Table of Contents
1. Product Overview
The LTS-3403LJF is a single-digit numeric display module, specifically designed for applications requiring clear and reliable numeric or limited character indication. Its primary function is to provide visual output for digital data from microcontrollers, logic circuits, or other driver integrated circuits. A core advantage of this device lies in its LED chips, which utilize aluminum indium gallium phosphide semiconductor technology, offering higher efficiency and color purity within the yellow-orange spectrum compared to older technologies like gallium arsenide phosphide. The device features a gray panel with white segment markings, providing excellent contrast for the illuminated segments. It is graded by luminous intensity to ensure brightness consistency across different production batches. Designed for easy integration, it is suitable for direct mounting on printed circuit boards or in compatible sockets, making it an ideal choice for industrial control panels, test equipment, consumer appliances, and instrumentation requiring single-digit readouts.
1.1 Core Features and Target Market
LTS-3403LJF yana da sifofi da yawa waɗanda ke ayyana yankin aikace-aikacensa. Tsarin harafi na inci 0.8 ya sami daidaito tsakanin bayyanawa da ƙanƙanta, yana dacewa da na'urorin da aka ɗora a kan panel waɗanda ke da iyakataccen sarari amma karantawa tana da mahimmanci. Sashinsa mai ci gaba da daidaito yana tabbatar da kamanni mai haɗin kai da ƙwararru lokacin haskakawa. Ƙarancin amfani da wutar lantarki da ƙarancin buƙatun wutar lantarki sun sa ya dace da na'urorin da ake amfani da baturi ko tsarin da ke da mahimmanci ga ingantaccen amfani da wutar lantarki. Kyakkyawan kamannin haruffa da faɗin kusurwar kallo sakamako ne kai tsaye na fasahar AlInGaP chip da ƙirar ruwan tabarau mai watsawa, wanda ke sa mai nuni ya iya karantawa daga kowane kusurwa. Ingantaccen amintaccen ƙaƙƙarfan LED na asali yana tabbatar da tsawon rayuwa, ba tare da sassa masu motsi da ke lalacewa ba. A ƙarshe, dacewa da haɗaɗɗun kewayen yana nufin cewa ana iya tuƙa shi kai tsaye ta hanyar fitarwar dabaru na lambobi na yau da kullun ko ta hanyar ƙwararrun haɗaɗɗun kewayen tuƙi na nuni tare da madaidaicin resistor mai iyakancewar ƙarfi. Kasuwannin da aka yi niyya sun haɗa da na'urorin lantarki masu ɗaukuwa, tsarin da aka haɗa, dashboard na mota, na'urorin kiwon lafiya, da kuma duk wanda ke ƙirƙira tsarin lantarki da ke buƙatar mai nuni na lambobi masu ƙarfi, ƙarancin amfani da wutar lantarki.
2. Detailed Technical Parameters
Takaddar ƙayyadaddun bayanai tana ba da cikakkun ƙayyadaddun bayanai na lantarki, na gani, da na zafi, waɗanda ke da mahimmanci ga daidaitaccen ƙirar kewaye da aiki mai aminci.
2.1 Photometric and Optical Characteristics
Optical performance is central to the display's function. The average luminous intensity is measured at a forward current of 1 mA, with a minimum of 320 µcd, a typical value of 900 µcd, and no maximum specified. This parameter represents the perceived brightness of a single segment. The low test current highlights the device's efficiency. Color characteristics are defined by three wavelength parameters. The peak emission wavelength is measured at If=20mA, with a typical value of 611 nm. The typical spectral line half-width is 17 nm, indicating spectral purity or the concentration of emitted light around the peak; a smaller value indicates a color closer to monochromatic. The dominant wavelength is typically 605 nm. It is important to note that luminous intensity is measured using a sensor and filter combination that simulates the CIE photopic response curve, ensuring the measurements correlate with human visual perception. The maximum luminous intensity matching ratio is 2:1, meaning the brightness difference between the brightest and dimmest segments within a single unit will not exceed a factor of two, ensuring a uniform appearance.
2.2 Electrical Parameters
Electrical specifications define the operating limits and conditions for the LED segments. Absolute maximum ratings set the safe operating boundaries. The power dissipation per segment is 70 mW. The peak forward current per segment is 60 mA, but this is only permitted under pulse conditions to manage heat. At 25°C, the continuous forward current per segment is 25 mA, with a derating factor of 0.33 mA/°C. This means that when the ambient temperature exceeds 25°C, the maximum allowable continuous current decreases to prevent overheating. The reverse voltage per segment is 5 V; exceeding this value may damage the LED junction. Under standard operating conditions, the forward voltage per segment has a typical value of 2.6 V and a maximum value of 2.6 V at a test current of 10 mA. The minimum value is 2.05 V. When a 5 V reverse voltage is applied, the reverse current per segment is a maximum of 100 µA, indicating the leakage current in the off state.
