LTS-5825CKR-PR LED Display Datasheet - 0.56 Inch Digit Height - Super Red - 2.6V Forward Voltage - English Technical Document

1. Product Overview

The LTS-5825CKR-PR is a single-digit, surface-mount LED display module designed for applications requiring clear, high-visibility numeric readouts. It features a digit height of 0.56 inches (14.22 mm), making it suitable for medium-sized displays in various electronic devices. The core technology utilizes AlInGaP (Aluminum Indium Gallium Phosphide) epitaxial layers on a GaAs substrate to produce a Super Red emission. This material system is known for its high efficiency and excellent color purity. The display has a gray face with white segments, providing high contrast for optimal readability under different lighting conditions.

1.1 Key Features

• 0.56 Inch Digit Height: Provides a clear and easily readable character size.
• Continuous Uniform Segments: Ensures consistent illumination across all segments for a professional appearance.
• Low Power Requirement: Operates efficiently, making it suitable for battery-powered or energy-conscious applications.
• High Brightness & High Contrast: The Super Red AlInGaP chips deliver intense light output against the gray background.
• Wide Viewing Angle: Offers good visibility from various angles.
• Categorized for Luminous Intensity: Devices are binned for consistent brightness levels.
• Lead-Free Package: Compliant with RoHS (Restriction of Hazardous Substances) directives.
• Solid-State Reliability: Benefits from the inherent longevity and shock resistance of LED technology.

1.2 Device Configuration

This is a common anode, single-digit display with a right-hand decimal point (DP). The specific part number LTS-5825CKR-PR identifies this configuration. The common anode design simplifies circuit design when using microcontroller or driver ICs that source current.

2. Technical Parameters: In-Depth Objective Interpretation

2.1 Absolute Maximum Ratings

These ratings define the limits beyond which permanent damage to the device may occur. They are specified at an ambient temperature (Ta) of 25°C.

• Power Dissipation per Segment: 70 mW maximum. Exceeding this can lead to overheating and reduced lifespan.
• Peak Forward Current per Segment: 90 mA, but only under pulsed conditions (1/10 duty cycle, 0.1ms pulse width). This rating is for brief, high-current pulses, not continuous operation.
• Continuous Forward Current per Segment: 25 mA at 25°C. This current derates linearly by 0.28 mA/°C as the ambient temperature increases above 25°C. This is a critical parameter for thermal management design.
• Operating & Storage Temperature Range: -35°C to +105°C. The device is robust for industrial and automotive environments.
• Soldering Temperature: Iron soldering should be performed at 260°C for a maximum of 3 seconds, with the iron tip at least 1/16 inch (approx. 1.6mm) below the seating plane of the component.

2.2 Electrical & Optical Characteristics

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

• Average Luminous Intensity (Iv): Ranges from 501 µcd (min) to 18000 µcd (max) depending on forward current. At a typical drive current of 10mA, the intensity is 1700 µcd (min). Luminous intensity is measured using a filter that mimics the human eye's photopic response (CIE curve).
• Peak Emission Wavelength (λp): 639 nm (typical). This is the wavelength at which the emitted light intensity is highest.
• Dominant Wavelength (λd): 631 nm (typical). This is the single wavelength perceived by the human eye to match the color of the light, defining its \"Super Red\" hue.
• Spectral Line Half-Width (Δλ): 20 nm (typical). This indicates the spectral purity; a narrower width means a more monochromatic color.
• Forward Voltage per Chip (Vf): 2.6V (max) at IF=20mA. Designers must ensure the driving circuit can provide sufficient voltage.
• Reverse Current (Ir): 100 µA (max) at VR=5V. This parameter is for test purposes only; applying continuous reverse bias is not recommended.
• Luminous Intensity Matching Ratio: 2:1 (max). This means the brightest segment should not be more than twice as bright as the dimmest segment within the same device at the same drive current, ensuring uniformity.
• Cross Talk: ≤ 2.5%. This specifies the maximum amount of unintended light leakage between adjacent segments when one is on and the other is off.

3. Binning System Explanation

The datasheet explicitly states that the devices are \"Categorized for Luminous Intensity.\" This implies a binning process where displays are sorted based on their measured light output at a standard test current (likely 1mA or 10mA as per the characteristics table). This ensures that end products have consistent brightness levels across different units. Designers should consult the manufacturer for specific bin code details if tight brightness matching is required across multiple displays.

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 include:

• I-V (Current-Voltage) Curve: Shows the relationship between forward voltage and forward current, crucial for selecting current-limiting resistors.
• Luminous Intensity vs. Forward Current: Demonstrates how light output increases with drive current, helping to optimize the balance between brightness and power consumption/heat.
• Luminous Intensity vs. Ambient Temperature: Shows how light output decreases as temperature rises, important for applications in high-temperature environments.
• Spectral Distribution: A graph plotting relative intensity against wavelength, visually confirming the peak and dominant wavelengths and spectral width.

5. Mechanical & Package Information

5.1 Package Dimensions

The display conforms to a specific SMD footprint. Key dimensional notes include: all dimensions are in millimeters with a general tolerance of ±0.25 mm. Specific quality controls are in place: foreign material on a segment must be ≤10 mils, surface ink contamination ≤20 mils, bubbles in a segment ≤10 mils, bending ≤1% of the reflector length, and plastic pin burr maximum of 0.14 mm.

