T-1 3/4 Bicolor LED Datasheet - Dimensions 5.0mm Dia. - Voltage 2.0-2.6V - Power 75-120mW - Red/Green - English Technical Document

1. Product Overview

This document details the specifications for a bicolor, through-hole LED component housed in a standard T-1 3/4 (5mm) diffused package. The device integrates two distinct semiconductor chips within a single package: one emitting in the red spectrum using AllnGaP (Aluminum Indium Gallium Phosphide) technology, and another emitting in the green spectrum using GaP (Gallium Phosphide) technology. This design allows for the generation of two colors from a single component, which is useful for status indicators, bi-state signals, and simple multi-color displays. The white diffused lens provides a wide viewing angle and soft, evenly dispersed light output. The product is designed for general-purpose indicator applications in consumer electronics, industrial controls, and instrumentation.

1.1 Core Advantages

• Dual Color Source: Integration of red and green chips in one package saves board space and simplifies assembly compared to using two separate LEDs.
• Matched Output: The chips are selected and matched to provide uniform light output characteristics, ensuring consistent appearance in application.
• Solid-State Reliability: LEDs offer long operational life, typically exceeding 50,000 hours, due to the absence of filaments or moving parts.
• Low Power Consumption: Operates at standard low currents (e.g., 20mA), making it energy-efficient and suitable for battery-powered devices.
• Environmental Compliance: The product is manufactured to be Pb-Free and compliant with the RoHS (Restriction of Hazardous Substances) directive.

2. In-Depth Technical Parameter Analysis

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 and should be avoided for reliable performance.

• Power Dissipation (P_d): 75 mW for the Red chip, 120 mW for the Green chip. This is the maximum amount of power the LED chip can dissipate as heat at an ambient temperature (T_A) of 25°C. Exceeding this can lead to overheating and accelerated degradation.
• Continuous Forward Current (I_F): 30 mA for both colors. This is the maximum DC current that can be applied continuously.
• Peak Forward Current: 90 mA for both colors, permissible only under pulsed conditions (1/10 duty cycle, 0.1ms pulse width). This allows for brief, high-intensity flashes.
• Derating Factor: 0.4 mA/°C for both colors. For ambient temperatures above 50°C, the maximum allowable continuous current must be reduced linearly by this factor to prevent overheating.
• Reverse Voltage (V_R): 5 V. Applying a reverse voltage higher than this can cause junction breakdown.
• Operating & Storage Temperature: -55°C to +100°C. The device can be stored and operated within this full range.
• Lead Soldering Temperature: 260°C for 5 seconds, measured 2.0mm from the LED body. This defines the process window for hand or wave soldering.

2.2 Electrical & Optical Characteristics

These are the typical performance parameters measured at T_A=25°C and I_F=20mA, representing normal operating conditions.

• Luminous Intensity (I_v): A key measure of perceived brightness.
  • Red (AllnGaP): Typical 180 mcd, ranging from a minimum of 110 mcd to a maximum of 310 mcd.
  • Green (GaP): Typical 50 mcd, ranging from a minimum of 30 mcd to a maximum of 85 mcd.
  • The guarantee includes a ±15% tolerance on these values.
• Viewing Angle (2θ_1/2): Approximately 30 degrees for both colors. This is the full angle at which the luminous intensity drops to half of its on-axis value. The diffused lens creates this wide viewing characteristic.
• Forward Voltage (V_F): The voltage drop across the LED when operating.
  • Red: Typical 2.4V (range 2.0V - 2.4V).
  • Green: Typical 2.6V (range 2.1V - 2.6V).
  • The difference in V_F is due to the different bandgap energies of the AllnGaP and GaP materials.
• Wavelength:
  • Peak Emission Wavelength (λ_p): The wavelength at which the spectral output is strongest. Red: ~650 nm. Green: ~565 nm.
  • Dominant Wavelength (λ_d): The single wavelength perceived by the human eye that defines the color. Red: 634-644 nm. Green: 563-580 nm.
• Spectral Line Half-Width (Δλ): The bandwidth of the emitted light. Red: ~20 nm. Green: ~30 nm. A narrower half-width indicates a more spectrally pure color.
• Reverse Current (I_R): < 100 μA at V_R=5V. This is the small leakage current when the LED is reverse-biased.
• Capacitance (C): Measured at zero bias. Red: ~80 pF. Green: ~35 pF. This parameter can be relevant in high-frequency switching applications.

3. Binning System Explanation

To manage natural variations in the semiconductor manufacturing process, LEDs are sorted into performance bins. This part uses a two-character bin code (X-X) representing the luminous intensity bin for the Red chip and the Green chip, respectively.

