1. Product Overview
The LTS-3861JS is a single-digit, seven-segment alphanumeric display module designed for applications requiring clear, high-visibility numeric or limited alphanumeric readouts. Its primary function is to convert electrical signals into a visible, segmented light pattern representing numbers and some letters. The core technology is based on Aluminium Indium Gallium Phosphide (AlInGaP) semiconductor material, which is specifically engineered to emit light in the yellow wavelength region. This material system is known for its high efficiency and excellent brightness compared to older technologies like standard Gallium Phosphide (GaP). The device features a gray faceplate and white segment markings, which work in conjunction with the yellow emission to create a high-contrast, easily readable character, especially under various ambient lighting conditions.
1.1 Core Advantages and Target Market
The display offers several key advantages that make it suitable for a range of industrial and consumer applications. Its high brightness and excellent contrast ratio ensure readability even in brightly lit environments. The wide viewing angle allows the display to be seen clearly from various positions, which is crucial for panel meters and instrumentation. The solid-state reliability of LED technology means it has a long operational lifetime, is resistant to shock and vibration, and has a fast response time. The low power requirement makes it compatible with battery-powered or low-voltage digital logic circuits. Typical target markets and applications include test and measurement equipment (multimeters, oscilloscopes), industrial control panels, automotive dashboard indicators, consumer appliances, and any electronic device where a compact, reliable numeric display is needed.
2. Technical Parameters and Objective Interpretation
2.1 Photometric and Optical Characteristics
Ayyukan photometric yana da muhimmanci ga aikin nuni. Matsakaicin Ƙarfin Hasken (Iv) an ƙayyade shi tsakanin 200 zuwa 600 microcandelas (µcd) a gaba na halin yanzu (If) na 1 mA. Wannan kewayon yana nuna tsarin rarrabuwa ko binning don haske. Ƙimar ta yau da kullun tana faɗowa a tsakiyar wannan kewayon. Kololuwar Tsawon Tsawon Watsi (λp) shine 588 nm, kuma Tsawon Tsawon Rinjaye (λd) shine 587 nm, duk an auna su a If=20mA. Waɗannan ƙimar suna sanya fitarwa a cikin yankin rawaya mai tsafta na bakan gani. Tsayin Ramin Layin Bakan (Δλ) na 15 nm yana nuna ƙunƙuntaccen bandwidth na bakan, yana haifar da cikakken launin rawaya mai tsafta ba tare da yaɗuwa mai mahimmanci zuwa kusancin kore ko rawaya ba. Matsakaicin Matsakaicin Daidaitawar Ƙarfin Hasken na 2:1 yana ƙayyade bambancin da aka yarda a cikin haske tsakanin sassa daban-daban na lamba ɗaya, yana tabbatar da kamanni iri ɗaya.
2.2 Electrical Parameters
The electrical characteristics define the interface between the display and the driving circuitry. The Forward Voltage per Segment (Vf) has a typical value of 2.6V and a maximum of 2.6V at If=20mA. This is a critical parameter for designing the current-limiting resistors or constant-current driver circuits. The low forward voltage is beneficial for low-voltage system design. The Reverse Current per Segment (Ir) is a maximum of 100 µA at a Reverse Voltage (Vr) of 5V, indicating the leakage current when the LED is reverse-biased, which is important for multiplexing circuits. The Absolute Maximum Ratings provide hard limits: a Continuous Forward Current per Segment of 25 mA (derated above 25°C), a Peak Forward Current of 60 mA under pulsed conditions, and a maximum Power Dissipation per Segment of 40 mW. Exceeding these ratings can cause immediate or gradual degradation of the LED chip.
2.3 Thermal and Environmental Specifications
The device is rated for an Operating Temperature Range of -35°C to +85°C. This wide range makes it suitable for use in harsh environments, both indoors and outdoors. The Storage Temperature Range is identical. The solder temperature rating is crucial for assembly: the device can withstand a maximum temperature of 260°C for a maximum of 3 seconds, measured at a point 1.6mm (1/16 inch) below the seating plane of the package. This defines the reflow soldering profile that must be used during PCB assembly to prevent thermal damage to the internal die, wire bonds, or plastic package.
