LTL-R14FSGAJ LED Lamp Datasheet - T-1 Package - Voltage 2.0V - Power 52mW - Yellow/Yellow-Green - English Technical Document

1. Product Overview

The LTL-R14FSGAJ is a through-hole LED lamp designed for status indication and signaling applications. It is offered in a standard T-1 type package with a white diffused lens, which helps to broaden the viewing angle and soften the light output. The product is available in two distinct colors: Yellow and Yellow-Green, utilizing AlInGaP (Aluminum Indium Gallium Phosphide) semiconductor technology. This technology is known for its high luminous efficiency and stability.

1.1 Core Features and Advantages

• Low Power Consumption & High Efficiency: Designed for energy-sensitive applications, offering bright output with minimal power draw.
• Environmental Compliance: The product is lead-free and fully compliant with RoHS (Restriction of Hazardous Substances) directives.
• Versatile Package: The white diffused T-1 package provides a wide, uniform viewing angle suitable for panel indication.
• Color Options: Available in specific shades of Yellow and Yellow-Green, providing clear visual distinction.

1.2 Target Applications and Markets

This LED is suitable for a broad range of electronic equipment requiring reliable and clear status indication. Primary application sectors include:

• Communication Equipment: Status lights on routers, modems, and network hardware.
• Computer Peripherals: Power and activity indicators on external drives, hubs, and keyboards.
• Consumer Electronics: Indicator lights on audio/video equipment, home appliances, and toys.
• Home Appliances: Power-on, mode, or timer indicators on various household devices.

2. In-Depth Technical Parameter Analysis

This section provides a detailed, objective interpretation of the key electrical and optical parameters that define the LED's performance.

2.1 Absolute Maximum Ratings

These ratings define the limits beyond which permanent damage to the device may occur. Operation under these conditions is not guaranteed.

• Power Dissipation (Pd): 52 mW. This is the maximum allowable power the LED can dissipate as heat at an ambient temperature (TA) of 25°C. Exceeding this limit risks overheating and reduced lifespan.
• DC Forward Current (IF): 20 mA. The recommended continuous operating current. The device can handle a higher Peak Forward Current of 60 mA, but only under pulsed conditions (duty cycle ≤ 1/10, pulse width ≤ 10 µs).
• Temperature Ranges: The device is rated for operation from -40°C to +85°C and can be stored from -40°C to +100°C.
• Lead Soldering Temperature: 260°C for a maximum of 5 seconds, measured 2.0mm from the LED body. This is critical for hand soldering or wave soldering processes.

2.2 Electrical & Optical Characteristics

These are the typical performance parameters measured at TA=25°C and IF=20mA, which is the standard test condition.

• Luminous Intensity (Iv): Typical value is 20 mcd for both colors, with a range from 7 mcd (Min) to 44 mcd (Max). This parameter is binned (see Section 4) to ensure consistency in brightness for production batches. The measurement includes a ±30% testing tolerance.
• Viewing Angle (2θ1/2): 120 degrees. This wide angle, facilitated by the diffused lens, makes the LED visible from a broad range of positions.
• Peak Emission Wavelength (λP): Approximately 590 nm for Yellow and 574 nm for Yellow-Green. This is the wavelength at which the emitted light intensity is highest.
• Dominant Wavelength (λd): Defines the perceived color. For Yellow, it ranges from 585-594 nm. For Yellow-Green, it ranges from 565-573 nm. This parameter is also binned.
• Spectral Line Half-Width (Δλ): Approximately 20 nm for both, indicating the spectral purity of the color.
• Forward Voltage (VF): Typically 2.0V, ranging from 1.6V to 2.5V at 20mA. This is a critical parameter for designing the current-limiting circuit.
• Reverse Current (IR): Maximum 10 µA at a Reverse Voltage (VR) of 5V. Important: This LED is not designed for reverse-bias operation; this test is for characterization only.

3. Binning System Specification

To ensure color and brightness consistency in mass production, LEDs are sorted into bins. The LTL-R14FSGAJ uses a two-dimensional binning system.