3.1 Luminous Intensity Binning

Red Chip (AllnGaP) Bins:
F: 110 - 140 mcd
G: 140 - 180 mcd
H: 180 - 240 mcd
J: 240 - 310 mcd

Green Chip (GaP) Bins:
A: 30 - 38 mcd
B: 38 - 50 mcd
C: 50 - 65 mcd
D: 65 - 85 mcd

Example: A bin code of \"H-B\" indicates a Red chip from the H bin (180-240 mcd) paired with a Green chip from the B bin (38-50 mcd). Designers can specify bins to ensure brightness consistency across multiple units in an assembly. A tolerance of ±15% applies to each bin limit.

4. Performance Curve Analysis

While specific graphs are referenced in the datasheet (Fig.1, Fig.6), their general implications are analyzed here based on standard LED physics.

4.1 Luminous Intensity vs. Forward Current (I-V Curve)

The light output (I_v) is approximately proportional to the forward current (I_F) over a significant range. Operating above the recommended 20mA will increase brightness but also generate more heat, potentially reducing lifespan and shifting color. Operating below 20mA will dim the output. The relationship is linear only within certain bounds; at very high currents, efficiency drops (efficacy decrease).

4.2 Temperature Dependence

LED performance is temperature-sensitive.

• Forward Voltage (V_F): Decreases as junction temperature increases. This has a minor negative temperature coefficient.
• Luminous Intensity (I_v): Decreases as junction temperature rises. High ambient temperatures or excessive drive current leading to self-heating will reduce light output. The derating factor (0.4 mA/°C above 50°C) is applied to manage this thermal effect.
• Wavelength: The peak and dominant wavelengths typically shift slightly (usually towards longer wavelengths) with increasing temperature.

4.3 Spectral Distribution

The referenced spectral distribution graph (Fig.1) would show the relative radiant power versus wavelength for each chip. The Red AllnGaP chip typically exhibits a narrower, more symmetric peak centered around 650 nm. The Green GaP chip has a broader peak around 565 nm. The dominant wavelength is calculated from this spectrum using the CIE colorimetric standards to define the perceived hue.

5. Mechanical & Packaging Information

5.1 Package Dimensions

The device uses a standard T-1 3/4 radial leaded package with a white diffused epoxy lens. Key dimensional notes include:

• All dimensions are in millimeters (inches provided in parenthesis).
• A standard tolerance of ±0.25mm (±0.010\") applies unless specified otherwise.
• The resin under the flange may protrude up to 1.0mm max.
• Lead spacing is measured at the point where the leads exit the package body, which is critical for PCB footprint design.

5.2 Polarity Identification & Lead Forming

Typically, the longer lead denotes the anode (positive side). For a bicolor LED with two anodes and a common cathode (or vice-versa, depending on internal circuit), the datasheet's internal schematic would define the pinout. During lead forming, the bend must be made at least 3mm from the base of the lens to avoid stress on the seal. Forming must be done at room temperature and before the soldering process.

5.3 Cross-Section & Materials

The component is constructed from:

1. Lead Frame: Iron alloy with copper and silver plating, finished with solder dip for improved solderability.
2. Die Bond: Silver-filled epoxy paste attaches the semiconductor chips to the lead frame.
3. LED Chips: Separate AllnGaP (Red) and GaP (Green) dice.
4. Bonding Wire: Gold wire connects the top of the chips to the corresponding lead frame posts.
5. Encapsulation: Epoxy resin with a hardener forms the diffused lens and provides environmental protection.
6. Product Weight: Approximately 0.36 grams.

6. Soldering & Assembly Guidelines

6.1 Soldering Process Parameters

Hand Soldering (Iron):

• Temperature: 350°C - 400°C maximum.
• Time: 3.0 seconds maximum per lead.
• Distance: Maintain at least 2.0mm clearance from the base of the lens to the solder point.

Wave Soldering:

• Pre-heat Temperature: < 100°C maximum.
• Pre-heat Time: < 60 seconds maximum.
• Solder Wave Temperature: < 260°C maximum.
• Contact Time: < 5 seconds maximum.

Critical Warning: Excessive temperature or time can melt the epoxy lens, cause internal delamination, or destroy the semiconductor junction. Never immerse the lens in solder.

6.2 Storage & Handling

• Storage Conditions: Should not exceed 30°C and 70% relative humidity.
• Shelf Life: Once removed from the original moisture-barrier bag, components should be used within three months.
• Long-Term Storage: For extended periods out of the original packaging, store in a sealed container with desiccant or in a nitrogen atmosphere.
• Cleaning: Use only alcohol-based solvents like isopropyl alcohol (IPA). Avoid aggressive or ultrasonic cleaning that may stress the package.

