LTL1DETGELJ Bi-Color LED Datasheet - T-1 Package - Red/Green - 20mA - 53-79mW - English Technical Document

1. Product Overview

The LTL1DETGELJ is a bi-color, through-hole LED indicator lamp designed for status indication across a wide range of electronic applications. It features a popular T-1 (3mm) diameter package with a white diffused lens, housing both an AlInGaP red chip and an InGaN green chip within a single device. This configuration allows for two distinct color outputs from one compact component, offering design flexibility and space savings on printed circuit boards (PCBs).

1.1 Core Features and Advantages

The device offers several key advantages for designers. It provides low power consumption and high luminous efficiency, making it suitable for battery-powered or energy-conscious applications. The product is lead-free and fully RoHS compliant, meeting modern environmental regulations. Its standard T-1 form factor ensures compatibility with existing PCB layouts and automated insertion equipment. The combination of red and green in one package simplifies inventory and enables multi-state indication (e.g., power on/off, standby/active) without requiring multiple single-color LEDs.

1.2 Target Markets and Applications

This LED is engineered for broad applicability in consumer, industrial, and communication electronics. Typical application sectors include communication equipment (routers, modems, network switches), computer peripherals (desktops, laptops, external drives), consumer electronics (audio/video equipment, gaming consoles, toys), and home appliances (microwaves, coffee makers, washing machines). Its primary function is to provide clear, reliable visual status feedback to the end-user.

2. Technical Parameter Analysis

This section provides a detailed, objective interpretation of the key electrical, optical, and thermal parameters specified in the datasheet, crucial for reliable circuit design.

2.1 Absolute Maximum Ratings

These ratings define the stress limits beyond which permanent damage to the device may occur. Operation under or at these limits is not guaranteed. Key parameters include:

• Power Dissipation (Pd): 53 mW for the Red chip, 79 mW for the Green chip. This difference reflects the typical lower efficiency of InGaN (Green) compared to AlInGaP (Red) materials. Designers must ensure the operating point (Forward Current * Forward Voltage) remains below these values, considering ambient temperature (Ta).
• Forward Current: The maximum continuous DC forward current (IF) is 20 mA for both colors. A higher peak forward current of 60 mA is permissible only under strict pulsed conditions (duty cycle ≤ 1/10, pulse width ≤ 0.1ms). Exceeding the DC rating will accelerate lumen depreciation and can cause catastrophic failure.
• Temperature Ranges: The operating temperature range is -30°C to +85°C. The storage range is wider, from -40°C to +100°C. These ranges are typical for epoxy-encapsulated LEDs.
• Soldering Temperature: Leads can withstand 260°C for a maximum of 5 seconds, measured 2.0mm from the LED body. This is critical for wave or hand soldering processes.

2.2 Electrical and Optical Characteristics

These are the typical performance parameters measured at TA=25°C and IF=15 mA, the recommended test/operating condition.

• Luminous Intensity (Iv): The Green LED has a typical intensity of 2500 mcd (Min: 880, Max: 4200). The Red LED has a typical intensity of 1150 mcd (Min: 520, Max: 2500). The datasheet notes a ±30% testing tolerance must be included when guaranteeing intensity values. The high typical intensity, especially for green, makes this LED suitable for applications requiring high visibility.
• Viewing Angle (2θ1/2): Both colors have a typical viewing angle of 45 degrees. This defines the off-axis angle where luminous intensity drops to half its on-axis value, resulting in a moderately wide beam suitable for panel indicators.
• Wavelength: The Green LED has a typical dominant wavelength (λd) of 522 nm (range: 516-527 nm). The Red LED has a typical λd of 623 nm (range: 617-629 nm). The peak wavelengths (λp) are approximately 522 nm and 633 nm, respectively. The spectral half-width (Δλ) is 35 nm for Green and 20 nm for Red, indicating the Red LED has a more spectrally pure, narrower emission.
• Forward Voltage (VF): At 15 mA, VF is typically 3.1V for Green (Max: 3.8V) and 2.1V for Red (Max: 2.5V). This significant difference is due to the different semiconductor materials and must be accounted for in driver design, especially when using a common current-limiting resistor for both colors.
• Reverse Current (IR): Maximum reverse current is 100 μA at VR=5V. The datasheet explicitly states the device is not designed for reverse operation; this test is for characterization only. Applying reverse voltage in-circuit can damage the LED.