3. Binning System Explanation
The datasheet explicitly states that the device is "Categorized for Luminous Intensity." This refers to a binning or sorting process performed during manufacturing. Due to inherent variations in the semiconductor epitaxial growth and chip fabrication processes, LEDs from the same production batch can have slightly different optical outputs. To ensure consistency for the end user, the manufactured units are tested and sorted into different "bins" based on their measured luminous intensity at a standard test current (likely 1mA or 20mA). The specified range of 200 to 600 µcd represents the spread across bins that are offered for this product. Designers must be aware that the actual brightness of a specific unit will fall within this pre-defined range. The tight spectral specifications (wavelength) suggest that color binning is also tightly controlled, ensuring a consistent yellow hue across all units.
4. Performance Curve Analysis
While the specific graphs are not detailed in the provided text, typical curves for such a device would be essential for in-depth design. These would normally include: Forward Current vs. Forward Voltage (I-V Curve): This non-linear curve shows the relationship between the voltage applied across the LED and the resulting current. It is crucial for determining the appropriate series resistor value to achieve the desired operating current. Luminous Intensity vs. Forward Current (L-I Curve): This graph shows how the light output increases with increasing drive current. It is generally linear over a range but will saturate at high currents. Luminous Intensity vs. Ambient Temperature: This curve shows how light output decreases as the junction temperature of the LED increases. Understanding this derating is vital for applications operating at high ambient temperatures. Spectral Distribution Curve: A plot of relative intensity versus wavelength, visually confirming the narrow 15nm half-width and the peak at 588nm.
5. Mechanical and Packaging Information
The device uses a standard single-digit, 10-pin, side-view DIP (Dual In-line Package) format. The package dimensions are provided in millimeters with a standard tolerance of ±0.25 mm. The 0.3-inch digit height (7.62mm) refers to the physical size of the illuminated character. The gray face and white segments are part of the plastic molding. The Pin Connection diagram is critical: it shows a common anode configuration with two common anode pins (1 and 6) for redundancy or lower current density per pin. The other pins (2, 3, 4, 5, 7, 8, 9, 10) are the cathodes for segments F, G, E, D, Decimal Point, C, B, and A respectively. The internal circuit diagram confirms that all LED segments for the digit share a common positive connection (anode), and each segment has its own negative connection (cathode). This configuration is typically driven by a "sink" driver IC that grounds the cathode of the segment to be lit.
6. Soldering and Assembly Guidelines
The key assembly guideline is the solder temperature specification: 260°C maximum for 3 seconds at 1.6mm below the seating plane. This translates to a standard lead-free reflow soldering profile (e.g., IPC/JEDEC J-STD-020). The profile must ensure that the body of the component does not exceed this temperature/time limit to prevent damage to the epoxy resin, the LED chip, or the internal wire bonds. For hand soldering, a temperature-controlled iron should be used, and contact time should be minimized. Standard ESD (Electrostatic Discharge) precautions should be observed during handling and assembly, as LED chips are sensitive to static electricity. Storage should be in a dry, ambient environment within the specified -35°C to +85°C range, preferably in moisture-sensitive device (MSD) bags if the shelf life is extended.
7. Packaging and Ordering Information
The part number is LTS-3861JS. The "LTS" prefix likely denotes a Lite-On display product, "3861" is the specific series/model, and "JS" may indicate the color (Yellow) and package style. The datasheet does not specify bulk packaging details (tubes, trays, or reels), but such displays are commonly supplied in anti-static tubes or ammo packs for automated insertion, or in reels for tape-and-reel automated placement. The label on the packaging would typically include the part number, quantity, date code, and luminous intensity bin code if applicable.
