LTL30EGRPJ Through Hole LED Lamp Datasheet - T-1 3/4 Package - 2.1V Typ - Red/Green - 78mW - English Technical Document

1. Product Overview

The LTL30EGRPJ is a bi-color, common cathode, through-hole LED lamp designed for status indication and visual signaling applications. It features a popular T-1 3/4 (approximately 5mm) diameter diffused package, housing both a red and a green LED chip. This configuration allows for the display of two distinct colors from a single component, controlled via its common cathode terminal arrangement. The device is characterized by its low power consumption, high luminous efficiency, and compliance with lead-free and RoHS environmental standards, making it suitable for a wide range of modern electronic designs.

1.1 Core Advantages

• Dual-Color Output: Integrates red and green emitters in one compact package, saving board space and simplifying assembly compared to using two separate LEDs.
• High Efficiency: Delivers high luminous intensity (up to 520 mcd for green, 400 mcd for red) at a standard 20mA drive current, ensuring bright and clear visibility.
• Design Flexibility: The common cathode configuration simplifies circuit design for multiplexing or independent control of the two colors using a microcontroller or logic circuits.
• Robust Construction: The through-hole design provides strong mechanical attachment to the PCB and is suitable for wave soldering processes.
• Environmental Compliance: Manufactured to be lead-free and RoHS compliant, meeting global environmental regulations.

1.2 Target Markets and Applications

This LED is versatile and targets applications across multiple industries where reliable, low-cost status indication is required. Its primary application sectors include:

• Communication Equipment: Status lights on routers, modems, switches, and telecommunication devices.
• Computer Peripherals: Power, activity, and mode indicators on keyboards, monitors, external drives, and printers.
• Consumer Electronics: Indicator lights on audio/video equipment, home appliances, toys, and gaming devices.
• Home Appliances: Operational status, power-on, timer, and function mode indicators on microwaves, washing machines, and air conditioners.
• Industrial Controls: Panel indicators for machinery, test equipment, and control systems.

2. In-Depth Technical Parameter Analysis

A thorough understanding of the electrical and optical parameters is crucial for reliable circuit design and achieving desired performance.

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.

• Power Dissipation (P_D): 78 mW for both colors. This is the maximum amount of power the LED package can dissipate as heat at an ambient temperature (T_A) of 25°C. Exceeding this limit risks overheating and reduced lifespan.
• DC Forward Current (I_F): 30 mA continuous for both colors. This is the maximum recommended continuous current for reliable long-term operation.
• Peak Forward Current: 60 mA, permissible only under pulsed conditions (duty cycle ≤ 10%, pulse width ≤ 10ms). Useful for brief, high-brightness flashes.
• Temperature Ranges: Operating: -30°C to +85°C; Storage: -40°C to +100°C. The device is robust across a wide industrial temperature range.
• Lead Soldering Temperature: 260°C for a maximum of 5 seconds, measured 2.0mm from the LED body. This is critical for wave or hand soldering processes to prevent thermal damage to the epoxy lens or internal bonds.

2.2 Electrical & Optical Characteristics

These are the typical performance parameters measured at T_A=25°C and I_F=20mA, providing the basis for design calculations.

• Luminous Intensity (I_v): A key optical parameter. For Green: Typical 310 mcd (Min 180, Max 520). For Red: Typical 240 mcd (Min 140, Max 400). Intensity is binned (see Section 4) to ensure consistency. The measurement includes a ±30% testing tolerance.
• Forward Voltage (V_F): For both colors: Typical 2.1V (Min 1.6V, Max 2.6V). This parameter has a spread; the current-limiting resistor value must be calculated using the maximum V_F to ensure the current never exceeds the maximum rating under all conditions.
• Viewing Angle (2θ_1/2): Approximately 50 degrees for both colors. This is the full angle at which the luminous intensity drops to half of its peak axial value. The diffused lens provides a wide, even viewing cone suitable for panel indicators.
• Wavelength: Peak Wavelength (λ_P): Green: 573 nm; Red: 639 nm. Dominant Wavelength (λ_d): Green: 566-578 nm; Red: 621-642 nm. The dominant wavelength defines the perceived color. The red LED is in the standard red region, while the green is in the pure green spectrum.
• Spectral Line Half-Width (Δλ): Approximately 20 nm for both, indicating relatively pure color emission.
• Reverse Current (I_R): 100 μA maximum at V_R=5V. Important Note: The device is not designed for reverse bias operation. Applying reverse voltage is for test purposes only and should be avoided in application circuits, typically by ensuring proper polarity or using protection diodes in AC or bipolar drive scenarios.

