LTS-4817CKG-P LED Display Datasheet - 0.39-inch Digit Height - AlInGaP Green - 2.6V Forward Voltage - 70mW Power Dissipation - English Technical Document

1. Product Overview

The LTS-4817CKG-P is a surface-mount device (SMD) designed for electronic displays requiring a single numeric digit. It is characterized by its compact size and efficient light output, making it suitable for integration into various electronic products where space and power consumption are considerations.

1.1 Core Features and Target Market

This display offers a digit height of 0.39 inches (10.0 mm), providing good readability in a small form factor. Its key advantages include low power requirement, high brightness, excellent character appearance with continuous uniform segments, and a wide viewing angle. The device utilizes solid-state AlInGaP LED technology on a GaAs substrate, which contributes to its reliability and performance. It is categorized for luminous intensity and is supplied in a lead-free package compliant with RoHS directives. The primary target applications include consumer electronics, instrumentation panels, industrial controls, and household appliances where clear, reliable numeric indication is needed.

1.2 Device Identification

The part number LTS-4817CKG-P specifies a device with AlInGaP green LED chips in a common anode configuration, featuring a right-hand decimal point. This naming convention helps in precise identification and ordering.

2. Technical Parameters: In-Depth Objective Interpretation

2.1 Absolute Maximum Ratings

At an ambient temperature (Ta) of 25°C, the device has defined limits to ensure reliable operation. The maximum power dissipation per segment is 70 mW. The peak forward current per segment is rated at 60 mA, but this is only permissible under pulsed conditions (1/10 duty cycle, 0.1ms pulse width). The continuous forward current per segment is 25 mA at 25°C, with a derating factor of 0.28 mA/°C as temperature increases. The operating and storage temperature range is specified from -35°C to +105°C. The device can withstand iron soldering at 260°C for 3 seconds, measured 1/16 inch below the seating plane.

2.2 Electrical and Optical Characteristics

Measured at Ta=25°C, the typical average luminous intensity per segment is 500 µcd at a forward current (IF) of 1mA, and can reach 5500 µcd at IF=10mA. The peak emission wavelength (λp) is typically 571 nm, with a spectral line half-width (Δλ) of 15 nm and a dominant wavelength (λd) of 572 nm, all measured at IF=20mA. The forward voltage (VF) per chip ranges from 2.05V to 2.6V at IF=20mA. The reverse current (IR) is a maximum of 100 µA at a reverse voltage (VR) of 5V, though this condition is for test purposes only and not for continuous operation. The luminous intensity matching ratio between segments in a similar light area is 2:1 maximum at IF=1mA. Cross-talk between segments is specified to be ≤ 2.5%.

3. Binning System Explanation

The datasheet indicates that the product is categorized for luminous intensity. This implies a binning process where devices are sorted based on their measured light output at a standard test current (likely 1mA or 10mA as per the characteristics table). This ensures consistency in brightness across segments within a single device and between different production batches, which is crucial for achieving uniform display appearance.

4. Performance Curve Analysis

The datasheet references typical electrical/optical characteristics curves. While the specific graphs are not detailed in the provided text, such curves typically illustrate the relationship between forward current (IF) and luminous intensity (IV), forward voltage (VF) versus temperature, and the spectral distribution of the emitted light. These curves are essential for designers to understand the device's behavior under different operating conditions, such as how brightness varies with current or how forward voltage drops with increasing temperature.

5. Mechanical and Package Information

5.1 Package Dimensions and Tolerances

All critical dimensions for the SMD package are provided in millimeters. The general tolerance for dimensions is ±0.25 mm unless otherwise specified. Key quality notes include limits on foreign material within segments (≤10 mil), surface ink contamination (≤20 mils), bubbles in segments (≤10 mil), bending of the reflector (≤1% of its length), and maximum burr size on plastic pins (0.14 mm). A date code and LED batch information are marked on the device for traceability.

5.2 Pin Connection and Circuit Diagram

The device has a 10-pin configuration. Pins 3 and 8 are the common anodes. The cathodes for segments A through G and the decimal point (DP) are connected to specific pins (1: E, 2: D, 4: C, 5: DP, 6: B, 7: A, 9: F, 10: G). One pin is noted as having no connection (N/C). The internal circuit diagram shows the common anode connection to all LED segments, which is a typical configuration for simplifying drive circuitry in multiplexed applications.

5.3 Recommended Soldering Pattern

A land pattern for PCB design is provided, with a key dimension of 17.5 mm noted. This pattern is crucial for ensuring proper solder joint formation, mechanical stability, and thermal management during the reflow process.

6. Soldering and Assembly Guidelines

6.1 SMT Soldering Instructions

The device is designed for surface-mount technology (SMT) assembly. A maximum of two reflow soldering processes is allowed, with a mandatory cooling period to normal temperature between the first and second process. The recommended reflow profile includes a pre-heat stage at 120-150°C for a maximum of 120 seconds, with a peak temperature not exceeding 260°C for up to 5 seconds. For hand soldering with an iron, the maximum temperature is 300°C for a maximum of 3 seconds.

