ELS-315SURWA/S530-A3 Seven Segment Display Datasheet - 9.14mm Digit Height - Brilliant Red (632nm) - 2.0V Forward Voltage - 25mA Forward Current - English Technical Document

1. Product Overview

The ELS-315SURWA/S530-A3 is a single-digit, seven-segment alphanumeric display designed for through-hole mounting. It features a standard industrial size with a digit height of 9.14mm (0.36 inches). The display is constructed with brilliant red AlGaInP LED chips, housed within a white diffused resin package that provides a gray surface appearance. This combination is engineered to deliver high reliability and excellent readability even in bright ambient lighting conditions, making it suitable for a variety of indicator and readout applications.

1.1 Core Advantages and Target Market

The primary advantages of this display include its compliance with industrial standards for size and pinout, ensuring easy replacement and design integration. It offers low power consumption, contributing to energy-efficient system designs. The device is categorized (binned) for luminous intensity, allowing for consistent brightness matching in multi-digit applications. Furthermore, it is manufactured to be Pb-free and RoHS compliant, adhering to modern environmental regulations. Its target markets are primarily industrial and consumer electronics applications requiring clear, reliable numeric or limited alphanumeric readouts.

2. Technical Parameter Deep Dive

This section provides a detailed, objective analysis of the device's electrical, optical, and thermal specifications as defined in the datasheet.

2.1 Absolute Maximum Ratings

The Absolute Maximum Ratings define the stress limits beyond which permanent damage to the device may occur. These are not conditions for normal operation.

• Reverse Voltage (V_R): 5V. Exceeding this voltage in reverse bias can cause junction breakdown.
• Forward Current (I_F): 25mA DC. This is the maximum continuous current allowed through a segment.
• Peak Forward Current (I_FP): 60mA. This is permissible only under pulsed conditions (duty cycle ≤ 10%, frequency ≤ 1kHz).
• Power Dissipation (P_d): 60mW. The maximum power the device can dissipate, calculated as V_F * I_F.
• Operating Temperature (T_opr): -40°C to +85°C. The ambient temperature range for reliable operation.
• Storage Temperature (T_stg): -40°C to +100°C.
• Soldering Temperature (T_sol): 260°C for a maximum of 5 seconds, typical for wave or hand soldering.

2.2 Electro-Optical Characteristics

These parameters are measured at a standard junction temperature (T_a=25°C) and define the device's performance under normal operating conditions.

• Luminous Intensity (I_v): 4.0mcd (Min), 8.0mcd (Typ) at I_F=10mA. This is the average light output per segment. A ±10% tolerance is specified.
• Peak Wavelength (λ_p): 632nm (Typ) at I_F=20mA. This is the wavelength at which the spectral emission is strongest.
• Dominant Wavelength (λ_d): 624nm (Typ) at I_F=20mA. This is the wavelength perceived by the human eye, defining the color (brilliant red).
• Spectral Bandwidth (Δλ): 20nm (Typ) at I_F=20mA. This indicates the narrowness of the emitted red light spectrum.
• Forward Voltage (V_F): 2.0V (Typ), 2.4V (Max) at I_F=20mA. The voltage drop across the LED when conducting, with a ±0.1V tolerance.
• Reverse Current (I_R): 100µA (Max) at V_R=5V. The small leakage current when the device is reverse-biased.

3. Binning System Explanation

The datasheet indicates the device is "Categorized for luminous intensity." This means units are tested and sorted (binned) based on their measured light output at a specific test current. This allows designers to select displays from the same intensity bin to ensure uniform brightness across all digits in a multi-digit display, avoiding noticeable variations in segment luminosity. The specific binning codes or ranges are not detailed in the provided excerpt but would typically be part of the ordering information.

4. Performance Curve Analysis

The datasheet includes typical characteristic curves which are crucial for understanding device behavior under non-standard conditions.

4.1 Spectrum Distribution

The spectrum curve shows the relative intensity of light emitted across different wavelengths. For this AlGaInP-based red LED, the curve will be centered around the 632nm peak with the stated 20nm bandwidth, confirming a pure, saturated red color without significant emission in other color bands.

