LTS-5825CKG-PST1 LED Display Datasheet - 0.56-inch Digit Height - AlInGaP Green - 2.6V Forward Voltage - 25mA Continuous Current - English Technical Document

1. Product Overview

The LTS-5825CKG-PST1 is a high-performance, single-digit, surface-mount device (SMD) LED display designed for applications requiring clear, bright numeric readouts. Its core technology is based on Aluminum Indium Gallium Phosphide (AlInGaP) semiconductor material, which is grown on a non-transparent Gallium Arsenide (GaAs) substrate. This material system is renowned for producing high-efficiency green light emission. The display features a black face for enhanced contrast and white segments for optimal light diffusion and visibility. With a digit height of 0.56 inches (14.22 mm), it offers excellent character appearance and is suitable for a wide range of consumer and industrial electronic devices where space is at a premium but readability is critical.

1.1 Core Advantages and Target Market

This display is engineered for reliability and performance. Key advantages include low power consumption, high brightness output, and a wide viewing angle, ensuring legibility from various positions. The solid-state construction provides inherent reliability and long operational life. It is categorized for luminous intensity, allowing for consistent brightness matching in multi-digit applications. The primary target markets include instrumentation panels, test and measurement equipment, point-of-sale terminals, industrial control systems, and automotive dashboard displays where a single, highly visible digit is required.

2. Technical Parameters Deep Objective Interpretation

2.1 Absolute Maximum Ratings

These ratings define the limits beyond which permanent damage to the device may occur. 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 kHz frequency, 10% duty cycle) to manage heat. The continuous forward current per segment, which is the safe limit for steady-state operation, is 25 mA at an ambient temperature (Ta) of 25°C. This rating derates linearly by 0.28 mA for every degree Celsius increase in ambient temperature above 25°C. The device can operate and be stored within a temperature range of -40°C to +105°C. The soldering condition specifies that the device body should be at least 1/16 inch above the seating plane during a 3-second reflow at a peak temperature of 260°C.

2.2 Electrical and Optical Characteristics

These parameters are measured at a standard test condition of Ta = 25°C and provide the expected performance. The luminous intensity (Iv) ranges from a minimum of 501 μcd to a typical 1700 μcd at a forward current (IF) of 1 mA. The peak emission wavelength (λp) is 571 nm, and the dominant wavelength (λd) is 572 nm at IF=20mA, placing it firmly in the green spectrum. The spectral line half-width (Δλ) is 15 nm, indicating a relatively pure color. The forward voltage per segment (VF) has a maximum of 2.6V at IF=20mA, with a typical value of 2.05V. The reverse current (IR) is a maximum of 100 μA at a reverse voltage (VR) of 5V, though continuous operation under reverse bias is prohibited. The luminous intensity matching ratio between segments is specified at 2:1 maximum, ensuring uniform brightness across the digit.

3. Mechanical and Package Information

3.1 Package Dimensions and Construction

The device is a surface-mount package. Critical dimensional tolerances are ±0.25mm unless otherwise specified. The construction details include specifications for plastic burr (maximum 0.14 mm) and PCB warping (maximum 0.06 mm). The solder pad finish is critical for reliable soldering and consists of a layered structure: a minimum of 1200 micro-inches of copper, a minimum of 150 micro-inches of nickel, and 4 micro-inches of gold plating. An additional painting layer of 400 micro-inches is applied.

3.2 Pin Connection and Internal Circuit

The display has a 10-pin configuration and utilizes a common anode circuit design. The internal circuit diagram shows that all segment anodes are connected internally to two common anode pins (Pin 3 and Pin 8). Each segment cathode (A, B, C, D, E, F, G, and Decimal Point DP) has its own dedicated pin. This configuration is common for multiplexing applications where multiple digits share driver lines.

4. Soldering and Assembly Guidelines

4.1 SMT Soldering Instructions

For reflow soldering, a specific profile must be followed. The pre-heat stage should be between 120-150°C for a maximum of 120 seconds. The peak temperature during reflow must not exceed 260°C, and the time above this critical temperature should be limited to a maximum of 5 seconds. Crucially, the number of reflow process cycles must be less than two. If a second reflow is necessary (e.g., for double-sided assembly), the board must be allowed to cool completely to normal ambient temperature between the first and second processes. For hand soldering with an iron, the tip temperature should not exceed 300°C, and contact time should be limited to 3 seconds maximum per joint.

4.2 Recommended Soldering Pattern

A recommended land pattern (footprint) is provided with dimensions in millimeters. Adhering to this pattern is essential for achieving proper solder joint formation, mechanical stability, and thermal relief during operation.

5. Packaging and Handling

5.1 Packing Specifications

The devices are supplied on tape and reel for automated assembly. The carrier tape is made of black conductive polystyrene alloy with a thickness of 0.30±0.05 mm. The camber (warp) of the carrier tape is controlled within 1 mm over a 250 mm length. Each 13-inch reel contains 700 pieces, and the total tape length on a 22-inch reel is 44.5 meters. The packaging includes leader and trailer tape sections (minimum 400 mm and 40 mm, respectively) to facilitate machine feeding. A minimum packing quantity of 200 pieces is specified for remainder lots. The direction of pulling the tape out of the reel is clearly indicated.

