Bicolor LED Lamp LTLR1DESTBKJH155T Datasheet - Blue/Yellow - 3.2V/2.1V - 70mW/75mW - English Technical Document

1. Product Overview

This document details the specifications for a bicolor through-hole LED lamp assembly. The product consists of a T-1 sized LED lamp, featuring InGaN blue and AlInGaP yellow chips, housed within a black plastic right-angle holder (housing). This assembly is designed as a Circuit Board Indicator (CBI), offering a high-contrast visual signal suitable for various electronic equipment. The primary function is to provide status indication through two distinct colors from a single package, mounted perpendicular to the PCB plane.

1.1 Core Advantages

• Ease of Assembly: The design is optimized for straightforward circuit board assembly and is compatible with tape-and-reel automated placement processes.
• Enhanced Visibility: The black housing material significantly improves the contrast ratio, making the illuminated LED more visible against the board background.
• Dual-Color Functionality: Integrates blue (470nm typical) and yellow (589nm typical) LEDs in one package, allowing for multiple status indications.
• Environmental Compliance: The product is lead-free and fully compliant with RoHS (Restriction of Hazardous Substances) directives.
• Low Power Consumption: Designed for efficient operation with typical forward currents of 10-20mA.

1.2 Target Applications

This component is intended for status indication and visual signaling in a wide range of electronic devices. Key application markets include:

• Communication Equipment: Network switches, routers, modems.
• Computer Systems: Servers, desktop PCs, peripheral devices.
• Consumer Electronics: Audio/video equipment, home appliances, gaming consoles.
• Industrial Controls: Instrumentation panels, control systems, automation equipment.

2. In-Depth Technical Parameter Analysis

The following section provides a detailed, objective interpretation of the key electrical, optical, and thermal parameters specified for the device. All data is referenced at an ambient temperature (TA) of 25°C unless otherwise stated.

2.1 Absolute Maximum Ratings

These ratings define the stress limits beyond which permanent damage to the device may occur. Operation at or near these limits is not recommended for normal use.

• Power Dissipation (PD): Blue: 70 mW, Yellow: 75 mW. This parameter limits the total electrical power (IF * VF) that can be converted into heat within the LED die.
• Forward Current: Continuous DC: Blue: 20 mA, Yellow: 30 mA. Peak (pulsed): 60 mA for both colors under specific conditions (Duty Cycle ≤1/10, Pulse Width ≤10µs). Exceeding the DC current will accelerate lumen depreciation and may cause catastrophic failure.
• Temperature Ranges: Operating: -30°C to +85°C. Storage: -40°C to +100°C. These define the environmental limits for reliable function and non-operational storage.
• 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 Electro-Optical Characteristics

These are the typical performance parameters under specified test conditions, representing the expected behavior of the device.

• Luminous Intensity (Iv): Measured at IF=10mA. Blue: 520 mcd (Typical), Yellow: 310 mcd (Typical). The datasheet notes a ±30% testing tolerance must be included for guarantee purposes, indicating significant unit-to-unit variation.
• Viewing Angle (2θ1/2): Approximately 40 degrees for both colors. This is the full angle at which luminous intensity drops to half its on-axis value, defining the beam spread.
• Wavelength:
  • Peak Wavelength (λP): Blue: 468 nm, Yellow: 591 nm (at measurement peak).
  • Dominant Wavelength (λd): Blue: 470 nm (Typical), Yellow: 589 nm (Typical). Dominant wavelength is the perceptual color as defined by the CIE chromaticity diagram.
• Forward Voltage (VF): At IF=10mA. Blue: 3.2V (Typical, range 2.6-3.5V), Yellow: 2.1V (Typical, range 1.7-2.5V). The different VF values for the two colors are crucial for circuit design, especially when driving them from a common current source.
• Reverse Current (IR): Maximum 10 µA at VR=5V. The datasheet explicitly states the device is not designed for reverse operation; this test is for characterization only.

3. Binning System Explanation

The product is sorted into bins based on key optical parameters to ensure consistency within a production lot. Designers must account for these ranges.

3.1 Luminous Intensity Binning

LEDs are grouped by their measured luminous intensity at 10mA. The bin code is part of the full part number (e.g., 'HJ' in LTLR1DESTBKJH155T).

• Blue LED Bins: FG (110-180 mcd), HJ (180-310 mcd), KL (310-520 mcd).
• Yellow LED Bins: DE (65-110 mcd), FG (110-180 mcd), HJ (180-310 mcd).
• Tolerance: Each bin limit has a ±30% tolerance, meaning the actual minimum/maximum values for a given bin can vary by this amount.

