LSHD-7501 LED Display Datasheet - 0.3-inch Digit Height - AlInGaP Red - 2.6V Forward Voltage - 70mW Power Dissipation - English Technical Document

1. Product Overview

The LSHD-7501 is a single-digit, seven-segment plus decimal point LED display module. It features a digit height of 0.3 inches (7.62 mm), making it suitable for applications requiring clear, medium-sized numeric readouts. The device utilizes advanced AlInGaP (Aluminum Indium Gallium Phosphide) red LED chips epitaxially grown on a GaAs substrate. This material technology is known for its high efficiency and excellent luminous performance in the red spectrum. The display presents a light gray face with white segments, providing a high-contrast appearance that enhances readability under various lighting conditions.

1.1 Key Features

• 0.3-inch Digit Height: Offers a balanced size for good visibility without excessive space consumption.
• Continuous Uniform Segments: Ensures consistent light emission across each segment for a professional, clean character appearance.
• Low Power Requirement: Designed for energy-efficient operation, suitable for battery-powered or low-power systems.
• High Brightness & High Contrast: The AlInGaP technology delivers intense red light output, and the light gray/white color scheme maximizes contrast for superior legibility.
• Wide Viewing Angle: Provides clear visibility from a broad range of angles, ideal for panel meters and consumer electronics.
• Solid-State Reliability: LEDs offer long operational life, shock resistance, and fast switching times compared to other display technologies.
• Categorized for Luminous Intensity: Units are binned for intensity, allowing for consistent brightness matching in multi-digit applications.
• Lead-Free Package (RoHS Compliant): Manufactured in accordance with environmental regulations restricting hazardous substances.

1.2 Device Identification

The part number LSHD-7501 specifies a common anode configuration with a right-hand decimal point. The common anode design simplifies driving circuitry in many microcontroller-based applications, where sinking current is often more straightforward.

2. Technical Parameters: In-Depth Objective Interpretation

2.1 Electrical & Optical Characteristics

The performance of the LSHD-7501 is defined under standard test conditions at an ambient temperature (Ta) of 25°C. Key parameters include:

• Average Luminous Intensity (I_V): Ranges from a minimum of 320 µcd at a forward current (I_F) of 1mA to a typical value of 5400-12000 µcd at I_F=10mA. This indicates a highly efficient device where brightness scales significantly with current.
• Peak Emission Wavelength (λ_p): Typically 632 nm, placing it in the bright red portion of the visible spectrum.
• Dominant Wavelength (λ_d): Typically 624 nm, which is the wavelength perceived by the human eye and is slightly shorter than the peak emission due to the shape of the emission spectrum.
• Forward Voltage per Chip (V_F): Ranges from 2.10V to 2.60V at I_F=20mA. This parameter is crucial for driver design; the circuit must supply enough voltage to overcome the maximum V_F to achieve the desired current.
• Reverse Current (I_R): Maximum 100 µA at a reverse voltage (V_R) of 5V. This specification highlights the importance of avoiding reverse bias in the application circuit.
• Luminous Intensity Matching Ratio: Specified as 2:1 maximum for segments with similar light area. This means the brightest segment should not be more than twice as bright as the dimmest, ensuring uniform appearance.

2.2 Absolute Maximum Ratings

These are stress limits that must not be exceeded, even momentarily, to prevent permanent damage.

• Power Dissipation per Segment: 70 mW maximum.
• Peak Forward Current per Segment: 90 mA under pulsed conditions (1/10 duty cycle, 0.1ms pulse width).
• Continuous Forward Current per Segment: 25 mA at 25°C, derating linearly at 0.28 mA/°C as temperature rises. This derating is critical for thermal management.
• Reverse Voltage per Segment: 5 V maximum (for test purposes only, not for continuous operation).
• Operating & Storage Temperature Range: -35°C to +105°C, indicating robustness for a wide range of environments.
• Solder Temperature: Maximum 260°C for 5 seconds at 1/16 inch (1.6mm) below the seating plane.

2.3 Binning System Explanation

The datasheet explicitly states the device is \"categorized for luminous intensity.\" This implies a binning process where displays are sorted based on measured light output at a standard test current. Using binned parts ensures consistency in multi-digit displays, preventing some digits from appearing brighter or dimmer than others. Designers should specify or verify the intensity bin when ordering for critical applications requiring uniform appearance.

3. Performance Curve Analysis

While specific graphical data is referenced in the PDF (\"Typical Electrical / Optical Characteristics Curves\"), the textual data allows for analysis of key relationships:

• Current vs. Luminance (I-V Curve implied): The significant jump in luminous intensity from 1mA to 10mA (320 µcd to 5400+ µcd) indicates a non-linear, highly efficient relationship. Operating at higher currents within limits yields disproportionately higher brightness.
• Temperature Characteristics: The derating of continuous forward current (0.28 mA/°C) is a direct indicator of thermal performance. As the junction temperature increases, the maximum allowable current to avoid damage decreases. Proper heat sinking or airflow is necessary if operating near the maximum current rating in elevated ambient temperatures.
• Spectral Distribution: The peak wavelength (632 nm) and spectral half-width (20 nm) define the color purity. A 20 nm half-width is relatively narrow, resulting in a saturated, pure red color.

