LSHD-7503 0.3-inch Single Digit Red LED Display Datasheet - Digit Height 7.62mm - Forward Voltage 2.6V - Power 75mW - English Technical Document

1. Product Overview

The LSHD-7503 is a single-digit, seven-segment numeric display utilizing high-brightness AlInGaP (Aluminum Indium Gallium Phosphide) red LED chips. The primary application is for clear numeric readouts in electronic equipment where visibility and reliability are key. The device features a light gray face and white segments, providing excellent contrast for the emitted red light. Its compact 0.3-inch (7.62 mm) digit height makes it suitable for space-constrained applications while maintaining good readability.

1.1 Core Advantages and Target Market

This display offers several key advantages that define its market position. It provides excellent segment uniformity, ensuring consistent brightness across all numerals. The low power requirement and high luminous intensity make it energy-efficient and highly visible. With a wide viewing angle and solid-state reliability, it is designed for long-term operation in consumer and industrial electronics. The primary target markets include office automation equipment, communication devices, instrumentation panels, household appliances, and other applications requiring a reliable, single-digit numeric indicator.

2. Technical Parameters: In-Depth Objective Interpretation

The following section provides a detailed analysis of the device's electrical and optical characteristics as defined in the specification sheet.

2.1 Photometric and Optical Characteristics

The luminous intensity is a critical parameter. At a forward current (I_F) of 1 mA, the typical average luminous intensity is 5400 µcd (microcandelas), with a minimum of 320 µcd and a maximum of 923 µcd. At 10 mA, the typical value rises significantly to 12000 µcd. This indicates high efficiency. The dominant wavelength (λ_d) is typically 624 nm, with a peak emission wavelength (λ_p) of 632 nm and a spectral half-width (Δλ) of 20 nm, defining its pure red color point. The luminous intensity matching ratio between segments is specified at 2:1 maximum, ensuring visual consistency.

2.2 Electrical Parameters

The forward voltage (V_F) per LED segment is 2.6V typical at I_F = 20 mA, with a tolerance of ±0.1V. Designers must account for this range to ensure proper current regulation. The reverse current (I_R) is a maximum of 100 µA at a reverse voltage (V_R) of 5V. It is crucial to note that the 5V reverse voltage rating is for leakage current testing only and the device should not be operated under continuous reverse bias.

2.3 Absolute Maximum Ratings and Thermal Considerations

The absolute maximum ratings define the operational limits. The power dissipation per LED chip is 75 mW. The continuous forward current per chip is 25 mA at 25°C, derating linearly by 0.28 mA/°C above 25°C. A peak forward current of 90 mA is allowed under pulsed conditions (1/10 duty cycle, 0.1 ms pulse width). The operating and storage temperature range is -35°C to +85°C. Exceeding these ratings, especially current and temperature, will accelerate degradation and can cause premature failure. The solder condition is specified as 260°C for 3 seconds at 1/16 inch (approx. 1.6 mm) below the seating plane.

3. Binning System Explanation

The datasheet explicitly states the device is \"Binned for Luminous Intensity.\" This means units are sorted and grouped (binned) based on their measured light output at a standard test current. This process ensures customers receive displays with consistent brightness levels. While the specific bin codes are not detailed in this excerpt, using displays from the same bin within an assembly is strongly recommended to avoid perceptible differences in brightness (hue unevenness) between adjacent digits.

4. Performance Curve Analysis

Although the specific graphical curves are not reproduced in the provided text, the datasheet references \"Typical Electrical / Optical Characteristics Curves.\" Typically, such curves for LED displays include: Forward Current vs. Forward Voltage (I-V Curve): Shows the nonlinear relationship, critical for designing constant-current drivers. Luminous Intensity vs. Forward Current: Demonstrates how light output increases with current, often showing saturation at higher currents. Luminous Intensity vs. Ambient Temperature: Illustrates the decrease in light output as junction temperature rises, highlighting the importance of thermal management. Spectral Distribution: A graph of relative intensity vs. wavelength, centered around the 624-632 nm range.

5. Mechanical and Package Information

5.1 Dimensions and Tolerances

All package dimensions are provided in millimeters. General tolerances are ±0.25 mm unless otherwise specified. Key mechanical notes include: Pin tip shift tolerance is ±0.4 mm. The recommended PCB hole diameter for the pins is 1.0 mm. Specific quality limits are set for foreign material on segments (≤10 mil), ink contamination on the surface (≤20 mil), bubbles within segments (≤10 mil), and bending of the reflector (≤1% of its length).

5.2 Pin Connection and Polarity Identification

The display has a 10-pin configuration in a dual-in-line package. It is a Common Cathode device. The internal circuit diagram shows all segment anodes are individually accessible, while the cathodes of all LEDs are connected together. Pin 1 and Pin 6 are both common cathode connections. The pinout is as follows: Pin 1: Common Cathode, Pin 2: Anode F, Pin 3: Anode G, Pin 4: Anode E, Pin 5: Anode D, Pin 6: Common Cathode, Pin 7: Anode DP (Decimal Point), Pin 8: Anode C, Pin 9: Anode B, Pin 10: Anode A. The \"Rt. Hand Decimal\" note suggests the decimal point is positioned on the right-hand side of the digit.

6. Soldering and Assembly Guidelines

6.1 Soldering Process

The specified soldering condition is 260°C for 3 seconds, measured at a point 1.6 mm (1/16 inch) below the seating plane of the display body. This is a typical wave soldering or hand soldering parameter. The temperature of the component body itself must not exceed the maximum storage temperature rating during the process.

