LTS-4817CKR-P LED Display Datasheet - 0.39 Inch Digit Height - Super Red Color - 2.6V Forward Voltage - English Technical Documentation

1. Product Overview

The LTS-4817CKR-P is a surface-mount device (SMD) designed as a single-digit numeric display. Its primary function is to provide clear, high-visibility numeric readouts in various electronic applications. The device utilizes advanced AlInGaP (Aluminium Indium Gallium Phosphide) semiconductor technology on a GaAs substrate to produce its characteristic super red light emission. This technology is known for its high efficiency and excellent color purity in the red spectrum.

The display features a gray face with white segments, a design choice that significantly enhances contrast and readability, especially under various lighting conditions. It is specifically engineered for reverse mount assembly processes, which is a common requirement in modern automated surface-mount technology (SMT) production lines. This configuration often allows for better light emission and viewing angle from the assembled product.

1.1 Key Features and Advantages

• Digit Size: Features a 0.39-inch (10.0 mm) digit height, offering a good balance between size and visibility for panel-mounted displays.
• Segment Quality: Provides continuous, uniform light segments without visible gaps or hotspots, ensuring a professional character appearance.
• Power Efficiency: Designed for low power requirement, making it suitable for battery-powered or energy-conscious devices.
• Optical Performance: Delivers high brightness and high contrast due to the AlInGaP chips and the gray-face/white-segment design.
• Viewing Angle: Offers a wide viewing angle, ensuring the display remains readable from various positions.
• Reliability: Benefits from solid-state reliability with no moving parts, leading to long operational life.
• Binning: The luminous intensity is categorized (binned), allowing for consistent brightness matching in multi-digit applications.
• Environmental Compliance: The package is lead-free and compliant with RoHS (Restriction of Hazardous Substances) directives.

1.2 Device Identification

The part number LTS-4817CKR-P decodes as follows: It indicates a Common Anode configuration with a Right-Hand Decimal point. The \"Super Red\" color is produced by the AlInGaP LED chips.

2. Technical Parameters: In-Depth Objective Interpretation

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 per Segment: 70 mW maximum. Exceeding this can lead to overheating and catastrophic failure.
• Peak Forward Current per Segment: 90 mA under pulsed conditions (1/10 duty cycle, 0.1ms pulse width). This is for short-term signaling, not continuous operation.
• Continuous Forward Current per Segment: 25 mA at 25°C. This current derates linearly at 0.28 mA/°C as ambient temperature (Ta) increases above 25°C. Proper heat sinking or current reduction is necessary at higher temperatures.
• Temperature Range: Operating and storage temperature range is -35°C to +105°C.
• Soldering Limit: The device can withstand iron soldering at 260°C for 3 seconds, with the iron tip at least 1/16 inch (approx. 1.6mm) below the seating plane.

2.2 Electrical and Optical Characteristics

These are the typical performance parameters measured at Ta=25°C under specified test conditions.

• Luminous Intensity (I_V): Ranges from 500 to 1600 µcd at a forward current (I_F) of 1 mA. At 10 mA, the typical intensity is 20,800 µcd. This high output at low current demonstrates the efficiency of the AlInGaP technology.
• Wavelength: The peak emission wavelength (λ_p) is typically 639 nm. The dominant wavelength (λ_d) is typically 631 nm. The spectral line half-width (Δλ) is 20 nm, indicating a relatively pure red color.
• Forward Voltage (V_F): Per chip, typically 2.6V at I_F=20mA, with a minimum of 2.05V. This parameter is crucial for designing the driving circuit's voltage supply.
• Reverse Current (I_R): Maximum 100 µA at a reverse voltage (V_R) of 5V. Important: This test condition is for characterization only; the device is not designed for continuous reverse voltage operation.
• Luminous Intensity Matching Ratio: Maximum 2:1 for segments within a similar light area at I_F=1mA. This ensures visual consistency across all segments of the digit.
• Cross Talk: Specified as ≤ 2.5%, meaning minimal unwanted light leakage between adjacent segments.

3. Performance Curve Analysis

While specific graphical curves are referenced in the datasheet, their implications are standard for LED devices:

• I-V Curve (Current vs. Voltage): Would show the exponential relationship typical of a diode. The forward voltage has a negative temperature coefficient (decreases slightly as temperature increases).
• Luminous Intensity vs. Forward Current: Would show a near-linear relationship at lower currents, potentially saturating at very high currents due to thermal effects.
• Luminous Intensity vs. Ambient Temperature: Would show a decrease in light output as ambient temperature rises, highlighting the importance of thermal management for maintaining brightness.
• Spectral Distribution: Would show a single peak around 639 nm, confirming the monochromatic red output.

4. Mechanical and Package Information

4.1 Package Dimensions

The device conforms to a standard SMD outline. Key dimensional tolerances are ±0.25 mm unless otherwise specified. Additional quality notes include limits on foreign material, ink contamination, bubbles within the segment area, bending of the reflector, and plastic pin burrs.

4.2 Pin Connection and Circuit Diagram

The display has a 10-pin configuration. It is a Common Anode type, meaning the anodes of all LED segments are connected internally to common pins (Pin 3 and Pin 8). Individual segment cathodes (A-G and DP) are brought out to separate pins for independent control. Pin 1 is marked as \"No Connection\" (N/C). The internal circuit diagram shows the common anode connections to the two anode pins and the individual cathodes for each segment and the decimal point.

4.3 Recommended Soldering Pattern (Footprint)

A land pattern design is provided for PCB layout. Adhering to this pattern is critical for achieving reliable solder joints, proper alignment, and managing heat during reflow. The pattern ensures the correct amount of solder paste is deposited.