2.3 Thermal and Environmental Specifications
Reliability under various environmental conditions is crucial. The operating temperature range is specified as -35°C to +85°C. This wide range allows the display to function in harsh environments, from industrial freezers to high-temperature engine compartments. The storage temperature range is the same, defining safe conditions when the device is not powered. A key parameter for assembly is the soldering temperature. The datasheet specifies that the device can withstand 260°C for 3 seconds at a point 1/16 inch below the mounting plane. This is a standard reference for wave soldering or reflow processes. Designers must ensure their PCB assembly profiles do not exceed these limits to avoid damaging internal wire bonds or the LED chip itself.
3. Binning System Description
The datasheet indicates that the device is "binned for luminous intensity." This refers to a grading or sorting process performed during manufacturing. Due to natural variations in semiconductor epitaxial growth and chip fabrication, LEDs from the same production batch can have slight differences in key parameters like luminous intensity and forward voltage. To ensure consistency for end users, manufacturers test each unit and sort them into different "bins" based on measured performance. The LTS-3403LJF is specifically binned for luminous intensity. This means when a designer orders a quantity of these displays, the variation in brightness between individual units will be confined to a predefined range. This is critical for applications using multiple digits side-by-side, as it prevents noticeable brightness differences between displays. The datasheet does not specify separate binning for wavelength or forward voltage, suggesting either tight process control over these parameters or that the product's binning is primarily focused on intensity.
4. Performance Curve Analysis
Although the datasheet lists a "Typical Electrical/Optical Characteristics Curves" page, the provided content does not include the actual graphs. Typically, such curves are invaluable for design. One would expect to see a Forward Current vs. Forward Voltage curve, which shows the non-linear relationship between current and voltage across the LED junction. This curve helps designers select an appropriate current-limiting resistor value for a given supply voltage. The Relative Luminous Intensity vs. Forward Current curve would show how brightness increases with current, typically in a sub-linear fashion, aiding in optimizing the trade-off between brightness and power consumption/efficiency. The Relative Luminous Intensity vs. Ambient Temperature curve is essential for understanding how brightness decreases as operating temperature rises, which is critical for designing systems that operate over a full temperature range. Finally, a Spectral Distribution graph would visually depict the intensity of light emitted at different wavelengths around the 611 nm peak, showing the shape and width of the emission spectrum. Designers should consult the manufacturer's full datasheet for these graphical representations to make informed decisions about drive current and thermal management.
5. Mechanical and Package Information
Mechanical design ensures reliable physical integration. The package outline drawing provides all critical dimensions required for PCB pad design, including overall length, width, height, pin pitch, mounting hole diameter and location, and the distance from the bottom of the package to the mounting plane. The pin connection table is a functional map of the 17-pin package. It shows this is a common cathode configuration, where the cathodes of all LED segments are internally connected together. The anode of each segment, as well as the left and right decimal points, are brought out to separate pins. Several pins are listed as "No Pin," meaning they are physically present but not electrically connected. Polarity is clearly indicated by the common cathode designation. The gray panel and white segments provide the visual interface.
6. Soldering and Assembly Guide
Proper handling during assembly is critical for long-term reliability. The key guideline provided is the soldering temperature specification: 260°C for 3 seconds at 1/16 inch below the mounting plane. This is guidance for wave soldering. For reflow soldering, a standard lead-free profile with a peak temperature of 260°C is applicable, but the time above liquidus should be controlled to minimize thermal stress. Designers should ensure the PCB pad layout matches the recommended pad pattern from the outline drawing to prevent tombstoning or misalignment. Devices should be stored in their original moisture barrier bag prior to use, especially if not intended for immediate assembly, to prevent moisture absorption leading to "popcorning" during reflow. Operating and storage temperature ranges should be observed throughout the supply chain and product lifecycle. Avoid mechanical stress on the lens or pins during handling.