3. Binning System Specification

To manage natural variations in the semiconductor manufacturing process, LEDs are sorted into performance bins. This ensures designers receive parts with consistent optical output within defined ranges.

The LTL30EGRPJ uses separate bin codes for its green and red chips based on luminous intensity measured at 20mA.

• Green Chip Bins:
  • HJ Bin: Luminous Intensity from 180 mcd to 310 mcd.
  • KL Bin: Luminous Intensity from 310 mcd to 520 mcd.
• Red Chip Bins:
  • GH Bin: Luminous Intensity from 140 mcd to 240 mcd.
  • JK Bin: Luminous Intensity from 240 mcd to 400 mcd.

Critical Tolerance: The limits for each bin have a ±30% tolerance. This means a part in the HJ bin (180-310 mcd) could realistically measure as low as 126 mcd (180 - 30%) or as high as 403 mcd (310 + 30%) during verification. Designers must account for this potential spread in brightness when specifying minimum required light levels for their application.

4. Performance Curve Analysis

While specific graphical curves are referenced in the datasheet (Typical Electrical/Optical Characteristics Curves on page 4/9), the underlying relationships are standard for LED behavior and critical for understanding.

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

The LED is a diode and exhibits an exponential I-V relationship. The specified V_F range (1.6V to 2.6V) at 20mA highlights this variance. A small increase in voltage beyond the typical point can cause a large, potentially damaging, increase in current. This underscores the absolute necessity of using a series current-limiting resistor or constant-current driver, not a constant-voltage source, to operate the LED safely.

4.2 Luminous Intensity vs. Forward Current

Luminous intensity is approximately proportional to the forward current. Operating below 20mA will reduce brightness; operating above it (up to the 30mA maximum) will increase brightness but also increase power dissipation and junction temperature, which can affect longevity and cause a color shift. Pulsing at higher peak currents (within the 60mA rating) can achieve very high momentary brightness.

4.3 Temperature Dependence

LED performance is temperature-sensitive. As the junction temperature increases:

• Forward Voltage (V_F): Decreases slightly. This can lead to an increase in current if driven by a constant voltage source with a resistor, further increasing temperature—a potential thermal runaway scenario in poorly designed circuits.
• Luminous Intensity (I_v): Decreases. High temperatures reduce light output efficiency.
• Wavelength (λ_d): Shifts slightly. For AlInGaP-based red LEDs, the wavelength may shift to longer (redder) wavelengths with heat. For the green LED (likely InGaN-based), the shift might be less pronounced or different.

Proper heat management through PCB layout and adherence to power dissipation limits is essential for stable performance.

5. Mechanical & Package Information

5.1 Outline Dimensions

The device conforms to the standard T-1 3/4 radial leaded package profile. Key dimensional notes from the datasheet include:

• All dimensions are in millimeters (inches).
• Standard tolerance is ±0.25mm (±0.010\") unless otherwise specified.
• A maximum of 1.0mm (0.04\") of protruded resin under the flange is permissible.
• Lead spacing is measured where the leads emerge from the package body, which is critical for PCB hole spacing.

Designers should refer to the detailed dimensional drawing on page 2/9 of the original document for precise measurements of lens diameter, body length, lead diameter, and bend positions.

5.2 Polarity Identification

As a common cathode device, the two LED anodes are separate, and the cathodes are connected internally to a single lead. Polarity is typically indicated by:

• Lead Length: The cathode (common) lead is usually the longer lead.
• Flat on Lens: Many packages have a small flat on the lens rim near the cathode lead.
• Internal Flag: Viewed from below, the larger metal flag inside the package is often the cathode.

Correct polarity identification is vital to prevent reverse connection, which could damage the LED.

6. Soldering, Assembly & Handling Guidelines

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

6.1 Storage Conditions

LEDs should be stored in an environment not exceeding 30°C and 70% relative humidity. If removed from their original moisture-barrier packaging, they should be used within three months. For longer storage outside the original bag, they must be kept in a sealed container with desiccant or in a nitrogen desiccator to prevent moisture absorption, which can cause \"popcorning\" (package cracking) during soldering.