5. Soldering and Assembly Guidelines

5.1 SMT Soldering Instructions

The device is intended for reflow soldering processes.

• Reflow Profile: Maximum of two reflow cycles. A cooling period to normal temperature is required between cycles. The recommended peak reflow temperature is 260°C maximum.
• Pre-heat: 120-150°C for a maximum of 120 seconds to minimize thermal shock.
• Hand Soldering: If necessary, a soldering iron can be used once, at a maximum temperature of 300°C for no more than 3 seconds.

5.2 Moisture Sensitivity and Storage

The SMD package is moisture-sensitive.

• Storage: Unopened moisture-proof bags should be stored at ≤30°C and ≤60% Relative Humidity.
• Baking: If exposed to ambient humidity after bag opening, the components must be baked before reflow to prevent \"popcorning\" (package cracking due to vapor pressure). Baking conditions: 60°C for ≥48 hours (in reel) or 100°C for ≥4 hours / 125°C for ≥2 hours (in bulk). Baking should be performed only once.

6. Packaging and Ordering Information

6.1 Packing Specifications

The device is supplied on embossed carrier tape wound onto reels, suitable for automated pick-and-place machines.

• Reel Dimensions: Provided for both standard reel sizes (e.g., 13-inch and 22-inch diameter).
• Carrier Tape: Dimensions and specifications (like camber, sprocket hole pitch tolerance) meet EIA-481-C standards.
• Quantities: A 13\" reel contains 800 pieces. A 22\" reel contains tape length for 45.5 meters. Minimum packing quantity for remnants is 200 pieces.
• Leader/Trailer Tape: Includes a leader (min. 400mm) and trailer (min. 40mm) for machine handling.

7. Application Notes and Design Considerations

7.1 Intended Use and Cautions

The display is designed for ordinary electronic equipment in office, communication, and household applications. For safety-critical applications (aviation, medical, etc.), consultation with the manufacturer is required prior to use.

7.2 Critical Design Rules

• Absolute Maximum Ratings: The driving circuit must never exceed the specified limits for current, power, and temperature.
• Current Drive: Constant current driving is strongly recommended over constant voltage driving. This ensures stable luminous output regardless of minor variations in forward voltage (V_F) between individual units or with temperature changes.
• Thermal Management: The forward current must be derated above 25°C ambient. Excess operating temperature accelerates light output degradation (lumen depreciation) and can cause premature failure. Consider PCB layout for heat dissipation.
• Reverse Voltage Protection: The driving circuit must incorporate protection (e.g., series diodes, integrated circuit features) to prevent the application of reverse voltage or transient voltage spikes during power-up/shutdown, as LEDs have very low reverse breakdown voltage.

7.3 Typical Application Scenarios

This display is well-suited for:

• Consumer appliance control panels (microwaves, ovens, washing machines).
• Test and measurement equipment readouts.
• Industrial control and instrumentation panels.
• Audio/video equipment status displays.
• Any device requiring a bright, reliable, single-digit numeric indicator.

8. Technical Comparison and Differentiation

The LTS-4817CKR-P differentiates itself through several key aspects:

• Material Technology: The use of AlInGaP for super red offers higher efficiency and potentially longer life compared to older technologies like GaAsP (Gallium Arsenide Phosphide) for standard red LEDs.
• Optical Design: The gray face with white segments is a specific design for high contrast, which may offer better readability in brightly lit environments compared to all-black or all-gray displays.
• Reverse Mount Design: This specific feature makes it ideal for applications where the display is mounted from the back of the panel, often yielding a cleaner front appearance.
• Intensity Binning: Providing categorized luminous intensity is a value-add for applications requiring uniform brightness across multiple displays or digits.

9. Frequently Asked Questions (Based on Technical Parameters)

Q: Can I drive this display with a 5V microcontroller pin directly?

A: No. The typical forward voltage is 2.6V at 20mA. A series current-limiting resistor is mandatory when using a voltage source. For a 5V supply and a target current of 10-20mA per segment, the resistor value would be approximately (5V - 2.6V) / 0.02A = 120 Ohms. Constant current drivers are recommended for precision.

Q: Why is the maximum reflow count two times?

A> Repeated thermal cycling during reflow can induce mechanical stress on the plastic package and solder joints, potentially leading to delamination or cracking. The limit ensures long-term reliability.

Q: What does \"Common Anode\" mean for my circuit design?

A: In a Common Anode display, you connect the common pins (3 & 8) to the positive supply voltage (Vcc). You then sink current to ground through the individual cathode pins (A-G, DP) to illuminate each segment. This typically matches well with microcontroller ports configured as active-low outputs.

Q: How critical is the baking process before soldering?

A> Very critical if the components have been exposed to humid air after the sealed bag is opened. Moisture absorbed into the plastic package can turn to steam during reflow, causing internal cracks (popcorning) that may not be immediately visible but will cause early field failure.

10. Operational Principles and Technology Trends

10.1 Basic Operating Principle

An LED is a semiconductor diode. When a forward voltage exceeding its bandgap is applied, electrons and holes recombine in the active region (the AlInGaP epi-layer), releasing energy in the form of photons (light). The specific composition of the AlInGaP alloy determines the bandgap energy and thus the wavelength (color) of the emitted light, in this case, super red (~631-639 nm).

10.2 Industry Trends

The trend in display components like this continues towards:

• Higher Efficiency: More light output (lumens) per unit of electrical input power (watts), reducing energy consumption and heat generation.
• Miniaturization: Maintaining or increasing brightness in smaller package footprints to enable sleeker product designs.
• Enhanced Reliability: Improved materials and packaging techniques to extend operational lifetime, especially under higher temperature conditions.
• Integration: Moving towards displays with integrated drivers (IC-driven) to simplify external circuitry for the end designer.