LTS-5825CTB-PR LED Display Datasheet - 0.56-inch Digit Height - InGaN Blue - 3.8V Forward Voltage - English Technical Document

1. Product Overview

The LTS-5825CTB-PR is a surface-mount device (SMD) designed as a single-digit alphanumeric display. Its primary function is to provide clear, bright numeric and limited alphanumeric character output in electronic equipment. The core technology utilizes Indium Gallium Nitride (InGaN) semiconductor material grown on a sapphire substrate, which is responsible for its efficient blue light emission. The device features a gray face and white segments, enhancing contrast and readability. It is categorized as a Common Anode type display, meaning the anodes of all LED segments are connected internally, simplifying circuit design for multiplexing.

1.1 Key Features and Advantages

• Digit Size: A 0.56-inch (14.22 mm) character height offers excellent visibility for medium-range viewing distances.
• Optical Performance: Delivers high brightness and high contrast, facilitated by continuous uniform segments that ensure consistent illumination across the character.
• Viewing Angle: Provides a wide viewing angle, making the display legible from various positions.
• Power Efficiency: Has a low power requirement, contributing to energy-efficient designs.
• Reliability: Benefits from solid-state reliability with no moving parts, leading to long operational life.
• Quality Control: Devices are categorized (binned) for luminous intensity, allowing for consistent brightness matching in multi-digit applications.
• Environmental Compliance: The package is lead-free and complies with the RoHS (Restriction of Hazardous Substances) directive.

1.2 Target Applications and Market

This display is intended for use in ordinary electronic equipment. Typical application areas include office automation devices (e.g., copiers, printers), communication equipment, household appliances, instrumentation panels, and consumer electronics where clear numeric readouts are required. It is suitable for applications demanding reliability, good visibility, and a compact form factor. Designers should consult for applications involving exceptional reliability requirements, such as in aviation, medical, or safety-critical systems.

2. Technical Specifications Deep Dive

2.1 Absolute Maximum Ratings

These ratings define the limits beyond which permanent damage to the device may occur. Operating the device continuously at or near these limits is not recommended.

• Power Dissipation per Segment: 70 mW maximum.
• Peak Forward Current per Segment: 30 mA (under pulsed conditions: 1/10 duty cycle, 0.1ms pulse width).
• Continuous Forward Current per Segment: 25 mA at 25°C. This rating derates linearly by 0.28 mA/°C as ambient temperature increases above 25°C.
• Operating & Storage Temperature Range: -35°C to +105°C.
• Soldering Temperature: Withstands 260°C for 3 seconds at 1/16 inch (approx. 1.6mm) below the seating plane.

2.2 Electrical & Optical Characteristics

These are the typical performance parameters measured at an ambient temperature (Ta) of 25°C.

• Average Luminous Intensity (I_V): 8600 to 28500 µcd (microcandelas) at a forward current (I_F) of 10mA. A 15% tolerance applies to this measurement.
• Peak Emission Wavelength (λ_p): 468 nm (nanometers), indicating the strongest point of light emission in the blue spectrum.
• Dominant Wavelength (λ_d): 470 nm, which is the wavelength perceived by the human eye, with a tolerance of ±1 nm.
• Spectral Line Half-Width (Δλ): 25 nm, defining the spectral purity or bandwidth of the emitted blue light.
• Forward Voltage per Chip (V_F): 3.3V to 3.8V at I_F=5mA, with a tolerance of ±0.1V. This is a critical parameter for driver circuit design.
• Reverse Current (I_R): Maximum 100 µA at a reverse voltage (V_R) of 5V. Note that this is a test condition; the device is not designed for continuous reverse bias operation.
• Luminous Intensity Matching Ratio: 2:1 maximum for segments within a similar light area, ensuring visual uniformity.
• Crosstalk: Specified as ≤ 2.5%, minimizing unwanted illumination of adjacent off segments.

2.3 Electrostatic Discharge (ESD) Sensitivity

LEDs are susceptible to damage from electrostatic discharge. The datasheet strongly recommends implementing ESD control measures during handling and assembly:

• Use grounded wrist straps or anti-static gloves.
• Ensure all workstations, tools, and storage facilities are properly grounded.
• Employ ionizers to neutralize static charges that may accumulate on the plastic package.

