LTS-547AJG 0.52-inch AlInGaP Green LED Digital Tube Datasheet - Character Height 13.2mm - Forward Voltage 2.6V - Technical Documentation

1. Product Overview

LTS-547AJG is a high-performance, single-digit alphanumeric display module, specifically designed for applications requiring clear and bright numeric indication. Its primary function is to provide highly legible numeric readouts. The core technology utilizes AlInGaP (Aluminum Indium Gallium Phosphide) semiconductor material as the light-emitting chip, which is renowned for generating high-efficiency green light. The device features a design with a gray panel and white segment markings, optimizing contrast to enhance readability under various lighting conditions. It is constructed as a common-cathode type display, meaning the cathodes of all individual LED segments are internally connected to a common pin, thereby simplifying the driving circuit design. This display is classified as a lead-free component, complying with environmental directives such as RoHS.

1.1 Core Advantages and Target Market

The display offers several key advantages, making it suitable for a wide range of industrial and consumer applications. Its high brightness and excellent contrast ensure clear visibility even in bright ambient conditions. The wide viewing angle allows the displayed characters to be read from different positions without significant loss of brightness or clarity. The device features solid-state reliability, meaning it has no moving parts and offers resistance to shock and vibration compared to other display technologies. It has low power requirements, making it ideal for battery-powered or high-efficiency devices. Continuous, uniform segments provide a clean, professional character appearance. Typical target markets include test and measurement equipment, industrial control panels, medical devices, automotive dashboards (for auxiliary displays), consumer appliances, and any electronic equipment requiring compact, reliable numeric readouts.

2. Detailed Technical Parameters

This section provides a detailed and objective interpretation of the key electrical and optical parameters defined in the datasheet. Understanding these parameters is crucial for proper circuit design and ensuring long-term reliability.

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 and should be avoided.

• Power Dissipation per Segment:Maximum 70 mW. This is the maximum power that a single LED segment can safely dissipate as heat under continuous operation. Exceeding this value may cause the LED chip to overheat and accelerate aging.
• Peak forward current per segment:Maximum 60 mA, but only under specific pulse conditions (1/10 duty cycle, 0.1 ms pulse width). This rating applies to short, high-current pulses used in multiplexing schemes and is not suitable for continuous DC operation.
• Continuous forward current per segment:Maximum 25 mA at 25°C. This is a key parameter for designing the DC drive current. Crucially, this rating is linearly derated at a rate of 0.33 mA/°C above 25°C. For example, at an ambient temperature (Ta) of 85°C, the maximum allowable continuous current is: 25 mA - ((85°C - 25°C) * 0.33 mA/°C) = 25 mA - 19.8 mA =5.2 mA. This derating is critical for thermal management.
• Reverse voltage per segment:Maximum 5 V. Applying reverse bias above this value may cause LED junction breakdown and failure.
• Operating and storage temperature range:-35°C to +105°C. The device can operate and be stored within this wide temperature range.
• Soldering temperature:Maximum 260°C, up to 3 seconds, measured 1.6mm below the mounting plane. This is critical for wave soldering or reflow processes to prevent damage to the plastic package or internal bonds.

2.2 Electrical and Optical Characteristics

These are typical operating parameters measured at Ta=25°C and under specified test conditions. They define the expected performance of the device.

• Average Luminous Intensity (I_V):In I_F=1mA, 320 μcd (min), 750 μcd (typ). This is a measure of light output. The wide range indicates a binning process; devices are classified based on their actual measured intensity.
• Peak emission wavelength (λ_p):In I_F=20mA, 571 nm (typ). This is the wavelength at which the emitted light intensity is highest, placing it in the green region of the visible spectrum.
• Spectral line half-width (Δλ):15 nm (typical value). This indicates spectral purity or the distribution of emission wavelengths. A value of 15nm is typical for AlInGaP green LEDs, resulting in a relatively pure green.
• Dominant wavelength (λ_d):572 nm (typical value). This is the single wavelength that the human eye perceives as most closely matching the color of the emitted light, very close to the peak wavelength.
• Forward voltage per segment (V_F):In I_FAt =20mA, 2.05V (min), 2.6V (max). This is the voltage drop across the LED when operating. Designers must ensure the drive circuit can provide sufficient voltage to overcome this drop at the desired current. This variation necessitates a drive method that limits current, not voltage.
• Per segment reverse current (I_R):At V_R=5V, 100 μA (max). This is the small leakage current that flows when the LED is reverse-biased within its maximum ratings.
• Luminous intensity matching ratio (I_V-m):2:1 (Maximum). This specifies the maximum allowable ratio between the brightest and darkest segments within a single device under identical driving conditions (I_F=1mA). A ratio of 2:1 ensures uniformity in the digital appearance.

