0.56-inch Seven Segment LED Display Datasheet - Digit Height 14.22mm - Forward Voltage 2.6V - Power 70mW - Super Red Color - English Technical Document

1. Product Overview

This document details the specifications for a 0.56-inch (14.22mm) digit height, seven-segment LED display. The device is engineered for applications requiring clear, reliable numeric readouts with low power consumption. Its core design philosophy centers on providing excellent visual performance through high brightness and contrast while maintaining solid-state reliability.

The display utilizes advanced AlInGaP (Aluminum Indium Gallium Phosphide) semiconductor technology for its light-emitting segments. This material system is known for producing high-efficiency red and amber light. The specific chips used are fabricated on a non-transparent GaAs (Gallium Arsenide) substrate, which helps improve contrast by minimizing internal light scattering and reflection. The final product features a light gray faceplate with white segments, a combination chosen to enhance readability under various lighting conditions.

2. In-Depth Technical Parameter Analysis

2.1 Photometric and Optical Characteristics

The optical performance is characterized under standard test conditions at an ambient temperature (Ta) of 25°C. The key parameter, Average Luminous Intensity (Iv), has a typical value of 700 µcd (microcandelas) when driven at a forward current (IF) of 1mA per segment, with a minimum specified value of 320 µcd. This measurement is taken using a sensor and filter calibrated to the CIE photopic eye-response curve, ensuring the value correlates with human visual perception.

The color characteristics are defined by wavelength. The Peak Emission Wavelength (λp) is typically 639 nm, while the Dominant Wavelength (λd) is typically 631 nm, both measured at IF=20mA. The difference between these two values and the Spectral Line Half-Width (Δλ) of 20 nm describe the spectral purity and the specific shade of red light emitted, which falls into the \"super red\" category, offering high visibility.

A Luminous Intensity Matching Ratio (IV-m) of 2:1 (maximum) is specified. This ratio indicates the maximum allowable variation in brightness between the different segments of a single device when driven under identical conditions, ensuring a uniform appearance when displaying numbers.

2.2 Electrical and Thermal Characteristics

The electrical parameters highlight the device's suitability for low-power systems. The Forward Voltage per Segment (VF) ranges from 2.0V to 2.6V at a drive current of 1mA. The Reverse Current per Segment (IR) is limited to a maximum of 100 µA when a reverse voltage (VR) of 5V is applied, indicating the junction's leakage characteristics.

Thermal and power limits are defined in the Absolute Maximum Ratings. The Continuous Forward Current per Segment is rated at 25 mA, but this must be derated linearly from 25°C at a rate of 0.33 mA/°C as ambient temperature increases. The Power Dissipation per Segment must not exceed 70 mW. For pulsed operation, a Peak Forward Current of 90 mA is allowed under a 1/10 duty cycle with a 0.1ms pulse width. The device is rated for an Operating and Storage Temperature Range of -35°C to +85°C.

3. Binning and Selection System

The datasheet indicates that the devices are \"Categorized for Luminous Intensity.\" This implies a binning process where manufactured units are sorted based on their measured light output (Iv) into different groups or \"bins.\" This allows designers to select parts with consistent brightness levels for their application, which is crucial for multi-digit displays where uniformity is key. While specific bin codes are not listed in this summary, typical bins would define ranges for luminous intensity (e.g., 500-600 µcd, 600-700 µcd) and possibly forward voltage.

4. Performance Curve Analysis

The datasheet references \"Typical Electrical / Optical Characteristic Curves.\" Although the specific graphs are not provided in the text, standard curves for such devices would typically include:

• Relative Luminous Intensity vs. Forward Current (I-V Curve): This graph shows how light output increases with drive current. It is typically non-linear, with efficiency often decreasing at very high currents.
• Forward Voltage vs. Forward Current: This shows the diode's I-V characteristic, important for designing the current-limiting circuitry.
• Relative Luminous Intensity vs. Ambient Temperature: This curve demonstrates how light output decreases as the junction temperature rises, a critical factor for thermal management in designs.
• Spectral Distribution: A plot showing the relative intensity of light emitted across different wavelengths, centered around the peak wavelength of ~639 nm.

These curves are essential for understanding the device's behavior under non-standard conditions and for optimizing drive circuitry for efficiency and longevity.

5. Mechanical and Package Information

5.1 Physical Dimensions and Outline

The device's package dimensions are provided in a drawing (referenced but not detailed in the text). All dimensions are specified in millimeters with a standard tolerance of ±0.25 mm unless otherwise noted. The 0.56-inch digit height (14.22mm) defines the overall character size. The package is a standard single-digit, 10-pin configuration common for seven-segment displays with a right-hand decimal point.

5.2 Pin Configuration and Polarity Identification

The display has a Common Cathode configuration, meaning the cathodes (negative terminals) of all LED segments are connected internally and brought out to common pins. This is a common design for multiplexed driving. The pin connection is explicitly defined:

1. Anode E
2. Anode D
3. Common Cathode
4. Anode C
5. Anode D.P. (Decimal Point)
6. Anode B
7. Anode A
8. Common Cathode
9. Anode F
10. Anode G

Pins 3 and 8 are both Common Cathodes. The internal circuit diagram shows the standard seven-segment plus decimal point layout, with each segment's anode connected to its respective pin and all cathodes tied together to the common pins.

6. Soldering and Assembly Guidelines

A key assembly parameter specified is the solder temperature profile. 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 is a critical parameter for wave soldering or reflow processes to prevent thermal damage to the LED chips or the plastic package. Designers must ensure their assembly process does not exceed this time-temperature combination. For storage, the specified range of -35°C to +85°C should be maintained in a dry environment to prevent moisture absorption.