6.2 Lead Forming

If leads need to be bent for PCB insertion, bending must occur at a point at least 3mm from the base of the LED lens. The base of the lead frame must not be used as a fulcrum. All forming must be done at room temperature and before the soldering process to avoid transferring stress to the soldered joint.

6.3 Soldering Process

Critical Rule: Maintain a minimum distance of 2mm from the base of the epoxy lens to the solder point. The lens must never be immersed in solder.

• Hand Soldering (Iron): Maximum temperature: 350°C. Maximum time: 3 seconds per joint. Apply iron to the lead and pad, not the LED body.
• Wave Soldering: Pre-heat: ≤100°C for ≤60 seconds. Solder Wave: ≤260°C. Soldering Time: ≤5 seconds. Dipping position must be no lower than 2mm from the lens base.
• Not Recommended: IR reflow soldering is explicitly stated as unsuitable for this through-hole type LED lamp product.

Warning: Excessive temperature or time will melt or deform the epoxy lens, degrade the internal wire bonds, and cause catastrophic failure.

6.4 Electrostatic Discharge (ESD) Protection

LEDs are susceptible to damage from electrostatic discharge. A comprehensive ESD control program is recommended:

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

7. Packaging and Ordering Information

The standard packaging configuration is designed for high-volume manufacturing.

• Basic Unit: 500, 200, or 100 pieces per anti-static polyethylene packing bag.
• Inner Carton: Contains 10 packing bags, totaling 5,000 pieces.
• Master (Outer) Carton: Contains 8 inner cartons, totaling 40,000 pieces.

For shipping lots, only the final pack may contain a non-full quantity. The part number LTL30EGRPJ uniquely identifies this bi-color, common cathode, T-1 3/4, red/green diffused LED lamp.

8. Application Circuit Design & Recommendations

8.1 Drive Method Principle

An LED is a current-controlled device. Its brightness is determined by the current flowing through it, not the voltage across it. Therefore, the primary goal of the drive circuit is to regulate current.

8.2 Recommended Circuit

The datasheet strongly recommends Circuit Model A: using a separate, dedicated current-limiting resistor in series with each LED (or each color channel of the bi-color LED).

Calculation of Current-Limiting Resistor (R_LIMIT):

Use the formula: R_LIMIT = (V_SUPPLY - V_F) / I_F

Where:

• V_SUPPLY = Power supply voltage (e.g., 5V, 3.3V).
• V_F = Forward Voltage of the LED. Use the MAXIMUM value from the datasheet (2.6V) for a worst-case/worst-batch calculation to ensure current never exceeds the maximum rating.
• I_F = Desired forward current (e.g., 20mA = 0.02A).

Example for 5V supply: R_LIMIT = (5V - 2.6V) / 0.02A = 2.4V / 0.02A = 120 Ω. The nearest standard higher value (e.g., 120Ω or 150Ω) would be chosen, and its power rating (P = I²R) must be checked.

8.3 Circuit to Avoid

The datasheet warns against Circuit Model B: connecting multiple LEDs directly in parallel with a single shared current-limiting resistor. Due to the natural variance in the forward voltage (V_F) of individual LEDs (even from the same bin), the current will not divide equally. The LED with the lowest V_F will draw disproportionately more current, appearing brighter and potentially operating outside its safe limits, while the others will be dimmer. This leads to inconsistent brightness and reduced reliability.

8.4 Design Considerations for Bi-Color Operation

With a common cathode:

• To light the Green LED, apply a positive voltage (through its current-limiting resistor) to the green anode lead, while the common cathode is connected to ground.
• To light the Red LED, apply a positive voltage (through its separate current-limiting resistor) to the red anode lead, with the common cathode grounded.
• To light both simultaneously (resulting in a yellow/orange mix), apply positive voltage to both anodes simultaneously. The current for each color must still be controlled by its own resistor.
• Microcontroller I/O pins can directly drive the anodes (with series resistors) if they can source sufficient current (e.g., 20mA). For higher currents or multiplexing many LEDs, transistor drivers are recommended.

