Oval LED Lamp 3474DKRR/MS Datasheet - Dimensions 3.4x7.4mm - Voltage 1.6-2.6V - Power 120mW - Brilliant Red - English Technical Document

1. Product Overview

This document provides the complete technical specifications for the 3474DKRR/MS, a precision oval-shaped LED lamp. The device is engineered using AlGaInP chip technology to emit a brilliant red color, encapsulated within a red diffused lens. Its primary design purpose is for use in passenger information systems and various signage applications where clear, defined visual communication is critical.

The core advantages of this LED include its high luminous intensity output, a uniquely oval spatial radiation pattern that is well-defined, and a wide viewing angle configuration of 90° in the X-axis and 45° in the Y-axis. This asymmetric viewing angle is specifically tailored to match the requirements of color-mixing applications in signs. The package is constructed with UV-resistant epoxy resin, ensuring long-term reliability in outdoor environments. Furthermore, the product is compliant with RoHS, EU REACH, and halogen-free standards (Br <900 ppm, Cl <900 ppm, Br+Cl <1500 ppm), making it suitable for global markets with stringent environmental regulations.

1.1 Target Applications

The 3474DKRR/MS is ideally suited for applications requiring high visibility and color consistency. Its primary target markets include:

• Color Graphic Signs: Used in public transportation, airports, and stadiums.
• Message Boards: For displaying dynamic information in public spaces.
• Variable Message Signs (VMS): Critical for traffic management and highway information systems.
• Commercial Outdoor Advertising: Providing bright and reliable illumination for advertising displays.

2. In-Depth Technical Parameter Analysis

2.1 Absolute Maximum Ratings

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

• Reverse Voltage (V_R): 5V. Exceeding this voltage in reverse bias can cause junction breakdown.
• Forward Current (I_F): 50 mA (Continuous).
• Peak Forward Current (I_FP): 160 mA (Duty cycle 1/10 @ 1kHz). This allows for brief pulses of higher current, useful for multiplexing in display applications.
• Power Dissipation (P_d): 120 mW. This is the maximum power the package can dissipate at Ta=25°C. Proper thermal management is required if operating near maximum current.
• Operating Temperature (T_opr): -40°C to +85°C. This wide range ensures functionality in harsh outdoor environments.
• Storage Temperature (T_stg): -40°C to +100°C.
• Soldering Temperature (T_sol): 260°C for 5 seconds. This is typical for wave or reflow soldering processes.

2.2 Electro-Optical Characteristics (Ta=25°C)

These parameters are measured under standard test conditions (I_F=20mA) and represent typical device performance.

• Luminous Intensity (I_v): 1976-4600 mcd (Typical: 2800 mcd). This high output is a key feature for daylight visibility.
• Viewing Angle (2θ_1/2): X: 90°, Y: 45°. The oval pattern is optimized for horizontal viewing in signage.
• Peak Wavelength (λ_p): 632 nm (Typical). The specific wavelength of maximum spectral emission.
• Dominant Wavelength (λ_d): 619-629 nm (Typical: 621 nm). This defines the perceived color (brilliant red).
• Spectral Bandwidth (Δλ): 20 nm (Typical). Indicates the spectral purity of the emitted light.
• Forward Voltage (V_F): 1.6V - 2.6V (at I_F=20mA). Must be considered for driver circuit design.
• Reverse Current (I_R): 10 μA Max (at V_R=5V).

3. Binning System Explanation

To ensure color and brightness consistency in production, LEDs are sorted into bins. This allows designers to select parts that meet specific application requirements.

3.1 Luminous Intensity Binning

Bins are defined with a ±10% tolerance. Designers can choose bins based on required brightness levels, with higher bins (e.g., RE) offering maximum intensity.

• RA: 1976 - 2370 mcd
• RB: 2370 - 2840 mcd
• RC: 2840 - 3400 mcd
• RD: 3400 - 4080 mcd
• RE: 4080 - 4600 mcd

3.2 Dominant Wavelength Binning

Wavelength bins ensure color uniformity across a display. The tolerance is ±1nm.

• R1: 619 - 624 nm
• R2: 624 - 629 nm

4. Performance Curve Analysis

The datasheet provides several characteristic curves that are essential for understanding device behavior under different operating conditions.

4.1 Spectral Distribution

The Relative Intensity vs. Wavelength curve shows a narrow, Gaussian-like distribution centered around 632 nm (peak), with a typical bandwidth of 20 nm. This confirms the pure red color emission.