3. Binning and Categorization System

The LTS-5825CTB-PR employs a categorization system primarily for Luminous Intensity. Devices are tested and sorted into bins based on their measured light output at a standard test current (10mA). This allows designers to select displays with matched brightness levels, which is crucial for multi-digit applications to avoid uneven appearance. The specified intensity range is 8600-28500 µcd. While not explicitly detailed for wavelength in this document, the tight tolerance on dominant wavelength (±1 nm) inherently ensures good color consistency from device to device.

4. Performance Curve Analysis

The datasheet references typical characteristic curves, which are essential for understanding device behavior under varying conditions. While the specific graphs are not reproduced in the provided text, they typically include:

• Forward Current vs. Forward Voltage (I-V Curve): Shows the nonlinear relationship, crucial for determining the required driving voltage for a desired current.
• Luminous Intensity vs. Forward Current: Illustrates how light output increases with current, helping to optimize the trade-off between brightness and power consumption/heat.
• Luminous Intensity vs. Ambient Temperature: Demonstrates the decrease in light output as temperature rises, which is vital for thermal management in the application.
• Spectral Distribution: A plot of relative intensity versus wavelength, confirming the peak and dominant wavelengths and spectral width.

5. Mechanical and Package Information

5.1 Package Dimensions

The device 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 for the display face: foreign material on segments ≤ 10 mils, ink contamination ≤ 20 mils, bubbles in segments ≤ 10 mils, and bending of the reflector ≤ 1% of its length. The plastic pin burr is limited to a maximum of 0.14 mm.

5.2 Pin Configuration and Circuit Diagram

The display has a 10-pin configuration. The internal circuit diagram shows a Common Anode architecture. The pinout is as follows: Pin 3 and Pin 8 are Common Anodes. Pins 1, 2, 4, 5, 6, 7, 9, and 10 are Cathodes for segments E, D, C, DP (decimal point), B, A, F, and G respectively. Pin 5 is specifically for the right-hand decimal point cathode.

5.3 Recommended Soldering Land Pattern

A recommended footprint (land pattern) for PCB design is provided to ensure reliable solder joint formation and proper mechanical alignment during the reflow process. Adhering to this pattern is critical for manufacturing yield.

6. Soldering and Assembly Guidelines

6.1 Reflow Soldering Parameters

The device is suitable for reflow soldering. Critical parameters are:

• Pre-heat: 120–150°C.
• Pre-heat Time: Maximum 120 seconds.
• Peak Temperature: Maximum 260°C.
• Time Above Liquidus: Maximum 5 seconds.
• Number of Reflow Cycles: Maximum 2 times. The assembly must cool to normal temperature between the first and second soldering process.

6.2 Hand Soldering (Iron)

If hand soldering is necessary, the iron temperature should not exceed 300°C, and the soldering time per joint should be limited to a maximum of 3 seconds.

6.3 Moisture Sensitivity and Storage

The SMD package is moisture-sensitive. Devices are shipped in moisture-proof packaging with a desiccant. They should be stored at ≤ 30°C and ≤ 60% Relative Humidity. Once the sealed bag is opened, the devices begin to absorb moisture from the environment. If the exposure time exceeds the specified limits (not detailed in this excerpt), or if the parts are not stored in a dry cabinet, they must be baked before reflow to prevent popcorn cracking or delamination during soldering. Baking conditions are: 60°C for ≥48 hours (in reel), or 100°C for ≥4 hours / 125°C for ≥2 hours (in bulk). Baking should only be performed once.

7. Packaging and Ordering Information

7.1 Packing Specifications

The devices are supplied on tape and reel for automated assembly. The carrier tape is made of black conductive polystyrene alloy. The packaging complies with EIA-481-D standards. Key reel specifications include a packing length of 44.5 meters per 22-inch reel, containing 700 pieces per 13-inch reel. A minimum packing quantity of 200 pieces applies for remainder orders. The tape includes leader and trailer sections (minimum 400mm and 40mm, respectively) to facilitate machine feeding.

7.2 Part Number Interpretation

The part number LTS-5825CTB-PR can be decoded as: LTS (product family), 5825 (likely a series/model identifier), C (likely color code for blue), T (package type), B (brightness bin or variant), PR (may indicate right-hand decimal point).

8. Application Notes and Design Considerations

8.1 Driver Circuit Design

As a common anode display, the anodes (pins 3 & 8) should be connected to the positive supply voltage (V_CC). Individual segments are turned ON by sinking current through their respective cathode pins to ground. The forward voltage (V_F) of 3.3-3.8V must be considered when selecting the supply voltage. A current-limiting resistor is required in series with each cathode (or a constant current driver can be used) to set the forward current (I_F) to the desired level, typically between 5-20 mA, balancing brightness and longevity. For multiplexing multiple digits, the common anodes are switched sequentially at a high frequency.