9. Technical Comparison & Differentiation

Compared to single-color 5mm LEDs or surface-mount alternatives, the LTL30EGRPJ offers distinct advantages:

• vs. Two Single-Color LEDs: Saves one PCB footprint, reduces part count, and simplifies assembly. The common cathode simplifies wiring for multiplexed displays.
• vs. Tri-Color (RGB) LEDs: Provides a cost-effective solution where only two status colors (e.g., OK/Error, On/Standby) are needed, without the complexity and cost of a blue channel and a 4-pin package.
• vs. Surface-Mount Device (SMD) LEDs: Through-hole design offers superior mechanical strength for applications subject to vibration or manual handling, easier manual prototyping, and better vertical viewing angle in some panel mounts. SMDs offer smaller size and are better for automated, high-density assembly.
• vs. Incandescent Lamps: Far lower power consumption, much longer lifetime, higher shock/vibration resistance, and cooler operation. LEDs are solid-state with no filament to burn out.

10. Frequently Asked Questions (FAQs)

Q1: Can I drive this LED directly from a 3.3V or 5V microcontroller pin without a resistor?

A1: No, this is dangerous and will likely destroy the LED or the microcontroller pin. The LED's low forward voltage (1.6V-2.6V) means connecting it directly to 3.3V or 5V will cause excessive current to flow, limited only by the small internal resistance of the LED and the MCU pin. A series resistor is absolutely mandatory to limit the current to a safe value (e.g., 20mA).

Q2: Why is there such a wide range in the luminous intensity (e.g., 180-520 mcd)? How do I ensure consistent brightness in my product?

A2: The wide range is due to semiconductor process variations. The binning system (HJ/KL for green, GH/JK for red) sorts them into groups. To ensure consistency, you must specify the required bin code when ordering. For critical applications, order a tighter bin (e.g., only KL for green) and design your circuit to provide adequate current even for LEDs at the lower end of that bin's range.

Q3: Can I use this LED outdoors?

A3: The datasheet states it is suitable for \"indoor and outdoor sign\" applications. However, for prolonged outdoor use, consider additional environmental protection. The epoxy lens provides basic moisture resistance, but prolonged exposure to UV sunlight may cause lens yellowing over many years, slightly affecting light output and color. For harsh environments, a conformal coating on the PCB or a sealed enclosure is recommended.

Q4: What happens if I accidentally connect the polarity in reverse?

A4: Applying a reverse voltage (e.g., -5V) can cause a high reverse current (up to the 100 μA specified at 5V) or, if the reverse voltage exceeds the device's breakdown rating (not specified, but typically low for LEDs), it can cause immediate and catastrophic failure (short circuit). Always observe correct polarity.

11. Practical Application Examples

Example 1: Dual-Status Panel Indicator: On a network switch, the LTL30EGRPJ can indicate port status. Green = Link Active, Red = Data Transmitting/Receiving, Both On = Error/Collision. A simple microcontroller can control the two anodes based on PHY chip status signals.

Example 2: Battery Charger Indicator: In a simple charger, the LED can show Red = Charging, Green = Charge Complete. The control circuit switches the appropriate anode based on the battery voltage threshold.

Example 3: Multiplexed Display Segment: In a low-cost multi-digit 7-segment display, each segment could use a bi-color LED. By multiplexing the common cathodes of digits and driving the red/green anodes in sequence, a display capable of showing numbers in two colors can be created, indicating different modes (e.g., normal vs. alarm).

12. Operating Principle

Light Emitting Diodes (LEDs) are semiconductor p-n junction devices. When a forward voltage exceeding the junction's built-in potential is applied, electrons from the n-type region and holes from the p-type region are injected across the junction. When these charge carriers recombine in the active region, 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 used in the active region. The LTL30EGRPJ contains two such junctions within one package: one using material (likely AlInGaP) that emits red light (~639 nm peak), and another (likely InGaN) that emits green light (~573 nm peak). The diffused epoxy lens serves to scatter the light, creating a wide viewing angle, and also acts as a protective dome for the semiconductor chips.

13. Technology Trends

The through-hole LED lamp remains a staple in electronics due to its robustness, ease of use, and low cost for many applications. However, the broader industry trend is towards Surface-Mount Device (SMD) packages for most new designs, driven by the demand for miniaturization, higher-density PCB assembly, and lower profile products. SMD LEDs offer better thermal performance to the PCB, faster automated placement, and smaller footprints. Bi-color and multi-color SMD LEDs are also widely available. Nevertheless, through-hole LEDs like the T-1 3/4 will continue to serve in applications requiring high mechanical reliability, easier manual servicing, legacy designs, or where vertical mounting through a panel is desired. The technology within the package—the efficiency and brightness of the semiconductor chips—continues to improve steadily across all package types.