LTL1DETGSN4J Bicolor LED Lamp Datasheet - T-1 Package - Voltage 2.0-3.6V - Power 72-120mW - Green/Yellow - English Technical Document

1. Product Overview

The LTL1DETGSN4J is a bicolor, through-hole LED lamp designed for use as a Circuit Board Indicator (CBI). It features a black plastic right-angle holder (housing) that mates with the LED, enhancing contrast ratio for improved visibility. The device is part of a family of indicators available in various configurations, including top-view and right-angle orientations, which are stackable for easy assembly into arrays.

1.1 Core Features and Advantages

• Ease of Assembly: Designed specifically for straightforward circuit board assembly and integration.
• Enhanced Visibility: The black housing provides a high contrast background, improving the perceived brightness and readability of the indicator.
• Energy Efficiency: Features low power consumption coupled with high luminous efficiency.
• Environmental Compliance: This is a lead-free product and is compliant with RoHS (Restriction of Hazardous Substances) directives.
• Optical Design: Utilizes a T-1 sized lamp with a white diffused lens. The emitted colors are generated by InGaN (Indium Gallium Nitride) for green and AlInGaP (Aluminum Indium Gallium Phosphide) for yellow.

1.2 Target Applications and Markets

This LED lamp is suitable for a wide range of electronic equipment and signage. Its primary application sectors include:

• Computer peripherals and status indicators
• Communication equipment
• Consumer electronics
• Industrial control panels and machinery

2. Technical Parameters: In-Depth Objective Interpretation

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 (P_D): 120 mW (Yellow), 72 mW (Green). This is the maximum power the LED can dissipate as heat at an ambient temperature (T_A) of 25°C.
• Peak Forward Current (I_FP): 100 mA (Yellow), 60 mA (Green). This current can only be applied under pulsed conditions (duty cycle ≤ 1/10, pulse width ≤ 10µs) to avoid overheating.
• DC Forward Current (I_F): 50 mA (Yellow), 20 mA (Green). This is the maximum continuous forward current recommended for reliable operation.
• Temperature Ranges: Operating: -30°C to +85°C; Storage: -40°C to +100°C.
• Lead Soldering Temperature: 260°C maximum for 5 seconds, measured 2.0mm (0.079\") from the LED body.

2.2 Electrical and Optical Characteristics

These are the typical performance parameters measured at T_A=25°C and I_F=20mA, unless otherwise specified.

• Luminous Intensity (I_v): A key measure of brightness.
  • Yellow: 1900-4200 mcd (millicandela), Typical 4200 mcd.
  • Green: 3200-5500 mcd, Typical 5500 mcd.
  • Note: Guaranteed intensity values include a ±30% testing tolerance.
• Viewing Angle (2θ_1/2): Approximately 40 degrees for both colors. This is the full angle at which the intensity drops to half of its peak axial value.
• Wavelength Specifications:
  • Peak Wavelength (λ_P): Yellow: 591 nm; Green: 519 nm.
  • Dominant Wavelength (λ_d): The single wavelength defining the perceived color. Yellow: 586-594 nm; Green: 515-530 nm.
  • Spectral Half-Width (Δλ): Yellow: 16 nm; Green: 35 nm. This indicates the spectral purity; a smaller value means a more monochromatic color.
• Forward Voltage (V_F): The voltage drop across the LED at the test current.
  • Yellow: 1.6-2.5 V, Typical 2.0 V.
  • Green: 2.6-3.6 V, Typical 3.2 V.
• Reverse Current (I_R): 10 µA maximum at V_R=5V. Important: This device is not designed for operation under reverse bias; this test condition is for characterization only.

3. Binning System Specification

The product is sorted into bins based on luminous intensity to ensure consistency within an application. The tolerance for each bin limit is ±15%.

3.1 Green LED Binning

• Bin Code U: Luminous Intensity range 3200 - 4200 mcd @ 20mA.
• Bin Code V: Luminous Intensity range 4200 - 5500 mcd @ 20mA.

