Table of Contents
1. Product Overview
LTS-5703AJF is a single-digit numeric display module, specifically designed for applications requiring clear, high-visibility numeric readouts. Its primary function is to convert electrical signals into visible numeric characters. Its core technology utilizes aluminum indium gallium phosphide (AlInGaP) semiconductor material deposited on a gallium arsenide (GaAs) substrate to generate light in the yellow-orange spectrum. Compared to traditional technologies like gallium phosphide (GaP), this material system was chosen for its high efficiency and excellent brightness within the amber/orange range. The device features a light gray panel with white segment design, enhancing contrast and readability under various lighting conditions.
This display is classified as a common cathode type, meaning the cathodes (negative terminals) of all individual LED segments are internally connected to a common pin. This configuration is common in numeric displays and simplifies circuit design when used with microcontrollers or driver ICs that sink current. The target markets for this component include industrial control panels, test and measurement equipment, consumer appliances, automotive dashboards (for non-critical indicators), and any embedded system requiring reliable, low-power numeric display.
2. In-depth Technical Parameter Analysis
2.1 Optical characteristics
Optical performance is defined by several key parameters measured under standard test conditions (Ta=25°C).Average luminous intensity (Iv)At a forward current (IF) of 1mA, the specified minimum is 800 μcd, the typical value is 1667 μcd, and no maximum is specified. This parameter represents the perceived brightness of the illuminated segment. Luminous intensity is measured using a sensor and a filter that approximates the photopic (daylight-adapted) human eye response curve as defined by CIE (Commission Internationale de l'Éclairage).
Color characteristics are defined by wavelength.Peak Emission Wavelength (λp)The typical value is 611 nanometers (nm) at IF=20mA. This is the wavelength at which the optical power output is maximum.Dominant Wavelength (λd)The typical value is 605 nm. This is the single wavelength that most closely matches the perceived color of the emitted light and is more relevant for color specifications.Spectral Line Half Width (Δλ)The typical value is 17 nm, indicating the spectral purity or the distribution of emitted wavelengths around the peak; a narrower half-width indicates a more monochromatic (pure) color.
2.2 Electrical characteristics
The main electrical parameters areForward Voltage (VF) per segment, at a forward current of 20mA, the typical value is 2.6V, and the maximum value is 2.6V. This is the voltage drop when the LED segment is turned on. The minimum value is 2.05V.Reverse current per segment (IR)Specifies a maximum of 100 μA when a reverse voltage (VR) of 5V is applied, indicating the leakage characteristics of the device in the off state.
Luminous intensity matching ratioIt is stipulated that within a similar luminous area, the maximum ratio between segment codes is 2:1. This means that under identical driving conditions, the brightness of one segment code should not exceed twice that of another, thereby ensuring uniform digital display.
2.3 Absolute Maximum Ratings and Thermal Considerations
These ratings define the stress limits that may cause permanent damage.Continuous Forward Current per SegmentThe rated maximum is 25 mA. A derating factor of 0.33 mA/°C is specified when the ambient temperature (Ta) exceeds 25°C. 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 is 25 mA - (0.33 mA/°C * (85-25)°C) = 5.2 mA.
Peak forward current per segmentIt is 60 mA, but only under pulse conditions (1/10 duty cycle, 0.1ms pulse width). This allows for multiplexing schemes or brief overdrive to increase brightness.Power consumption per segmentis 70 mW.Reverse voltage per segmentmust not exceed 5V. Operating and storage temperature range is -35°C to +105°C. Soldering temperature rating applies to wave or reflow soldering: 260°C for 3 seconds at 1/16 inch (approximately 1.6mm) below the seating plane of the package.3. Binning System Description
The datasheet indicates that the device
is classified by luminous intensity.This implies the existence of a binning system. Binning is a standard industry practice where manufactured LEDs are sorted (binned) after production based on key parameters such as luminous intensity, forward voltage, and dominant wavelength. This ensures consistency within a single production lot or order. While this excerpt does not provide specific bin codes, designers should note that typical binning groups devices with similar Iv (e.g., 800-1200 μcd, 1200-1667 μcd) and potentially similar VF ranges. For critical applications requiring color or brightness uniformity across multiple displays, specifying tight bins or requesting devices from the same bin is essential.4. Performance Curve Analysis
Although the provided text does not detail specific charts, the typical characteristic curves for such devices include:
Forward Current (IF) vs. Forward Voltage (VF) Curve:
- This shows an exponential relationship. The curve has a knee voltage at approximately 1.8-2.0V, beyond which the current increases rapidly with a small increase in voltage. The typical VF value of 2.6V is read from this curve at IF=20mA.Luminous intensity (Iv) vs. Forward current (IF) curve:
- This curve is typically linear at lower currents, but at very high currents, it may show saturation or reduced efficiency due to thermal effects.Luminous intensity (Iv) versus ambient temperature (Ta) curve:
- This shows how brightness decreases as the LED junction temperature increases. The light output of AlInGaP LEDs typically has a negative temperature coefficient.Spectral distribution curve:
- A plot of relative intensity versus wavelength, showing a peak near 611 nm and a half-width of about 17 nm, confirming the yellow-orange emission.These curves are crucial for designers to understand the nonlinear behavior of LEDs, plan thermal management, and design appropriate current-limiting circuits.
