T-1 3mm Bi-Color LED LTL1DETGEVK Datasheet - Red/Green - 30mA - 120mW - English Technical Document

1. Product Overview

The LTL1DETGEVK is a through-hole bi-color LED lamp featuring a popular T-1 (3mm) diameter package. It is designed to provide status indication in a wide range of electronic applications. The device incorporates both red and green LED chips within a single water-clear lens, offering design flexibility for visual feedback systems.

1.1 Core Advantages

• Low Power Consumption & High Efficiency: Designed for energy-efficient operation, making it suitable for battery-powered or power-sensitive applications.
• Lead-Free & RoHS Compliant: Manufactured in compliance with environmental regulations, ensuring suitability for global markets.
• Standard Package: The T-1 (3mm) form factor is widely used and compatible with standard PCB layouts and mounting hardware.
• Bi-Color Functionality: Integrates red and green emission in one device, simplifying board design and reducing part count for multi-color indication.

1.2 Target Applications

This LED is suitable for status indication across multiple industries, including:

• Communication Equipment
• Computer Peripherals and Motherboards
• Consumer Electronics
• Home Appliances and Control Panels

2. Technical Parameter Deep Dive

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

2.1 Absolute Maximum Ratings

These ratings define the stress limits beyond which permanent damage to the device may occur. Operation outside these limits is not advised.

• Power Dissipation (Pd): Green: 120 mW max, Red: 79 mW max. This difference is due to the typical lower forward voltage and potentially different internal construction of the red chip, resulting in different thermal characteristics. The designer must ensure the operating conditions do not exceed this limit, considering ambient temperature and any heat sinking.
• Forward Current: DC Forward Current is rated at 30 mA for both colors. A higher Peak Forward Current of 90 mA is permissible only under strict pulsed conditions (duty cycle ≤ 1/10, pulse width ≤ 0.1µs). Continuous operation must not exceed the DC rating.
• 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 Electrical & Optical Characteristics

These are typical and minimum/maximum values measured under specific test conditions (TA=25°C, IF=20mA unless noted).

• Luminous Intensity (Iv): A key performance metric. For Green, typical is 9500 mcd (Min: 3200, Max: 16000). For Red, typical is 900 mcd (Min: 350, Max: 2500). The significant difference in output between colors is normal and must be accounted for in circuit design if uniform perceived brightness is required.
• Viewing Angle (2θ1/2): Approximately 30 degrees for both colors. This defines the cone within which the luminous intensity is at least half of the on-axis intensity. It is a standard, narrow viewing angle suitable for directed indication.
• Wavelength:
  • Peak Wavelength (λP): Green: 518 nm (typ), Red: 633 nm (typ). This is the wavelength at the highest point of the emission spectrum.
  • Dominant Wavelength (λd): Green: 525 nm (typ, range 519-531 nm), Red: 625 nm (typ). This is the single wavelength perceived by the human eye that defines the color.
  • Spectral Half-Width (Δλ): Green: 35 nm (typ), Red: 20 nm (typ). This indicates the color purity; a smaller value means a more monochromatic light.
• Forward Voltage (VF): Green: 3.5V (typ, max 4.0V). Red: 2.1V (typ, max 2.5V). This is crucial for designing the current-limiting resistor. The voltage drop differs significantly between colors, meaning a single resistor value for both may not provide equal current.
• Reverse Current (IR): Maximum 100 µA at VR=5V. This device is not designed for reverse bias operation; this parameter is for leakage test purposes only. Protection against reverse voltage in the application circuit is essential.

3. Binning System Specification

The product is sorted into bins based on key optical parameters to ensure consistency within a production lot. Tolerance on bin limits is specified.

3.1 Luminous Intensity Binning

Units: mcd @ 20mA.

• Red Bins: KL (350-520), MN (520-680), PQ (680-1500), RS (1500-2500).
• Green Bins: VW (3200-5500), XY (5500-9300), Z5A (9300-16000).
• Tolerance: ±15% on each bin limit. This means a part binned as "KL" could have an intensity as low as ~298 mcd or as high as ~598 mcd.

3.2 Dominant Wavelength Binning (Green Only)

Units: nm @ 20mA.

• Green Bins: G2 (519-525 nm), G3 (525-531 nm).
• Tolerance: ±1 nm on each bin limit. This tight control ensures consistent green color perception across devices from the same bin.

4. Performance Curve Analysis

While specific graphical curves are referenced in the datasheet (Fig.1, Fig.6), their implications are standard for LED technology.

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

The I-V curve is exponential. A small increase in voltage causes a large increase in current. This nonlinear relationship is why LEDs must be driven with a current-limiting mechanism (e.g., a series resistor or constant current source) and not directly with a voltage source.

4.2 Luminous Intensity vs. Forward Current

Luminous intensity is approximately proportional to forward current within the operating range. However, efficiency may drop at very high currents due to increased heat.

