0.56-inch 7-Segment LED Display Datasheet - Digit Height 14.22mm - Forward Voltage 2.6V - AlInGaP Yellow Orange - English Technical Document

1. Product Overview

The LTS-5703AJF is a single-digit, 7-segment LED display module designed for applications requiring clear, high-visibility numeric readouts. Its primary function is to convert electrical signals into a visible numeric character. The core technology utilizes Aluminium Indium Gallium Phosphide (AlInGaP) semiconductor material deposited on a Gallium Arsenide (GaAs) substrate to produce light in the yellow-orange spectrum. This material system is chosen for its high efficiency and excellent brightness in the amber/orange color range compared to older technologies like standard Gallium Phosphide (GaP). The device features a light gray face and white segments, which enhances contrast and readability under various lighting conditions.

The display is categorized as a common cathode type, meaning all the cathodes (negative terminals) of the individual LED segments are connected internally to common pins. This configuration is common in digital displays and simplifies circuit design when using microcontroller or driver ICs that sink current. The target market for this component includes industrial control panels, test and measurement equipment, consumer appliances, automotive dashboards (for non-critical indicators), and any embedded system requiring a reliable, low-power numeric display.

2. In-Depth Technical Parameter Analysis

2.1 Optical Characteristics

The optical performance is defined by several key parameters measured under standard test conditions (Ta=25°C). The Average Luminous Intensity (Iv) is specified with a minimum of 800 μcd, typical of 1667 μcd, and no maximum limit stated, when driven at a forward current (IF) of 1mA. This parameter indicates the perceived brightness of the lit segments. The luminous intensity is measured using a sensor and filter that approximates the photopic (daylight-adapted) human eye response curve as defined by the CIE (Commission Internationale de l'Éclaiage).

The color characteristics are defined by wavelength. The Peak Emission Wavelength (λp) is typically 611 nanometers (nm) at IF=20mA. This is the wavelength at which the optical power output is maximum. The Dominant Wavelength (λd) is typically 605 nm. This is the single wavelength that best matches the perceived color of the light emitted and is more relevant for color specification. The Spectral Line Half-Width (Δλ) is typically 17 nm, indicating the spectral purity or the spread of wavelengths emitted around the peak; a narrower half-width indicates a more monochromatic (pure) color.

2.2 Electrical Characteristics

The primary electrical parameter is the Forward Voltage per Segment (VF), which has a typical value of 2.6V and a maximum of 2.6V at a forward current of 20mA. This is the voltage drop across the LED segment when it is conducting. The minimum value is listed as 2.05V. The Reverse Current per Segment (IR) is specified with a maximum of 100 μA when a reverse voltage (VR) of 5V is applied, indicating the device's leakage characteristics in the off-state.

Luminous Intensity Matching Ratio is specified as 2:1 maximum for segments within a similar light area. This means the brightness of one segment should not be more than twice the brightness of another segment under identical driving conditions, ensuring uniform appearance of the digit.

2.3 Absolute Maximum Ratings and Thermal Considerations

These ratings define the stress limits beyond which permanent damage may occur. The Continuous Forward Current per Segment is rated at 25 mA maximum. A derating factor of 0.33 mA/°C is specified above 25°C ambient temperature (Ta). This is crucial for thermal management; as ambient temperature rises, the maximum allowable current must be reduced linearly to prevent overheating. For example, at 85°C, the maximum current would be 25 mA - (0.33 mA/°C * (85-25)°C) = 5.2 mA.

The Peak Forward Current per Segment is 60 mA, but only under pulsed conditions (1/10 duty cycle, 0.1ms pulse width). This allows for multiplexing schemes or brief over-driving for increased brightness. The Power Dissipation per Segment is 70 mW. The Reverse Voltage per Segment must not exceed 5V. The operating and storage temperature range is -35°C to +105°C. The solder temperature rating is for wave or reflow soldering: 260°C for 3 seconds at a point 1/16 inch (approximately 1.6mm) below the seating plane of the package.

3. Binning System Explanation

The datasheet indicates the device is Categorized for Luminous Intensity. This implies a binning system is in place. Binning is a standard industry practice where manufactured LEDs are sorted (binned) based on key parameters like luminous intensity, forward voltage, and dominant wavelength after production. This ensures consistency within a single production batch or order. While specific bin codes are not provided in this excerpt, designers should be aware that typical bins would group devices with similar Iv (e.g., 800-1200 μcd, 1200-1667 μcd) and possibly similar VF ranges. For critical applications requiring color or brightness uniformity across multiple displays, specifying a tight bin or requesting devices from the same bin is essential.