7. Application Suggestions7.1 Typical Application Circuit
The LTS-3403LJF, as a common-cathode display, is typically driven by a "current-sinking" driver. This means the microcontroller or driver IC pin is connected to the segment anode and supplies current to illuminate it, while the common-cathode pin is connected to ground, usually through a transistor capable of handling the total current of all segments. A basic circuit involves connecting each anode pin to a GPIO pin of the microcontroller via a current-limiting resistor. The value of this resistor is calculated using Ohm's Law: R = (Vcc - Vf) / If. The common-cathode pin will be connected to the collector of an NPN transistor, with the emitter grounded. The microcontroller will turn on the transistor to enable the digit display. For dynamic scanning of multi-digit displays, the anodes of corresponding segments are connected together across digits, and the common cathode of each digit is controlled individually, rapidly illuminating each digit in sequence.
7.2 Design Considerations and Precautions
Several important considerations must be addressed.Current Limiting:Do not connect an LED directly to a voltage source without a current-limiting resistor or constant-current driver, otherwise the LED will draw excessive current and be damaged.Heat Dissipation:Although LEDs are efficient, each segment can dissipate up to 65 mW of power. In applications where many segments are continuously lit, ensure adequate ventilation or heat dissipation if operating near the maximum temperature.Viewing Angle:A wide perspective is beneficial, but to achieve optimal readability, the main user's line of sight must be considered when positioning the display within the chassis.ESD Protection:AlInGaP LEDs may be sensitive to electrostatic discharge. Implement standard ESD handling precautions during assembly.Decoupling and Noise:In an electrically noisy environment, consider adding a small decoupling capacitor near the power connection of the display to stabilize the power supply.
8. Technical Comparison and Differentiation
The LTS-3403LJF primarily achieves differentiation through its semiconductor material, AlInGaP. Compared to older red LEDs based on GaAsP, AlInGaP offers significantly higher luminous efficiency, better color and brightness temperature stability, and more saturated, purer colors in the amber/yellow-orange/red spectral regions. Compared to white LEDs, it provides a single, narrow-band emission, which is advantageous in applications requiring specific wavelength filtering or color purity without the broad spectrum of white light. Its 0.8-inch size fills the gap between smaller indicator lights and larger, higher-power displays. The common-cathode configuration is standard and is compatible with a wide range of driver ICs and microcontroller port configurations designed for common-cathode dynamic scanning.
9. FAQ
Q: What is the difference between peak wavelength and dominant wavelength?
A: Peak wavelength is the single wavelength at which the emission spectrum intensity reaches its maximum. Dominant wavelength is the wavelength of monochromatic light that appears to the human eye to be the same color as the LED's output. They are typically slightly different. Dominant wavelength is more relevant for color specification.
Q: Can I drive this display with a 3.3V microcontroller?
A: Yes, but the forward voltage must be checked. The typical Vf is 2.6V. When using a 3.3V power supply, the voltage drop across the current-limiting resistor is only 0.7V. To achieve a 15mA current, a resistor of approximately 46.7 ohms is needed. This is feasible, but the current will be more sensitive to changes in Vf. It is generally acceptable, but the brightness must be verified to meet requirements.
Q: Why are there four common cathode pins?
A: Multiple cathode pins help to shunt the total current when all segments are lit. The sum of current for 7 segments plus the decimal point may exceed 200 mA. Distributing the current across multiple pins and PCB traces reduces current density, minimizes voltage drop, and improves reliability.
Q: What does "IC-compatible" mean?
A: It means the LED's electrical characteristics are within the range that can be directly driven by a standard digital integrated circuit output pin, provided an appropriate current-limiting resistor is used. It does not mean it can be connected directly without a resistor.
10. Design and Application Case Studies
Consider designing a simple digital thermostat controller. The system uses a microcontroller to read a temperature sensor and display the setpoint or current temperature on a single seven-segment display. The LTS-3403LJF is chosen for its clarity, low power consumption, and wide viewing angle. The microcontroller operates at 5V. The designer calculates resistor values for a segment current of 12 mA to balance brightness and power consumption. Seven 200-ohm resistors are used for each segment anode. The common cathode pins are tied together and connected to the collector of an NPN transistor. The transistor's emitter is grounded, and its base is driven by a microcontroller GPIO pin through a 10k resistor. To display a digit, the microcontroller sets the pattern on the segment anode pins to high and turns on the transistor to complete the circuit to ground. The yellow-orange color is clearly visible under typical indoor lighting conditions. Robust temperature ratings ensure the display works reliably even if the thermostat is placed in a hot attic or cold garage.