3. Bin System Description

The datasheet indicates that the device is "binned by luminous intensity." This refers to the binning or sorting process performed during manufacturing. Due to inherent variations in semiconductor epitaxial growth and chip fabrication, LEDs from the same production batch can have slightly different optical and electrical characteristics. To ensure consistency for end users, manufacturers test and sort (bin) the LEDs into groups with closely matched parameters. For the LTS-547AJG, the primary binning parameter isLuminous intensity, as indicated by the minimum (320 μcd) and typical (750 μcd) values. The devices are tested under standard conditions (I_F=1mA) and binned by intensity. For applications requiring tight brightness matching across multiple displays, customers can order specific bins. Forward voltage (V_F) also has a specified range (2.05V to 2.6V), which may involve secondary binning or be guaranteed as a maximum/minimum specification.

4. Performance Curve Analysis

Although the provided PDF excerpt mentions "Typical Electrical/Optical Characteristic Curves" on the last page, the specific curves are not included in the provided text. Typically, such datasheets contain charts crucial for in-depth design analysis. Based on standard LED datasheet conventions, the following curves are expected, along with their analysis:

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

This graph shows the relationship between the current flowing through an LED and the voltage across it. For an LED, this is an exponential curve. The "knee" voltage is where the current begins to increase significantly—this is close to the typical V_Fvalue of 2.6V at 20mA. This curve illustrates why an LED must be driven by a current-limiting source; a voltage slightly exceeding the knee point leads to a large, potentially damaging increase in current. The slope of the curve is also related to the dynamic resistance of the LED.

4.2 Luminous Intensity vs. Forward Current

This graph shows how the light output (intensity) increases with the drive current. For AlInGaP LEDs, the relationship is typically linear within the medium current range, but may become sublinear at very high currents due to efficiency droop (heating and other non-radiative effects). This curve helps designers select an operating current that provides the required brightness without overstressing the LED or reducing its efficiency.

4.3 Relative Luminous Intensity vs. Ambient Temperature

This is one of the most critical curves for reliability. It shows how the light output decreases as the ambient (or junction) temperature rises. AlInGaP LEDs are particularly temperature-sensitive, with output dropping significantly as temperature increases. This curve, combined with current derating specifications, provides the basis for thermal management decisions. If a display is used in a high-temperature environment, it may be necessary to reduce the current (derate), and a lower brightness should be expected.

4.4 Spectral Distribution

A graph plotting relative intensity versus wavelength. It will show a peak around 571-572 nm with a characteristic width (15 nm FWHM). This curve confirms the green chromaticity point, which is crucial for applications requiring specific color coordinates.

5. Mechanical and Packaging Information

5.1 Package Dimensions

The device features a standard single-digit seven-segment display outline. Key dimensions in the drawing (not fully detailed in the text) typically include overall height, width, and depth, character height (specified as 0.52 inches or 13.2 mm), segment dimensions, and pin pitch. Notes specify that all dimensions are in millimeters, with a standard tolerance of ±0.25 mm unless otherwise stated. A specific note mentions a pin tip offset tolerance of +0.4 mm, which is crucial for PCB hole placement and wave soldering processes to ensure proper alignment.