4. Mechanical & Package Information

4.1 Package Dimensions

The display's physical outline and pin spacing are defined in a dimensional drawing. Key notes include: all dimensions in millimeters with a standard tolerance of ±0.25mm, pin tip shift tolerance of ±0.40 mm, and a recommended PCB hole diameter of 1.0 mm for the leads. Quality control points address segment integrity (foreign materials, bubbles), reflector straightness, and surface contamination.

4.2 Pin Connection and Circuit Diagram

The device has a 10-pin single-row configuration. The internal circuit diagram shows a common anode structure, where the anodes of all LED segments are connected internally to two pins (1 and 6). Each segment cathode (A-G and DP) has its own dedicated pin. This configuration is verified by the pin connection table:
1: Common Anode, 2: Cathode F, 3: Cathode G, 4: Cathode E, 5: Cathode D, 6: Common Anode, 7: Cathode DP, 8: Cathode C, 9: Cathode B, 10: Cathode A.

5. Soldering & Assembly Guidelines

5.1 Soldering Profile

Two methods are specified:
Auto Soldering (Wave/Reflow): 260°C for 5 seconds at 1/16 inch (1.6mm) below the seating plane.
Manual Soldering: 350°C ± 30°C for a maximum of 5 seconds.
Adherence to these time-temperature profiles is critical to prevent thermal damage to the LED chips, the epoxy package, and the internal wire bonds.

5.2 Application Cautions & Design Considerations

The datasheet provides essential design and usage warnings:
Circuit Design: Constant current driving is strongly recommended over constant voltage to ensure consistent brightness and longevity. The driver circuit must be designed to accommodate the full range of forward voltage (V_F = 2.10V to 2.60V). Protection against reverse voltages and transient spikes during power cycling is mandatory to prevent degradation.
Thermal Management: The safe operating current must be derated based on the maximum ambient temperature. Exceeding current or temperature ratings leads to severe light output degradation or catastrophic failure.
Application Scope: The display is intended for standard commercial/consumer electronics. It is not designed or qualified for safety-critical applications (aviation, medical life-support, etc.) without prior consultation and additional qualification.

6. Reliability Testing

The device undergoes a comprehensive suite of reliability tests based on military (MIL-STD), Japanese (JIS), and internal standards. Key tests include:
Operation Life (RTOL): 1000 hours at maximum rated current.
Environmental Stress: High Temperature/Humidity Storage (500 hrs at 65°C/90-95% RH), High/Low Temperature Storage (1000 hrs at 105°C and -35°C), Temperature Cycling, and Thermal Shock.
Process Robustness: Solder Resistance and Solderability tests. These tests validate the product's ability to withstand assembly processes and long-term operational stresses in various environments.

7. Application Suggestions

7.1 Typical Application Scenarios

• Consumer Electronics: Digital clocks, appliance timers, audio equipment displays.
• Instrumentation: Panel meters, test equipment readouts, handheld measurement devices.
• Industrial Controls: Process indicators, counter displays, simple human-machine interface (HMI) elements.
• Automotive Aftermarket: Non-critical interior displays (e.g., auxiliary gauges).

7.2 Design Considerations and Common Questions

Q: How do I drive this display with a microcontroller?
A: For a common anode display, connect the common pins (1 & 6) to a positive supply voltage (through a current-limiting resistor or, better, a transistor switch). Connect each cathode pin (A-G, DP) to a microcontroller GPIO pin configured as an output. To illuminate a segment, set its corresponding cathode pin to a logic LOW (sink current). Use a driver IC or transistor array if the microcontroller cannot sink the total segment current.

Q: What value current-limiting resistor should I use?
A: Use Ohm's Law: R = (V_supply - V_F) / I_F. Assume the worst-case V_F (2.60V) to ensure sufficient current. For example, with a 5V supply and a target I_F of 10mA: R = (5V - 2.6V) / 0.01A = 240 Ω. Use the nearest standard value (e.g., 220 Ω or 270 Ω) and calculate the actual current. A constant current driver is preferred for precision.

Q: Can I multiplex multiple digits?
A: Yes, this display is suitable for multiplexing. You would connect the segment cathodes in parallel across all digits and then control each digit's common anode individually, turning on only one digit at a time at a high frequency. The peak current per segment can be higher in this mode (up to the 90mA pulsed rating), but the average current must respect the continuous rating.

8. Technical Comparison and Trends

8.1 Differentiation from Other Technologies

Compared to older GaAsP or GaP red LEDs, AlInGaP offers significantly higher luminous efficiency and better temperature stability. Compared to white LEDs filtered to produce red, AlInGaP provides superior color purity and efficiency for monochromatic red applications. The 0.3-inch size fills a niche between smaller (0.2\") displays for portable devices and larger (0.5\"+) displays for longer viewing distances.

8.2 Principle of Operation and Trends

The device operates on the principle of electroluminescence in a semiconductor p-n junction. When forward biased, electrons and holes recombine in the active AlInGaP layer, releasing energy as photons with a wavelength corresponding to the material's bandgap. The trend in such displays is towards higher efficiency (more light per watt), lower operating voltages, and integration of driver electronics directly into the package. However, discrete 7-segment displays remain vital for their simplicity, reliability, and cost-effectiveness in dedicated numeric readout applications.