7. Application Recommendations

7.1 Typical Application Scenarios

This display is ideal for portable, battery-powered devices, instrumentation panels, consumer electronics, and industrial controls where a clear, low-power numeric readout is required. Examples include multimeters, timers, scales, medical devices, and appliance control panels. Its low current operation (down to 1mA per segment) makes it suitable for microcontroller-driven systems where GPIO pins can often source or sink limited current.

7.2 Design Considerations and Circuitry

When designing the drive circuit, the following points are crucial:

• Current Limiting: Always use series current-limiting resistors for each segment anode. The resistor value is calculated based on the supply voltage (Vcc), the LED forward voltage (Vf, use max value for safety), and the desired forward current (If): R = (Vcc - Vf) / If.
• Multiplexing: For multi-digit displays, a multiplexed driving scheme is standard. The common cathodes of each digit are switched sequentially (scanned) while the anodes for the desired segments are driven in sync. This reduces the number of required microcontroller pins and total power consumption. The peak current during the short ON time can be higher than the DC rating, as allowed by the peak current specification (90mA at 1/10 duty).
• Microcontroller Interface: The display can be driven directly from microcontroller GPIO pins if the current per segment is within the MCU's pin drive capability (typically 20-25mA). For higher brightness or multiplexing with more digits, external drivers (e.g., transistor arrays or dedicated LED driver ICs) are recommended.
• Viewing Angle: The \"Wide Viewing Angle\" feature means the display remains readable from off-axis positions, which is important for panels viewed from various angles.

8. Technical Comparison and Differentiation

The primary differentiating factors of this display are its use of AlInGaP technology and its optimized low-current performance. Compared to older GaAsP or GaP LED technology, AlInGaP offers significantly higher luminous efficiency, resulting in brighter output at the same current or equivalent brightness at lower current. The explicit testing and selection for \"excellent low current characteristics\" and segment matching are key quality assurances. The ability to operate effectively at currents as low as 1mA per segment is a distinct advantage for ultra-low-power designs over displays that require 5-20mA for adequate brightness.

9. Frequently Asked Questions (FAQ)

Q: What is the difference between peak wavelength and dominant wavelength?
A: Peak wavelength (λp) is the wavelength at which the emitted light spectrum has its maximum intensity. Dominant wavelength (λd) is the wavelength of a pure monochromatic light that would appear to have the same color to the human eye as the LED's light. λd is more relevant for color perception.

Q: Can I drive this display without current-limiting resistors?
A: No. LEDs are current-driven devices. Connecting them directly to a voltage source will cause excessive current to flow, potentially destroying the LED instantly due to thermal overstress. A series resistor or constant-current circuit is mandatory.

Q: The datasheet shows two common cathode pins (3 and 8). Do I need to connect both?
A: Yes, for optimal performance and current distribution, both common cathode pins should be connected to ground (or the current sink) in your circuit. This helps balance the thermal load and ensures even segment brightness.

Q: How do I calculate the appropriate resistor value for a 5V supply and 10mA segment current?
A: Using the maximum Vf of 2.6V: R = (5V - 2.6V) / 0.01A = 240 Ohms. The nearest standard value (220 or 270 Ohms) would be used. Always verify actual brightness meets your needs.

10. Design and Usage Case Study

Scenario: Designing a 4-digit battery-powered digital timer.
The goal is to maximize battery life while maintaining good readability. The display will be driven by a low-power microcontroller using a multiplexing scheme.

Implementation: The four digits' common cathodes are connected to four NPN transistors (or a transistor array IC) controlled by MCU pins. The seven segment anodes (A-G) and the decimal point are connected to MCU output pins via individual current-limiting resistors. The MCU runs a timer interrupt (e.g., at 1kHz). In each interrupt cycle, it turns off all digit cathodes, sets the anode pins to the segment pattern for the next digit in sequence, and then turns on that digit's cathode transistor. This cycles through all four digits rapidly, creating the illusion of all digits being on simultaneously.

Power Optimization: By driving each segment at only 2-3mA (well within spec) and using a 1:4 multiplexing duty cycle, the average current per segment is very low, significantly extending battery life compared to static (non-multiplexed) driving. The high efficiency of the AlInGaP LEDs ensures the display remains clearly visible even at these low average currents.

11. Technical Principle Introduction

A seven-segment LED display is an assembly of individual Light Emitting Diodes (LEDs) arranged in a figure-eight pattern. Each of the seven main segments (labeled A through G) is a separate LED, and an additional LED serves as the decimal point (DP). By selectively illuminating specific combinations of these segments, all decimal digits (0-9) and some letters can be formed.

The underlying principle of light emission is electroluminescence in a semiconductor p-n junction. When a forward voltage exceeding the diode's bandgap voltage is applied, electrons from the n-type region recombine with holes from the p-type region in the active layer (in this case, made of AlInGaP). This recombination releases energy in the form of photons (light). The specific wavelength (color) of the light is determined by the bandgap energy of the semiconductor material. AlInGaP has a bandgap corresponding to red/orange/amber light. The non-transparent GaAs substrate absorbs stray light, improving contrast by preventing it from scattering out through the sides or back of the chip.

12. Technology Trends and Context

While newer display technologies like OLED and high-resolution dot-matrix LEDs exist, the seven-segment LED display remains a robust, cost-effective, and highly reliable solution for applications requiring simple numeric output. The trend within this segment is towards higher efficiency (more light per watt), lower operating voltages to match modern logic levels, and improved consistency (tighter binning). AlInGaP technology represents a significant step in efficiency over older materials. Furthermore, there is a growing emphasis on displays that perform well under very low drive currents to enable energy-efficient and battery-powered Internet of Things (IoT) devices. The device described in this datasheet, with its focus on low-current operation and categorized luminous intensity, aligns well with these industry trends towards efficiency, reliability, and design flexibility for portable electronics.