5. Mechanical and Packaging Information
The device's
The character height is 0.56 inches (14.22 mm).Package dimensions are provided in the drawing (not fully detailed here), all dimensions are in millimeters. Key tolerances are noted: unless otherwise specified, general dimensional tolerance is ±0.25 mm, and lead tip offset tolerance is ±0.4 mm. This offset tolerance accounts for slight misalignment of leads extending from the plastic package body, which is crucial for PCB pad design and automatic insertion equipment.Pin connection diagram.
Clearly defined as a Dual In-line Package (DIP) configuration with a total of 10 pins. Pin arrangement is: 1(E), 2(D), 3(Common Cathode), 4(C), 5(Decimal Point DP), 6(B), 7(A), 8(Common Cathode), 9(F), 10(G). The presence of two common cathode pins (3 and 8) helps distribute current and reduce current density in a single pin, which is beneficial for reliability. The decimal point (DP) anode is on pin 5. The internal circuit diagram shows each segment (A-G, DP) as an independent LED, with its anode connected to the corresponding pin and all cathodes connected together and routed to the common cathode pins.6. Welding and Assembly GuideAbsolute maximum ratings specify the soldering profile: during assembly, the component body temperature must not exceed the maximum rating. Specifically, it stipulates that the soldering temperature should be 260°C for 3 seconds, measured at a point 1/16 inch (1.6mm) below the mounting plane. This is the standard reference for wave soldering. For reflow soldering, using a standard lead-free profile with a peak temperature of 260°C is appropriate, ensuring control over the Time Above Liquidus (TAL) and the duration of peak temperature at the component leads to prevent thermal damage to the plastic package or internal bonding wires.
Storage Conditions
The specified storage temperature range of -35°C to +105°C should be observed. It is recommended to store components in a dry, anti-static environment to prevent moisture absorption (which can cause the "popcorn" effect during reflow soldering) and electrostatic discharge damage, although the risk for LEDs is lower than for some ICs.
7. Packaging and Ordering InformationThe part number is LTS-5703AJF. The "AJF" suffix may encode specific attributes, such as color (yellow-orange), package type, and possibly brightness binning. The datasheet revision is indicated, and the document is marked as proprietary to the manufacturer. Standard packaging for such through-hole components is typically anti-static tubes or tape-and-reel for automatic insertion. The exact quantity per tube/reel and packaging materials are not specified in this excerpt but can be found in separate packaging specifications.
8. Application Suggestions
Typical Application Circuit:
As a common-cathode display, it is typically driven by a microcontroller or a dedicated display driver IC (such as a 74HC595 shift register with current-limiting resistors or a MAX7219). A current-limiting resistor is required for each segment anode. The resistor value can be calculated using R = (Vcc - VF) / IF. For a 5V power supply (Vcc), with VF=2.6V and IF=20mA, R = (5 - 2.6) / 0.02 = 120 ohms. A slightly higher value (e.g., 150-220 ohms) is commonly used to increase lifespan and reduce power consumption while maintaining good brightness.
Design Considerations:Current Drive:
Do not exceed the absolute maximum continuous current of 25 mA per segment. Use a derating factor in high-temperature environments.
- Multiplexing:For multi-digit displays, multiplexing is common. The peak current rating (60 mA, 1/10 duty cycle) allows for higher instantaneous current during the multiplexed on-time to achieve higher perceived brightness. Ensure the long-term average current does not exceed the continuous rating.
- Viewing Angle:The datasheet mentions a wide viewing angle, which is characteristic of LED displays with diffuser lenses. Consider the intended viewing position when mounting the display.
- PCB Layout:Follow the recommended pad pattern in the dimension drawing. Ensure the hole size is suitable for the lead diameter and provide sufficient clearance.