4.2 Forward Current vs. Forward Voltage (I-V Curve)

This curve illustrates the non-linear relationship between current and voltage. It shows the turn-on voltage (where current begins to flow significantly, around 1.8-2.0V for red AlGaInP) and how the forward voltage increases with current. Designers use this to calculate series resistor values (R = (V_supply - V_F) / I_F) to set the desired operating current, typically between 10-20mA for a balance of brightness and longevity.

4.3 Forward Current Derating Curve

This is a critical thermal management graph. It shows the maximum allowable continuous forward current as a function of the ambient temperature. As ambient temperature rises, the LED junction temperature increases, and the maximum safe current must be reduced to prevent overheating and accelerated degradation. The curve typically shows the rated current (e.g., 25mA) permissible up to a certain temperature (e.g., 25°C or 40°C), after which it slopes downward to zero at the maximum junction temperature. This curve must be consulted for designs operating in elevated temperature environments.

5. Mechanical and Package Information

5.1 Package Dimensions and Drawing

The device is in a standard through-hole DIP (Dual In-line Package) format. The dimensional drawing provides critical measurements: overall height, width, and length; segment size and spacing; lead (pin) diameter, length, and spacing (pitch). The note specifies a general tolerance of ±0.25mm unless otherwise stated. Designers must use this drawing to create the PCB footprint, ensuring correct pad size, spacing, and placement for the digit's segments and common pins.

5.2 Internal Circuit Diagram and Polarity Identification

The internal circuit diagram shows the electrical connection of the 10 pins. A standard seven-segment display has 7 pins for the segments (a through g), 1 or more common pins (anode or cathode, depending on common-anode or common-cathode configuration), and sometimes a decimal point (dp). The diagram clarifies which pin controls which segment and identifies the common connection, which is essential for correct wiring and driver circuit design (e.g., using a multiplexer or dedicated display driver IC).

6. Soldering and Assembly Guidelines

The datasheet specifies a maximum soldering temperature of 260°C for ≤5 seconds. This is a standard rating for wave soldering or hand soldering with a temperature-controlled iron. For reflow soldering, a specific profile would be needed but is not provided. Key considerations include:

• ESD Sensitivity: The LED dice are sensitive to electrostatic discharge. Handling precautions such as grounded workstations, wrist straps, and conductive foam are strongly recommended during assembly.
• Thermal Stress: Avoid prolonged exposure to high temperatures during soldering to prevent damage to the plastic package or internal wire bonds.
• Cleaning: If cleaning is required, use methods compatible with the plastic resin.

7. Packaging and Ordering Information

The device follows a specific packing hierarchy: 35 pieces are packed in a tube, 140 tubes (totaling 4,900 pieces) are packed in a box, and 4 boxes (totaling 19,600 pieces) are packed in a master carton. The label on the packaging includes fields for Customer Part Number (CPN), Manufacturer Part Number (P/N), Packing Quantity (QTY), Luminous Intensity Category (CAT), and Lot Number (LOT No.), among other references, ensuring traceability and correct identification.

8. Application Suggestions

8.1 Typical Application Scenarios

• Home Appliances: Timers, temperature readouts on ovens/microwaves, cycle indicators on washing machines.
• Instrument Panels: Test and measurement equipment, industrial control panels, automotive aftermarket gauges.
• Digital Readout Displays: Simple counters, clocks, scoreboards, and any device requiring a clear numeric indicator.

8.2 Design Considerations

• Current Limiting: Always use a series resistor for each segment or common line to set the forward current. Calculate based on the power supply voltage and the typical V_F at the desired I_F.
• Multiplexing: For multi-digit displays, multiplexing is common to reduce pin count on the microcontroller. Ensure the driver circuit can handle the peak current during the multiplexing cycle without exceeding the device's peak current rating.
• Viewing Angle: The white diffused resin provides a wide viewing angle. Consider the display's orientation relative to the user.
• Brightness Control: Brightness can be adjusted by varying the forward current (within limits) or by using PWM (Pulse Width Modulation) on the drive signal.