4.3 Temperature Characteristics

LED performance is temperature-dependent:

• Forward Voltage (VF): Decreases with increasing junction temperature (negative temperature coefficient).
• Luminous Intensity (Iv): Decreases with increasing junction temperature. The datasheet specifies characteristics at 25°C; output will be lower at higher ambient temperatures.
• Wavelength: Typically shifts slightly with temperature (usually towards longer wavelengths for AlInGaP and InGaN LEDs).

5. Mechanical & Package Information

5.1 Outline Dimensions

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

• All dimensions are in millimeters (inches provided in parenthesis).
• Standard tolerance is ±0.25mm unless otherwise specified.
• Maximum resin protrusion under the flange is 1.0mm.
• Lead spacing is measured where leads exit the package body, which is critical for PCB footprint design.

5.2 Polarity Identification

For through-hole LEDs, polarity is typically indicated by two features:

• Lead Length: The longer lead is usually the anode (positive).
• Package Flat: Many LED packages have a flat side on the rim (flange) nearest the cathode (negative) lead. The datasheet outline drawing should be consulted for the specific polarity marking of this device.

Applying reverse voltage can damage the LED.

6. Soldering & Assembly Guidelines

Adherence to these guidelines is critical for reliability and preventing damage during manufacturing.

6.1 Storage Conditions

Recommended storage ambient: ≤ 30°C and ≤ 70% relative humidity. LEDs removed from their original moisture-barrier bags should be used within three months. For longer storage, use a sealed container with desiccant or a nitrogen atmosphere.

6.2 Lead Forming

• Bend leads at a point at least 3mm from the base of the LED lens.
• Do not use the package body as a fulcrum for bending.
• Perform all lead forming at room temperature and before the soldering process.
• Use minimum clinch force during PCB insertion to avoid mechanical stress on the epoxy lens or internal bonds.

6.3 Soldering Process

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

• Hand/Iron Soldering: Maximum temperature: 350°C. Maximum time: 3 seconds per lead. One-time soldering only.
• Wave Soldering:
  • Pre-heat: Max 100°C for up to 60 seconds.
  • Solder Wave: Max 260°C.
  • Contact Time: Max 5 seconds.
  • Dipping Position: No lower than 2mm from the lens base.
• Not Recommended: IR reflow soldering is not suitable for this through-hole package type. Excessive heat or time can cause lens deformation or catastrophic failure.

6.4 Cleaning

If cleaning is necessary, use alcohol-based solvents such as isopropyl alcohol. Avoid harsh or abrasive cleaners.

7. Packaging & Ordering Information

7.1 Packaging Specification

The device is packed in a multi-level hierarchy:

1. Basic Unit: 500, 200, or 100 pieces per anti-static packing bag.
2. Inner Carton: Contains 10 packing bags, totaling 5,000 pieces.
3. Outer Carton (Shipping Box): Contains 8 inner cartons, totaling 40,000 pieces.

Note: Within a shipping lot, only the final pack may contain a non-full quantity.

8. Application Design Recommendations

8.1 Drive Circuit Design

An LED is a current-driven device. To ensure consistent brightness and longevity:

• Use a Series Current-Limiting Resistor: This is the most common and recommended method (Circuit A in the datasheet). The resistor value is calculated using Ohm's Law: R = (Vcc - Vf_LED) / I_desired, where Vf_LED is the forward voltage of the active LED color (Red or Green).
• Avoid Direct Parallel Connection: Connecting multiple LEDs directly in parallel with a single resistor (Circuit B) is not recommended. Small variations in the forward voltage (Vf) characteristic between individual LEDs will cause significant imbalance in current sharing, leading to uneven brightness and potential over-stress of the LED with the lowest Vf.
• Bi-Color Control: To control red and green independently, two separate drive circuits (each with its own resistor and switch/GPIO pin) are required, connected with opposite polarity (common-cathode or common-anode configuration). The datasheet does not specify the internal chip configuration; the schematic must be designed accordingly.

8.2 Electrostatic Discharge (ESD) Protection

LEDs are sensitive to electrostatic discharge. Preventive measures must be implemented in the handling and assembly environment:

• Personnel must wear grounded wrist straps or anti-static gloves.
• All equipment, workstations, and storage racks must be properly grounded.
• Use ionizers to neutralize static charge that may build up on the plastic lens.
• Implement ESD training and certification programs for all handling personnel.

8.3 Thermal Management

While this is a low-power device, adhering to the maximum power dissipation and operating temperature ratings is essential for long-term reliability. Ensure adequate airflow in the end application, especially if multiple LEDs are used in close proximity or are driven near their maximum current rating.

