0.8-inch Seven-Segment LED Display Datasheet - Digit Height 20.32mm - Forward Voltage 2.6V - Hyper Red Color - English Technical Document

1. Product Overview

This document details the specifications for a single-digit, seven-segment light-emitting diode (LED) display. The device is designed for applications requiring clear, bright numeric readouts. Its core advantages include a continuous, uniform segment appearance for excellent character legibility, low power consumption making it suitable for battery-powered devices, and a wide viewing angle for visibility from various positions. The display utilizes solid-state technology, ensuring high reliability and long operational life. It is categorized for luminous intensity, providing consistency in brightness across production batches, and is directly compatible with integrated circuit (IC) drivers, simplifying system design. The device is intended for integration into consumer electronics, industrial instrumentation, test equipment, and any system requiring a compact, reliable numeric display.

2. Technical Specifications and Objective Interpretation

2.1 Photometric and Optical Characteristics

The display employs Aluminum Indium Gallium Phosphide (AlInGaP) semiconductor material on a non-transparent Gallium Arsenide (GaAs) substrate to produce a Hyper Red emission. The typical peak emission wavelength (λp) is 650 nanometers (nm) when driven at a forward current (IF) of 20mA. The dominant wavelength (λd) is specified at 639 nm. The spectral line half-width (Δλ) is 20 nm, indicating a relatively narrow bandwidth of emitted light which contributes to color purity. The average luminous intensity (Iv) per segment ranges from a minimum of 320 microcandelas (μcd) to a maximum of 700 μcd when operated at a standard test current of 1mA. A luminous intensity matching ratio of 2:1 (maximum to minimum) is specified, ensuring reasonable uniformity in brightness between different segments of the same digit.

2.2 Electrical Parameters

The absolute maximum ratings define the operational limits beyond which permanent damage may occur. The maximum continuous power dissipation per segment is 70 milliwatts (mW). The peak forward current per segment is 90mA, but this is only permissible under pulsed conditions with a 1/10 duty cycle and a 0.1ms pulse width. The continuous forward current per segment is rated at 25mA at 25°C, with a derating factor of 0.33 mA/°C for ambient temperatures (Ta) above 25°C. This means the allowable continuous current decreases as temperature increases to prevent overheating. The maximum reverse voltage that can be applied across a segment is 5 Volts (V). Under typical operating conditions, the forward voltage (VF) per segment is between 2.1V and 2.6V when a current of 10mA is applied. The reverse current (IR) is limited to a maximum of 100 microamperes (μA) when a reverse voltage (VR) of 5V is applied.

2.3 Thermal and Environmental Specifications

The device is rated for an operating temperature range of -35°C to +85°C. This wide range makes it suitable for use in environments subject to significant temperature variations. The storage temperature range is identical, from -35°C to +85°C. For assembly, the device can withstand a soldering temperature of 260°C for 3 seconds, measured 1/16 inch (approximately 1.59mm) below the seating plane of the package. This parameter is critical for defining the reflow soldering profile during printed circuit board (PCB) assembly.

3. Binning and Categorization System

The product datasheet explicitly states that the devices are \"Categorized for Luminous Intensity.\" This indicates a binning process where displays are sorted based on their measured light output at a standard test current (typically 1mA as per the electrical characteristics). Binning ensures that customers receive parts with consistent brightness levels, which is crucial for applications where multiple digits are used side-by-side to avoid noticeable variations in intensity. While the specific bin codes or ranges are not detailed in this excerpt, the typical intensity range of 320-700 μcd and the 2:1 matching ratio provide the performance envelope for this categorization.