7. Packaging & Ordering Information

7.1 Packaging Specifications

The components are packed in anti-static bags to prevent electrostatic discharge damage.

• Basic Unit: 500 pieces or 250 pieces per packing bag.
• Inner Carton: Contains 16 packing bags, totaling 8,000 pieces.
• Outer Carton (Shipping Box): Contains 8 inner cartons, totaling 64,000 pieces.
• In any shipping lot, only the final pack may contain a non-full quantity.

7.2 Part Number Interpretation

The part number LTL30EKDFGJ follows an internal coding system. While the full logic isn't disclosed here, it typically encodes attributes like package type (T-1 3/4), color (Bicolor), lens style (Diffused), and the specific intensity bin codes (e.g., \"J\" for Red, implied by context). The \"FGJ\" suffix likely relates to the performance binning.

8. Application Recommendations

8.1 Typical Application Scenarios

This bicolor LED is ideal for applications requiring dual-state indication from a single point:

• Status Indicators: Power On (Green) / Standby (Red) or Normal (Green) / Fault (Red).
• Bi-State Alarms: Warning (Flashing Red) / Clear (Green).
• Simple Displays: Basic panel lights, backlighting for switches or legends where two colors are needed.
• Consumer Electronics: Charging status, connectivity indicators on routers, modems, or audio equipment.
• Industrial Controls: Machine state indicators, go/no-go signals.

8.2 Circuit Design Considerations

Current Drive is Essential: LEDs are current-driven devices. The forward voltage (V_F) has a tolerance and varies with temperature. Connecting LEDs directly to a voltage source or in parallel without individual current limiting is not recommended, as small differences in V_F will cause significant imbalance in current sharing and brightness.

Recommended Circuit (Model A): Use a series current-limiting resistor for each LED chip (or each color channel of the bicolor LED). The resistor value is calculated using Ohm's Law: R = (V_supply - V_F) / I_F. For example, with a 5V supply, a Green LED (V_F ~2.6V) at 20mA: R = (5 - 2.6) / 0.02 = 120 Ω. This ensures stable and matched brightness.

Heat Management: While power dissipation is low, ensure adequate ventilation if used in high ambient temperatures or enclosed spaces. Adhere to the current derating guidelines above 50°C.

9. Technical Comparison & Differentiation

Compared to using two discrete single-color LEDs, this integrated bicolor solution offers clear advantages:

• Space Efficiency: One component footprint versus two.
• Assembly Simplicity: One placement and soldering operation versus two, reducing cost and potential defects.
• Optical Alignment: Guarantees the red and green sources are co-located, providing a consistent visual point.

Compared to a tri-color (RGB) LED, this device is simpler, often has higher light output per color due to dedicated chips, and requires fewer control lines (2 anodes vs. 3 for a common-cathode RGB), making it suitable for applications where only two distinct states are needed without the complexity of color mixing.

10. Frequently Asked Questions (FAQ)

Q1: Can I drive this LED directly from a microcontroller pin?
A: It depends on the pin's current sourcing/sinking capability. Most MCU pins can source/sink up to 20-25mA, which matches the LED's typical current. However, you MUST include a series resistor to limit the current. Never connect an LED directly between an MCU pin and power or ground.

Q2: Why are the typical forward voltages different for Red and Green?
A: The forward voltage is determined by the bandgap energy of the semiconductor material. Gallium Phosphide (GaP, Green) has a larger bandgap than Aluminum Indium Gallium Phosphide (AllnGaP, Red), requiring a slightly higher voltage to \"turn on\" and conduct current.

Q3: What does the bin code mean, and do I need to specify it?
A: The bin code (e.g., H-B) indicates the guaranteed range of luminous intensity for the Red and Green chips. For applications where uniform brightness across multiple units is critical (e.g., a panel of identical indicators), specifying a tight bin is important. For non-critical single indicators, a wider bin range is acceptable.

Q4: How do I identify the anode and cathode for each color?
A: The specific pinout (common anode or common cathode) is defined by the internal circuit diagram, which should be consulted from the full datasheet. Typically, for a 3-pin bicolor LED, the middle pin is the common terminal, and the two outer pins are for the individual colors.

11. Practical Design & Usage Examples

11.1 Dual-Status Power Indicator

Scenario: A device needs one indicator to show \"Mains Power Present\" (Green) and \"Battery Charging\" (Red).
Implementation: Use the bicolor LED. Connect the Green anode through a resistor to a regulated 5V line that is active when mains power is on. Connect the Red anode through a resistor to a control signal from the charging circuit that goes high during charging. Use a common cathode connected to ground. A simple transistor or logic gate can drive the anodes if the control signals are weak.

11.2 Simple Bi-State Alert System

Scenario: A sensor module needs a visual alert: steady Green for \"Normal\\