3.2 Hue (Dominant Wavelength) Binning

LEDs are also sorted by their dominant wavelength to control color consistency.

• Blue LED Hue Bins: Code 1 (464.0-470.0 nm), Code 2 (470.0-476.0 nm).
• Yellow LED Hue Bins: Code 3 (582.0-589.0 nm), Code 4 (589.0-596.0 nm).
• Tolerance: Each bin limit has a tight ±1 nm tolerance.

The complete part number specifies the exact intensity and hue bin for both the blue and yellow components, allowing precise selection for application requirements.

4. Performance Curve Analysis

While the PDF references typical curves, their general behavior can be inferred from the tabular data and semiconductor physics.

4.1 Current vs. Voltage (I-V) Characteristic

The forward voltage (VF) exhibits a logarithmic relationship with current. For the blue LED (InGaN), VF is higher (~3.2V @10mA) compared to the yellow LED (AlInGaP, ~2.1V @10mA) due to different semiconductor bandgap energies. VF has a negative temperature coefficient, decreasing as junction temperature rises.

4.2 Optical Output vs. Current (L-I Characteristic)

Luminous intensity is approximately linear with forward current in the specified operating range (up to 20-30mA). However, efficiency (lumens per watt) may decrease at higher currents due to increased heat generation and droop effects. The different intensity bins represent variations in this L-I characteristic across the manufacturing population.

4.3 Temperature Dependence

LED light output decreases as junction temperature increases. The yellow AlInGaP LED typically has a more pronounced temperature sensitivity (greater output drop with heat) than the blue InGaN LED. Proper thermal management is essential to maintain consistent brightness and long-term reliability.

5. Mechanical and Packaging Information

5.1 Outline Dimensions and Construction

The device uses a black plastic right-angle holder. Key mechanical notes include:

• All dimensions are in millimeters, with a general tolerance of ±0.25mm unless specified otherwise.
• The housing material is black plastic.
• The integrated T-1 lamp has a white diffused lens, which broadens the viewing angle and softens the appearance of the LED die.
• The right-angle design allows the LED to be mounted on the edge of a PCB, emitting light parallel to the board surface, which is ideal for front-panel indication.

5.2 Polarity Identification

As a bicolor LED in a common-cathode or common-anode configuration (specific configuration must be verified from the detailed pinout diagram, which is referenced but not fully detailed in the provided excerpt), correct polarity is essential. Applying reverse voltage exceeding 5V can cause immediate damage. The longer lead typically denotes the anode for a single-color LED, but for bicolor types, marking on the housing or datasheet diagram must be consulted.

6. Soldering and Assembly Guidelines

6.1 Storage Conditions

LEDs are moisture-sensitive devices (MSD).

• Sealed Bag: Store at ≤30°C and ≤70% RH. Shelf life is one year in the original moisture barrier bag (MBB) with desiccant.
• Opened Bag: Store at ≤30°C and ≤60% RH. Components should be IR-reflowed within 168 hours (1 week) of bag opening.
• Extended Exposure: If exposed >168hrs, a bake at 60°C for at least 48 hours is required before soldering to prevent popcorn cracking during reflow.

6.2 Lead Forming and Handling

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

6.3 Soldering Process

• Maintain a minimum 2mm clearance from the base of the lens to the solder point.
• Avoid dipping the lens into solder or flux.
• Do not apply external stress to the leads during or after soldering.
• For cleaning, use only alcohol-based solvents like isopropyl alcohol.

7. Packaging and Ordering Information

7.1 Packaging Specification

The device is supplied in tape-and-reel packaging for automated assembly.

• Carrier Tape: Black conductive polystyrene alloy, 0.50mm thickness.
• Reel Capacity: 450 pieces per 13-inch reel.
• Carton Packing:
  • 1 Reel + desiccant + humidity card in 1 Moisture Barrier Bag (MBB).
  • 2 MBBs in 1 Inner Carton (900 pieces total).
  • 10 Inner Cartons in 1 Outer Carton (9,000 pieces total).

8. Application Design Recommendations

8.1 Typical Application Circuits

Each color LED should be driven independently with a current-limiting resistor. Due to the different forward voltages (Blue ~3.2V, Yellow ~2.1V), using a common resistor for both LEDs in parallel is not recommended, as it will cause severe current imbalance. Separate current-limiting resistors must be calculated based on the supply voltage (Vcc), the desired current (IF, typically 10-20mA), and the LED's VF. Formula: R = (Vcc - VF) / IF.