9. Technical Comparison & Differentiation

The LTL1DETGEVK's primary differentiation lies in its combination of features within the ubiquitous T-1 package:

• Bi-Color in Standard Package: Offers two colors (Red/Green) in a single 3mm device, saving board space and simplifying inventory compared to using two single-color LEDs.
• Water-Clear Lens: Provides the true color of the chip emission. This differs from diffused lenses which scatter light for a wider viewing angle but with reduced on-axis intensity.
• Balanced Performance: Offers relatively high luminous intensity for green and standard intensity for red, with defined binning for predictable performance.
• Robust Specifications: Includes detailed absolute maximum ratings, soldering guidelines, and application cautions that are critical for reliable manufacturing.

10. Frequently Asked Questions (Based on Technical Parameters)

Q1: Why is the typical luminous intensity for the green LED so much higher than for the red?
A1: This is primarily due to the spectral sensitivity of the human eye (photopic response), which peaks in the green-yellow region (~555 nm). The eye is less sensitive to red light (~625 nm). Therefore, to achieve a similar perceived brightness, a red LED would need to emit more radiant power. The difference in chip technology (InGaN for green, AlInGaP for red) also influences efficiency.

Q2: Can I drive the red and green LEDs simultaneously to create yellow/orange?
A2: No, this device is a bi-color LED, not a tri-color or RGB LED. The internal construction typically has two dies connected in inverse parallel (common-cathode or common-anode). Applying voltage in one polarity lights one color; reversing the polarity lights the other. They cannot be energized simultaneously to mix light within the package.

Q3: What resistor value should I use for a 5V supply?
A3: You need separate calculations for each color due to different Vf.

• For Green (Vf_typ=3.5V, I=20mA): R = (5V - 3.5V) / 0.02A = 75 Ohms. Use the nearest standard value (e.g., 75Ω or 82Ω). Check power rating: P = I²R = (0.02)² * 75 = 0.03W, so a 1/8W or 1/10W resistor is sufficient.
• For Red (Vf_typ=2.1V, I=20mA): R = (5V - 2.1V) / 0.02A = 145 Ohms. Nearest standard value is 150Ω.

Always use the maximum Vf from the datasheet for a conservative design to limit maximum current.

Q4: Is this LED suitable for outdoor use?
A4: The datasheet states it is good for indoor and outdoor signs. However, for harsh outdoor environments, consider additional factors not fully detailed in this sheet: UV resistance of the epoxy (which is water-clear), moisture ingress protection, and extended temperature cycling performance. Conformal coating on the PCB may be necessary for long-term outdoor reliability.

11. Practical Design & Usage Case

Scenario: Dual-Status Indicator on a Network Router
A designer needs a single indicator to show Power (Green) and Network Activity (Blinking Red). Using the LTL1DETGEVK simplifies the design.

1. Circuit: A microcontroller GPIO pin is connected to the LED anode through a 75Ω resistor. The LED cathode is connected to a second GPIO pin configured as an output.
2. Operation:
   • To light Green: Set Pin1 (anode) HIGH and Pin2 (cathode) LOW.
   • To light Red: Set Pin1 LOW and Pin2 HIGH.
   • To turn Off: Set both pins to the same logic level (both HIGH or both LOW).
   • Network Activity: Rapidly toggle between the Red and Off states by switching Pin2.
3. Benefits: Uses only one component footprint, two GPIO pins, and two resistors, providing clear, dual-function status indication in a compact space.

12. Operating Principle

Light Emitting Diodes (LEDs) are semiconductor devices that emit light through electroluminescence. When a forward voltage is applied across the p-n junction, electrons from the n-type material recombine with holes from the p-type material in the active region. This recombination releases energy in the form of photons (light). The wavelength (color) of the emitted light is determined by the energy bandgap of the semiconductor materials used in the active region. The LTL1DETGEVK contains two such semiconductor structures within one package: one engineered to emit green light (likely using Indium Gallium Nitride - InGaN) and one to emit red light (likely using Aluminum Indium Gallium Phosphide - AlInGaP).

13. Technology Trends

The through-hole LED market, particularly for standard indicator types like the T-1 package, is mature. Key trends influencing this segment include:

• Continued Demand for Legacy Support: While surface-mount device (SMD) LEDs dominate new designs, through-hole LEDs remain essential for servicing existing equipment, prototyping, hobbyist use, and applications requiring superior mechanical bond strength or higher single-point brightness in a radial package.
• Focus on Efficiency and Reliability: Even in established packages, incremental improvements in internal quantum efficiency and epoxy lens materials lead to higher luminous intensity and better long-term color stability.
• Environmental Compliance: The drive towards lead-free, RoHS, and potentially halogen-free materials continues to be a baseline requirement for all components, including through-hole LEDs.
• Integration: The bi-color feature of this device represents a form of integration, packing more functionality into a standard footprint. This trend continues with more complex multi-chip packages.

While not at the forefront of cutting-edge LED technology like micro-LEDs, through-hole LEDs like the LTL1DETGEVK will remain a reliable, cost-effective solution for indicator applications for the foreseeable future.