5.2 Pin Connection & Polarity

The device has a 10-pin configuration. The internal circuit diagram and pinout table show it is a common anode type. Pins 3 and 8 are the common anodes. The other pins are cathodes for specific segments (A, B, C, D, E, F, G, DP). Pin 1 is marked as \"No Connection.\" Correct polarity identification is essential to prevent damage during installation.

5.3 Recommended Soldering Pattern

A land pattern (footprint) is provided for PCB design. Adhering to this pattern ensures proper solder joint formation, mechanical stability, and thermal relief during the soldering process.

6. Soldering & Assembly Guidelines

6.1 SMT Soldering Instruction

A critical process constraint is that the number of reflow soldering cycles must be less than two. A complete cooling process to normal temperature is required between the first and second soldering process to minimize thermal stress.

• Reflow Soldering (Max 2 cycles): Pre-heat at 120–150°C for a maximum of 120 seconds. The peak temperature must not exceed 260°C.
• Hand Soldering with Iron (Max 1 cycle): The iron tip temperature should not exceed 300°C, and contact time should be limited to 3 seconds maximum.

7. Packaging & Ordering Information

7.1 Packing Specification

The devices are supplied on tape and reel for automated assembly. Key packaging details include:

• Reel Dimensions: Compliant with standard EIA-481-D requirements.
• Carrier Tape: Made of black conductive polystyrene alloy. 10-sprocket hole pitch cumulative tolerance is ±0.20 mm. Camber is within 1 mm over 250 mm. Tape thickness is 0.30 ±0.05 mm.
• Packing Quantities: Standard reel length is 44.5 meters on a 22-inch reel. A 13-inch reel contains 700 pieces. The minimum packing quantity for remainder parts is 200 pieces.
• Leader/Trailer Tape: Includes a leader part (minimum 400mm) and trailer part (minimum 40mm) for machine feeding.

7.2 Moisture Sensitivity & Storage

The SMD displays are shipped in moisture-proof packaging. They must be stored at ≤30°C and ≤60% Relative Humidity. Once the sealed bag is opened, the components begin to absorb moisture from the environment. If not used immediately and stored under dry conditions (e.g., in a dry cabinet), they must be baked before reflow soldering to prevent \"popcorning\" or delamination damage. Baking specifications: 60°C for ≥48 hours when in reel, or 100°C for ≥4 hours / 125°C for ≥2 hours when in bulk. Baking should only be performed once.

8. Application Suggestions

8.1 Typical Application Scenarios

• Consumer Electronics: Digital readouts in appliances, audio equipment, or power strips.
• Industrial Instrumentation: Panel meters, process controllers, test and measurement equipment.
• Automotive Aftermarket: Displays for car audio systems, gauges, or diagnostic tools (consider extended temperature range).
• Medical Devices: Where clear, reliable numeric indication is needed (subject to further device-level qualification).

8.2 Design Considerations

• Current Limiting: Always use series resistors for each segment or employ a constant-current driver to set the forward current, typically between 5-20 mA depending on required brightness and power budget. Refer to the derating curve for high-temperature operation.
• Thermal Management: Ensure adequate PCB copper area or thermal vias if operating at high ambient temperatures or near maximum continuous current to manage junction temperature.
• ESD Protection: Implement standard ESD handling procedures during assembly, as LEDs are sensitive to electrostatic discharge.
• Optical Design: The gray face/white segment design offers good contrast. Consider the viewing angle requirements for the end product enclosure.

9. Frequently Asked Questions (Based on Technical Parameters)

9.1 What is the difference between peak wavelength and dominant wavelength?

Peak wavelength (639 nm) is the physical point of highest spectral power. Dominant wavelength (631 nm) is the perceptual color match. Designers concerned with color specification should reference the dominant wavelength.

9.2 Can I drive this display at 20mA continuously?

Yes, the maximum continuous current is 25 mA at 25°C. However, at 20mA, you must ensure the ambient temperature and PCB thermal design allow for proper heat dissipation, as the current rating derates with temperature (0.28 mA/°C above 25°C).

9.3 Why is the reflow process limited to two cycles?

Multiple reflow cycles subject the plastic package and internal wire bonds to repeated thermal stress, which can lead to mechanical failure, increased forward voltage, or reduced reliability. The limit ensures long-term performance.

9.4 How do I calculate the series resistor value?

Use Ohm's Law: R = (Vsupply - Vf_total) / If. For a common anode display, Vf_total is the forward voltage of one segment (use max 2.6V for design margin). If is your desired segment current (e.g., 10mA). If driving from a 5V microcontroller pin: R = (5V - 2.6V) / 0.01A = 240 Ohms. Use the nearest standard value.

10. Operating Principle Introduction

The LTS-5825CKR-PR is based on AlInGaP semiconductor technology. When a forward voltage exceeding the diode's threshold is applied across the anode and cathode of a segment, electrons and holes recombine in the active quantum well region of the AlInGaP epitaxial layer. This recombination releases energy in the form of photons (light) in the red spectrum (~631 nm dominant wavelength). The gray plastic package acts as a diffuser and contrast-enhancing lens, while the white segment areas allow the red light to pass through clearly. The common anode configuration means all the anodes of the LED chips for the different segments are connected internally; to illuminate a segment, its corresponding cathode pin is driven low (sinked to ground) while the common anode is held at a positive voltage.