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

1. Product Overview

The LSHD-5503 is a high-performance, single-digit numeric display module designed for applications requiring clear, bright, and reliable numerical readouts. Its core technology is based on Advanced Semiconductor Aluminum Indium Gallium Phosphide (AS-AlInGaP) red LED chips, which are epitaxially grown on a Gallium Arsenide (GaAs) substrate. This material system is renowned for its high efficiency and excellent color purity in the red spectrum. The device features a light gray faceplate with white segment delineations, providing high contrast for optimal readability under various lighting conditions. The primary design goals are low power consumption, high brightness output, uniform segment illumination, and solid-state reliability, making it suitable for integration into a wide range of consumer, industrial, and instrumentation products where numeric data presentation is critical.

2. In-Depth Technical Parameter Analysis

The performance of the LSHD-5503 is defined by a comprehensive set of electrical and optical parameters, each critical for proper circuit design and performance prediction.

2.1 Photometric and Optical Characteristics

The luminous performance is a key differentiator. The average luminous intensity per segment is specified with minimum, typical, and maximum values under different drive conditions. At a forward current (I_F) of 1 mA, the intensity ranges from 320 μcd (min) to 1300 μcd (max), with a typical value provided. At a higher drive current of 10 mA, the typical intensity rises significantly to 5400 μcd, demonstrating the device's capability for high-brightness applications. The luminous intensity matching ratio between segments is specified as 2:1 maximum at I_F=1mA, ensuring visual uniformity across the digit. The dominant wavelength (λ_d) is 624 nm, and the peak emission wavelength (λ_p) is 632 nm at I_F=20mA, placing it firmly in the red portion of the visible spectrum. The spectral line half-width (Δλ) is 20 nm, indicating a relatively narrow spectral bandwidth which contributes to the pure red color.

2.2 Electrical Characteristics

The forward voltage (V_F) per segment is between 2.1V (min) and 2.6V (max) when driven at 20 mA. This parameter is essential for calculating the necessary current-limiting resistor value in a circuit: R_limit = (V_supply - V_F) / I_F. The reverse current (I_R) is limited to a maximum of 100 μA at a reverse voltage (V_R) of 5V, which is a standard test condition and not a continuous operating mode.

2.3 Absolute Maximum Ratings and Thermal Management

These ratings define the stress limits beyond which permanent damage may occur. The continuous forward current per segment is 25 mA. The peak forward current per segment is rated at 90 mA, but only under pulsed conditions (1 kHz frequency, 15% duty cycle), which is useful for multiplexing schemes to achieve higher perceived brightness. The power dissipation per segment is 70 mW, calculated as V_F * I_F. A forward current derating factor of 0.28 mA/°C is specified above 25°C ambient temperature (T_a). This means for every degree Celsius above 25°C, the maximum allowable continuous current must be reduced by 0.28 mA to prevent overheating. For example, at 50°C, the maximum current would be 25 mA - (0.28 mA/°C * 25°C) = 18 mA. The operating and storage temperature range is -35°C to +105°C, indicating robustness for harsh environments.

3. Binning and Classification System

The datasheet explicitly states that the devices are "Binned for Luminous Intensity." This is a critical quality control and selection process. During manufacturing, variations occur. Binning involves testing each unit's luminous output at a standard test current (likely 1 mA or 10 mA as per the datasheet) and grouping them into specific intensity ranges or "bins." This allows designers to select parts with consistent brightness levels for their application, ensuring uniform appearance in multi-digit displays or across different products. While the datasheet provides the overall min/max range, specific bin codes and their corresponding intensity ranges would typically be defined in a separate binning document from the manufacturer.

