Oval LED Lamp 3474BKBR/MS Datasheet - Blue Color - 20mA Forward Current - 110mW Power Dissipation - English Technical Document

1. Product Overview

This document details the specifications for a precision optical performance oval LED lamp, identified as model 3474BKBR/MS. This component is engineered specifically for applications requiring high visibility and reliable performance in information display systems.

1.1 Core Advantages and Product Positioning

The primary design objective of this oval LED is to serve passenger information signs and similar display applications. Its key advantages stem from its unique optical design:

• High Luminous Intensity Output: Delivers bright, clear illumination essential for daylight-readable signs.
• Oval Shape & Defined Radiation Pattern: The oval lens geometry creates a well-defined spatial radiation pattern, optimizing light distribution for rectangular or oval display apertures common in signage.
• Wide and Asymmetric Viewing Angle: Features a viewing angle (2θ1/2) of 110° in one axis and 60° in the perpendicular axis. This asymmetric pattern is ideal for directing light effectively towards the viewer in typical sign mounting configurations.
• Robust Material Construction: Utilizes UV-resistant epoxy resin, enhancing long-term reliability and preventing lens yellowing or degradation when used in outdoor or high-UV environments.
• Environmental Compliance: The product is designed to comply with RoHS (Restriction of Hazardous Substances), EU REACH regulations, and is Halogen-free (with Bromine <900 ppm, Chlorine <900 ppm, Br+Cl <1500 ppm).

1.2 Target Market and Applications

This LED is targeted at the commercial and transportation signage market. Its matched radiation patterns make it suitable for mixing with yellow, red, or green filters or secondary optics in color applications. Typical use cases include:

• Color Graphic Signs
• Message Boards
• Variable Message Signs (VMS)
• Commercial Outdoor Advertising Displays

2. Technical Parameter Deep Dive

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

2.1 Device Selection and Absolute Maximum Ratings

The LED uses an InGaN (Indium Gallium Nitride) chip material to produce blue light, which is then diffused through a blue-tinted lens. Understanding the Absolute Maximum Ratings is critical for ensuring device longevity and preventing immediate failure.

• Reverse Voltage (V_R): 5V - Applying a reverse bias voltage exceeding this value can cause irreversible damage to the LED junction.
• Forward Current (I_F): 30mA - The maximum continuous DC current that can be applied. Operating at or near this limit will generate more heat and may reduce lifespan.
• Peak Forward Current (I_FP): 100mA - This is a pulsed rating (duty cycle 1/10 @ 1kHz). It should not be used for DC operation. It indicates the LED can handle short current spikes, which might be relevant in certain multiplexed driving schemes.
• Power Dissipation (P_d): 110mW - The maximum power the package can dissipate as heat at Ta=25°C. Exceeding this limit risks overheating. Actual power is calculated as Forward Voltage (V_F) × Forward Current (I_F).
• Operating & Storage Temperature: Ranges from -40°C to +85°C (operating) and -40°C to +100°C (storage). These wide ranges confirm suitability for harsh outdoor environments.
• Soldering Temperature (T_sol): 260°C for 5 seconds - This defines the reflow soldering profile tolerance, crucial for PCB assembly without damaging the epoxy package or internal bonds.

2.2 Electro-Optical Characteristics Analysis

All parameters are specified at a standard test condition of Ta=25°C and I_F=20mA, which is the recommended operating point.

• Luminous Intensity (I_v): Ranges from 550 mcd (min) to 1130 mcd (max), with a typical value of 800 mcd. This high intensity is a key feature for signage.
• Viewing Angle (2θ_1/2): Confirmed as 110° (X-axis) / 60° (Y-axis). This asymmetry is a deliberate design feature for signage.
• Peak Wavelength (λ_p): Typical 468 nm. This is the wavelength at which the emitted optical power is greatest.
• Dominant Wavelength (λ_d): Ranges from 460 nm to 475 nm. This is the single wavelength perceived by the human eye, defining the "color" of the blue light.
• Forward Voltage (V_F): Ranges from 2.4V to 3.4V at 20mA. Designers must ensure the driving circuit can accommodate this variance, especially when using constant-voltage supplies.
• Reverse Current (I_R): Maximum 50 µA at V_R=5V. A low value indicates good junction quality.