5.2 Pin Definition and Polarity Identification

The display has 10 pins with a pitch of 0.1 inches (2.54 mm), arranged in two rows. A pin connection table is provided:

• Pin 1: Segment E Anode
• Pin 2: Anode of Segment D
• Pin 3: Common Cathode 1
• Pin 4: Segment C Anode
• Pin 5: Decimal Point (D.P.) Anode
• Pin 6: Segment B Anode
• Pin 7: Segment A Anode
• Pin 8: Common Cathode 2
• Pin 9: F segment anode
• Pin 10: G segment anode

The device adoptsCommon CathodeConfiguration. There are two common cathode pins (3 and 8), which are internally connected. This provides flexibility for PCB routing and helps distribute current. To illuminate a segment, its corresponding anode pin must be driven to a positive voltage relative to the common cathode, while the common cathode must be connected to ground (or a lower voltage). The decimal point is an independent LED with its own anode (pin 5).

5.3 Internal Circuit Diagram

The schematic provided in the datasheet visually confirms the common-cathode architecture. It shows eight independent LED chips (segments A-G plus the decimal point). All cathodes (negative side) are connected together and brought out to pins 3 and 8. Each anode (positive side) is brought out to its respective pin. This diagram is crucial for understanding how to interface the display with a microcontroller or driver IC.

6. Soldering and Assembly Guide

Adherence to these guidelines is critical to prevent damage during PCB assembly.

• Welding method:This device is suitable for wave soldering or reflow soldering processes.
• Temperature profile:The absolute maximum soldering temperature is 260°C. The temperature at the pin/solder joint interface must not exceed this value. For reflow soldering, the standard profile for lead-free components (peak temperature approximately 245-250°C) is suitable, but the time above liquidus must be controlled.
• Exposure time:The maximum exposure time at peak temperature is 3 seconds. Prolonged exposure may melt the plastic package or damage the internal bond wires.
• Measurement point:Temperature is measured 1.6 mm below the mounting plane (the point where the pins protrude from the plastic body). This is typically lower than the PCB pad temperature.
• Cleaning:If cleaning is required, use a solvent compatible with the LED plastic packaging material to avoid cracking or hazing.
• Operation:Avoid applying mechanical stress to the pins. Take appropriate ESD (Electrostatic Discharge) precautions during handling and assembly.
• Storage Conditions:Store within the specified temperature range (-35°C to +105°C) in a dry, anti-static environment. Avoid exposure to excessively humid conditions; if the device is stored in a high-humidity environment, baking may be required before soldering to prevent the "popcorn" phenomenon during reflow.

7. Application Recommendations

7.1 Typical Application Circuit

LTS-547AJG requires an external current limiting mechanism. The simplest driving method is to use a microcontroller GPIO pin connected to the segment anode through a current limiting resistor, with the common cathode grounded. The resistor value is calculated using the formula R = (V_{Power supply}- V_F) / I_F Calculation. For a 5V power supply, the expected I_FFor 20mA, typical V_FFor 2.6V: R = (5 - 2.6) / 0.02 = 120 Ω. A 120Ω resistor will be used. For multiplexing multiple digits, use a dedicated driver IC (such as MAX7219 or TM1637) or a transistor array to sink the higher combined cathode current.

7.2 Design Considerations

• Current Limiting:Always use a series resistor or constant current driver. Never connect an LED directly to a voltage source.
• Multiplexing:When driving multiple digits, segment anodes can use the peak pulse current rating (60mA at 1/10 duty cycle), but the average current per segment, averaged over time, must not exceed the continuous DC rating.
• Heat Dissipation:Consider the operating environment. If the display is in an enclosed space or at a high ambient temperature, use the 0.33 mA/°C rule to reduce the operating current accordingly to ensure service life.
• Viewing Angle:Wide viewing angle is an advantage, but for optimal readability, the display should be positioned so that the typical viewer's line of sight is approximately perpendicular to the panel.
• PCB Layout:Ensure the package matches the dimension drawing. The two common cathode pins can be connected together on the PCB to reduce trace resistance and improve current distribution.