4.2 Directivity Pattern

The radiation pattern plot visually confirms the oval shape, with the 1/2 intensity points at 90° (horizontal) and 45° (vertical). This is crucial for designing optical systems to achieve desired illumination profiles.

4.3 Electrical Characteristics

The Forward Current vs. Forward Voltage (I-V) curve shows the typical exponential relationship of a diode. At the test current of 20mA, the forward voltage typically falls between 1.6V and 2.6V. The Relative Intensity vs. Forward Current curve is nearly linear in the operating range, indicating that brightness can be effectively controlled via current.

4.4 Temperature Dependence

The Relative Intensity vs. Ambient Temperature curve shows that luminous output decreases as temperature increases, a common characteristic of LEDs. The Forward Current vs. Ambient Temperature curve (likely at constant voltage) illustrates how the device's operating point shifts with temperature, important for thermal management in the final application.

5. Mechanical and Package Information

5.1 Package Dimensions

The LED features a standard oval lamp package. Key dimensions include the overall body size and lead spacing. The leads are on a 2.54mm pitch, compatible with standard PCB layouts. A critical note is the maximum 1.5mm protrusion of resin under the flange, which must be accounted for in mechanical mounting and PCB keep-out areas. All unspecified dimensions have a tolerance of ±0.25mm.

5.2 Polarity Identification

The cathode is typically indicated by a flat side on the lens or a shorter lead. The datasheet diagram should be consulted for the exact marking on this specific package (3474DKRR/MS). Correct polarity is essential to prevent reverse bias damage.

6. Soldering and Assembly Guidelines

Proper handling is critical to maintain LED performance and reliability.

6.1 Lead Forming

• Bending must occur at least 3mm from the base of the epoxy bulb to avoid stress on the internal die attach.
• Forming should always be done before soldering.
• Excessive stress during forming can crack the epoxy or damage the wire bonds.
• Cut leads at room temperature; high-temperature cutting can induce thermal shock.
• PCB holes must align perfectly with LED leads to avoid mounting stress, which can degrade the epoxy seal over time.

6.2 Storage Conditions

• Recommended storage: ≤30°C and ≤70% Relative Humidity.
• Shelf life after shipping: 3 months under these conditions.
• For longer storage (up to 1 year), devices should be kept in a sealed container with a nitrogen atmosphere and desiccant.
• Avoid rapid temperature changes in humid environments to prevent condensation on the components.

6.3 Soldering Process

• During hand or wave soldering, the solder joint should be more than 3mm away from the epoxy bulb.
• It is recommended to solder only up to the base of the tie bar on the leadframe.
• The maximum soldering temperature is 260°C for 5 seconds, which is compatible with standard lead-free reflow profiles.

7. Packaging and Ordering Information

7.1 Moisture Resistant Packing

The LEDs are supplied in moisture-resistant packaging to prevent damage during storage and transit. They are typically housed on embossed carrier tapes.

7.2 Carrier Tape and Reel Specifications

Detailed tape dimensions are provided, including feed hole pitch (P=12.70mm), component pitch (F=2.54mm), and pocket dimensions. These are essential for setting up automated pick-and-place equipment.

7.3 Packing Quantities

• Standard packing: 2500 pieces per inner carton.
• Shipping packing: 10 inner cartons (25,000 pieces) per outside carton.

7.4 Label Explanation & Part Numbering

The packaging label includes critical information for traceability and specification:

• CPN: Customer's internal part number.
• P/N: Manufacturer's part number (e.g., 3474DKRR/MS).
• QTY: Quantity in the package.
• CAT: Luminous Intensity bin code (e.g., RA, RB, RC...).
• HUE: Dominant Wavelength bin code (e.g., R1, R2).
• REF: Forward Voltage bin code (if applicable).
• LOT No: Manufacturing lot number for quality tracking.

The part number structure 3474 D K R R - □ □ □ □ allows for the specification of different bins and optional features.

8. Application Design Considerations

8.1 Driver Circuit Design

Due to the diode's exponential I-V characteristic, current regulation (not voltage regulation) is strongly recommended for driving LEDs. A simple series resistor can be used for basic applications, but a constant current driver provides better stability over temperature and supply voltage variations. The maximum continuous current is 50mA; for pulsed operation, refer to the I_FP rating.