3.1 Luminous Intensity Binning

LEDs are categorized into three bins (A, B, C) based on their measured luminous intensity at 20mA.

• Bin A: 7 - 13 mcd
• Bin B: 13 - 24 mcd
• Bin C: 24 - 44 mcd

A tolerance of ±30% applies to each bin limit.

3.2 Dominant Wavelength Binning

LEDs are further categorized into bins based on their dominant wavelength, which defines the precise hue.

• For Yellow:
  • Bin 1: 585 - 589 nm
  • Bin 2: 589 - 594 nm
• For Yellow-Green:
  • Bin 1: 565 - 570 nm
  • Bin 2: 570 - 573 nm

A tolerance of ±1 nm applies to each bin limit. A full product code would specify both the intensity bin and the wavelength bin (e.g., C2).

4. Performance Curve Analysis

While specific graphical curves are referenced in the datasheet, their implications are described here. Typical curves for such LEDs include:

• Forward Current vs. Forward Voltage (I-V Curve): Shows the exponential relationship. A small change in voltage can cause a large change in current, underscoring the need for current-limiting resistors.
• Luminous Intensity vs. Forward Current: Intensity generally increases with current but may saturate or decrease at very high currents due to heating.
• Luminous Intensity vs. Ambient Temperature: Intensity typically decreases as ambient temperature rises. Understanding this derating is crucial for high-temperature applications.
• Spectral Distribution: A plot of relative intensity vs. wavelength, showing the peak (λP) and half-width (Δλ).

5. Mechanical & Packaging Information

5.1 Outline Dimensions

The LED conforms to the standard T-1 (3mm) radial leaded package dimensions. Key mechanical notes include:

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

5.2 Polarity Identification

Typically, the longer lead denotes the anode (positive), and the shorter lead denotes the cathode (negative). The cathode may also be indicated by a flat spot on the lens rim. Always verify polarity before soldering.

6. Soldering & Assembly Guidelines

Proper handling is essential to prevent damage.

6.1 Storage Conditions

Store in an environment not exceeding 30°C and 70% relative humidity. If removed from the original moisture-barrier bag, use within three months. For longer storage, use a sealed container with desiccant or a nitrogen ambient.

6.2 Lead Forming

• Bend leads at a point at least 3mm from the base of the LED lens.
• Do not use the lens base as a fulcrum.
• Perform forming before soldering, at room temperature.
• Use minimal clinch force during PCB assembly to avoid stress on the leads.

6.3 Soldering Process

Critical Rule: Maintain a minimum distance of 2mm from the base of the lens to the solder point. Do not immerse the lens in solder.

• Hand Soldering (Iron): Max temperature 350°C, max time 3 seconds per lead.
• Wave Soldering: Pre-heat to max 100°C for up to 60 seconds. Solder wave at max 260°C for up to 5 seconds.
• Not Recommended: IR reflow soldering is not suitable for this through-hole package type.

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

7. Packaging and Ordering Information

7.1 Packing Specification

The product is packed in bulk quantities for production use:

• Basic unit: 1000, 500, 200, or 100 pieces per anti-static packing bag.
• 10 packing bags are placed in one inner carton (total: 10,000 pcs).
• 8 inner cartons are packed in one outer shipping carton (total: 80,000 pcs).
• The last pack in a shipping lot may be a non-full pack.

8. Application Design Recommendations

8.1 Drive Circuit Design

LEDs are current-driven devices. To ensure uniform brightness, especially when connecting multiple LEDs in parallel, a series current-limiting resistor for each LED is mandatory (Circuit A). Direct parallel connection without individual resistors (Circuit B) is strongly discouraged due to variations in the forward voltage (VF) of individual LEDs, which will cause significant differences in current and, consequently, brightness.

The resistor value (R) can be calculated using Ohm's Law: R = (V_supply - V_F) / I_F, where V_F is the LED forward voltage (use typical or max value for reliability) and I_F is the desired forward current (e.g., 20mA).