8. Technical Comparison and Differentiation

Compared to other seven-segment display technologies, the LTS-547AJG offers specific advantages:

• Compared to red GaAsP or GaP LEDs:AlInGaP technology provides significantly higher luminous efficacy, resulting in a brighter display at the same drive current. The green light (approximately 570nm) is also close to the peak of the human eye's photopic sensitivity curve, making it subjectively appear brighter than red light at the same radiant power.
• Kwa kulinganisha na kioleza cha LCD:LED zinatoa mwanga wenyewe (zinazalisha mwanga wao wenyewe), na hii huwafanya ziwe wazi kuonekana gizani bila mwanga wa nyuma. Zina wakati wa kukabiliana wa haraka, anuwai pana ya halijoto ya kufanya kazi, na hazipatikani kwa urahisi na masalia ya picha au matatizo ya kukabiliana polepole katika halijoto ya chini.
• Kwa kulinganisha na VFD (Kioleza cha Fluorescent cha Vacuum):LED are more robust and durable, require lower operating voltage (20-50V for VFD, 3-5V for LED), and have simpler drive circuits. They also do not require filament power.
• In AlInGaP displays:The key differentiators of the LTS-547AJG are its specific 0.52-inch character height, common-cathode configuration, gray panel/white segment design for contrast, and its guaranteed luminous intensity classification, which provides a degree of brightness uniformity.

9. Frequently Asked Questions (based on technical specifications)

Q1: Ina iya amfani da ma'aunin 3.3V don sarrafa wannan nuni?
A: A'a, amma dole ne a duba ƙarfin lantarki mai kyau. A cikin V na yau da kullun_Fyana 2.6V, akwai sauran 0.7V kawai (3.3V - 2.6V). Resistan iyakancewar zai zama ƙarami sosai: R = (3.3 - 2.6)/0.02 = 35 Ω. A ƙaramin ƙarfi (misali 5mA), zai yi aiki da kyau. Don cikakken haske na 20mA, tabbatar da cewa hanyar wutar lantarki 3.3V ta tsaya kuma tana iya samar da ƙarfi. Don tsarin 3.3V, ana ba da shawarar amfani da mai sarrafa ƙarfi mai dorewa.

Q2: Me yasa akwai fil ɗin cathode guda biyu na gama gari?
A: Two pins are used to distribute the total cathode current, which can be the sum of up to 8 segments (if all are lit). This reduces current density in a single pin/PCB trace, improves reliability, and provides layout flexibility.

Q3: How to calculate the power consumption of the display?
A: For one segment: P = V_F* I_F. A cikin yanayin 20mA na yau da kullun da 2.6V, P_segment = 52 mW. Ga adadi gabaɗaya, duk sassan 7 suna haskakawa (babu maki goma), P_total ≈ 7 * 52 mW = 364 mW. Idan aka yi la'akari da raguwar zafin jiki, koyaushe a tabbatar da cewa wannan ƙimar ta kasance ƙasa da ikon ɓarnawar fakitin gabaɗaya.

Q4: Me "Fakitin maras gubar" ke nufi ga tsarin haɗa na?
A: Fil ɗin na'urar an lulluɓe su da abin rufe fuska wanda ya dace da haɗin gwal maras gubar (misali, tin-silver-copper). A cikin tsarin haɗawa, dole ne ku yi amfani da man gwal maras gubar da madaidaicin lanƙwasa sake zagayawa mai zafi (kololuwa kusan 245-250°C).

10. Actual Design Case Study

Scenario:Design a simple digital thermometer for an indoor/outdoor weather station. The unit must display temperatures from -35°C to 105°C (matching the display's operating range). It will be battery-powered for portability.

Design Choices:
1. Display Selection:LTS-547AJG is suitable due to its wide temperature range, high brightness (readable outdoors), and low power requirements (important for battery life). Green is comfortable for the eyes.
2. Drive circuit:Use a low-power microcontroller (e.g., ARM Cortex-M0+ or PIC), which remains in sleep mode most of the time and wakes up to update the display. To save power and pins, use a dedicated LED driver IC with built-in multiplexing and constant current output. This can efficiently drive multiple digits (for tens and units places).
3. Current Setting:For indoor use, set the segment current to 5-10 mA to save battery. For outdoor use in bright light, press a button to temporarily increase the current to 15-20 mA for maximum brightness. The drive IC's current setting must be programmed accordingly.
4. Thermal Considerations:If the device is placed in direct sunlight, the internal temperature may exceed 50°C. According to the derating formula, at 50°C, the maximum continuous current is 25 mA - ((50-25)*0.33) = 25 - 8.25 = 16.75 mA. Our maximum setting of 20mA will exceed this value. Therefore, the design should limit the "high brightness" mode to a duty cycle or pulse width that keeps the average current within the derating limit under high ambient temperatures.