- 9. Technical Comparison and AdvantagesCompared to older red GaAsP or standard GaP yellow/green LEDs, the AlInGaP technology employed in the LTS-5703AJF offers significant advantages:
Haskakafi da inganci mafi girma:
AlInGaP yana ba da ingancin haske mai girma, wanda ke ba da damar samun nuni mai haske a ƙarƙashin ƙarfin tuƙi iri ɗaya, ko kuma samun haske mai kama da haka a ƙarƙashin ƙarfin wutar lantarki mafi ƙanƙanta.
- Cikakkiyar launi mafi kyau:Halayen bakan haske suna haifar da rawaya mai haske da daidaito.
- Solid State Reliability:LEDs have no filaments or fragile glass components, offering high resistance to shock and vibration, as well as an exceptionally long service life (typically tens of thousands of hours).
- Low Power Consumption Requirements:Operates at low voltage and low current, suitable for battery-powered devices.
- Lead-free package:Complies with the RoHS (Restriction of Hazardous Substances) directive, suitable for global markets with environmental regulations.
- Compared to modern surface-mount device (SMD) seven-segment displays, this through-hole version is easier for prototyping, manual assembly, and applications where display replacement may be required.10. Frequently Asked Questions (Based on Technical Specifications)
A1: They are internally connected. Having two pins helps distribute the total cathode current (the sum of currents from all lit segments) across two physical leads, reducing the 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: Yana yiwuwa, amma dole ne a duba ƙarfin lantarki na gaba. VF na yau da kullun shine 2.6V, don haka 3.3V na wutar lantarki ya bar 0.7V kawai don resistor iyakacin kwarara. Bisa dokar Ohm, don kwararar da ake tsammani na 10mA, R = (3.3 - 2.6) / 0.01 = 70 ohms. Wannan yana yiwuwa, amma haske na iya zama ɗan ƙasa da ƙimar 20mA. Tabbatar cewa fil ɗin microcontroller zai iya samar da kwararar da ake buƙata.
Q3: Me "matsakaicin haske daidai gwargwado 2:1" ke nufi ga ƙirar na?
A3: Yana tabbatar da cewa a cikin na'urar guda ɗaya, idan an yi amfani da yanayin tuƙi iri ɗaya, hasken kowane sashe ba zai wuce sau biyu na hasken kowane sashe na sauran ba. Wannan yana hana lambobi su bayyana ba daidai ba (misali, sashe A yana duhu sosai yayin da sashe G yana haske sosai). Don ƙira mai lambobi da yawa, kayyade na'urori daga rukunin ƙarfi iri ɗaya, don tabbatar da daidaito tsakanin lambobi.
Q4: Yadda ake lissafin amfanin wutar lantarki na gabaɗayan na'urar nuni?
A4: Don mafi munin yanayi, wato duk sassa 8 na lambobi (sassa 7 na lambobi + maki goma DP) suna kunne a kowane sashi da matsakaicin ci gaba na 25 mA, yawan VF shine 2.6V. Amfanin wutar lantarki na kowane sashi = VF * IF = 2.6V * 0.025A = 65 mW. Jimlar amfanin wutar lantarki = 8 * 65 mW = 520 mW. Wannan shine ƙarfin da LED ɗin kansa ke ɓata a matsayin zafi, wanda dole ne a yi la'akari da shi a cikin sarrafa zafi a cikin sarari mai rufewa.
11. Misalan ƙira da amfani na ainihi
Example 1: Digital Voltmeter Reading.
In a simple benchtop digital multimeter prototype, the LTS-5703AJF can be used to display voltage readings. The 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 connected in series with each segment anode. If a multi-digit display is used, the common cathodes are switched by transistors controlled by the microcontroller to achieve multiplexing. High contrast and brightness ensure readability in well-lit laboratory 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 character height, is well-suited. 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) allows it to adapt to factory floor environments where temperatures may fluctuate.
12. Introduction to Technical PrinciplesLTS-5703AJF is based on
Aluminum Indium Gallium Phosphide (AlInGaP)
semiconductor heterostructure, which is epitaxially grown onGallium Arsenide (GaAs)on the 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 (quantum well). There, they undergo radiative recombination, 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 contains a molded lens to shape the light output, provide environmental protection, and form the distinctive segment shapes.13. Technology Development TrendsAlthough this is a mature through-hole component, the development trend of display technology affects its background. The broader LED industry continues to focus on:
Improving efficiency (lm/W):
Ongoing materials science research aims to reduce non-radiative recombination and improve light extraction from semiconductor chips, thereby enabling brighter displays at lower power consumption.
- Miniaturization and SMD dominance:The market has primarily shifted to Surface Mount Device (SMD) packaging to enable automated assembly, reduce board space, and lower profile. Through-hole displays like these remain relevant in specific niche markets requiring robustness, ease of hand soldering, or replacement.