3.2 Yellow LED Binning

• Bin Code S: Luminous Intensity range 1900 - 2500 mcd @ 20mA.
• Bin Code T: Luminous Intensity range 2500 - 3200 mcd @ 20mA.
• Bin Code U: Luminous Intensity range 3200 - 4200 mcd @ 20mA.

4. Performance Curve Analysis

The datasheet references typical characteristic curves which are essential for design. While the specific graphs are not reproduced in text, their implications are analyzed below.

4.1 Forward Current vs. Forward Voltage (I-V Curve)

The I-V curve is exponential. For the green LED (higher V_F), the curve will be shifted to the right compared to the yellow LED. This difference necessitates the use of individual current-limiting resistors when driving multiple LEDs in parallel to prevent current hogging by the LED with the lowest V_F.

4.2 Luminous Intensity vs. Forward Current

This curve is generally linear within the recommended operating current range. Increasing current increases brightness, but also power dissipation and junction temperature, which can affect longevity and wavelength.

4.3 Temperature Characteristics

LED performance is temperature-dependent. Typically, luminous intensity decreases as junction temperature increases. The forward voltage also has a negative temperature coefficient (decreases with increasing temperature). Designers must consider thermal management, especially when operating at high ambient temperatures or near maximum current ratings.

5. Mechanical and Packaging Information

5.1 Outline Dimensions

The device uses a standard T-1 (3mm) lamp diameter housed in a black right-angle holder. Key dimensional notes include:

• All dimensions are in millimeters (inches provided in parenthesis).
• Standard tolerance is ±0.25mm (.010\") unless specified otherwise.
• Maximum protrusion of resin under the flange is 1.0mm (.04\").
• Lead spacing is measured at the point where leads emerge from the package body.

5.2 Polarity Identification

For through-hole LEDs, the cathode is typically identified by a flat spot on the lens, a shorter lead, or other marking on the holder. The datasheet diagram should be consulted for the specific polarity indicator for this model.

6. Soldering and Assembly Guidelines

6.1 Lead Forming

• Bending must be done at a point at least 3mm from the base of the LED lens.
• Do not use the base of the lead frame as a fulcrum.
• Lead forming must be performed before soldering and at normal room temperature.

6.2 Soldering Process

A minimum clearance of 2mm must be maintained between the base of the lens/holder and the solder point.

• Soldering Iron: Max temperature 350°C, max time 3 seconds per lead (one time only).
• Wave Soldering:
  • Pre-heat: Max 120°C for up to 100 seconds.
  • Solder Wave: Max 260°C for up to 5 seconds.
  • The LED should not be dipped lower than 2mm from the base of the lens/holder into the solder wave.
• Critical Warning: Excessive temperature or time can deform the lens or cause catastrophic failure. IR reflow soldering is not suitable for this through-hole type product.

6.3 Storage and Handling

• Storage: Recommended environment is ≤ 30°C and ≤ 70% relative humidity. LEDs removed from original packaging should be used within three months. For longer storage, use a sealed container with desiccant or a nitrogen ambient.
• Cleaning: Use alcohol-based solvents like isopropyl alcohol if necessary.
• ESD Protection: LEDs are sensitive to electrostatic discharge. Use grounded wrist straps, workstations, and ionizers. Handle with care to avoid static buildup.

7. Packaging and Ordering Information

7.1 Packing Specification

The standard packaging flow is as follows:

1. Packing Bag: Contains 500, 200, or 100 pieces.
2. Inner Carton: Contains 10 packing bags, totaling 5,000 pieces.
3. Outer Carton: Contains 8 inner cartons, totaling 40,000 pieces.

Note: In a shipping lot, only the final pack may be a non-full pack.

