, 0.1ms pulse width).
• DC Forward Current (I_F): 30 mA - The maximum continuous forward current.
• Operating Temperature Range: -25°C to +80°C.
• Storage Temperature Range: -30°C to +100°C.
• Lead Soldering Temperature: 260°C for 5 seconds, measured 1.6mm from the LED body.

2.2 Electrical & Optical Characteristics

Key performance parameters are measured at T_A=25°C and a standard test current (I_F) of 20mA.

• Luminous Intensity (I_V): 310 mcd (Min), 880 mcd (Typ). This is the perceived brightness as measured by a sensor filtered to match the human eye's photopic response (CIE curve). A ±15% tolerance applies to the guaranteed value.
• Viewing Angle (2θ_1/2): 30 degrees (Typ). This is the full angle at which the luminous intensity drops to half of its axial (on-center) value.
• Peak Emission Wavelength (λ_P): 468 nm (Typ). The wavelength at which the spectral power output is highest.
• Dominant Wavelength (λ_d): 470 nm (Typ). Derived from the CIE chromaticity diagram, this single wavelength best represents the perceived color of the LED.
• Spectral Line Half-Width (Δλ): 25 nm (Typ). The width of the emission spectrum at half its maximum power, indicating color purity.
• Forward Voltage (V_F): 3.5V (Min), 3.8V (Typ) at I_F=20mA.
• Reverse Current (I_R): 100 µA (Max) at a Reverse Voltage (V_R) of 5V. Important: This device is not designed for reverse operation; this test condition is for characterization only.

3. Binning System Explanation

To ensure consistency in applications, LEDs are sorted (binned) based on key optical parameters.

3.1 Luminous Intensity Binning

Units: mcd @ 20mA. Each bin has a ±15% tolerance on its limits.

• K: 310 - 400 mcd
• L: 400 - 520 mcd
• M: 520 - 680 mcd
• N: 680 - 880 mcd
• P: 880 - 1150 mcd
• Q: 1150 - 1500 mcd

The bin code is marked on each packing bag for identification.

3.2 Dominant Wavelength Binning

Units: nm @ 20mA. Each bin has a ±1nm tolerance.

• B08: 465.0 - 470.0 nm
• B09: 470.0 - 475.0 nm

4. Performance Curve Analysis

While specific graphs are referenced in the datasheet (Typical Electrical/Optical Characteristics Curves on page 4), the following trends are typical for such devices:

• I-V Curve: The forward voltage (V_F) exhibits a logarithmic relationship with forward current (I_F), with a characteristic "knee" voltage around 3V before rising more linearly.
• Luminous Intensity vs. Current: I_V is approximately proportional to I_F within the recommended operating range but may saturate or degrade at very high currents.
• Temperature Dependence: Luminous intensity typically decreases with increasing junction temperature. The forward voltage also has a negative temperature coefficient (decreases as temperature rises).
• Spectral Distribution: The emission spectrum is a bell-shaped curve centered around the peak wavelength (468 nm), with a typical half-width of 25 nm.

5. Mechanical & Package Information

5.1 Package Dimensions

The device is housed in a cylindrical, water-clear lens package with a diameter of 3.1mm. Key dimensional notes include:

• All dimensions are in millimeters (inches provided in parentheses).
• General tolerance is ±0.25mm unless specified otherwise.
• Maximum protrusion of resin under the flange is 1.0mm.
• Lead spacing is measured at the point where leads emerge from the package body.

Polarity Identification: The longer lead is the anode (positive), and the shorter lead is the cathode (negative). This is a standard convention for through-hole LEDs.

6. Soldering & Assembly Guidelines

6.1 Lead Forming & Handling

• Bend leads at a point at least 3mm from the base of the LED lens. Do not use the package base as a fulcrum.
• Lead forming must be done at room temperature and before soldering.
• Use minimum clinch force during PCB assembly to avoid mechanical stress.

6.2 Soldering Process

• Maintain a minimum clearance of 2mm from the lens base to the solder point. Avoid immersing the lens in solder.
• Avoid applying external stress to the leads while the LED is hot from soldering.
• IR reflow is not suitable for this through-hole type LED.

Recommended Soldering Conditions:

• Soldering Iron: Max. 300°C for max. 3 seconds (one time only).
• Wave Soldering: Pre-heat to max. 100°C for max. 60 sec, then solder wave at max. 260°C for max. 10 sec.

Excessive temperature or time can deform the lens or cause catastrophic failure.

6.3 Cleaning & Storage

• Cleaning: Use alcohol-based solvents like isopropyl alcohol if necessary.
• Storage: Store in an environment not exceeding 30°C and 70% relative humidity. LEDs removed from original packaging should be used within three months. For extended storage, use a sealed container with desiccant or a nitrogen ambient.

7. Packaging & Ordering Information

7.1 Packaging Specification

• Packing Bag: 1000, 500, or 250 pieces per bag.
• Inner Carton: 10 bags per carton (total 10,000 pcs).
• Outer Carton: 8 inner cartons per outer carton (total 80,000 pcs).
• Note: In every shipping lot, only the last pack may be non-full.

7.2 Part Number

The specific part number covered by this datasheet is LTL1CHTBK5. The lens is water clear, the light source is InGaN, and the emitted color is blue.

