LTS-546AJG 0.52-Inch Seven-Segment LED Display Datasheet - Character Height 13.2mm - Green (AlInGaP) - Forward Voltage 2.6V - Power Consumption 70mW - Technical Documentation

1. Product Overview

LTS-546AJG is a single-digit alphanumeric display module. Its primary function is to provide clear, legible numeric or limited character readouts in electronic devices. Its core technology is based on Aluminum Indium Gallium Phosphide (AlInGaP) semiconductor material grown on a Gallium Arsenide (GaAs) substrate, which is engineered to emit green light. This material choice is significant because AlInGaP LEDs are renowned for their high efficiency and brightness in the red to yellow-green part of the spectrum. The device features a gray face with white segment outlines, enhancing contrast and improving character appearance under various lighting conditions. It is binned for luminous intensity, meaning devices are graded and sorted based on their measured light output to ensure consistency in applications where multiple displays are used side-by-side.

1.1 Key Features and Core Advantages

• Digital Size:A character height of 0.52 inches (13.2 mm) strikes a balance between readability and compactness, making it suitable for panel meters, test equipment, and consumer appliances.
• Optical Quality:The display provides continuous, uniform segments with high brightness and high contrast, resulting in excellent character appearance.
• Viewing Angle:It features a wide viewing angle, ensuring the display remains clearly readable even when viewed from off-axis positions.
• Energy Efficiency:Low power consumption, suitable for battery-powered or energy-conscious devices.
• Reliability:As a solid-state device, it offers high reliability and long service life compared to mechanical or vacuum tube displays.
• Environmental Compliance:The package is designed lead-free and complies with the RoHS (Restriction of Hazardous Substances) directive.

1.2 Device Identification and Configuration

Part number LTS-546AJG specifies an AlInGaP green LED chip device in a common anode configuration. The "Rt. Hand Decimal" notation indicates the inclusion of a right-hand decimal point. In a common anode display, the anodes (positive terminals) of all LED segments are internally connected together. To illuminate a specific segment, its corresponding cathode (negative terminal) pin must be driven low (grounded or to a low voltage), while the common anode is held at a positive voltage. This configuration is common and often simplifies circuit design when using microcontroller or transistor sink drivers.

2. Technical Parameters: In-depth Objective Interpretation

2.1 Absolute Maximum Ratings

These ratings define the stress limits that may cause permanent damage to the device. Operation at or beyond these limits is not guaranteed.

• Power dissipation per segment:Maximum 70 mW. Exceeding this value may cause overheating and catastrophic failure.
• Peak forward current per segment:60 mA under pulse conditions (1/10 duty cycle, 0.1 ms pulse width). This rating applies to short, high-current pulses used during multiplexing.
• Each segment continuous forward current:At 25°C, it is 25 mA. When the ambient temperature (Ta) exceeds 25°C, this current must be linearly derated at a rate of 0.33 mA/°C. For example, at 50°C, the maximum continuous current is approximately 25 mA - (0.33 mA/°C * 25°C) = 16.75 mA.
• Temperature range:Operating and storage temperature range is -35°C to +85°C.
• Soldering conditions:Wave soldering or reflow soldering should be performed with the solder joint located 1/16 inch (≈1.6 mm) below the mounting plane, for up to 3 seconds at a maximum of 260°C.

I-V (Current-Voltage) Curve: Shows the relationship between forward voltage and forward current. It is nonlinear, featuring a threshold voltage (approximately 1.8-2.0V for AlInGaP) below which little current flows. This curve aids in designing appropriate current-limiting circuits. Luminous Intensity vs. Forward Current (IV vs. IF): Shows how light output increases with drive current. It is typically linear at lower currents but may saturate at higher currents due to thermal effects and efficiency droop. Luminous Intensity vs. Ambient Temperature: Shows how light output decreases as junction temperature rises. This is crucial for designing systems that operate over a wide temperature range. Spectral Distribution Graph: A plot of relative intensity versus wavelength, showing a peak at 571 nanometers and a half-width of 15 nanometers.

These are typical performance parameters measured under specified test conditions (Ta=25°C).

• Average Luminous Intensity (I_V):At a forward current (I_F) of 1 mA, the range is from 200 microcandelas (minimum) to 577 microcandelas (typical). The luminous intensity is measured using a filter matched to the CIE photopic response curve, with a tolerance of ±15%.
• Wavelength parameters:
  • Peak emission wavelength (λ_p): 571 nanometers (at I_F=20 mA).
  • Dominant wavelength (λ_d): 572 nanometers (at I_F=20 mA), with a tolerance of ±1 nanometer. This is the wavelength of monochromatic light that the human eye perceives as matching the color of the LED.
  • Spectral line half-width (Δλ): 15 nanometers (at I_F=20 mA). This indicates spectral purity; a smaller value means the light is closer to monochromatic.
• Forward voltage per chip (V_F):at I_F=20 mA is 2.1 V to 2.6 V, with a tolerance of ±0.1 V. This is a key parameter for driving circuit design.
• Reverse current (I_R):At a reverse voltage (V_R) of 5 volts, maximum 100 microamperes. This test is for characterization only; continuous reverse bias operation is prohibited.
• Luminous intensity matching ratio:The maximum segment-to-segment ratio within the same display is 2:1. This means that under identical driving conditions, the brightness difference between the brightest segment and the darkest segment does not exceed two times, ensuring uniformity.
• Crosstalk:Specified as ≤2.5%. This refers to the unwanted illumination of a segment due to internal optical or electrical leakage when adjacent segments are driven.