4. Performance Curve Analysis

While the specific graphs are not detailed in the provided text, typical characteristic curves for such a device would include:

• Forward Current (IF) vs. Forward Voltage (VF) Curve: This shows the exponential relationship. The curve will have a knee voltage around 1.8-2.0V, after which current increases rapidly with a small increase in voltage. The typical VF of 2.6V is read from this curve at IF=20mA.
• Luminous Intensity (Iv) vs. Forward Current (IF) Curve: This curve is generally linear at lower currents but may show saturation or reduced efficiency at very high currents due to thermal effects.
• Luminous Intensity (Iv) vs. Ambient Temperature (Ta) Curve: This shows how brightness decreases as the junction temperature of the LED increases. AlInGaP LEDs typically have a negative temperature coefficient for light output.
• Spectral Distribution Curve: A plot of relative intensity vs. wavelength, showing a peak around 611 nm and a half-width of approximately 17 nm, confirming the yellow-orange emission.

These curves are vital for designers to understand the non-linear behavior of LEDs, plan for thermal management, and design appropriate current-limiting circuits.

5. Mechanical and Packaging Information

The device has a digit height of 0.56 inches (14.22 mm). The package dimensions are provided in a drawing (not fully detailed here) with all dimensions in millimeters. Key tolerances are noted: general dimensional tolerances are ±0.25 mm unless otherwise specified, and the pin tip shift tolerance is ±0.4 mm. This shift tolerance accounts for minor misalignment of the leads coming out of the plastic package body, which is important for PCB footprint design and automatic insertion equipment.

The pin connection diagram is clearly defined with 10 pins in a dual-in-line package (DIP) configuration. The pinout is: 1(E), 2(D), 3(Common Cathode), 4(C), 5(DP), 6(B), 7(A), 8(Common Cathode), 9(F), 10(G). The presence of two common cathode pins (3 and 8) helps in distributing current and reducing current density in a single pin, which is good for reliability. The decimal point (DP) anode is on pin 5. The internal circuit diagram shows each segment (A-G, DP) as an individual LED with its anode connected to the respective pin and all cathodes tied together to the common cathode pins.

6. Soldering and Assembly Guidelines

The absolute maximum ratings specify the soldering profile: the component body temperature must not exceed the maximum rating during assembly. Specifically, it states the solder temperature should be 260°C for 3 seconds, measured 1/16 inch (1.6mm) below the seating plane. This is a standard reference for wave soldering. For reflow soldering, a standard lead-free profile with a peak temperature of 260°C would be appropriate, ensuring the time above liquidus (TAL) and the peak temperature duration at the component leads are controlled to prevent thermal damage to the plastic package or the internal wire bonds.

Storage conditions should adhere to the specified storage temperature range of -35°C to +105°C. It is advisable to store components in a dry, anti-static environment to prevent moisture absorption (which can cause \"popcorning\" during reflow) and electrostatic discharge damage, although the risk for LEDs is lower than for some ICs.

7. Packaging and Ordering Information

The part number is LTS-5703AJF. The \"AJF\" suffix likely encodes specific attributes like color (Yellow Orange), package type, and possibly a brightness bin. The datasheet revision is indicated, and the document is marked as property of the manufacturer. Standard packaging for such through-hole components is typically in anti-static tubes or ammo tapes on reels for automated insertion. The exact quantity per tube/reel and the packaging material are not specified in this excerpt but would be available in separate packing specifications.

8. Application Recommendations

Typical Application Circuits: As a common cathode display, it is typically driven by a microcontroller or a dedicated display driver IC (like a 74HC595 shift register with current-limiting resistors or a MAX7219). Each segment anode requires a current-limiting resistor. The resistor value can be calculated using R = (Vcc - VF) / IF. For a 5V supply (Vcc), VF=2.6V, and IF=20mA, R = (5 - 2.6) / 0.02 = 120 Ohms. A slightly higher value (e.g., 150-220 Ohms) is often used to increase lifespan and reduce power consumption while maintaining good brightness.

Design Considerations:

• Current Driving: Do not exceed the absolute maximum continuous current of 25 mA per segment. Use the derating factor for high-temperature environments.
• Multiplexing: For multi-digit displays, multiplexing is common. The peak current rating (60 mA at 1/10 duty cycle) allows for higher instantaneous current during the multiplexed on-time to achieve a higher perceived brightness. Ensure the average current over time does not exceed the continuous rating.
• Viewing Angle: The datasheet mentions a wide viewing angle, which is characteristic of LED displays with a diffused lens. Consider the intended viewing position when mounting the display.
• PCB Layout: Follow the recommended footprint from the dimensional drawing. Ensure the holes are sized correctly for the lead diameter and provide adequate clearance.

9. Technical Comparison and Advantages

Compared to older red GaAsP or standard GaP yellow/green LEDs, the AlInGaP technology in the LTS-5703AJF offers significant advantages:

• Higher Brightness and Efficiency: AlInGaP provides superior luminous efficacy, resulting in brighter displays at the same drive current or similar brightness at lower power.
• Better Color Saturation: The spectral characteristics yield a more vivid and consistent yellow-orange color.
• Solid-State Reliability: LEDs have no filaments or glass to break, offering high shock and vibration resistance and a very long operational lifetime (typically tens of thousands of hours).
• Low Power Requirement: Operates at low voltage and current, making it suitable for battery-powered devices.
• Lead-Free Package: Compliant with RoHS (Restriction of Hazardous Substances) directives, making it suitable for global markets with environmental regulations.