6.2 Storage Conditions

For optimal shelf life, the LED display should be stored in its original packaging. The recommended storage conditions are a temperature between 5°C and 30°C with relative humidity below 60% RH. Failure to meet these conditions may lead to oxidation of the pins, requiring replating before use. Long-term storage of large inventories is discouraged. If the original sealed package is opened and the components are not used within 168 hours (7 days, MSL Level 3), or if an unsealed package has been stored for over 6 months, baking at 60°C for 48 hours is recommended prior to assembly, which should then be completed within one week.

7. Application Recommendations

7.1 Typical Application Scenarios

This display is intended for ordinary electronic equipment, including office equipment (calculators, copier displays), communication devices, household appliances (microwave ovens, washing machine timers), and instrumentation. It is not designed for applications where failure could jeopardize life or health (aviation, medical systems, safety devices) without prior consultation and qualification.

7.2 Critical Design Considerations

• Drive Circuitry: Constant current driving is strongly recommended to maintain consistent brightness and longevity. The circuit must be designed to deliver the intended current across the entire forward voltage range (2.5V to 2.7V).
• Protection: The circuit must protect against reverse voltages and transient voltage spikes during power-up/down to prevent damage from metal migration and increased leakage current.
• Thermal Management: The operating current must be derated based on the maximum ambient temperature. Excess current or high temperature leads to severe light degradation.
• Mechanical Assembly: Avoid using tools or methods that apply abnormal force to the display body. If a decorative film is applied, ensure it does not cause the film to shift by pressing directly against a front panel.
• Binning for Multi-Digit Use: Always use displays from the same luminous intensity bin when assembling multiple digits in one unit to ensure uniform appearance.

8. Technical Comparison and Differentiation

Compared to older technologies like GaAsP (Gallium Arsenide Phosphide) red LEDs, the AlInGaP technology used in the LSHD-7503 offers significantly higher luminous efficiency and brightness. This results in better visibility at lower currents or in high-ambient-light conditions. The light gray face/white segment design provides a higher contrast ratio than all-diffused packages when the LED is off, improving aesthetics. The common cathode configuration offers design flexibility with certain driver ICs. Its 0.3-inch size fills a niche between smaller, harder-to-read displays and larger, higher-power-consuming ones.

9. Frequently Asked Questions (Based on Technical Parameters)

Q: What is the purpose of the two common cathode pins (Pin 1 and Pin 6)?

A: This is a standard design practice for multi-segment displays. It provides two connection points for the common return path, which can help with PCB layout, reduce current density in a single pin, and improve reliability.

Q: Can I drive this display with a 5V supply and a simple current-limiting resistor?

A: Yes, but careful calculation is needed. Using V_supply = 5V, V_F = 2.6V, and I_F = 10 mA, the resistor value would be R = (5 - 2.6) / 0.01 = 240 Ω. You must recalculate for the maximum V_F (2.7V) to ensure the minimum current is acceptable, and consider power dissipation in the resistor.

Q: Why is the reverse voltage rating only 5V, and what happens if it is exceeded?

A> AlInGaP LEDs have a relatively low reverse breakdown voltage. Exceeding 5V, even transiently, can cause immediate and catastrophic failure of the PN junction.

Q: What does \"cross talk specification ≤ 2.5%\" mean?

A: This refers to unwanted illumination of a segment that is meant to be off, caused by electrical leakage or optical coupling from adjacent powered segments. A value below 2.5% ensures good visual separation between on and off states.

10. Practical Application Case Study

Scenario: Designing a simple digital timer display. A designer needs two digits to show minutes from 00 to 99. They select two LSHD-7503 displays. First, they ensure procurement specifies the same luminous intensity bin for both units. The circuit uses a microcontroller with segment driver pins connected to the anodes (Pins 2,3,4,5,7,8,9,10) of each display via current-limiting resistors or a constant-current driver array. The common cathode pins (1 & 6) of each digit are connected to separate microcontroller pins configured as open-drain/sink outputs, enabling multiplexing. The software cycles through turning on one digit at a time at a fast rate (e.g., 100Hz). The PCB layout follows the recommended 1.0 mm hole size and ensures no mechanical stress is placed on the display bodies during assembly. The final product offers a clear, uniform, and reliable numeric readout.

11. Operating Principle Introduction

The LSHD-7503 is based on semiconductor electroluminescence. The AlInGaP epitaxial layers are grown on a GaAs substrate. When a forward voltage exceeding the junction's threshold is applied, electrons and holes are injected into the active region where they recombine. This recombination process in the AlInGaP material releases energy primarily in the form of photons in the red wavelength range (around 624-632 nm). Each of the seven segments (and the decimal point) contains one or more of these tiny LED chips. By selectively applying current to the anode pins corresponding to segments A through G and DP, while connecting the common cathode to ground, specific numeric characters (0-9) can be formed.

12. Technology Trends and Developments

While discrete LED segment displays like the LSHD-7503 remain relevant for specific applications, the broader trend in display technology is towards integration and miniaturization. Dot-matrix LED displays and OLEDs offer greater flexibility for showing alphanumeric characters and graphics. Furthermore, surface-mount device (SMD) packages are increasingly replacing through-hole types like this one for automated assembly. In terms of materials, AlInGaP remains the dominant technology for high-efficiency red and amber LEDs, though ongoing research focuses on improving efficiency, reducing wavelength shift with temperature, and lowering production costs. For simple, low-cost, single-digit indicators, however, devices like the LSHD-7503 continue to offer a robust and straightforward solution.