8. Aikace-aikace Shawarwari
Na'urori Aikace-aikace na Al'ada: Tsarin anode na gama gari ya fi dacewa da sarrafawa ta microcontroller ko na'urar turawa ta musamman tare da fitar da buɗaɗɗen magudanar ruwa ko buɗaɗɗen mai tattara. Dole ne a haɗa resistor mai iyakancewar kwarara a jere tare da kowane filin cathode (ko kowane fitarwar direba). Ana ƙididdige ƙimar resistor ta amfani da R = (Vcc - Vf) / If, inda Vcc shine ƙarfin wutar lantarki, Vf shine ƙarfin gaba na LED (yi amfani da 2.6V don gefen ƙira), kuma If shine kwararar gaba da ake so (misali, 10-20 mA don cikakken haske). Don haɗa lambobi da yawa, ana sauya anodes na gama gari a jere (ana duba su) yayin da ake turawa madaidaicin cathodes don kowane lamba. Abubuwan La'akari na Ƙira: 1) Current Limiting: Always use series resistors or constant-current drivers. 2) Heat Management: While power dissipation is low, ensure adequate ventilation if operating at high ambient temperatures or high continuous current. 3) Viewing AngleMount the display considering the intended user's line of sight relative to the specified wide viewing angle. 4) Brightness ControlBrightness can be adjusted by varying the forward current (within ratings) or by using pulse-width modulation (PWM) on the driver.
9. Technical Comparison and Differentiation
LTS-3861JS-ko farko bambancewa shine amfani da kayan AlInGaP don fitar da rawaya. Idan aka kwatanta da tsohuwar fasahar GaP:Y (Gallium Phosphide da aka yi wa doping don rawaya), AlInGaP yana ba da ingantaccen haske sosai, yana haifar da haske mafi girma don irin wannan yanayin tuƙi, ko kuma irin wannan haske a ƙaramin wutar lantarki. Hakanan yana ba da ingantaccen tsaftar launi da jikewa. Idan aka kwatanta da LED mai launin fari da aka yi amfani da tacewa ko canza phosphor a bayan tacewa mai launi don yin rawaya, rawaya ta kai tsaye ta AlInGaP tana da inganci kuma tana da madaidaicin wurin launi akan canjin zafin jiki da na yanzu. Tsayin lamba 0.3-inch shine daidaitaccen girman, yana ba da daidaito mai kyau tsakanin karantawa da amfani da sararin allo, yana dacewa tsakanin ƙananan nuni na 0.2-inch da manyan 0.5-inch ko 0.56-inch.
10. Tambayoyin da ake yawan yi (Dangane da Ma'auni na Fasaha)
Q: Wane darajar resistor ya kamata in yi amfani da shi don wadata 5V? A: For a target current of 20mA and a Vf of 2.6V, R = (5V - 2.6V) / 0.02A = 120 Ohms. A standard 120Ω or 150Ω resistor would be suitable. Q: Can I drive it directly from a microcontroller pin? A: It is not recommended to source the current for the common anode from an MCU pin, as the total digit current (e.g., 8 segments * 20mA = 160mA) exceeds pin ratings. Use the MCU to control a transistor or driver IC. Sinking the cathode current (per segment) via an MCU pin may be possible if the pin's current sink rating (e.g., 25mA) is not exceeded per segment. Q: Why are there two common anode pins (1 and 6)? A: For redundancy and to distribute the total anode current. When all segments are lit, the total current flows into the common anode. Having two pins reduces current density per pin, improves reliability, and provides a backup connection. They should be connected together on the PCB. Q: What does the luminous intensity matching ratio of 2:1 mean? A: It means the brightest segment in the digit will be no more than twice as bright as the dimmest segment under the same test conditions, ensuring visual uniformity.