3. Binning System Specification

The product is sorted into bins based on luminous intensity and dominant wavelength to ensure consistency within a production lot. Designers can specify bins for color and brightness matching in critical applications.

3.1 Luminous Intensity Binning

Green LEDs are sorted into three intensity bins: PQ (880-1500 mcd), RS (1500-2500 mcd), and TU (2500-4200 mcd). Red LEDs are sorted into three bins: MN (520-880 mcd), PQ (880-1500 mcd), and RS (1500-2500 mcd). Each bin limit has a tolerance of ±15%.

3.2 Dominant Wavelength Binning

Green LEDs are binned into two wavelength codes: 1 (516-522 nm) and 2 (522-527 nm). Red LEDs are binned into codes 3 (617-623 nm) and 4 (623-629 nm). The tolerance for each bin limit is ±1 nm. This tight control helps maintain consistent color appearance, which is important for user interface design.

4. Mechanical and Packaging Information

4.1 Outline Dimensions and Polarity

The LED conforms to the standard T-1 (3mm) round through-hole package. Key dimensional notes include: all dimensions are in mm (inches), with a general tolerance of ±0.25mm; the maximum resin protrusion under the flange is 1.0mm; lead spacing is measured where leads emerge from the package. The longer lead typically denotes the anode (+). Designers must refer to the detailed dimensioned drawing (implied in the datasheet) for precise PCB hole spacing and placement.

4.2 Packing Specifications

The LEDs are supplied in industry-standard packaging: 500, 200, or 100 pieces per anti-static packing bag. Ten bags are packed into an inner carton (total 5,000 pcs). Eight inner cartons are packed into a master outer shipping carton (total 40,000 pcs). The datasheet notes that in every shipping lot, only the final pack may be a non-full pack.

5. Assembly, Handling, and Application Guidelines

Proper handling is essential for reliability. This section translates the datasheet\'s \"Cautions\" into actionable design and manufacturing advice.

5.1 Storage and Cleaning

For long-term storage outside the original packaging, store in a sealed container with desiccant or in a nitrogen ambient. The recommended storage condition is ≤30°C and ≤70% relative humidity. If cleaning is necessary, use alcohol-based solvents like isopropyl alcohol.

5.2 Lead Forming and PCB Assembly

Bend leads at a point at least 3mm from the base of the LED lens. Do not use the LED body as a fulcrum. Form leads before soldering and at room temperature. During PCB insertion, use the minimum clinch force required to avoid imposing mechanical stress on the epoxy lens or the internal wire bonds.

5.3 Soldering Process

Maintain a minimum distance of 2mm from the base of the lens to the solder point. Never immerse the lens in solder. Avoid external stress on the leads during soldering while the LED is hot. Recommended conditions:

• Soldering Iron: 350°C max, 3 seconds max per lead (one time only).
• Wave Soldering: Pre-heat to 100°C max for 60s max; solder wave at 260°C max for 5s max. Ensure the dipping position is no lower than 2mm from the lens base.
• Critical Note: IR reflow soldering is not suitable for this through-hole LED product. Excessive heat will damage the epoxy lens.

5.4 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 individual current-limiting resistor in series with each LED (Circuit A). Using a single resistor for multiple parallel LEDs (Circuit B) is not recommended, as small variations in the forward voltage (Vf) characteristic between individual LEDs will cause significant differences in current share and, therefore, brightness. The typical drive current is 15-20 mA DC.