11. Introduction to Working Principle
The LTS-3403LJF operates based on the fundamental principle of electroluminescence in a semiconductor p-n junction. The device uses aluminum indium gallium phosphide as the active semiconductor material. This compound is epitaxially grown on an opaque gallium arsenide substrate. When a forward voltage exceeding the material's bandgap voltage is applied, electrons from the n-type region and holes from the p-type region are injected into the active region. When these carriers recombine, they release energy. In a direct bandgap semiconductor like AlInGaP, this energy is released primarily as photons. The specific wavelength of the emitted light is determined by the bandgap energy of the AlInGaP alloy composition, which is tightly controlled during manufacturing. The gray panel and white segments act as a diffuser and contrast filter, respectively, shaping the light output into recognizable digit segments.
12. Teknologi Trends da Background
LTS-3403LJF yana wakiltar fasaha mai cikakken ci gaba da ingantacce. An haɓaka AlInGaP LED a cikin shekarun 1990, kuma a mafi yawan lokuta ya maye gurbin GaAsP, don ingantacciyar haske ja, orange, da rawaya, da kuma nuni. Tun daga wannan lokacin, trends na fasahar nuni sun karkata zuwa mafi girman mahimmanci na mafita, kamar matrix OLED, micro LED, da LCD, don zane-zane masu rikitarwa. Duk da haka, don buƙatun nuni mai sauƙi, ƙarfi, ƙarancin farashi, da amincin gaske na lamba ɗaya ko da yawa, nuni na LED guda bakwai har yanzu suna da alaƙa sosai. Fa'idodinsu sun haɗa da sarrafawa mai sauƙi sosai, haske mai ƙarfi da bambanci sosai, kewayon zafin aiki mai faɗi, ikon farawa nan take, da tsawon rayuwar aiki na dubunnan sa'o'i. Ci gaban yanzu a wannan fanni yana mai da hankali kan mafi inganci, ƙananan ƙarfin tuƙi, da haɗa da'irar tuƙi kai tsaye a cikin kayan nuni. Ka'idar tushe na amintaccen haske mai ƙarfi don nuna lambobi da LTS-3403LJF ke wakilta, har yanzu shine ginshiƙin gine-ginen ƙira na lantarki a masana'antu da yawa.
Cikakken Bayani kan Kalmomin Ƙayyadaddun LED
Complete Explanation of LED Technical Terminology
I. Core Indicators of Photoelectric Performance
| Terminology | Unit/Representation | Layman's Explanation | Why is it important |
|---|---|---|---|
| Luminous Efficacy | lm/W | The luminous flux emitted per watt of electrical energy; the higher the value, the more energy-efficient. | Directly determines the energy efficiency rating 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 are yellowish/warm, higher values are whitish/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, 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) | 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 | It shows the intensity distribution of light emitted by an LED at various wavelengths. | It affects color rendering and color quality. |
II. Electrical Parameters
| Terminology | Symbol | Layman's 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 | Peak current that can be withstood for a short period, used for dimming or flashing. | Pulse width and duty cycle must be strictly controlled, otherwise overheating damage will occur. |
| Reverse Voltage | Vr | LED yana iya jurewa mafi girman ƙarfin lantarki na baya, wanda ya wuce hakan zai iya lalacewa. | A cikin da'ira, ya kamata a hana haɗuwa ta baya ko kuma ƙarfin lantarki mai ƙarfi. |
| 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 | Anti-static strike capability, the higher the value, the less susceptible to electrostatic damage. | Anti-static measures must be implemented during production, especially for high-sensitivity LEDs. |
III. Thermal Management and Reliability
| Terminology | Key Metrics | Layman's 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 lead to lumen depreciation and color shift. |
| Lumen Depreciation | L70 / L80 (hours) | The time required for brightness to drop to 70% or 80% of its initial value. | Define the "useful life" of an LED directly. |
| 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 | Layman's Explanation | Features and Applications |
|---|---|---|---|
| Package Type | EMC, PPA, Ceramic | A 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 Layout 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 to 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 | Optical structure of the encapsulation surface, controlling light distribution. | Determines the emission angle and light distribution curve. |
V. Quality Control and Binning
| Terminology | Grading Content | Layman's 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 | Layman's 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 | Estimating lifespan under actual use conditions based on LM-80 data. | Providing scientific lifespan prediction. |
| IESNA standard | Illuminating Engineering Society Standard | Covers optical, electrical, and thermal test methods. | Industry-recognized testing basis. |
| RoHS / REACH | Environmental certification. | Ensure products do 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. |