- Integrated Solutions:There is a trend towards displays with integrated driver ICs ("smart displays"), which simplify the host microcontroller interface by handling multiplexing, decoding, and current control internally.
- Expanded Color Gamut & RGB:For displays capable of full-color reproduction, developing efficient red, green, and blue LEDs, including micro-LEDs, is a major trend. Although this is a monochrome device, improvements in the underlying materials benefit all LED colors.
- Flexible Transparent Substrates:Research on displays using flexible or transparent substrates is active, although this is more applicable to advanced panel displays than traditional segmented numeric units.
- LTS-5703AJF yana wakiltar ingantaccen mafita mai dogaro, mai tsada a cikin waɗannan ci gaban fasaha na ci gaba.Bincike kan nuni akan allunan sassauka ko na bayyane yana aiki, kodayake wannan ya fi dacewa da na'urorin nuni na ci gaba fiye da na'urorin lamba na yanki na gargajiya.
Cikakken bayani game da kalmomin ƙayyadaddun LED
Complete Interpretation of LED Technical Terminology
I. Core Indicators of Photoelectric Performance
| Terminology | Unit/Representation | Popular Explanation | Why it matters |
|---|---|---|---|
| Luminous Efficacy | lm/W (lumens per watt) | The luminous flux emitted per watt of electrical power; higher values indicate greater energy efficiency. | It directly determines the energy efficiency rating of the luminaire and the electricity cost. |
| 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), e.g., 120° | The angle at which luminous intensity drops to half, determining the beam width. | Affects the range and uniformity of illumination. |
| Correlated Color Temperature (CCT) | K (Kelvin), such as 2700K/6500K | Launin haske mai dumi ko sanyi, ƙananan ƙima sun fi rawaya/dumi, manyan ƙima sun fi fari/sanyi. | Yana ƙayyade yanayin hasken wuta da yanayin da ya dace. |
| 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 preferable. | Affects color fidelity, used in high-demand places such as shopping malls and art galleries. |
| Color tolerance (SDCM) | MacAdam ellipse step, such as "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) | Wavelength values corresponding to the colors of colored LEDs. | 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 | Symbols | 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; the voltages add 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 for a short period of time, used for dimming or flashing. | Pulse width and duty cycle must be strictly controlled to prevent overheating and damage. |
| Reverse Voltage | Vr | Maximum reverse voltage that an LED can withstand; exceeding it may cause breakdown. | Reverse connection or voltage surges must be prevented in the circuit. |
| Thermal Resistance (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 stronger cooling design, otherwise junction temperature rises. |
| Electrostatic Discharge Immunity (ESD Immunity) | V (HBM), such as 1000V | Electrostatic discharge immunity; a higher value indicates greater resistance to electrostatic damage. | 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 "useful life" of an 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 long-term high temperature. | Zai iya haifar da raguwar haske, canjin launi ko gazawar bude hanya. |
IV. Kullewa da Kayan aiki
| Terminology | Nau'o'in gama gari | Popular Explanation | Characteristics and Applications |
|---|---|---|---|
| Package Types | EMC, PPA, Ceramic | The housing material that protects the chip and provides optical and thermal interfaces. | EMC offers good heat resistance and low cost; ceramic provides superior heat dissipation and long lifespan. |
| Chip Structure | Front-side, 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 | Coated on the blue LED chip, partially converted to yellow/red light, mixed to form white light. | Different phosphors affect luminous efficacy, color temperature, and color rendering. |
| Lens/Optical Design | Flat, microlens, total internal reflection | Optical structure on the packaging surface, controlling light distribution. | Determines the emission angle and light distribution curve. |
V. Quality Control and Grading
| Terminology | Grading Content | Popular Explanation | Purpose |
|---|---|---|---|
| Luminous Flux Binning | Codes such as 2G, 2H | Group by brightness level, each group has a minimum/maximum lumen value. | Ensure consistent brightness for products in the same batch. |
| Voltage binning | Codes such as 6W, 6X | Grouped by forward voltage range. | Ease of matching the driving power supply, improving system efficiency. |
| Color binning | 5-step MacAdam ellipse | Group by color coordinates to ensure colors fall within an extremely small range. | Ensure color consistency to avoid color unevenness within the same luminaire. |
| Color Temperature Grading | 2700K, 3000K, etc. | Group by color temperature, each group has a corresponding coordinate range. | 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 luminance attenuation data. | For estimating LED lifetime (in conjunction with TM-21). |
| TM-21 | Lifetime projection standard | Estimating lifespan under actual usage conditions based on LM-80 data. | Providing 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. |