5.5 Electrostatic Discharge (ESD) Protection

The LED is susceptible to damage from static electricity. Prevention measures include: using grounded wrist straps and anti-static gloves; ensuring all equipment, worktables, and storage racks are properly grounded; using an ion blower to neutralize static charge that may build up on the plastic lens during handling. A checklist for ESD-safe areas should include verification of personnel training and certification.

6. Application Notes and Design Considerations

6.1 Typical Application Scenarios

The bi-color functionality is ideal for dual-state indication. Common implementations include: Power Status (Green=On, Red=Off/Standby), Battery Condition (Green=Charged/Good, Red=Charging/Low), System Fault (Green=Normal, Red=Error/Alarm), and Communication Activity (Green=Link, Red=Data Tx/Rx). The high intensity allows for use in moderately bright ambient light conditions.

6.2 Circuit Design Example

To drive one color at a time from a microcontroller GPIO pin (assuming a 5V supply, Vf_green=3.1V, Vf_red=2.1V, desired If=15mA):
For Green: R = (Vcc - Vf_green) / If = (5 - 3.1) / 0.015 ≈ 127 Ω (use 130 Ω). Resistor power rating: P = I²R = (0.015)² * 130 = 0.029W (a standard 1/8W or 1/10W resistor is sufficient).
For Red: R = (5 - 2.1) / 0.015 ≈ 193 Ω (use 200 Ω).
Two separate resistors are needed if driving both colors from different pins. A series diode or transistor may be used to prevent reverse voltage if the driving circuit can go high-impedance or negative.

6.3 Thermal Management Considerations

While power dissipation is low, continuous operation at maximum current (20mA) and maximum junction temperature should be considered for long-term reliability. Ensure adequate airflow if the LED is enclosed. The maximum lead soldering temperature (260°C) also serves as a guideline for the maximum temperature the LED body should see during operation, which is well above the specified 85°C ambient.

7. Technical Comparison and Positioning

Compared to single-color T-1 LEDs, the primary advantage of the LTL1DETGELJ is component count reduction and simplified assembly for dual-indication needs. Against surface-mount bi-color LEDs, it offers easier manual prototyping and repair, higher potential current handling per package (due to lead frame), and greater robustness in high-vibration environments due to through-hole mounting. Its key differentiator is the combination of relatively high luminous intensity (especially green) with the reliability and simplicity of the through-hole T-1 form factor.

8. Frequently Asked Questions (FAQ)

8.1 Can I drive both the red and green LEDs simultaneously to create yellow/orange?

No, this specific bi-color LED package is designed for mutually exclusive operation of the red and green chips. Driving both at the same time is not specified in the datasheet and could lead to unpredictable color mixing, uneven current sharing, and potential overheating, as the thermal path is shared. For a true amber or yellow indication, a dedicated single-color LED of that wavelength should be selected.

8.2 Why is the forward voltage so different between the red and green chips?

The difference stems from the fundamental semiconductor materials. The Red chip uses AlInGaP (Aluminum Indium Gallium Phosphide), which has a lower bandgap energy, resulting in a lower forward voltage (~2.1V). The Green chip uses InGaN (Indium Gallium Nitride), which has a higher bandgap energy, requiring a higher forward voltage (~3.1V) to achieve the same current. This is a physical characteristic, not a manufacturing variance.

8.3 What is the expected lifetime of this LED?

While the datasheet does not specify a formal L70/B50 lifetime (hours to 70% lumen maintenance), typical indicator LEDs of this construction, when operated within their absolute maximum ratings (especially current and temperature), can have operational lifetimes exceeding 50,000 hours. Lifetime is primarily reduced by operating at high junction temperatures or driving currents.

8.4 How do I interpret the bin codes when ordering?

To ensure color and brightness consistency in your application, you should specify both the Luminous Intensity Bin Code (e.g., RS for Green) and the Dominant Wavelength Bin Code (e.g., 1 for Green) when placing an order. For example, requesting \"Green Bin RS-1\" would target LEDs with an intensity between 1500-2500 mcd and a dominant wavelength between 516-522 nm. Consult with the component supplier for availability of specific bin combinations.