9. Technical Comparison and Differentiation

Compared to older technologies or smaller displays, the ELS-315SURWA/S530-A3 offers a balance of size, brightness, and efficiency. Its 9.14mm digit height is a common standard, ensuring wide compatibility. The use of AlGaInP material provides higher efficiency and a more vibrant, saturated red compared to older GaAsP-based red LEDs. The through-hole design offers mechanical robustness and ease of prototyping compared to surface-mount devices, though it requires more board space. Its key differentiator in its class is the combination of industrial standard pinout, luminous intensity binning for consistency, and RoHS compliance.

10. Frequently Asked Questions (Based on Technical Parameters)

10.1 Can I drive this display directly from a 5V microcontroller pin?

No, not directly. A typical microcontroller GPIO pin can source/sink 20-25mA, which matches the display's I_F rating. However, the LED's forward voltage is only about 2.0V. Connecting it directly to a 5V pin without a current-limiting resistor would attempt to drive a much higher current, potentially damaging both the LED and the microcontroller pin. You must use a series resistor: R = (5V - 2.0V) / 0.020A = 150Ω (use 150Ω or 180Ω standard value).

10.2 What is the difference between Peak Wavelength and Dominant Wavelength?

Peak Wavelength (λ_p) is the physical wavelength where the emission spectrum has its maximum intensity. Dominant Wavelength (λ_d) is the wavelength of monochromatic light that would appear to have the same color to the human eye. For LEDs, λ_d is often slightly shorter than λ_p and is the more relevant parameter for color specification in visual applications.

10.3 Is this a common-anode or common-cathode display?

The provided datasheet excerpt does not explicitly state this. This critical information is contained in the Internal Circuit Diagram. The designer must consult this diagram to determine the configuration before designing the driver circuit. Using the wrong configuration will prevent the display from lighting up.

11. Practical Design and Usage Case

Case: Designing a 4-Digit Multiplexed Counter. To drive four ELS-315SURWA/S530-A3 displays with a microcontroller:

1. Determine the common pin type (anode/cathode) from the internal diagram.
2. Connect all corresponding segment pins (a-g, dp) together across the four digits.
3. Connect each digit's common pin to a separate microcontroller pin via a transistor (for current handling) if it's a common-anode type, or directly/inverted if common-cathode and within the MCU's sink capability.
4. Calculate a single current-limiting resistor for each segment line, based on the peak current per segment during multiplexing. If each digit is active 1/4 of the time, to achieve an average current of 10mA, the peak current during its active time slot should be 40mA. Ensure this 40mA peak does not exceed the device's I_FP rating (60mA) and is within the driver's capability.
5. Write firmware to cycle through the digits rapidly (e.g., 100Hz per digit, 400Hz total refresh), illuminating the correct segments for the active digit.

12. Operating Principle Introduction

A seven-segment display is an assembly of seven LED bars (segments) arranged in a figure-eight pattern. By selectively illuminating specific combinations of these segments, all decimal digits (0-9) and some letters can be formed. Each segment is an individual LED. In a common-anode display, all the anodes of the segment LEDs are connected together to a common pin (V_CC), and each cathode is controlled separately. To light a segment, its cathode pin is driven LOW (connected to ground through a current-limiting resistor). In a common-cathode display, the cathodes are common (ground), and the anodes are driven HIGH to illuminate. The ELS-315SURWA/S530-A3 uses AlGaInP (Aluminum Gallium Indium Phosphide) semiconductor material, which emits light in the red to yellow-orange spectrum when electrons recombine with holes across the material's bandgap, a process called electroluminescence.

13. Technology Trends and Developments

While through-hole seven-segment displays like the ELS-315SURWA/S530-A3 remain popular for robustness and ease of use, the overall trend in electronics is towards surface-mount technology (SMT) for automated assembly, smaller size, and lower profile. High-brightness and sunlight-readable versions are also in demand. Furthermore, there is a growing shift towards integrated display modules with built-in controllers (I2C, SPI) that simplify microcontroller interfacing. However, discrete seven-segment LEDs continue to have a strong position in cost-sensitive applications, hobbyist projects, and situations where the high visibility and simple direct drive of a standard component are paramount. The use of more efficient materials like AlGaInP, as seen in this device, is part of the ongoing evolution to provide better performance within the classic form factor.