LTS-5503AJE-H1 LED Display Datasheet - 0.56-inch Digit Height - AlInGaP Red - 2.6V Forward Voltage - 70mW Power Dissipation - English Technical Document

1. Product Overview

The LTS-5503AJE-H1 is a high-performance, single-digit numeric display module designed for applications requiring clear, bright, and reliable numerical readouts. Its primary function is to visually represent a single digit (0-9) and a decimal point using solid-state LED technology.

Core Advantages: The device's key strengths lie in its excellent character appearance, high brightness and contrast levels, and a wide viewing angle, ensuring readability from various positions. It offers solid-state reliability with no moving parts and features a low power requirement, making it suitable for energy-conscious designs. The segments are continuous and uniform, providing a clean and professional visual output.

Target Market: This display is ideal for integration into a wide range of electronic equipment including test and measurement instruments, industrial control panels, medical devices, consumer appliances, and automotive dashboards where a compact, single-digit indicator is needed.

2. Technical Parameter Deep Dive

2.1 Photometric and Optical Characteristics

The optical performance is central to the device's functionality. At a standard test current of 1mA, the average luminous intensity (Iv) has a typical value of 1282 µcd, with a minimum specified value of 320 µcd. This high brightness is achieved using Aluminium Indium Gallium Phosphide (AlInGaP) red LED chips epitaxially grown on a Gallium Arsenide (GaAs) substrate, a technology known for high efficiency in the red/orange spectrum.

The device emits red light with a peak wavelength (λp) of 632 nm and a dominant wavelength (λd) of 624 nm when driven at 20mA. The spectral line half-width (Δλ) is 20 nm, indicating a relatively pure color emission. The luminous intensity matching ratio between segments in the same light area is specified at a maximum of 2:1, ensuring consistent brightness across all parts of the digit.

2.2 Electrical Parameters

The electrical specifications define the operating limits and conditions. The absolute maximum ratings are critical for design reliability: the power dissipation per segment must not exceed 70 mW. The continuous forward current per segment is rated at 25 mA at 25°C, with a derating factor of 0.33 mA/°C for temperatures above this. A higher peak forward current of 90 mA is permissible under pulsed conditions (1 kHz, 15% duty cycle). The maximum reverse voltage per segment is 5 V.

Under typical operating conditions (Ta=25°C, IF=20mA), the forward voltage (Vf) per segment ranges from 2.05V to 2.6V. The reverse current (Ir) is a maximum of 100 µA at the full reverse voltage of 5V.

2.3 Thermal and Environmental Specifications

The device is rated for an operating temperature range of -35°C to +85°C, with an identical storage temperature range. This wide range makes it suitable for use in harsh environments. For assembly, the solder temperature is specified as 260°C for 3 seconds, measured 1/16 inch (approximately 1.59 mm) below the seating plane, which is a standard reference for wave or reflow soldering processes.

3. Binning System Explanation

The datasheet indicates that the devices are categorized for luminous intensity. This implies a binning process where units are sorted based on their measured light output at a standard test current (likely 1mA or 20mA). Designers can select bins to ensure consistent brightness levels across multiple displays in a product. While not explicitly detailed for wavelength/color or forward voltage in this document, such categorization is common in LED manufacturing to group parts with closely matched performance characteristics.

4. Performance Curve Analysis

While the specific graphs are not detailed in the provided text, typical characteristic curves for such a device would include:

• Relative Luminous Intensity vs. Forward Current (I-V Curve): This curve shows how light output increases with drive current, typically in a sub-linear fashion, highlighting the importance of current regulation over voltage regulation for consistent brightness.
• Forward Voltage vs. Temperature: This curve demonstrates the negative temperature coefficient of the LED's forward voltage, a key consideration for thermal management and constant-current driver design.
• Luminous Intensity vs. Temperature: This shows the degradation of light output as junction temperature rises, emphasizing the need for effective heat sinking in high-power or high-ambient-temperature applications.
• Spectral Distribution: A graph plotting intensity against wavelength, centered around the 632 nm peak, visually confirming the color purity and dominant wavelength.

5. Mechanical and Package Information

The device features a 0.56-inch digit height, equivalent to 14.22 mm. The package has a light gray face with white segments, which enhances contrast when the LEDs are off. The physical dimensions are provided in a detailed drawing with all tolerances specified as ±0.25 mm unless otherwise noted. The pin connection diagram is essential for correct PCB layout.

5.1 Pin Configuration and Polarity

The LTS-5503AJE-H1 is a common cathode device. It has two common cathode pins (pins 3 and 8). The ten pins control the following segments:

1. Anode E
2. Anode D
3. Common Cathode
4. Anode C
5. Anode D.P (Decimal Point)
6. Anode B
7. Anode A
8. Common Cathode
9. Anode F
10. Anode G

The internal circuit diagram shows the interconnection of these anodes to form the standard 7-segment plus decimal point layout, with the cathodes tied together internally.

6. Soldering and Assembly Guidelines

The key assembly parameter provided is the solder temperature profile: 260°C for 3 seconds at a point 1/16 inch (1.59 mm) below the seating plane. This is a standard reference for wave soldering. For reflow soldering, a standard lead-free profile peaking at 240-250°C would typically be suitable, but the component-specific maximum of 260°C should not be exceeded.

Precautions: Avoid mechanical stress on the leads during handling. Ensure the PCB footprint matches the package dimensions precisely to prevent misalignment or tombstoning. Follow standard ESD (Electrostatic Discharge) precautions during handling and assembly.