8.2 Thermal Management

The linear derating of continuous forward current (0.28 mA/°C above 25°C) highlights the importance of thermal management. In high ambient temperatures or high duty-cycle applications, the effective maximum current must be reduced accordingly. Adequate PCB copper pour and ventilation help dissipate heat.

8.3 Optical Integration

The gray face and white segments provide inherent contrast. For further enhancement, consider adding a neutral density filter or a colored diffuser. The wide viewing angle makes it suitable for applications where the user may not be directly in front of the display.

9. Comparison and Differentiation

Compared to older technologies like red GaAsP LEDs or larger through-hole LED displays, the LTS-5825CTB-PR offers several advantages: Smaller Form Factor: The SMD package saves significant board space and enables lower profile designs. Higher Efficiency: InGaN technology provides higher brightness at lower currents. Better Reliability: Solid-state construction and robust SMD packaging improve shock and vibration resistance. Ease of Assembly: Compatible with high-speed, automated pick-and-place and reflow soldering processes, reducing manufacturing cost. Its primary differentiator within its category is the specific combination of 0.56-inch digit height, blue color, common anode configuration, and the detailed performance specifications and quality controls documented.

10. Frequently Asked Questions (FAQ)

Q1: What is the difference between peak wavelength and dominant wavelength?
A1: Peak wavelength (λ_p=468 nm) is the point of maximum spectral power output. Dominant wavelength (λ_d=470 nm) is the single wavelength of monochromatic light that would match the perceived color of the LED. They are often close but not identical.

Q2: Can I drive this display with a 5V supply?
A2: Yes, but you must use a series current-limiting resistor for each segment. The resistor value is calculated as R = (V_supply - V_F) / I_F. For a 5V supply, V_F of 3.5V, and I_F of 10mA, R = (5 - 3.5) / 0.01 = 150 Ω.

Q3: Why is the number of reflow cycles limited to two?
A3: Repeated exposure to high soldering temperatures can cause thermal stress on the internal die attach, wire bonds, and plastic package, potentially leading to reduced reliability or failure. The limit ensures long-term device integrity.

Q4: What happens if I don't bake a moisture-exposed reel before reflow?
A4: Trapped moisture can rapidly vaporize during the high-temperature reflow profile, creating high internal pressure. This can cause package cracking (\"popcorning\"), internal delamination, or bond wire damage, resulting in immediate or latent failure.

11. Practical Use Case Example

Scenario: Designing a Digital Multimeter Display. A designer needs a bright, reliable, single-digit display for a compact multimeter. The LTS-5825CTB-PR is selected. Four displays are used to show up to 1999 counts. The microcontroller uses a multiplexing technique: it sets the pattern for digit 1 on the cathode lines, enables the common anode for digit 1, waits a short time, then disables digit 1, sets the pattern for digit 2, enables its anode, and so on, cycling rapidly. The current for each segment is set to 8 mA via resistors, providing adequate brightness with low power consumption. The gray face ensures good contrast under the protective glass of the multimeter. The devices are sourced from the same luminous intensity bin to guarantee uniform brightness across all four digits.

12. Technical Principle Introduction

The light emission is based on electroluminescence in a semiconductor p-n junction. The active material is Indium Gallium Nitride (InGaN). When a forward voltage exceeding the diode's turn-on voltage (approx. 3.3V) is applied, electrons from the n-type region and holes from the p-type region are injected into the active region (quantum well). When an electron recombines with a hole, energy is released in the form of a photon. The specific composition of the InGaN alloy determines the bandgap energy, which in turn dictates the wavelength (color) of the emitted light—in this case, blue (~470 nm). The sapphire substrate provides a crystalline template for growing the high-quality InGaN layers.

13. Technology Trends and Context

This device represents a mature application of InGaN blue LED technology. The trend in alphanumeric SMD displays is towards higher pixel density (multi-digit and dot-matrix in a single package), full-color capability (integrating red, green, and blue chips), and even lower power consumption. There is also a move towards chip-on-board (COB) and integrated driver solutions that reduce external component count. Furthermore, advancements in phosphor-converted technology allow single blue or UV chips to produce white or other colors, expanding application possibilities. The principles of efficiency, reliability, and miniaturization seen in this component continue to drive innovation across the LED industry.