4. Performance Curve Analysis

The datasheet references "Typical Electrical / Optical Characteristic Curves" which are essential for understanding device behavior beyond single-point specifications. Although the specific graphs are not detailed in the provided text, standard curves for such devices typically include:

• Relative Luminous Intensity vs. Forward Current (I_V vs. I_F): Shows how light output increases with current, usually in a sub-linear fashion at higher currents due to heating and efficiency droop.
• Forward Voltage vs. Forward Current (V_F vs. I_F): Demonstrates the diode's I-V characteristic, crucial for driver design.
• Relative Luminous Intensity vs. Ambient Temperature (I_V vs. T_a): Illustrates how light output decreases as the junction temperature rises, highlighting the importance of thermal management.
• Spectral Distribution: A plot of relative intensity vs. wavelength, showing the peak at ~632 nm and the 20 nm half-width.

These curves allow engineers to model performance under non-standard conditions (e.g., different drive currents, temperatures) and optimize their designs.

5. Mechanical and Package Information

The LSHD-5503 has a digit height of 0.56 inches (14.22 mm). The package dimensions are provided in a detailed drawing with all critical measurements in millimeters. Tolerances are generally ±0.25 mm unless otherwise specified. This information is vital for PCB footprint design, ensuring proper fit within the enclosure, and maintaining alignment of the decimal point. The package houses the LED chips, the light-gray face/white segment mask, and the connecting pins.

6. Pin Connection and Internal Circuit

The device has a standard 10-pin configuration for a 7-segment plus decimal point display. It utilizes a common cathode architecture. This means the cathodes (negative terminals) of all LED segments are connected together internally and brought out to pins 3 and 8, which are also tied together. The anodes (positive terminals) of each individual segment (A through G) and the decimal point (DP) are brought out to separate pins (1, 2, 4, 5, 6, 7, 9, 10). The internal circuit diagram visually represents this arrangement, showing eight individual LEDs (seven segments + DP) with their anodes isolated and their cathodes connected to the common node. This configuration is ideal for multiplexing, where digits are powered one at a time in rapid sequence.

7. Soldering and Assembly Guidelines

The absolute maximum ratings include specific soldering conditions: the device can be subjected to a soldering iron temperature of 260°C for 5 seconds, with the condition that the iron tip must be at least 1/16 inch (approximately 1.6 mm) below the seating plane of the package. This is a critical instruction to prevent excessive heat from traveling up the pins and damaging the internal LED chips or the plastic package. For wave or reflow soldering, the profile must be carefully controlled to stay within the package's thermal limits, typically referencing the IPC/JEDEC J-STD-020 standard for moisture sensitivity and reflow profiles, though not explicitly stated here. Proper ESD (Electrostatic Discharge) handling procedures should always be followed during assembly.

8. Application Suggestions and Design Considerations

8.1 Typical Application Scenarios

The LSHD-5503 is suited for any application requiring a bright, reliable, single-digit numeric display. Common uses include: test and measurement equipment (multimeters, frequency counters), industrial control panels (temperature displays, counter readouts), consumer appliances (microwave ovens, washing machines, audio equipment), automotive aftermarket gauges, and point-of-sale terminals.

8.2 Critical Design Considerations

• Current Limiting: LEDs are current-driven devices. A series resistor must be used with each segment (or a constant current driver) to limit the forward current to a safe value (≤25 mA continuous). The resistor value is calculated using the supply voltage and the forward voltage drop from the datasheet.
• Multiplexing: For multi-digit displays, a common-cathode device like the LSHD-5503 is ideal. A microcontroller can sequentially enable the common cathode of one digit while driving the segment anodes for that digit's pattern. The peak current rating (90 mA pulsed) allows for higher instantaneous current during the short multiplexing period to achieve a bright average luminosity.
• Thermal Design: Adhere to the current derating curve. Ensure adequate ventilation if operating at high ambient temperatures or high continuous currents. The PCB layout can help dissipate heat from the pins.
• Viewing Angle: The datasheet claims a wide viewing angle, which is beneficial for applications where the display may be viewed from off-axis positions.

9. Technical Comparison and Differentiation

Compared to older technologies like standard GaAsP (Gallium Arsenide Phosphide) red LEDs, the AlInGaP technology in the LSHD-5503 offers significantly higher luminous efficiency, resulting in greater brightness for the same drive current. It also provides superior color purity and stability over temperature and time. Compared to some modern white LEDs with color filters, AlInGaP red LEDs are inherently monochromatic and more efficient for producing pure red light. The 0.56-inch digit height places it in a common size category, offering a good balance between readability and physical footprint. Its common-cathode configuration offers a direct advantage for microcontroller-based multiplexed designs over common-anode types in certain circuit topologies.