8.2 Electrostatic Discharge (ESD) Protection

These LEDs are susceptible to damage from static electricity. Preventive measures include:

• Operators should wear grounded wrist straps or anti-static gloves.
• All workstations, tools, and equipment must be properly grounded.
• Use ionizers to neutralize static charges on work surfaces.

8.3 Cleaning

If cleaning is necessary after soldering, use only alcohol-based solvents like isopropyl alcohol. Avoid harsh or abrasive chemicals.

9. Technical Comparison and Considerations

Compared to older technologies like GaAsP, the AlInGaP used in this LED offers superior luminous efficiency and color stability over time and temperature. The T-1 through-hole package provides ease of use for prototyping and for applications where surface-mount technology (SMT) is not required or desired. Its wide viewing angle makes it ideal for front-panel indicators where the viewing position is not fixed.

10. Frequently Asked Questions (FAQ)

Q: Can I drive this LED at 30mA for higher brightness?

A: No. The Absolute Maximum Rating for continuous DC forward current is 20mA. Exceeding this rating violates the specifications and risks permanent damage or reduced reliability.

Q: What is the difference between Peak Wavelength and Dominant Wavelength?

A: Peak Wavelength (λP) is where the spectral output is physically highest. Dominant Wavelength (λd) is a calculated value from colorimetry that best represents the color perceived by the human eye. λd is more relevant for color specification.

Q: Can I use this LED outdoors?

A: The datasheet states it is suitable for indoor and outdoor signs. However, for harsh outdoor environments, consider additional protection (conformal coating, UV-stable enclosures) as the epoxy lens may degrade under prolonged UV exposure.

Q: Why is a series resistor needed for each LED in parallel?

A> Due to manufacturing tolerances, each LED has a slightly different forward voltage (VF). Without individual resistors, the LED with the lowest VF will draw disproportionately more current, becoming brighter and potentially failing, leading to a chain reaction.

11. Practical Design Case Study

Scenario: Designing a power indicator for a 5V USB-powered device using the Yellow-Green LTL-R14FSGAJ LED.

Step 1 - Choose Operating Point: Use the typical forward current, I_F = 20 mA.

Step 2 - Determine Forward Voltage: From the datasheet, use the typical V_F = 2.0V (or the maximum 2.5V for a more conservative, reliable design).

Step 3 - Calculate Resistor Value: Using V_supply = 5V and V_F = 2.5V.

R = (5V - 2.5V) / 0.020 A = 125 Ohms.

Step 4 - Select Standard Resistor: Choose the nearest standard value, e.g., 120 Ohms or 150 Ohms. A 120 Ohm resistor would yield I_F ≈ 20.8 mA, which is acceptable. A 150 Ohm resistor yields I_F ≈ 16.7 mA, resulting in slightly lower but still sufficient brightness with lower power consumption.

Step 5 - Calculate Resistor Power: P = I² * R = (0.020)² * 120 = 0.048 W. A standard 1/8W (0.125W) or 1/4W resistor is more than adequate.

12. 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 specific color of the light is determined by the energy band gap of the semiconductor material. The LTL-R14FSGAJ uses AlInGaP, which is engineered to produce light in the yellow to yellow-green spectrum. The white diffused epoxy lens encapsulates the semiconductor chip, provides mechanical protection, and scatters the light to create a wide viewing angle.

13. Industry Trends and Context

While surface-mount device (SMD) LEDs dominate modern high-density electronics, through-hole LEDs like the T-1 package remain relevant for several reasons: ease of manual assembly and prototyping, superior mechanical strength in connectors or devices subject to vibration, and suitability for applications where the LED needs to protrude through a panel. The trend for through-hole components is towards niche applications that leverage these specific advantages, while general indicator markets continue to shift towards smaller SMD packages. The technology inside, such as AlInGaP, continues to benefit from material science advancements leading to ever-higher efficiencies and reliability.