11. Practical Design and Usage Case
Case: Designing a Simple Digital Voltmeter Readout: A designer is creating a 3-digit DC voltmeter display. They choose three LTS-3861JS displays. The microcontroller's ADC reads the voltage, converts it to a value, and drives the displays. A dedicated 7-segment driver IC (like the MAX7219 or a multiplexing shift register) is used to interface between the MCU's few I/O pins and the 24 segment lines (3 digits * 8 segments) and 3 common anode lines. The driver IC handles the multiplexing scan, refreshing each digit sequentially at a high frequency to avoid flicker. The designer calculates the series resistors based on the driver's output voltage and the desired brightness. The PCB layout places the displays in a row, with careful routing to avoid crosstalk. The gray face and yellow segments provide a classic, high-contrast instrument look. The wide operating temperature range assures functionality in a workshop environment.
12. Operating Principle Introduction
The fundamental operating principle is based on electroluminescence in a semiconductor p-n junction. The AlInGaP chip consists of layers of aluminium, indium, gallium, and phosphide compounds grown epitaxially on a non-transparent Gallium Arsenide (GaAs) substrate. When a forward voltage exceeding the junction's built-in potential (around 2V) is applied, electrons from the n-type region and holes from the p-type region are injected into the active region. When these charge carriers recombine, they release energy in the form of photons (light). The specific bandgap energy of the AlInGaP alloy determines the wavelength (color) of the emitted light, which in this case is yellow (~587-588 nm). The non-transparent GaAs substrate absorbs any light emitted downwards, improving contrast by preventing internal reflection that could wash out the segments.
13. Technology Trends and Context
AlInGaP technology represents a significant advancement in visible LED efficiency for red, orange, amber, and yellow colors. It has largely superseded older GaAsP and GaP technologies in performance-critical applications. The trend in display technology is towards higher integration and miniaturization. While discrete 7-segment displays like the LTS-3861JS remain vital for many applications, there is a growing use of dot-matrix LED displays and OLEDs for greater flexibility in showing graphics and text. However, for simple, bright, low-cost, and highly reliable numeric readouts, dedicated 7-segment LEDs like this one, especially with efficient materials like AlInGaP, continue to have a strong and enduring role in electronic design due to their simplicity, robustness, and excellent readability.
LED Specification Terminology
Complete explanation of LED technical terms
Photoelectric Performance
| Term | Unit/Representation | Simple Explanation | Why Important |
|---|---|---|---|
| Luminous Efficacy | lm/W (lumens per watt) | Light output per watt of electricity, higher means more energy efficient. | Directly determines energy efficiency grade and electricity cost. |
| Luminous Flux | lm (lumens) | Total light emitted by source, commonly called "brightness". | Determines if the light is bright enough. |
| Viewing Angle | ° (degrees), e.g., 120° | Kwanin da ƙarfin haske ya ragu zuwa rabi, yana ƙayyade faɗin katako. | Yana shafar kewayon haskakawa da daidaito. |
| CCT (Color Temperature) | K (Kelvin), e.g., 2700K/6500K | Warmth/coolness of light, lower values yellowish/warm, higher whitish/cool. | Determines lighting atmosphere and suitable scenarios. |
| CRI / Ra | Unitless, 0–100 | Ability to render object colors accurately, Ra≥80 is good. | Affects color authenticity, used in high-demand places like malls, museums. |
| SDCM | MacAdam ellipse steps, e.g., "5-step" | Metric ya Usawa ya Rangi, hatua ndogo zina maana usawa mkubwa wa rangi. | Inahakikisha rangi sawa kwenye kundi moja la LEDs. |
| Dominant Wavelength | nm (nanometers), e.g., 620nm (red) | Wavelength corresponding to color of colored LEDs. | Determines hue of red, yellow, green monochrome LEDs. |
| Spectral Distribution | Wavelength vs intensity curve | Shows intensity distribution across wavelengths. | Affects color rendering and quality. |