5.2 Moisture Sensitivity and Baking

As a surface-mount device, the display is sensitive to moisture absorption, which can cause \"popcorning\" or delamination during the high-temperature reflow process. The devices are shipped in a sealed moisture-proof package and should be stored at ≤30°C and ≤90% relative humidity. Once the sealed bag is opened, the devices have a limited floor life. If the bag has been open for more than one week under conditions not meeting the storage specifications (less than 30°C and less than 60% RH), baking is required before reflow. Baking conditions depend on the packaging state: 60°C for ≥48 hours for parts in reel, or 100°C for ≥4 hours / 125°C for ≥2 hours for parts in bulk. Baking should be performed only once.

6. Application Suggestions and Design Considerations

6.1 Typical Application Scenarios

This display is ideal for any application requiring a single, highly legible numeric digit. Common uses include digital clocks (showing seconds or minutes), battery level indicators, single-digit counters, parameter setting displays on appliances, and status code displays on electronic equipment. Its SMD format makes it suitable for modern, compact PCB designs.

6.2 Design Considerations

• Current Limiting: Always use series current-limiting resistors for each segment cathode. The resistor value should be calculated based on the supply voltage, the forward voltage (VF) of the LED, and the desired forward current (IF), which must not exceed 25 mA continuous.
• Driver Circuit: The common anode configuration simplifies driving with low-side switches (transistors or ICs) that sink current from the cathodes.
• Thermal Management: Ensure adequate PCB copper area or thermal vias, especially if operating near maximum current or in high ambient temperatures, to prevent overheating and luminous decay.
• ESD Protection: Implement standard ESD precautions during handling and assembly, as with all semiconductor devices.

7. Performance Curve Analysis

The datasheet references typical characteristic curves, which are essential for detailed design. While the specific graphs are not detailed in the provided text, engineers would typically expect to see curves for Forward Current vs. Forward Voltage (IV Curve), Luminous Intensity vs. Forward Current, Luminous Intensity vs. Ambient Temperature, and perhaps Spectral Distribution. These curves allow designers to understand non-linear behaviors, such as how efficiency changes with current or how brightness drops as temperature rises, enabling optimization of the drive conditions for specific application environments.

8. Technical Comparison and Differentiation

The key differentiator of the LTS-5825CKG-PST1 is its use of AlInGaP technology for green emission. Compared to older technologies like traditional GaP, AlInGaP offers significantly higher luminous efficiency and brightness. The black face/white segment design provides a superior contrast ratio, especially in brightly lit conditions, compared to displays with a light-colored face. The 0.56-inch digit height fills a specific niche between smaller indicators and larger panel displays. Its categorization for luminous intensity is a quality assurance feature that ensures consistency in multi-digit applications, a critical factor not always guaranteed in basic LED components.

9. Frequently Asked Questions (Based on Technical Parameters)

Q: What is the difference between peak wavelength and dominant wavelength?
A: Peak wavelength (λp) is the wavelength at which the emitted optical power is maximum. Dominant wavelength (λd) is the single wavelength of monochromatic light that matches the perceived color of the emitted light. For a narrow spectrum LED like this one, they are very close (571 nm vs. 572 nm).

Q: Can I drive this display at 20mA continuously?
A: Yes, 20mA is below the maximum continuous forward current rating of 25mA. However, you must ensure the ambient temperature is considered, as the current rating derates above 25°C.

Q: Why is the reverse current specification important if I can't operate it in reverse?
A: The IR specification is a quality and leakage test parameter. A high reverse current can indicate a manufacturing defect in the semiconductor junction.

Q: What does \"categorization for luminous intensity\" mean?
A: It means the devices are tested and sorted (binned) based on their measured luminous output at a standard test current. This allows designers to select displays from the same intensity bin to ensure uniform brightness in an array, avoiding one digit appearing dimmer than another.

10. Practical Use Case Example

Consider designing a simple digital timer with a 1-second resolution. The unit's second digit could be implemented using the LTS-5825CKG-PST1. A microcontroller would be used to control the display. The common anode pins would be connected to a positive supply voltage (e.g., 5V) through a suitable current-limiting scheme if multiplexing other digits. The eight cathode pins (segments A-G and DP) would be connected to the microcontroller's GPIO pins, each via its own current-limiting resistor (e.g., ~150Ω for 20mA at 5V supply, considering a Vf of ~2.1V). The software would cycle through the numbers 0-9, turning on the appropriate combination of cathode pins every second. The high brightness and contrast ensure the digit is easily readable from a distance, while the low power consumption helps with overall system efficiency.

11. Operating Principle Introduction

The device operates on the principle of electroluminescence in a semiconductor p-n junction. When a forward voltage exceeding the junction's built-in potential is applied (anode positive relative to cathode), electrons from the n-type region and holes from the p-type region are injected into the active region where they recombine. In AlInGaP LEDs, this recombination primarily releases energy in the form of photons (light) in the green wavelength range. The specific alloy composition of Aluminum, Indium, Gallium, and Phosphide determines the bandgap energy and thus the color of the emitted light. The non-transparent GaAs substrate absorbs any downward-emitted light, improving overall light extraction efficiency from the top of the device.

12. Technology Trends

The trend in LED display technology continues towards higher efficiency, greater miniaturization, and improved reliability. While AlInGaP is a mature and efficient technology for red, orange, amber, and green LEDs, newer materials like Indium Gallium Nitride (InGaN) are now capable of covering the full visible spectrum with very high efficiency, including green and blue. For single-digit displays, the move is towards thinner packages, higher pixel density (for dot-matrix alphanumeric displays), and integration with driver ICs or smart capabilities. However, for specific applications requiring a simple, robust, high-brightness single digit, discrete segment displays like the LTS-5825CKG-PST1 remain a cost-effective and reliable solution. Environmental considerations are also driving the elimination of hazardous substances and improvements in recyclability of packaging materials.