4. Performance Curve Analysis

While the specific graphs are not reproduced in the text, the datasheet references \"Typical Electrical / Optical Characteristic Curves.\" These curves are essential for detailed design work. They typically include: Forward Current vs. Forward Voltage (I-V Curve): This graph shows the relationship between the current flowing through the LED and the voltage drop across it. It is non-linear and crucial for designing the current-limiting circuitry. Luminous Intensity vs. Forward Current (L-I Curve): This shows how the light output increases with increasing drive current. It helps designers choose an operating point that balances brightness with power consumption and device lifetime. Luminous Intensity vs. Ambient Temperature: This curve illustrates how light output decreases as the junction temperature of the LED increases. Understanding this derating is vital for applications operating at high ambient temperatures. Spectral Distribution: A plot of relative intensity versus wavelength, showing the shape of the emitted light spectrum, centered around the 650nm peak.

5. Mechanical and Package Information

5.1 Physical Dimensions and Drawing

The device is described as a 0.8-inch digit height display, which corresponds to 20.32 millimeters. The package dimensions are provided in a drawing (referenced but not shown here). All dimensions are specified in millimeters, with standard tolerances of ±0.25mm (or ±0.01 inches) unless otherwise noted. This information is critical for PCB layout, ensuring the footprint and keep-out areas are correctly designed.

5.2 Pin Configuration and Polarity

The display has a 17-pin configuration. It is a common cathode type, meaning the cathodes (negative terminals) of all LED segments are connected together internally and brought out to specific pins. The pin connection table lists the function of each pin:

• Pins 4, 6, 12, and 17: Common Cathode (CC). Multiple cathode pins are provided, likely for better current distribution and thermal management.
• Pins 2, 3, 5, 7, 10, 11, 13, 14, 15: These are the anode (positive) connections for individual segments (A, F, E, L.D.P, R.D.P, D, C, G, B).
• Pins 1, 8, 9, 16: These are listed as \"NO PIN\" (no connection).

The segments include the standard seven segments (A-G) plus two decimal points: a Left Decimal Point (L.D.P on pin 7) and a Right Decimal Point (R.D.P on pin 10).

5.3 Internal Circuit Diagram

The datasheet includes an internal circuit diagram. This schematic visually represents the common cathode architecture, showing how the anodes of each segment (and the decimal points) are isolated and connected to their respective pins, while all cathodes are tied together to the common cathode pins.

6. Soldering and Assembly Guidelines

The key assembly parameter provided is the solder temperature rating. The device can withstand a peak temperature of 260°C for 3 seconds, measured at a point 1/16 inch (1.59mm) below the seating plane of the package body. This is a standard rating for lead-free reflow soldering processes. Designers and assembly houses must ensure their reflow profile does not exceed this time-temperature combination to prevent damage to the internal LED chips, wire bonds, or the plastic package material. Proper ESD (Electrostatic Discharge) handling procedures should always be followed during assembly, as LEDs are sensitive to static electricity.

7. Application Recommendations

7.1 Typical Application Scenarios

This display is ideal for any embedded system requiring a single numeric digit. Common applications include: panel meters for voltage, current, or temperature readouts; digital clocks and timers; scoreboards; appliance control panels (e.g., microwave ovens, washing machines); test and measurement equipment; and portable consumer devices where low power consumption is a priority.

7.2 Design Considerations and Circuitry

When designing the drive circuit, the following points are critical: Current Limiting: LEDs are current-driven devices. A series current-limiting resistor must be used for each segment anode (or a constant current driver IC) to set the forward current (e.g., 10mA or 20mA) and prevent excessive current that would destroy the segment. The resistor value is calculated using Ohm's Law: R = (Vcc - VF) / IF, where Vcc is the supply voltage, VF is the forward voltage of the LED (use max value of 2.6V for reliability), and IF is the desired forward current. Multiplexing: For multi-digit displays, a multiplexing technique is often used where digits are illuminated one at a time in rapid succession. This display, with its common cathode configuration, is well-suited for multiplexed designs where the cathodes are switched by transistors. Viewing Angle: The wide viewing angle specification means the display remains readable even when viewed from sharp side angles, which should be considered during mechanical enclosure design. Heat Management: While power dissipation is low, adhering to the current derating curve at high ambient temperatures is essential for long-term reliability.

8. Frequently Asked Questions (Based on Technical Parameters)

Q: What is the difference between peak wavelength and dominant wavelength?