Electrical Parameters
| Term | Symbol | Simple Explanation | Abubuwan La'akari na Ƙira |
|---|---|---|---|
| Forward Voltage | Vf | Minimum voltage to turn on LED, like "starting threshold". | Driver voltage must be ≥Vf, voltages add up for series LEDs. |
| Forward Current | If | Current value for normal LED operation. | Usually constant current drive, current determines brightness & lifespan. |
| Max Pulse Current | Ifp | Peak current tolerable for short periods, used for dimming or flashing. | Pulse width & duty cycle must be strictly controlled to avoid damage. |
| Reverse Voltage | Vr | Max reverse voltage LED can withstand, beyond may cause breakdown. | Circuit must prevent reverse connection or voltage spikes. |
| Thermal Resistance | Rth (°C/W) | Resistance to heat transfer from chip to solder, lower is better. | High thermal resistance requires stronger heat dissipation. |
| ESD Immunity | V (HBM), e.g., 1000V | Ability to withstand electrostatic discharge, higher means less vulnerable. | Anti-static measures needed in production, especially for sensitive LEDs. |
Thermal Management & Reliability
| Term | Key Metric | Simple Explanation | Impact |
|---|---|---|---|
| Junction Temperature | Tj (°C) | Actual operating temperature inside LED chip. | Every 10°C reduction may double lifespan; too high causes light decay, color shift. |
| Lumen Depreciation | L70 / L80 (hours) | Time for brightness to drop to 70% or 80% of initial. | Directly defines LED "service life". |
| Lumen Maintenance | % (e.g., 70%) | Percentage of brightness retained after time. | Indicates brightness retention over long-term use. |
| Color Shift | Δu′v′ or MacAdam ellipse | Degree of color change during use. | Affects color consistency in lighting scenes. |
| Thermal Aging | Material degradation | Deterioration due to long-term high temperature. | May cause brightness drop, color change, or open-circuit failure. |
Packaging & Materials
| Term | Common Types | Simple Explanation | Features & Applications |
|---|---|---|---|
| Package Type | EMC, PPA, Ceramic | Housing material protecting chip, providing optical/thermal interface. | EMC: good heat resistance, low cost; Ceramic: better heat dissipation, longer life. |
| Chip Structure | Front, Flip Chip | Chip electrode arrangement. | Flip chip: kona mafuta mazuri zaidi, ufanisi wa juu, kwa nguvu kubwa. |
| Phosphor Coating | YAG, Silicate, Nitride | Covers blue chip, converts some to yellow/red, mixes to white. | Different phosphors affect efficacy, CCT, and CRI. |
| Lens/Optics | Flat, Microlens, TIR | Optical structure on surface controlling light distribution. | Determines viewing angle and light distribution curve. |
Quality Control & Binning
| Term | Binning Content | Simple Explanation | Purpose |
|---|---|---|---|
| Luminous Flux Bin | Code e.g., 2G, 2H | Grouped by brightness, each group has min/max lumen values. | E tabeta mwadogo wa mwanga sawa katika kundi moja. |
| Voltage Bin | Code e.g., 6W, 6X | Grouped by forward voltage range. | Facilitates driver matching, improves system efficiency. |
| Color Bin | 5-step MacAdam ellipse | Grouped by color coordinates, ensuring tight range. | Guarantees color consistency, avoids uneven color within fixture. |
| CCT Bin | 2700K, 3000K etc. | Grouped by CCT, each has corresponding coordinate range. | Meets different scene CCT requirements. |
Testing & Certification
| Term | Standard/Test | Simple Explanation | Significance |
|---|---|---|---|
| LM-80 | Lumen maintenance test | Long-term lighting at constant temperature, recording brightness decay. | Used to estimate LED life (with TM-21). |
| TM-21 | Life estimation standard | Estimates life under actual conditions based on LM-80 data. | Provides scientific life prediction. |
| IESNA | Illuminating Engineering Society | Covers optical, electrical, thermal test methods. | Industry-recognized test basis. |
| RoHS / REACH | Environmental certification | Yana tabbatar da babu abubuwa masu cutarwa (gubar, mercury). | Bukatar shiga kasuwa a duniya. |
| ENERGY STAR / DLC | Ilimin ingancin makamashi | Ilimin ingancin makamashi da aiki don hasken wuta. | Used in government procurement, subsidy programs, enhances competitiveness. |