11. Technical Introduction

LTS-547AJG is based onAlInGaPSemiconductor technology. This material system is epitaxially grown onan opaque GaAs (Gallium Arsenide) substrate. AlInGaP is a direct bandgap semiconductor whose bandgap energy can be tuned by varying the ratios of aluminum, indium, gallium, and phosphorus. For green emission around 570-580 nm, a specific composition is used. The opaque GaAs substrate absorbs some of the generated light, which is a disadvantage compared to devices using transparent substrates, such as GaP used in some older green LEDs. However, modern AlInGaP-on-GaAs processes achieve very high internal quantum efficiency, and the light is primarily emitted from the top surface of the chip. The gray panel and white segments of the package are not part of the semiconductor; they are part of the plastic molding. The gray panel reduces ambient light reflection, while the white segments diffuse and scatter the green light from the underlying LED chip, creating a uniform, bright segment appearance.

12. Technical Trends

The field of LED displays continues to evolve. For discrete seven-segment displays like the LTS-547AJG, trends focus on improving efficiency, achieving higher brightness, and a wider color gamut. While AlInGaP dominates the high-efficiency red, orange, amber, and green spectra, new materials like InGaN (Indium Gallium Nitride) can now produce efficient green and even yellow LEDs, potentially offering different chromaticity points and efficiency characteristics. There is also a trend towards higher integration, such as displays with built-in controllers (I2C or SPI interfaces), which greatly simplifies microcontroller interfacing. Furthermore, the demand for lower power consumption drives LED development, enabling usable brightness for ultra-low-power IoT devices at currents below 1 mA. Environmental regulations continue to push for the elimination of hazardous substances beyond lead, affecting plating and packaging materials.

Detailed Explanation of LED Specification Terminology

Complete Explanation of LED Technical Terms

I. Core Indicators of Photoelectric Performance

Terminology	Unit/Representation	Popular Explanation	Why is it important
Luminous Efficacy	lm/W	The luminous flux emitted per watt of electrical power, the higher the more energy-efficient.	Directly determines the energy efficiency class and electricity cost of the luminaire.
Luminous Flux	lm (lumen)	The total amount of light emitted by a light source, commonly known as "brightness".	Determines whether the luminaire is bright enough.
Viewing Angle	° (degree), such as 120°	The angle at which light intensity drops to half, determining the beam width.	Affects the illumination range and uniformity.
Color Temperature (CCT)	K (Kelvin), e.g., 2700K/6500K	The color temperature of light, lower values lean yellow/warm, higher values lean white/cool.	Determines the lighting ambiance and suitable application scenarios.
Color Rendering Index (CRI / Ra)	Unitless, 0–100	The ability of a light source to reproduce the true colors of objects, with Ra≥80 being good.	Affects color fidelity, used in high-demand places such as shopping malls and art galleries.
Color tolerance (SDCM)	MacAdam ellipse steps, e.g., "5-step"	A quantitative metric for color consistency; a smaller step number indicates better color consistency.	Ensure no color variation among luminaires from the same batch.
Dominant Wavelength	nm (nanometer), e.g., 620nm (red)	The wavelength value corresponding to the color of a colored LED.	Determines the hue of monochromatic LEDs such as red, yellow, and green.
Spectral Distribution	Wavelength vs. Intensity curve	Shows the intensity distribution of light emitted by an LED at each wavelength.	Affects color rendering and color quality.