8.2 Thermal Management

While the device has a wide operating temperature range, maintaining a lower junction temperature extends lifetime and maintains light output. Ensure adequate PCB copper area or heatsinking if operating near maximum current (I_F=50mA) or in high ambient temperatures.

8.3 Optical Integration

The asymmetric (oval) radiation pattern is ideal for illuminating rectangular areas common in signs. When designing an array, consider the viewing angles to ensure uniform appearance from the intended viewing positions. Mixing different intensity/wavelength bins in the same display should be avoided to prevent visible inconsistencies.

9. Technical Comparison and Differentiation

The 3474DKRR/MS differentiates itself through its specific oval beam pattern, which is not commonly found in standard round LEDs. This provides a more efficient and tailored light distribution for horizontal signage without the need for secondary optics. Its high luminous intensity from an AlGaInP chip offers superior brightness and color saturation compared to some alternative technologies for red emission. The combination of wide operating temperature, environmental compliance, and a well-defined binning structure makes it a robust and predictable choice for professional signage applications.

10. Frequently Asked Questions (FAQ)

10.1 What is the difference between Peak Wavelength and Dominant Wavelength?

Peak Wavelength (λ_p) is the wavelength at which the spectral power distribution is maximum (632 nm typical). Dominant Wavelength (λ_d) is the single wavelength of monochromatic light that matches the perceived color of the LED (621 nm typical). For LEDs, the dominant wavelength is often more relevant for color specification.

10.2 Can I drive this LED at 160mA continuously?

No. The 160mA rating is for peak forward current under pulsed conditions (duty cycle 1/10 @ 1kHz). The maximum continuous forward current (I_F) is 50mA. Exceeding this can lead to overheating, accelerated lumen depreciation, and catastrophic failure.

10.3 How do I interpret the viewing angle of 90°/45°?

This indicates the angular spread where the luminous intensity is at least half of the maximum intensity (the half-intensity points). The pattern is oval: 90° in the horizontal (X) plane and 45° in the vertical (Y) plane. This is ideal for wide horizontal viewing as found in roadside signs.

10.4 Why is storage condition important for LEDs?

LED packages can absorb moisture from the atmosphere. During the high-temperature soldering process, this trapped moisture can rapidly expand, causing internal delamination or "popcorning," which cracks the package and destroys the device. The specified storage conditions and shelf life prevent excessive moisture absorption.

11. Practical Application Example

Scenario: Designing a Single-Line Text Display for a Bus Stop.

1. Requirements: Bright red text visible in direct sunlight, wide horizontal viewing for pedestrians, continuous operation.
2. LED Selection: The 3474DKRR/MS is chosen for its high intensity (select bin RD or RE for maximum brightness) and 90° horizontal viewing angle.
3. Circuit Design: A constant current driver set to 20mA per LED is designed. This provides the typical luminous intensity while ensuring long-term reliability and consistency. Series resistors are calculated based on the driver's output voltage and the LED's V_F range.
4. Mechanical Layout: LEDs are placed on a PCB with holes matching the 2.54mm lead pitch. The oval lens orientation is aligned to maximize the 90° spread along the row of text. A diffuser panel may be placed in front to blend individual points into smooth characters.
5. Thermal Consideration: The PCB is designed with sufficient copper area to dissipate heat, as the display may be enclosed and exposed to summer sun.

12. Operating Principle

The 3474DKRR/MS is a semiconductor light source. Its core is a chip made of Aluminum Gallium Indium Phosphide (AlGaInP). When a forward voltage is applied, electrons and holes are injected into the active region of the semiconductor where they recombine. This recombination process releases energy in the form of photons (light). The specific composition of the AlGaInP alloy determines the bandgap energy, which directly defines the wavelength (color) of the emitted light—in this case, in the red spectrum (~621-632 nm). The red diffused epoxy lens encapsulates the chip, providing mechanical protection, shaping the radiation pattern into an oval, and diffusing the light to create a more uniform appearance.

13. Technology Trends

In the field of signage and specialized lighting, LED technology continues to evolve towards higher efficiency (more lumens per watt), improved color rendering, and greater optical control. While standard white LEDs advance rapidly, discrete colored LEDs like the AlGaInP-based red remain crucial for applications requiring specific saturated colors, high reliability, and simple drive electronics. Trends include the integration of onboard control circuitry (e.g., addressable RGB LEDs) and further miniaturization. However, for robust, high-brightness monochromatic applications like transportation signage, discrete components with proven reliability and specific beam patterns, such as the oval lamp discussed here, maintain a significant role in design.