3. Binning System Explanation

To manage manufacturing variations, LEDs are sorted into performance bins. This allows designers to select parts that meet specific intensity and color consistency requirements for their application.

3.1 Luminous Intensity Binning

Bins are defined by codes BA through BD, with minimum and maximum luminous intensity values measured at I_F = 20mA. The overall tolerance is ±10%.

• BA: 550 mcd to 660 mcd
• BB: 660 mcd to 790 mcd
• BC: 790 mcd to 945 mcd
• BD: 945 mcd to 1130 mcd

Selecting a higher bin (e.g., BD) ensures maximum brightness but may come at a premium cost. For uniform appearance in a multi-LED sign, specifying a tight bin or a single bin is essential.

3.2 Dominant Wavelength Binning

Wavelength bins are defined by codes B1 through B5, each spanning a 3 nm range from 460 nm to 475 nm. The tolerance is ±1 nm.

• B1: 460 nm to 463 nm (Bluer, towards cyan-blue)
• B2: 463 nm to 466 nm
• B3: 466 nm to 469 nm
• B4: 469 nm to 472 nm
• B5: 472 nm to 475 nm (Deeper, royal blue)

Color consistency across a display is critical. Specifying a single wavelength bin (e.g., B3) guarantees all LEDs will have nearly identical hue.

4. Performance Curve Analysis

The provided typical curves offer valuable insights into the LED's behavior under non-standard conditions.

4.1 Spectral Distribution and Directivity

The Relative Intensity vs. Wavelength curve shows a typical blue LED spectrum centered around 468 nm with a Full Width at Half Maximum (FWHM) of approximately 20 nm. The Directivity curve visually confirms the 110°/60° viewing angle, showing the relative intensity fall-off as a function of angle from the central axis.

4.2 Electrical and Thermal Characteristics

• Forward Current vs. Forward Voltage (I-V Curve): This curve is non-linear, typical of a diode. It shows the relationship between voltage and current, crucial for designing current-limiting circuits. The knee voltage is around 2.8V to 3.0V.
• Relative Intensity vs. Forward Current: Light output increases with current but not linearly. Driving above 20mA yields diminishing returns in efficiency and increases heat.
• Relative Intensity vs. Ambient Temperature: LED light output decreases as ambient temperature (T_a) increases. This derating must be accounted for in thermal design, especially in enclosed signs or hot climates.
• Forward Current vs. Ambient Temperature: This curve likely illustrates the recommended maximum operating current derating as temperature rises to stay within the 110mW power dissipation limit.

5. Mechanical and Package Information

5.1 Package Dimensions and Tolerances

The datasheet includes a detailed dimensioned drawing of the oval LED package. Key features include:

• Overall package shape and lead spacing.
• Location and size of the cathode identifier (typically a flat side or green dot on the package).
• Critical notes specify that all dimensions are in millimeters with a standard tolerance of ±0.25mm unless otherwise stated.
• A maximum protrusion of resin under the flange is specified as 1.5mm, which is important for clearance during PCB mounting.

5.2 Polarity Identification

Correct polarity is essential. The package includes a visual marker (e.g., a flat side, notch, or colored dot) to identify the cathode (-) lead. The anode (+) is typically the longer lead in through-hole versions, but for this SMD part, the marking on the package itself must be referenced against the dimension drawing.

6. Soldering and Assembly Guidelines

Proper handling is critical to maintain reliability.

6.1 Lead Forming (If Applicable)

If leads need to be formed for through-hole mounting:

• Bend at a point ≥ 3mm from the epoxy bulb base.
• Perform forming before soldering.
• Avoid stressing the package; stress can damage internal connections or crack the epoxy.
• Cut leads at room temperature.
• Ensure PCB holes align perfectly with LED leads to avoid mounting stress.