6.2 Storage and Moisture Sensitivity

The SMD displays are shipped in moisture-proof packaging. They should be stored at 30°C or less and 60% relative humidity (RH) or less. Once the sealed package is opened, the components begin to absorb moisture from the environment. If the parts are not stored under dry conditions (e.g., in a dry cabinet) after opening, they must be baked before the reflow soldering process to prevent popcorn cracking or delamination. Baking conditions are specified: 60°C for ≥48 hours if still on the reel, or 100°C for ≥4 hours / 125°C for ≥2 hours if in bulk. Baking should be performed only once.

7. Packaging and Ordering Information

7.1 Packing Specifications

The devices are supplied on tape-and-reel packaging compatible with automated pick-and-place equipment. Two reel sizes are mentioned: a 22-inch reel containing 45.50 meters of tape, and a 13-inch reel containing 800 pieces. The minimum packing quantity for remainder lots is 200 pieces. Detailed dimensions for the packing reel and the carrier tape (meeting EIA-481-C requirements) are provided, including sprocket hole pitch tolerance, camber limits, and tape thickness (0.40±0.05mm). The packaging includes leader and trailer parts on the tape for machine handling.

8. Application Suggestions

8.1 Typical Application Scenarios

This display is intended for ordinary electronic equipment such as office equipment, communication devices, and household applications. Its clear digits and SMD format make it suitable for front panels of audio/video equipment, test instruments, appliance controls, and automotive aftermarket displays where space is limited.

8.2 Design Considerations and Cautions

Critical Design Rules: The driving circuit must be designed to strictly adhere to the absolute maximum ratings for current and power dissipation. Exceeding these ratings, especially at elevated operating temperatures, can lead to severe light output degradation or premature failure. The circuit should incorporate protection against reverse voltages and transient voltage spikes that may occur during power-up or shutdown sequences, as these can damage the LED chips. Constant current driving is generally recommended over constant voltage driving for stable and consistent brightness. Designers should consult relevant application notes for circuits requiring exceptional reliability, particularly in safety-critical systems like aviation, medical, or transportation equipment.

9. Technical Comparison and Differentiation

Compared to older through-hole LED displays, the LTS-4817CKG-P offers significant advantages in assembly automation, board space savings, and potentially better thermal performance due to direct mounting on the PCB. Within the SMD segment display category, its use of AlInGaP technology typically offers higher efficiency and better temperature stability compared to some other semiconductor materials, resulting in consistent brightness over a wider temperature range. The specific binning for luminous intensity is a key differentiator that ensures visual consistency, which may not be guaranteed with unbinned or less strictly binned products.

10. Frequently Asked Questions (Based on Technical Parameters)

Q: What is the purpose of the derating factor for continuous forward current?

A: The derating factor (0.28 mA/°C) indicates that for every degree Celsius the ambient temperature rises above 25°C, the maximum allowable continuous current must be reduced by 0.28 mA. This is necessary to prevent the LED junction temperature from exceeding its safe limit, ensuring long-term reliability.

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

A: No. The forward voltage per segment is typically 2.05-2.6V. A series current-limiting resistor must always be used when connecting to a voltage source higher than the LED's forward voltage to control the current and prevent damage. The value of this resistor is calculated based on the supply voltage, the LED forward voltage, and the desired operating current.

Q: Why is baking required before soldering if the package has been opened?

A: SMD plastic packages can absorb moisture from the air. During the high-temperature reflow soldering process, this trapped moisture can vaporize rapidly, creating internal pressure that may cause package cracking (\"popcorning\") or internal delamination. Baking removes this absorbed moisture.

11. Practical Design and Usage Case

Consider designing a digital multimeter display. A microcontroller would be used to drive the LTS-4817CKG-P. Given its common anode configuration, the microcontroller ports would sink current (act as cathodes) for segments A-G and DP, while a transistor or driver IC would source current to the common anode pins (3 and 8). The drive current would be set, using current-limiting resistors, to a value like 10 mA per segment to achieve good brightness (5500 µcd typ.) while staying well within the 25 mA continuous rating. The PCB layout would follow the recommended soldering pattern for reliable assembly. If the multimeter is intended for field use with potential wide temperature variations, the designer must account for the forward voltage temperature coefficient and the current derating requirements.

12. Principle Introduction

The device operates on the principle of electroluminescence in a semiconductor p-n junction. When a forward voltage exceeding the diode's threshold is applied across the anode and cathode of an AlInGaP chip, electrons and holes recombine in the active region, releasing energy in the form of photons. The specific composition of the AlInGaP (Aluminum Indium Gallium Phosphide) semiconductor material determines the wavelength of the emitted light, in this case, green (~572 nm). The light from the tiny chip is directed and shaped by the plastic package, which includes a reflector cup and a diffused lens to form the recognizable segment shapes.

13. Development Trends

The trend in SMD LED displays continues towards higher efficiency (more light output per watt of electrical power), enabling lower power consumption and reduced heat generation. There is also a drive for miniaturization while maintaining or improving readability. Integration of driver electronics directly into the display package is another trend, simplifying the external circuit design. Furthermore, advancements in materials and packaging aim to improve reliability under harsh environmental conditions, such as higher temperature and humidity ranges. The move towards more precise and narrower binning parameters ensures superior visual consistency in end products.