Storage Conditions: Store in a dry, anti-static environment within the specified temperature range of -35°C to +85°C to prevent moisture absorption and degradation.

7. Packaging and Ordering Information

The part number is LTS-5503AJE-H1. The "H1" suffix likely denotes a specific bin or variant, possibly related to luminous intensity or color characteristics. The "Rt. Hand Decimal" description in the part number table confirms the position of the decimal point. Standard packaging for such components is typically on anti-static tape and reel for automated assembly, though the exact reel quantity is not specified in this excerpt.

8. Application Recommendations

Typical Application Scenarios: This display is perfectly suited for any device requiring a single numeric digit. Examples include: the units digit in a multi-digit counter or timer, a status code display, a single-digit setting indicator (e.g., temperature setting on a thermostat), or a error code display on network or industrial equipment.

Design Considerations:

• Current Limiting: Always use a series current-limiting resistor for each segment anode or employ a constant-current driver IC. Calculate the resistor value based on the supply voltage (Vcc), the typical forward voltage (Vf ~2.6V), and the desired forward current (e.g., 10-20 mA for full brightness).
• Multiplexing: For multi-digit displays, this single-digit unit can be multiplexed. Since it has a common cathode, a suitable NPN transistor or NFET can sink current from the common pins, while the segment data is provided by a microcontroller via current-limiting resistors or a driver IC.
• Viewing Angle: The wide viewing angle allows for flexible placement in an enclosure, but consider the primary user's sightline during mechanical design.
• Power Dissipation: Ensure the total power dissipated (Forward Current * Forward Voltage * number of lit segments) does not exceed the sum of individual segment limits and that thermal management is adequate, especially at high ambient temperatures.

9. Technical Comparison

Compared to older technologies like incandescent or vacuum fluorescent displays (VFDs), this AlInGaP LED display offers significantly lower power consumption, longer lifetime, and superior shock and vibration resistance. Within the LED display family, AlInGaP technology provides higher efficiency and better performance in the red/amber range compared to standard GaAsP (Gallium Arsenide Phosphide) LEDs, resulting in higher brightness for the same drive current. The common cathode configuration is often preferred in systems driven by microcontroller I/O pins, as it allows the MCU to source current (which it is typically better at) to the segment anodes while using transistors to sink the higher cumulative cathode current.

10. Frequently Asked Questions (FAQs)

Q: What is the purpose of having two common cathode pins (3 and 8)?

A: This is primarily for mechanical symmetry, easier PCB routing, and improved current distribution. Electrically, they are connected internally. You can connect one or both to your driver circuit, but connecting both is recommended for optimal performance and reliability.

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

A: No. You must use a current-limiting resistor. For a 5V supply and a target current of 20mA with a Vf of 2.6V, the resistor value would be R = (5V - 2.6V) / 0.02A = 120 Ohms. A 120Ω or 150Ω resistor would be appropriate.

Q: Why is the peak forward current (90mA) much higher than the continuous current (25mA)?

A> LEDs can handle short, high-current pulses without damage, as the heat generated does not have time to raise the junction temperature to a critical level. This allows for brief periods of overdrive to achieve even higher brightness for strobe or highlighting effects, provided the average power and temperature limits are respected.

Q: What does "categorized for luminous intensity" mean for my design?

A> It means you can order parts from a specific brightness bin. If your product uses multiple displays, specifying the same bin code ensures all digits have matched brightness. For a single display, it guarantees the brightness meets the minimum specified in the datasheet.

11. Practical Design Case

Scenario: Designing a simple single-digit counter with a microcontroller.

A microcontroller (e.g., an Arduino, PIC, or STM32) would be used. The seven segment anodes (A-G) and the decimal point anode (DP) would each be connected to a separate GPIO pin on the MCU via a 150Ω current-limiting resistor. The two common cathode pins would be connected together and then to the collector of an NPN transistor (like a 2N2222). The emitter of the transistor would connect to ground, and the base would be driven by another GPIO pin via a base resistor (e.g., 1kΩ). The microcontroller firmware would turn the transistor on to enable the digit, then set the appropriate GPIO pins high to light the segments that form the desired number. This is a direct drive method. For a more robust solution, especially with multiple digits, a dedicated LED driver IC (like the MAX7219 or TM1637) would handle multiplexing and current regulation.

12. Technology Principle Introduction

The LTS-5503AJE-H1 is based on AlInGaP (Aluminium Indium Gallium Phosphide) semiconductor material grown epitaxially on a GaAs substrate. When a forward voltage is applied across the p-n junction, electrons and holes are injected into the active region. Their recombination releases energy in the form of photons (light). The specific composition of the AlInGaP alloy determines the bandgap energy, which directly corresponds to the wavelength (color) of the emitted light—in this case, red at around 624-632 nm. The light gray face and white segments act as a diffuser and contrast-enhancing mask, respectively, shaping the light from the tiny LED chips into the recognizable segments of a digit.

13. Technology Development Trends

While this is a mature and reliable product, the broader field of LED displays continues to evolve. Trends include the development of even more efficient materials, such as improved AlInGaP structures and the rise of GaN-based LEDs for broader color gamuts. There is a constant drive towards higher pixel density (smaller pitch) and miniaturization. Integration is another key trend, with driver electronics, controllers, and sometimes even microcontrollers being combined with the display module into smart display units. Furthermore, advancements in packaging aim to improve thermal management, allowing for higher drive currents and brightness from smaller packages. However, for standard single-digit indicators, the core technology represented by the LTS-5503AJE-H1 remains a cost-effective and highly reliable solution for countless applications.