8.2 Design Considerations

• Current Driving: Always drive LEDs with a constant current or a voltage source with a series resistor. Direct connection to a voltage source will cause uncontrolled current flow and failure.
• Heat Management: Although power dissipation is low, ensure adequate PCB copper area or ventilation if operating at maximum current or in high ambient temperatures to maintain junction temperature within limits.
• Visual Design: The black holder provides excellent contrast. Consider the 40-degree viewing angle when designing light pipes or panel cutouts to ensure visibility from the intended viewing positions.
• Binning Impact: For applications requiring uniform brightness across multiple units, specify a tight intensity bin (e.g., HJ for both colors) and ensure procurement from the same manufacturing lot if possible.

9. Technical Comparison and Differentiation

Compared to single-color through-hole LEDs or surface-mount alternatives, this product offers specific advantages:

• vs. Two Single-Color LEDs: Saves PCB space, reduces part count, and simplifies assembly by using one footprint for two indication functions.
• vs. SMD Bicolor LEDs: The through-hole right-angle design is often more robust for manual assembly, repair, and applications subject to vibration or mechanical stress. It also facilitates front-panel mounting without additional light pipes.
• vs. Tri-color RGB LEDs: Offers a simpler, often lower-cost solution when only two specific colors (blue and yellow/amber) are required for status indication (e.g., power/standby, active/idle, OK/warning).

10. Frequently Asked Questions (Based on Technical Parameters)

10.1 Can I drive both LEDs simultaneously from one pin?

No, not directly. The blue and yellow LEDs have different forward voltages. Connecting them in parallel to a single current source will cause most of the current to flow through the yellow LED (lower VF), potentially overdriving it while leaving the blue LED dim or off. They must be driven by separate circuits or a driver IC capable of independent current control.

10.2 What is the difference between Peak and Dominant Wavelength?

Peak Wavelength (λP) is the wavelength at the highest point in the LED's spectral power distribution curve. Dominant Wavelength (λd) is a calculated value from the CIE color chart that represents the perceived color as a single wavelength. λd is more relevant for color indication applications, while λP is more relevant for spectral analysis.

10.3 Why is there a ±30% tolerance on luminous intensity guarantees?

This reflects inherent variations in the semiconductor epitaxy and manufacturing process. The binning system is used to sort LEDs into groups with much tighter relative performance. The tolerance applies to the bin limits themselves, meaning a bin labeled 180-310 mcd could have units as low as 126 mcd (180 -30%) or as high as 403 mcd (310 +30%) at the test limits.

11. Practical Use Case Examples

11.1 Network Switch Port Status Indicator

In an Ethernet switch, a single bicolor LED per port can indicate multiple states: Off (no link), Solid Yellow (10/100 Mbps link), Solid Blue (1 Gbps link), Blinking Yellow (data activity at lower speed), Blinking Blue (data activity at higher speed). This consolidates what might require two separate LEDs into one, saving front-panel space.

11.2 Power Supply Unit (PSU) Status

On a server or industrial PSU, the LED can indicate: Off (AC power absent), Solid Yellow (AC present, DC outputs off/standby), Solid Blue (DC outputs on and within regulation). The high contrast of the black holder ensures clear visibility in rack-mounted environments.

12. Operational Principle

Light Emitting Diodes (LEDs) are semiconductor p-n junction devices. When a forward voltage exceeding the material's bandgap energy is applied, electrons recombine with holes in the depletion region, releasing energy in the form of photons (light). The color of the light is determined by the bandgap energy of the semiconductor material. InGaN (Indium Gallium Nitride) is used for blue emission, and AlInGaP (Aluminum Indium Gallium Phosphide) is used for yellow/amber emission. The white diffused lens contains phosphors or scattering particles to widen the viewing angle and soften the light output. The two semiconductor chips are housed within a single T-1 package with a common electrical connection (common cathode or anode) for compactness.

13. Technology Trends

The through-hole LED market for indicators has matured, with a gradual shift towards surface-mount device (SMD) packages like 0603, 0402, and side-view types for higher-density PCB designs. However, through-hole LEDs, especially right-angle types, maintain strong relevance in applications requiring higher mechanical robustness, easier manual assembly/serviceability, and specific optical mounting angles without secondary optics. The technology trend within this segment focuses on improving efficiency (higher mcd/mA), achieving tighter color and intensity binning for consistency, and enhancing reliability under wider temperature and humidity ranges. The integration of multiple colors/chips in a single package, as seen in this product, remains a key method to increase functionality per unit area on a PCB.