3. Grading System Description

The datasheet clearly states that the device is "binned by luminous intensity." This means that during production, LEDs are tested and grouped into different categories (bins) based on their measured light output under standard test current. This is crucial for applications using multiple display units, as it prevents noticeable brightness differences between individual units. Designers should specify or ensure that display units from the same or adjacent bins are obtained to maintain overall visual consistency of the product. Although not detailed in this excerpt, binning may also apply to forward voltage (V_F) and dominant wavelength (λ_d), the latter having a specified tolerance of ±1 nm.

4. Performance Curve Analysis

The datasheet references "Typical Electrical/Optical Characteristic Curves," which are essential for understanding the device's behavior beyond single-point specifications. These curves typically include:

• I-V (Current-Voltage) Curve:It shows the relationship between forward voltage and forward current. It is nonlinear, with a threshold voltage (approximately 1.8-2.0 volts for AlInGaP) below which almost no current flows. This curve aids in designing appropriate current-limiting circuits.
• Luminous Intensity vs. Forward Current (I_Vvs. I_F):It shows how the light output increases with the driving current. It is typically linear at lower currents but may saturate at higher currents due to thermal effects and efficiency droop.
• Luminous Intensity vs. Ambient Temperature:It shows how the light output decreases as the junction temperature rises. This is crucial for designing systems that operate over a wide temperature range.
• Spectral Distribution Chart:A graph of relative intensity versus wavelength, showing a peak at 571 nanometers and a full width at half maximum of 15 nanometers.

These curves enable engineers to optimize the driving conditions for specific targets of brightness, efficiency, and lifetime.

5. Mechanical and Packaging Information

4. Performance Curve Analysis

This display conforms to the standard through-hole DIP (Dual In-line Package) style. Key dimensional descriptions include:

• All dimensions are in millimeters, and unless otherwise specified, the general tolerance is ±0.25 mm.
• The pin tip offset tolerance is ±0.4 mm.
• Quality control limits are set for foreign matter (≤10 mils), ink contamination (≤20 mils), and bubbles within segments (≤10 mils).
• Reflector bending is limited to ≤1% of its length.

The precise dimensional drawing (not fully detailed in the text) will define the overall height, width, depth, digit dimensions, segment dimensions, and the exact pitch and diameter of the 10 pins.

5.2 Pin Connection and Polarity Identification

The device employs a 10-pin configuration (Pin 1 is marked as "No Connect"). The internal circuit diagram and pin definition table indicate a common-anode design, with two common anode pins (3 and 8). Segment cathodes are assigned to specific pins: E(1), D(2), C(4), DP(5), B(6), A(7), F(9), G(10). Correct identification of Pin 1 (typically indicated on the package by a notch, bevel, or dot) is crucial for proper orientation during PCB assembly.

6. Soldering, Assembly, and Storage Guide

6.1 Welding and Assembly

The maximum soldering conditions are specified. For manual soldering, a temperature-controlled soldering iron should be used to avoid exceeding the limit of 260°C at the pins. Precautions warn against applying abnormal force to the display body using unsuitable tools or methods. Additionally, if a decorative film is attached to the display surface, it should not be pressed tightly against the front panel, as external force may cause it to shift.

6.2 Storage Conditions

Proper storage is crucial to prevent pin oxidation and moisture absorption.

• For LED displays (through-hole type):Store in original packaging at 5°C to 30°C with relative humidity below 60%. If stored outside the moisture barrier bag or if the bag has been open for more than 6 months, it is recommended to bake at 60°C for 48 hours before use and complete assembly within one week.
• General Principles:Avoid long-term inventory. Consume stock promptly. Non-compliant storage may require re-plating of oxidized pins before use.

7. Application Suggestions and Design Considerations

7.1 Target Applications and Precautions

This display is suitable for general electronic equipment: office equipment, communication equipment, and household appliances. It is explicitly stated that consultation is required for applications demanding extremely high reliability where failure could endanger life or health (e.g., aviation, medical systems). Designers must adhere to the absolute maximum ratings.