10. Frequently Asked Questions (Based on Technical Parameters)

Q: Can I drive this display directly from a 5V microcontroller pin?
A: No. You must use a current-limiting resistor. A typical red LED drops about 2V. Connecting 5V directly would cause excessive current, destroying the segment. Calculate the resistor: R = (5V - 2.6V) / 0.02A = 120Ω (using max V_F for safety).

Q: What does "Binned for Luminous Intensity" mean for my design?
A: It means you can order parts from a specific brightness range. If visual consistency across multiple units is critical (e.g., a multi-digit panel), specify the desired bin code to your distributor to ensure all digits have matched brightness.

Q: The peak current is 90mA, but continuous is only 25mA. Can I use 90mA for brighter output?
A: Only in a pulsed mode, as specified (1 kHz, 15% duty cycle). The average current in that case would be 90mA * 0.15 = 13.5mA, which is within the continuous rating. Continuous operation at 90mA would exceed the power dissipation limit and cause rapid failure.

Q: How do I connect the two common cathode pins (3 and 8)?
A: They are internally connected. You can use either one or connect both to your driver circuit (e.g., transistor sink) for potentially better current distribution and thermal performance.

11. Design and Usage Case Study

Scenario: Designing a simple 3-digit voltmeter display.
Three LSHD-5503 displays are used. A microcontroller with sufficient I/O pins is chosen. The design employs time-division multiplexing:
1. The common cathode pins of each digit are connected to individual NPN transistors (or a dedicated driver IC) controlled by the microcontroller.
2. The segment anode pins (A-G, DP) of all three digits are connected together and linked to the microcontroller via current-limiting resistors.
3. The microcontroller software: a) Turns off all cathode driver transistors. b) Calculates which segments need to be lit for the hundreds digit. c) Activates the segment pattern on the anode lines. d) Briefly enables the transistor for the hundreds digit's cathode. e) Repeats steps b-d for the tens and units digits in rapid succession (e.g., at 1 kHz overall rate).
The peak segment current during its brief on-time can be set higher (e.g., 40-60 mA) to compensate for the low duty cycle (≈33% per digit in a 3-digit system), achieving a bright, flicker-free display while keeping average power and heat within limits.

12. Technology Principle Introduction

The LSHD-5503 is based on Aluminum Indium Gallium Phosphide (AlInGaP) semiconductor material grown epitaxially on a Gallium Arsenide (GaAs) substrate. This is a compound semiconductor from the III-V group. 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 bandgap energy of the AlInGaP alloy determines the wavelength of the emitted light; in this case, it is tuned to produce red light around 624-632 nm. The use of a direct bandgap material like AlInGaP results in high internal quantum efficiency. The light is emitted through a molded epoxy package that incorporates a light-gray face with white-painted segments. The white paint reflects and diffuses the light from the underlying LED chip, creating the uniformly illuminated segments visible to the user.

13. Technology Trends and Context

While the LSHD-5503 represents mature and reliable technology, the broader field of display technology continues to evolve. AlInGaP remains the dominant high-efficiency technology for red and amber LEDs. Trends in discrete LED displays include the pursuit of even higher efficiency (more lumens per watt), which improves battery life in portable devices and reduces thermal load. There is also a trend towards miniaturization of the chip scale itself, allowing for potentially smaller package footprints or higher pixel density in multi-element displays. Furthermore, integration is a key trend; driver electronics and sometimes even microcontrollers are being integrated into "intelligent display" modules, simplifying the design process for end engineers. However, for standard, cost-effective, single-digit numeric displays, devices like the LSHD-5503, with their proven performance and wide availability, will remain a fundamental component in electronic design for the foreseeable future, especially in applications where custom graphical displays are unnecessary.