II. Electrical Parameters

Terminology	Symbol	Popular Explanation	Design Considerations
Forward Voltage (Forward Voltage)	Vf	The minimum voltage required to light up an LED, similar to a "starting threshold".	The driving power supply voltage must be ≥ Vf, and the voltage adds up when multiple LEDs are connected in series.
Forward Current	If	The current value that makes the LED emit light normally.	Constant current drive is often used, as the current determines brightness and lifespan.
Maximum Pulse Current	Ifp	The peak current that can be withstood in a short period of time, used for dimming or flashing.	Pulse width and duty cycle must be strictly controlled, otherwise overheating damage will occur.
Reverse Voltage	Vr	Maximum reverse voltage an LED can withstand; exceeding it may cause breakdown.	Reverse connection or voltage surges must be prevented in the circuit.
Thermal Resistance	Rth (°C/W)	The resistance to heat flow from the chip to the solder joint. A lower value indicates better heat dissipation.	High thermal resistance requires a stronger heat dissipation design, otherwise the junction temperature will increase.
Electrostatic Discharge Immunity (ESD Immunity)	V (HBM), such as 1000V	Electrostatic discharge immunity; a higher value indicates greater resistance to damage from static electricity.	Anti-static measures must be implemented during production, especially for high-sensitivity LEDs.

III. Thermal Management and Reliability

Terminology	Key Indicators	Popular Explanation	Impact
Junction Temperature	Tj (°C)	The actual operating temperature inside the LED chip.	For every 10°C reduction, the lifespan may double; excessively high temperatures cause lumen depreciation and color shift.
Lumen Depreciation	L70 / L80 (hours)	The time required for the brightness to drop to 70% or 80% of its initial value.	Directly define the "service life" of LED.
Lumen Maintenance	% (e.g., 70%)	The percentage of remaining brightness after a period of use.	Characterizes the ability to maintain brightness after long-term use.
Color Shift	Δu′v′ or MacAdam Ellipse	The degree of color change during use.	Affects the color consistency of the lighting scene.
Thermal Aging	Material performance degradation	Degradation of packaging materials due to prolonged high temperatures.	May lead to decreased brightness, color shift, or open-circuit failure.

IV. Packaging and Materials

Terminology	Common Types	Popular Explanation	Features and Applications
Package Type	EMC, PPA, Ceramic	The housing material that protects the chip and provides optical and thermal interfaces.	EMC offers good heat resistance and low cost; ceramics provide superior heat dissipation and long lifespan.
Chip Structure	Face-up, Flip Chip (Flip Chip)	Chip Electrode Arrangement Method.	Flip-chip offers better heat dissipation and higher luminous efficacy, suitable for high-power applications.
Phosphor coating	YAG, silicate, nitride	Covered on the blue light chip, partially converted into yellow/red light, mixed into white light.	Different phosphors affect luminous efficacy, color temperature, and color rendering.
Lens/Optical Design	Flat, microlens, total internal reflection	The optical structure on the encapsulation surface controls the distribution of light.	Determines the emission angle and the light distribution curve.

V. Quality Control and Binning

Terminology	Grading Content	Popular Explanation	Purpose
Luminous Flux Binning	Codes such as 2G, 2H	Grouped by brightness level, each group has a minimum/maximum lumen value.	Ensure consistent brightness within the same batch of products.
Voltage binning	Codes such as 6W, 6X	Group by forward voltage range.	Facilitates driver power matching and improves system efficiency.
Color binning	5-step MacAdam ellipse	Group by color coordinates to ensure colors fall within an extremely narrow range.	Ensure color consistency to avoid uneven color within the same luminaire.
Color temperature binning	2700K, 3000K, etc.	Group by color temperature, each group has a corresponding coordinate range.	To meet the color temperature requirements of different scenarios.

VI. Testing and Certification

Terminology	Standard/Test	Popular Explanation	Meaning
LM-80	Lumen maintenance test	Long-term operation under constant temperature conditions, recording brightness attenuation data.	Used to estimate LED lifetime (combined with TM-21).
TM-21	Lifetime projection standard	Life estimation under actual operating conditions based on LM-80 data.	Provide scientific life prediction.
IESNA standard	Illuminating Engineering Society Standard	Covers optical, electrical, and thermal test methods.	Industry-recognized testing basis.
RoHS / REACH	Environmental certification.	Ensure the product does not contain harmful substances (e.g., lead, mercury).	Entry requirements for the international market.
ENERGY STAR / DLC	Energy Efficiency Certification	Energy efficiency and performance certification for lighting products.	Commonly used in government procurement and subsidy programs to enhance market competitiveness.