LSHD-7801 0.3-inch Single Digit LED Display Datasheet - Digit Height 7.62mm - Green Color - English Technical Document

1. Product Overview

The LSHD-7801 is a single-digit, 7-segment alphanumeric LED display module. Its primary function is to provide clear, visible numeric and limited alphanumeric character output in electronic devices. The core application is in equipment requiring a compact, reliable, and energy-efficient numerical readout, such as instrumentation panels, consumer electronics, industrial controls, and test equipment.

The device's key advantages stem from its solid-state design. It offers excellent segment uniformity, ensuring consistent brightness across all lit segments for a clean appearance. It operates with a low power requirement, contributing to energy efficiency in the overall system. Furthermore, it provides high brightness and high contrast, making the display easily readable even in various ambient lighting conditions. A wide viewing angle ensures visibility from different perspectives, which is crucial for panel-mounted devices.

2. Technical Specifications and Objective Interpretation

2.1 Photometric and Optical Characteristics

The display utilizes GREEN LED chips, specifically GaP epi on GaP substrate and/or AlInGaP on a non-transparent GaAs substrate. This combination targets a green emission. The typical average luminous intensity (Iv) is 1600 ucd (microcandelas) at a forward current (IF) of 10mA per segment, with a minimum specified value of 500 ucd. This parameter defines the perceived brightness. The dominant wavelength (λd) is typically 569 nm, and the peak emission wavelength (λp) is typically 565 nm, placing the output firmly in the green region of the visible spectrum. The spectral line half-width (Δλ) is 30 nm, indicating the spectral purity of the emitted green light.

2.2 Electrical Parameters and Ratings

The absolute maximum ratings define the operational limits. The average power dissipation per dot (segment or decimal point) must not exceed 75 mW. The peak forward current per segment is 60 mA, but this is only permissible under pulsed conditions (1/10 duty cycle, 0.1ms pulse width). The continuous average forward current per dot is derated from 25 mA at 25°C by 0.28 mA/°C as ambient temperature increases. The typical forward voltage (VF) per segment is 2.6V at IF=20mA, with a maximum of 2.6V. The reverse current (IR) is specified at a maximum of 100 µA at a reverse voltage (VR) of 5V. It is critical to note that this reverse voltage condition is for test purposes only and the device should not be continuously operated under reverse bias.

2.3 Thermal Characteristics

The device is rated for an operating temperature range of -35°C to +105°C and a storage temperature range of -35°C to +105°C. The forward current derating curve (0.28 mA/°C from 25°C) is a key thermal management parameter. As the ambient temperature rises, the maximum allowable continuous current must be reduced to prevent overheating and premature failure. This necessitates careful thermal design in the application, especially in enclosed spaces or high-temperature environments.

3. Binning System Explanation

The datasheet explicitly states that the product is \"Binned for Luminous Intensity.\" This means units are sorted and grouped (binned) based on their measured luminous output at a standard test current. This process ensures consistency in brightness when multiple displays are used side-by-side in an application, preventing noticeable variations in intensity between digits. The luminous intensity matching ratio for similar lit areas is specified as 2:1 maximum, meaning the brightest segment should not be more than twice as bright as the dimmest segment within the acceptable bin.

4. Performance Curve Analysis

While the provided content excerpt references \"Typical Electrical/Optical Characteristics Curves,\" the specific graphs are not detailed in the text. Typically, such curves for an LED display would include:

• Forward Current (IF) vs. Forward Voltage (VF) Curve: Shows the nonlinear relationship, crucial for designing constant-current drivers.
• Luminous Intensity (Iv) vs. Forward Current (IF) Curve: Demonstrates how light output increases with current, up to the maximum ratings.
• Luminous Intensity (Iv) vs. Ambient Temperature (Ta) Curve: Illustrates the decrease in light output as temperature increases, informing thermal design.
• Spectral Distribution Curve: A plot of relative intensity versus wavelength, showing the peak and dominant wavelengths and spectral width.

Designers must consult these curves to optimize drive current for desired brightness while maintaining reliability across the operating temperature range.

5. Mechanical and Package Information

The LSHD-7801 is a through-hole package with a digit height of 0.3 inches (7.62 mm). The package has a gray face and green segments. The dimensional drawing (not fully detailed in text) would provide critical measurements for PCB footprint design, including overall dimensions, pin spacing, and seating plane height. Tolerances are typically ±0.25 mm. The pin connection is defined for a 10-pin configuration. It is a common anode type display. The pinout is: 1 & 6 (Common Anode), 2 (Cathode F), 3 (Cathode G), 4 (Cathode E), 5 (Cathode D), 7 (Cathode DP - Decimal Point), 8 (Cathode C), 9 (Cathode B), 10 (Cathode A). The internal circuit diagram shows the common anode connection to all segment LEDs.

6. Soldering and Assembly Guidelines

The datasheet specifies soldering conditions: 1/16 inch (approximately 1.6 mm) below the seating plane for 3 seconds at 260°C. This is a critical parameter for wave soldering processes to prevent thermal damage to the LED chips or plastic package. For storage, standard conditions are recommended: temperature between 5°C and 30°C with humidity below 60% RH. For SMD variants (noted in cautions), if the factory-sealed bag is opened, the device should be used within 168 hours (MSL Level 3) under the same temperature/humidity conditions to prevent pin oxidation. If unpacked for more than 168 hours, baking at 60°C for 24 hours before soldering is recommended. The general recommendation is to consume displays within 12 months from the shipping date.