7.2 Key Design Considerations

• Driving Method:It is strongly recommended to use constant current drive instead of constant voltage drive to ensure consistent luminous intensity and lifespan, as LED brightness is a function of current, not voltage.
• Current Limiting:The drive circuit must be designed to accommodate the full range of forward voltage (2.1V to 2.6V) in order to deliver the intended current to all devices.
• Thermal Management:The safe operating current must be derated based on the maximum ambient temperature. Excessive current or high temperature can lead to severe lumen depreciation or premature failure.
• Reverse Bias Protection:The circuit must prevent reverse voltage and voltage spikes during power cycling to prevent metal migration and increased leakage current.
• Environmental Protection:Avoid sudden temperature changes in humid environments to prevent condensation on the display screen.
• Consistency in Multi-Display Setup:Always use displays from the same luminous intensity grade to avoid uneven brightness (tone) in multi-digit readings.

8. Technical Comparison and Differentiation

Compared to older technologies such as incandescent bulbs or vacuum fluorescent displays (VFD), the LTS-546AJG offers superior solid-state reliability, lower power consumption, and higher resistance to shock and vibration. In the LED segment display market, it uses AlInGaP technology to produce green light, which is more efficient than older GaP (gallium phosphide) green LEDs and potentially brighter. The common anode configuration is one of the two standard types (the other being common cathode), and the choice between them depends primarily on the output configuration of the driving IC or microcontroller (source current vs. sink current).

9. Frequently Asked Questions (Based on Technical Parameters)

1. Q: What is the difference between peak wavelength and dominant wavelength?A: Peak wavelength is the single wavelength at the highest point of the emission spectrum. Dominant wavelength is the wavelength of monochromatic light that matches the perceived color of the LED to the human eye. They are usually close but not identical, especially for broader spectra.
2. Q: Why is constant current drive recommended?A: The light output of an LED is proportional to its forward current. A constant current source can compensate for differences in forward voltage (V_F) between different devices and with temperature changes, ensuring stable and uniform brightness.
3. Q: Can I directly drive this display with a 5V microcontroller pin?A: No. You must use a current-limiting resistor or a dedicated driver circuit. Direct connection may exceed the maximum continuous current, thereby damaging the LED. The formula for calculating the resistor value is R = (V_{Power Supply}- V_F) / I_F.
4. Q: What does "binned by luminous intensity" mean for my design?A: This means you should specify to your supplier that you need units from the same bin code, especially when using multiple displays in one product, to ensure uniform brightness across all digits.

10. Practical Application Examples

Scenario: Designing a simple digital voltmeter display.The microcontroller's analog-to-digital converter reads the voltage. The firmware converts this value into a decimal number. To display on the LTS-546AJG, the microcontroller will use a driver IC (such as a 74HC595 shift register with current-limiting resistors or a dedicated LED driver like MAX7219). The common anode pins will be connected to the positive power supply (e.g., to 5V via transistors if multiplexed). The microcontroller will sequentially set the corresponding segment cathode pins to ground (low) to form the desired digit. The driving circuit will be designed to provide a constant 15-20 mA per segment, well below the 25 mA continuous rating, with resistor values calculated based on the worst-case V_F(2.6 volts). For multi-digit meters, displays from the same luminous intensity bin will be used.

11. Working Principle

LTS-546AJG yana aiki bisa ga ka'idar haske ta lantarki na semiconductor p-n junction. Lokacin da aka yi amfani da ƙarfin lantarki mai kyau (anode yana da kyau idan aka kwatanta da cathode) wanda ya wuce ƙimar ƙofar diode, electrons daga kayan n-type AlInGaP/GaAs suna haɗuwa da ramuka daga kayan p-type. Wannan haɗuwar tana sakin makamashi a cikin nau'in photon (haske). Takamaiman abun da ke cikin gawa na AlInGaP yana ƙayyade ƙarfin tazarar band, wanda kuma ya ayyana tsawon zangon hasken da ake fitarwa (launi) – a cikin wannan misali, kusan nanometer 572 na kore. Kowane ɓangare na bakwai (gami da ma'auni) ya ƙunshi ɗaya ko fiye da irin waɗannan ƙananan guntu na LED. Tsarin anode gama gari yana haɗa duk anodes a ciki, yana buƙatar sarrafa kowane cathode daga waje.

12. Technology Trends

Duk da cewa na'urorin nuni bakwai har yanzu ginshiƙi ne na karatun lambobi, fagen fasahar nuni ta LED yana ci gaba da haɓaka. Abubuwan da ke faruwa sun haɗa da:Miniaturization and Integration:Develop displays with finer pitch and Chip-on-Board (COB) technology.Advanced Materials:Continuous research into more efficient materials, such as Gallium Nitride (GaN), to achieve a wider color gamut and higher efficiency, although AlInGaP still dominates the high-efficiency red-amber-yellow-green light field.Smart Display:Integrating the driver IC, memory, and communication interfaces (I2C, SPI) directly into the display module to simplify system design.Flexible and Unconventional Form Factors:Develop bendable or curved segment displays for innovative product designs.