8. Application Design Recommendations

8.1 Drive Circuit Design

LEDs are current-operated devices. To ensure uniform brightness when driving multiple LEDs in parallel, it is strongly recommended to use a current-limiting resistor in series with each LED (Circuit Model A). Driving LEDs directly in parallel (Circuit Model B) is not recommended, as slight variations in the forward voltage (V_F) characteristic between individual LEDs can cause significant differences in current sharing and, consequently, perceived brightness.

The series resistor value (R_s) can be calculated using Ohm's Law: R_s = (V_supply - V_F) / I_F, where V_F is the typical forward voltage (e.g., 3.8V) and I_F is the desired operating current (e.g., 20mA).

8.2 Electrostatic Discharge (ESD) Protection

This LED is susceptible to damage from electrostatic discharge. Precautions must be taken:

• Operators should wear conductive wrist straps or anti-static gloves.
• All equipment, workbenches, and storage racks must be properly grounded.
• Use an ionizer to neutralize static charge that may build up on the plastic lens due to handling friction.

8.3 Application Scope & Cautions

This LED is intended for ordinary electronic equipment (office, communications, household). It is not designed for applications where failure could jeopardize life or health (e.g., aviation, medical life-support, critical safety devices) without prior consultation and specific qualification.

9. Technical Comparison & Differentiation

Compared to older technology blue LEDs (e.g., based on silicon carbide), this InGaN-based LED offers significantly higher luminous efficiency and lower power consumption for a given light output. The 3.1mm diameter is a common industry standard, offering a good balance between light output and board space. Its key differentiators are the combination of a relatively narrow viewing angle (30°), which provides more directed light, and the availability of precise binning for both intensity and wavelength, allowing for tighter color and brightness matching in multi-LED applications.

10. Frequently Asked Questions (FAQs)

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

Peak Wavelength (λ_P) is the physical wavelength where the spectral power output is maximum (468 nm). Dominant Wavelength (λ_d) is a calculated value (470 nm) from color science that best represents the single-wavelength color perceived by the human eye. For monochromatic LEDs like this blue one, they are often close but not identical.

10.2 Can I drive this LED without a series resistor?

No. An LED's current-voltage relationship is exponential. A small increase in voltage above its forward voltage can cause a very large, potentially destructive, increase in current. A series resistor is essential for stable, safe, and predictable operation from a voltage source.

10.3 Why is there a ±15% tolerance on the luminous intensity?

This tolerance accounts for normal variations in the semiconductor manufacturing and packaging processes. The binning system is implemented to sort LEDs into tighter groups (e.g., K, L, M bins) within this overall variation to meet specific application needs for brightness consistency.

10.4 What does "I.C. compatible" mean?

It means the LED's electrical characteristics, particularly its low forward current requirement (e.g., 20mA), make it suitable for direct drive by the output pins of many standard integrated circuits (ICs) and microcontrollers, which can typically source or sink currents in this range.

11. Design-in Case Study Example

Scenario: Designing a status indicator panel requiring 10 uniformly bright blue indicators.

1. Binning Selection: Specify LEDs from the same luminous intensity bin (e.g., all from Bin 'M') and the same dominant wavelength bin (e.g., all B09) to ensure visual consistency.
2. Circuit Design: Use a 5V supply. Calculate the series resistor: R_s = (5V - 3.8V) / 0.020A = 60 Ω. A standard 62 Ω or 68 Ω resistor would be suitable. Implement this resistor in series with each of the 10 LEDs, connecting them in parallel from the 5V rail.
3. Layout & Assembly: Place LEDs with at least 3mm lead length before bending for strain relief. Ensure soldering is performed according to the wave soldering guidelines, keeping the iron or wave contact >2mm from the lens.
4. ESD Mitigation: Ensure the assembly line is ESD-protected. Store and handle LEDs in their original packaging until ready for use.

12. Technology Principle Introduction

This LED is based on InGaN (Indium Gallium Nitride) semiconductor material. When a forward voltage is applied across the p-n junction, electrons and holes are injected into the active region where they recombine. The energy released during this recombination is emitted as photons (light). The specific composition of the InGaN alloy determines the bandgap energy, which directly dictates the wavelength (color) of the emitted light. For blue emission, a specific ratio of indium to gallium is used. The water-clear epoxy lens serves to protect the semiconductor chip, shape the light output beam (30° viewing angle), and enhance light extraction from the package.

13. Industry Trends & Developments

While this is a standard through-hole component, the underlying InGaN technology is continuously evolving. Trends in the broader LED industry include:

• Increased Efficiency: Ongoing improvements in epitaxial growth and chip design yield higher luminous efficacy (more light output per watt of electrical input).
• Color Consistency: Advances in manufacturing control and binning algorithms allow for tighter tolerances on dominant wavelength and intensity, crucial for applications like full-color displays.
• Packaging: While through-hole remains popular for certain applications, surface-mount device (SMD) packages dominate new designs due to their smaller footprint and suitability for automated pick-and-place assembly. However, through-hole LEDs like this one maintain relevance in applications requiring higher mechanical robustness, easier manual prototyping, or specific optical characteristics from a radial package.
• Reliability: Improvements in materials (e.g., epoxy resins, lead frames) and packaging techniques continue to extend the operational lifetime and stability of LEDs under various environmental conditions.