A: Peak wavelength (λp) is the wavelength at which the emission spectrum has its maximum intensity. Dominant wavelength (λd) is the single wavelength of monochromatic light that would produce a color sensation most closely matching the actual color of the LED. For a narrow-spectrum red LED like this one, they are often close, but λd is the more perceptually relevant metric for color.

Q: Can I drive this display with a 5V supply directly?

A: No. The forward voltage per segment is only about 2.6V. Connecting a 5V supply directly to an LED segment without a current-limiting resistor would cause excessive current to flow, almost certainly destroying the segment. You must use a series resistor or constant-current driver.

Q: Why are there four common cathode pins?

A> Multiple cathode pins help distribute the total return current (which is the sum of currents from all illuminated segments) across several pins and PCB traces. This reduces current density in any single pin or solder joint, improving reliability and potentially allowing for higher multiplexing currents.

Q: What does \"AlInGaP on a non-transparent GaAs substrate\" mean?

A> The light-emitting layers are made of AlInGaP. This material is grown on a GaAs (Gallium Arsenide) substrate. The substrate is \"non-transparent,\" meaning light is primarily emitted from the top surface of the chip. This is a common structure for high-efficiency red and amber LEDs.

9. Design and Usage Case Study

Consider designing a simple digital thermometer with a single-digit display for showing temperature in tens of degrees Celsius. The microcontroller reads a temperature sensor, processes the data, and needs to drive the seven-segment display. The design would involve: 1. Microcontroller Interface: The MCU's GPIO pins would be connected to the segment anodes (A-G) via current-limiting resistors (e.g., 220Ω for a 5V supply and ~10mA per segment). 2. Cathode Drive: The single common cathode (using one of the four pins, with the others also connected for robustness) would be connected to ground through an NPN transistor. The MCU would turn this transistor on to enable the digit. 3. Decimal Points: One decimal point could be used to indicate a half-degree, driven by another MCU pin with its own resistor. 4. Software: The MCU code would convert the temperature value to the correct 7-segment bit pattern and output it to the GPIO pins, while enabling the cathode transistor. This simple circuit leverages the display's low power consumption and IC compatibility effectively.

10. Technical Principle Introduction

A seven-segment LED display is an assembly of individual Light Emitting Diodes arranged in a figure-eight pattern. Each segment (named A through G) is a separate LED. By selectively illuminating specific combinations of these segments, all decimal digits (0-9) and some letters can be formed. The underlying technology of each LED segment is based on a semiconductor p-n junction. When a forward voltage exceeding the diode's threshold is applied, electrons and holes recombine in the active region (the AlInGaP layer in this case), releasing energy in the form of photons (light). The specific material composition (AlInGaP) determines the bandgap energy of the semiconductor, which directly defines the wavelength (color) of the emitted light—in this instance, hyper red. The common cathode configuration means all LEDs share the same negative terminal, which is switched to ground to turn the digit on, while individual positive terminals (anodes) are controlled to select which segments light up.

11. Technology Trends and Context

Seven-segment LED displays represent a mature and highly reliable display technology. While newer technologies like dot-matrix OLEDs or LCDs offer more flexibility for displaying graphics and alphanumeric characters, seven-segment LEDs retain strong advantages in specific niches: High Brightness and Contrast: They are easily readable in direct sunlight and dark conditions, outperforming many LCDs. Wide Temperature Range: Their solid-state nature allows operation in extreme temperatures where LCDs may fail. Simplicity and Cost-Effectiveness: For applications that only need to show numbers, they offer a very simple interface and low system cost compared to more complex graphic displays. Longevity: LEDs have extremely long lifespans when operated within specifications. The trend within the segment itself is towards higher efficiency (more light output per watt), which allows for lower power consumption and reduced heat generation, and towards surface-mount device (SMD) packages for automated assembly, though through-hole types like this one remain popular for prototyping and certain industrial applications. The use of AlInGaP material, as seen in this datasheet, represents an advancement over older GaAsP-based red LEDs, offering higher efficiency and better color stability.