6.2 Storage Conditions

LEDs are moisture-sensitive devices (MSD):

• Store at ≤ 30°C and ≤ 70% Relative Humidity (RH) after receipt.
• The recommended storage life in this condition is 3 months.
• For storage beyond 3 months and up to 1 year, use a sealed container with a nitrogen atmosphere and desiccant.
• Avoid rapid temperature changes in humid environments to prevent condensation.

6.3 Soldering Process

• Maintain a distance of > 3mm from the solder joint to the epoxy bulb.
• Do not solder on the base of the LED itself.
• Follow the reflow profile with a peak temperature of 260°C for a maximum of 5 seconds.

7. Packaging and Ordering Information

7.1 Moisture Resistant Packing

The LEDs are supplied in moisture-resistant packing, typically involving:

• Carrier Tape: LEDs are placed in embossed carrier tape for automated pick-and-place assembly.
• Reel: The tape is wound onto a reel.
• Desiccant & Humidity Indicator Card: Included in the sealed bag to protect against moisture.
• Inner & Outer Cartons: For bulk shipping and storage.

7.2 Label Explanation and Taping Specifications

The packing label includes codes for:

• CPN (Customer's Part Number)
• P/N (Product Number: 3474BKBR/MS)
• QTY (Quantity)
• CAT (Luminous Intensity Bin, e.g., BC)
• HUE (Dominant Wavelength Bin, e.g., B3)
• REF (Forward Voltage Rank)
• LOT No. (Traceability)

Detailed carrier tape dimensions (D, F, P, W1, W3, etc.) are provided to ensure compatibility with standard SMD assembly equipment.

7.3 Packing Quantities and Model Numbering

• Standard packing: 2500 pieces per inner carton.
• 10 inner cartons per outside master carton (25,000 pieces total).
• The model number 3474BKBR/MS follows a designation likely indicating package style (3474), color (BKBR for Blue?), and mounting/style (MS for Moisture Sensitive or similar). The datasheet shows a placeholder for additional suffix codes (3474BKBR-□□□□) for specifying bins or other variants.

8. Application Suggestions and Design Considerations

8.1 Typical Application Circuits

For reliable operation:

• Constant Current Drive: Highly recommended over constant voltage. A simple series resistor can suffice for low-current applications, but a dedicated constant-current LED driver IC provides better stability, efficiency, and protection against voltage spikes.
• Current Setting: Operate at or below the 20mA typical test condition for optimal efficiency and longevity. Use the I-V curve to calculate the appropriate series resistor or driver settings based on your supply voltage.
• Reverse Voltage Protection: Consider adding a protection diode in parallel (cathode to anode, anode to cathode) if the LED could be exposed to reverse voltage transients.

8.2 Thermal Management

While the power is low (110mW max), heat can still affect performance and lifespan:

• Use a PCB with adequate copper area connected to the LED pads to act as a heat sink.
• In high-density arrays, ensure adequate spacing and consider active cooling if enclosed.
• Refer to the Relative Intensity vs. Ambient Temperature curve to derate expected light output in high-temperature environments.

8.3 Optical Integration

• The oval beam pattern is designed to match common sign apertures. Align the LED's major (110°) and minor (60°) axes with the sign's layout for optimal uniformity and efficiency.
• When using color filters, ensure they are compatible with the LED's blue spectrum and UV-resistant epoxy to prevent accelerated aging.

9. Technical Comparison and Differentiation

While a direct competitor comparison isn't in the datasheet, key differentiators of this product can be inferred:

• vs. Standard Round LEDs: The oval beam provides better coverage for rectangular pixels in signs, reducing the number of LEDs needed or improving uniformity compared to a round LED with a circular beam.
• vs. Non-UV Resistant LEDs: The UV-resistant epoxy is a critical advantage for any outdoor or long-life application, preventing the common failure mode of lens browning and output degradation.
• vs. Lower Intensity LEDs: The high luminous intensity (up to 1130 mcd) makes it suitable for sunlight-readable applications where ambient light is high.
• Comprehensive Binning: The detailed intensity and wavelength binning structure allows for high-color-consistency displays, a key requirement for professional signage.