8. Application Notes and Design Considerations

8.1 Drive Circuit Design

LEDs are current-driven devices. To ensure uniform brightness, especially when connecting multiple LEDs in parallel, a current-limiting resistor must be placed in series with each LED (Circuit Model A). Avoid connecting LEDs directly in parallel without individual resistors (Circuit Model B), as slight variations in their forward voltage (V_F) will cause significant differences in current share and thus brightness.

Recommended Circuit (A): [Vcc] -- [Resistor] -- [LED] -- [GND] (per LED branch).
Non-Recommended Circuit (B): [Vcc] -- [Resistor] -- [LED1 // LED2 // ...] -- [GND].

8.2 Thermal Management

While the power dissipation is low, operating at high ambient temperatures (up to 85°C) or at maximum current will increase the junction temperature. This reduces light output and can shift the dominant wavelength. For critical applications regarding color or brightness stability, derating the operating current or improving board-level airflow should be considered.

8.3 Optical Integration

The black housing provides inherent contrast. The 40-degree viewing angle offers a good balance between a focused beam and wide visibility. The white diffused lens helps to homogenize the light output, reducing hotspots and providing a more even appearance.

9. Frequently Asked Questions (Based on Technical Parameters)

9.1 Can I drive the green and yellow LEDs at the same current?

Yes, the recommended test and typical operating condition for both colors is I_F = 20mA. However, you must account for their different forward voltages (V_F) when designing the current-limiting resistor value for each color. The resistor value is calculated as R = (V_supply - V_F) / I_F.

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

Peak Wavelength (λ_P): The wavelength at which the spectral power distribution (the \"light output curve\") is maximum. It's a physical measurement.
Dominant Wavelength (λ_d): Derived from the color coordinates on the CIE chromaticity diagram, it represents the single wavelength of the pure spectral color that matches the perceived color of the LED. It is more relevant for color specification.

9.3 Why is the maximum power dissipation different for yellow and green?

The difference stems from the different semiconductor materials (AlInGaP for yellow, InGaN for green) and their respective internal efficiencies and thermal characteristics. The lower power rating for the green LED indicates a need for more careful thermal consideration at higher drive currents.

10. Practical Design Case Study

Scenario: Designing a status panel with 5 green and 3 yellow indicators, powered from a 5V rail. Goal: Achieve typical brightness at 20mA per LED.

1. Current Limiting Resistors:
   • For Green (Typ. V_F = 3.2V): R_green = (5V - 3.2V) / 0.020A = 90 Ω. Use a standard 91 Ω, 1/8W or 1/4W resistor.
   • For Yellow (Typ. V_F = 2.0V): R_yellow = (5V - 2.0V) / 0.020A = 150 Ω. Use a standard 150 Ω resistor.
2. Layout: Place resistors close to the LED anode pins. Ensure the 2mm soldering clearance from the LED holder is maintained on the PCB layout.
3. Power Calculation:
   • Total current: (5 * 20mA) + (3 * 20mA) = 160mA.
   • Ensure the 5V power supply can deliver this current with margin.

11. Operational Principle

Light Emitting Diodes (LEDs) are semiconductor p-n junction devices. When a forward voltage is applied, electrons from the n-region and holes from the p-region are injected into the junction region. When these charge carriers recombine, energy is released in the form of photons (light). The color (wavelength) of the emitted light is determined by the energy bandgap of the semiconductor material: AlInGaP for yellow/red/orange colors and InGaN for green/blue/white colors. The white diffused lens contains phosphors or scattering particles to soften and spread the light output.

12. Technology Trends

Through-hole LEDs like the T-1 package remain relevant in applications requiring robust mechanical mounting, high reliability in harsh environments, or manual assembly/prototyping. The industry trend, however, continues to shift towards surface-mount device (SMD) packages for automated assembly, higher density, and better thermal performance. Advancements in materials like InGaN have steadily improved the efficiency and brightness of green LEDs, closing the historical performance gap with other colors. Future developments may focus on increasing efficacy (lumens per watt) and color consistency across wider temperature ranges.