7. Packaging and Ordering Information

The part number is LSHD-7801. The description specifies a Green, Common Anode display with a right-hand decimal point. The datasheet is identified by Spec No. DS30-2002-152, Revision A, effective 01/13/2023. Specific packaging quantities (e.g., tape and reel, tube) are not detailed in the provided excerpt but would be part of the complete procurement specification.

8. Application Recommendations

8.1 Typical Application Scenarios

This display is intended for ordinary electronic equipment including office equipment, communication devices, and household applications. Examples include digital multimeters, clock radios, appliance timers, industrial sensor readouts, and panel meters.

2 Design Considerations and Cautions

Driver Circuit Design: Constant current driving is strongly recommended over constant voltage to ensure consistent luminous intensity and longevity, as LED forward voltage has tolerances and varies with temperature. The circuit must be designed to accommodate the full VF range (2.1V to 2.6V typical). Protection against reverse voltages and transient spikes during power cycling is essential to prevent damage from metal migration and increased leakage current.

Current Selection: The operating current must be chosen considering the maximum ambient temperature, using the current derating specification. Exceeding ratings causes severe light degradation or failure.

Optical Assembly: If a front panel or cover is used, it should not press directly against the display's pattern film, as this may cause it to shift. For multi-digit assemblies, using displays from the same luminous intensity bin is recommended to avoid uneven brightness (hue unevenness).

Environmental: Avoid exposing the display to rapid temperature changes in humid environments to prevent condensation.

9. Technical Comparison and Differentiation

While a direct comparison with other models is not provided, the LSHD-7801's key differentiators within its category (0.3-inch single-digit) include its use of specific green LED chip technologies (GaP and AlInGaP) for its color, its explicit binning for luminous intensity uniformity, its wide operating temperature range (-35°C to +105°C), and its compliance with lead-free/RoHS requirements. The high typical brightness (1600 ucd at 10mA) and low power requirement are also competitive advantages.

10. Frequently Asked Questions (Based on Technical Parameters)

Q: What is the difference between peak wavelength (λp) and dominant wavelength (λd)?
A: Peak wavelength is the wavelength at which the emission spectrum has its maximum intensity. Dominant wavelength is the single wavelength of monochromatic light that matches the perceived color of the LED's output. For green LEDs, they are often close, as seen here (565 nm vs. 569 nm).

Q: Why is constant current drive recommended?
A: LED brightness is primarily a function of current, not voltage. The forward voltage (VF) varies from unit to unit and decreases with increasing temperature. A constant current source ensures the desired light output is maintained regardless of these VF variations, providing stable performance and protecting the LED from overcurrent if VF drops.

Q: Can I drive it with a 5V supply and a resistor?
A: Yes, this is a common method. The series resistor value R is calculated as R = (Vsupply - VF) / IF. Using typical VF=2.6V and IF=10mA with a 5V supply: R = (5 - 2.6) / 0.01 = 240 Ohms. You must ensure the resistor power rating is sufficient (P = IF^2 * R). This method provides approximate constant current if Vsupply is stable and much larger than the variation in VF.

Q: What does \"common anode\" mean?
A: It means the anodes (positive sides) of all the individual segment LEDs are connected together internally to one or more pins (pins 1 & 6 in this case). To light a segment, its corresponding cathode pin must be connected to a lower voltage (ground) while the common anode pin is held at a positive voltage.

11. Practical Design and Usage Case

Case: Designing a simple 3-digit voltmeter readout.
Three LSHD-7801 displays would be used. A microcontroller with sufficient I/O pins would control the segments. A multiplexing technique is typically employed to minimize pin count: the common anodes of each digit are driven sequentially by the microcontroller, while the cathode lines for all segments are shared. This creates the illusion of all digits being on simultaneously if the switching is fast enough. The design must include current-limiting resistors on each cathode line (or use a constant current driver IC). The software must calculate the correct segment patterns for 0-9 and manage the multiplexing timing. Thermal considerations involve ensuring the PCB layout allows for some heat dissipation, especially if driven at higher currents in a warm enclosure.

12. Principle Introduction

The operating principle is based on electroluminescence in semiconductor materials. When a forward voltage exceeding the diode's turn-on threshold is applied across the LED chip (GaP or AlInGaP), electrons and holes recombine in the active region, releasing energy in the form of photons (light). The specific semiconductor material's bandgap energy determines the wavelength (color) of the emitted light. In a 7-segment display, multiple individual LED chips are arranged in a pattern and packaged behind a mask with the segment shapes. By selectively applying current to different combinations of these chips, numerals and some letters can be formed.

13. Development Trends

Trends in single-digit LED displays like the LSHD-7801 focus on several areas: Increased Efficiency: Developing chip materials and structures that deliver higher luminous intensity (brightness) at lower drive currents, reducing power consumption and heat generation. Miniaturization: While 0.3-inch is a standard size, there is ongoing work to maintain or improve readability in even smaller form factors. Enhanced Reliability and Lifetime: Improving package materials and chip designs to withstand higher operating temperatures and harsher environmental conditions, extending operational lifespan. Integration: Moving towards displays with integrated driver circuitry or smart functionalities to simplify system design for end-users. Color Options and Performance: Expanding the range of available colors and improving color consistency and saturation through advanced semiconductor materials like newer phosphor-converted or direct-emission technologies.