Compared to modern surface-mount device (SMD) 7-segment displays, this through-hole version is easier for prototyping, manual assembly, and applications where display replacement might be necessary.

10. Frequently Asked Questions (Based on Technical Parameters)

Q1: What is the purpose of the two common cathode pins (3 and 8)?
A1: They are internally connected. Having two pins helps distribute the total cathode current (which is the sum of currents from all lit segments) across two physical leads, reducing current density and thermal stress on each solder joint and lead frame, thereby improving reliability.

Q2: Can I drive this display directly from a 3.3V microcontroller pin?
A2: Possibly, but you must check the forward voltage. The typical VF is 2.6V, so a 3.3V supply leaves only 0.7V for the current-limiting resistor. Using Ohm's law, for a desired 10mA current, R = (3.3 - 2.6) / 0.01 = 70 Ohms. This is feasible, but the brightness may be slightly lower than the rated value at 20mA. Ensure the microcontroller pin can source the required current.

Q3: What does \"Luminous Intensity Matching Ratio 2:1\" mean for my design?
A3: It guarantees that within a single device, no segment will be more than twice as bright as any other segment when driven identically. This prevents an uneven-looking digit (e.g., a very dim segment A and a very bright segment G). For multi-digit designs, specify devices from the same intensity bin to ensure consistency across digits.

Q4: How do I calculate the power dissipation for the whole display?
A4: For the worst-case scenario with all 8 segments (7 segments + DP) lit continuously at the maximum continuous current of 25 mA each, with a typical VF of 2.6V. Power per segment = VF * IF = 2.6V * 0.025A = 65 mW. Total power = 8 * 65 mW = 520 mW. This is the power dissipated as heat by the LED package itself, which must be considered for thermal management in enclosed spaces.

11. Practical Design and Usage Examples

Example 1: Digital Voltmeter Readout. In a simple benchtop digital multimeter prototype, the LTS-5703AJF can be used to display voltage readings. A microcontroller's analog-to-digital converter (ADC) reads the voltage, processes it, and drives the display via a shift register like the 74HC595. Current-limiting resistors are placed in series with each segment anode. The common cathodes are switched by a transistor controlled by the microcontroller for multiplexing if multiple digits are used. The high contrast and brightness ensure readability in well-lit lab environments.

Example 2: Industrial Counter Display. For a production line piece counter, the display needs to be reliable and visible from a distance. The LTS-5703AJF, with its 0.56-inch digit height, is suitable. It can be driven by a programmable logic controller (PLC) output module designed for LED displays or via a simple counter IC. The wide operating temperature range (-35°C to +105°C) makes it robust for factory floor conditions where temperatures might fluctuate.

12. Technology Principle Introduction

The LTS-5703AJF is based on a Aluminium Indium Gallium Phosphide (AlInGaP) semiconductor heterostructure grown epitaxially on a Gallium Arsenide (GaAs) substrate. Light emission is achieved through electroluminescence. When a forward voltage exceeding the diode's bandgap voltage is applied, electrons from the n-type region and holes from the p-type region are injected into the active region (the quantum well). There, they recombine radiatively, releasing energy in the form of photons. The specific alloy composition of AlInGaP determines the bandgap energy, which directly corresponds to the wavelength (color) of the emitted light. For yellow-orange light, the bandgap energy is approximately 2.0-2.1 electron volts (eV). The GaAs substrate is opaque to the emitted light, so the chip is designed to emit light from the top surface. The plastic package incorporates a molded lens that shapes the light output, provides environmental protection, and creates the distinctive segment shape.

13. Technology Development Trends

While this is a mature through-hole component, trends in display technology influence its context. The broader LED industry continues to focus on:

• Increased Efficiency (lm/W): Ongoing material science research aims to reduce non-radiative recombination and improve light extraction from the semiconductor chip, leading to brighter displays at lower power.
• Miniaturization and SMD Dominance: The market has largely shifted towards surface-mount device (SMD) packages for automated assembly, reduced board space, and lower profile. Through-hole displays like this one remain relevant for specific niches requiring robustness, ease of hand-soldering, or replacement.
• Integrated Solutions: There is a trend towards displays with integrated driver ICs (\"intelligent displays\") that simplify the host microcontroller interface by handling multiplexing, decoding, and current control internally.
• Expanded Color Gamut and RGB: For full-color capable displays, the development of efficient red, green, and blue LEDs, including micro-LEDs, is a major trend. While this is a monochrome device, the underlying material improvements benefit all LED colors.
• Flexible and Transparent Substrates: Research into displays on flexible or transparent substrates is active, though this is more relevant for advanced panel displays than for traditional segmented numeric units.

The LTS-5703AJF represents a reliable, cost-effective solution within these ongoing technological advancements.