10. Frequently Asked Questions (Based on Technical Parameters)

Q: Can I drive this LED at 30mA continuously?

A: The Absolute Maximum Rating is 30mA, but the typical operating condition and all electro-optical specs are given at 20mA. Operating at 30mA will produce more heat, reduce efficiency (lumens per watt), and potentially shorten lifespan. It is advisable to design for 20mA or less for optimal reliability.

Q: What is the difference between Peak and Dominant Wavelength?

A: Peak Wavelength (λp) is the physical peak of the light spectrum emitted. Dominant Wavelength (λd) is the single wavelength that the human eye would perceive as the color, calculated from the full spectrum. λd is more relevant for color matching in displays.

Q: How do I interpret the bin codes when ordering?

A: To ensure a uniform sign, specify both the Luminous Intensity Bin (e.g., BC) and the Dominant Wavelength Bin (e.g., B3) in your order. This guarantees all LEDs will have very similar brightness and color.

Q: Is a heatsink required?

A: For a single LED at 20mA (~2.8V * 0.02A = 56mW), a heatsink is generally not required if there is some copper on the PCB. For arrays of LEDs or operation in high ambient temperatures, thermal design becomes important.

11. Practical Design and Usage Case

Scenario: Designing a Single-Line VMS (Variable Message Sign) Character.

A character is made of a 5x7 pixel matrix. Each "pixel" is a rectangular aperture. Using this oval LED:

1. Placement: Mount the LED behind each aperture, aligning its 110° wide axis with the longer side of the rectangle and its 60° narrow axis with the shorter side. This fills the aperture efficiently.
2. Circuit: Use a constant-current driver IC capable of driving 35 LEDs (5x7) in a multiplexed matrix to reduce wiring. Set the current to 18-20mA per LED when active.
3. Binning: Order all LEDs for the sign from the same CAT (e.g., BC) and HUE (e.g., B3) bin to guarantee uniform brightness and color across the entire display.
4. Thermal: Design the PCB with thermal vias under the LED pads connected to a ground plane on the back layer to dissipate heat from the 35-LED array.
5. Software: Implement PWM (Pulse Width Modulation) via the driver IC to achieve dimming control for different ambient light conditions.

12. Operating Principle Introduction

This LED operates on the principle of electroluminescence in a semiconductor diode. The core is a chip made of InGaN (Indium Gallium Nitride) semiconductor materials. When a forward voltage exceeding the diode's knee voltage (approx. 2.8-3.0V) is applied, electrons are injected from the n-type region and holes from the p-type region into the active region. When these charge carriers recombine, they release energy in the form of photons (light). The specific composition of the InGaN alloy determines the bandgap energy, which in turn defines the wavelength of the emitted light—in this case, blue (~468 nm). The oval-shaped epoxy lens surrounding the chip is engineered to refract and shape this raw light into the desired 110°/60° radiation pattern.

13. Technology Trends and Context

This component represents a specialized application of mainstream LED technology. General trends in the LED industry that provide context include:

• Increased Efficiency: Ongoing R&D continuously improves lumens per watt (efficacy), allowing for brighter displays or lower power consumption.
• Miniaturization: While this is a larger package for high output, the trend in general lighting is towards smaller, more densely packed chips (e.g., chip-scale packages).
• Smart and Connected Lighting: For signage, this translates into LEDs being integrated with intelligent drivers capable of networked control, dynamic content, and adaptive brightness.
• Color Quality and Consistency: Tighter binning and improved manufacturing processes, as seen in this datasheet's detailed bins, are driven by demand for superior and consistent visual performance in professional displays.
• Sustainability: The compliance with Halogen-free, RoHS, and REACH standards is now a baseline expectation, reflecting the industry's focus on environmental responsibility.

The oval LED lamp remains a purpose-built solution where optical control, reliability, and high-intensity output for specific aperture shapes are prioritized over the smallest possible form factor.