LTS-5703AJS 0.56-inch Yellow LED Digital Tube Datasheet - Character Height 14.22mm - Forward Voltage 2.6V - Power Consumption 40mW - Chinese Technical Documentation

1. Product Overview

LTS-5703AJS is a high-performance, low-power seven-segment LED digital display module. Its primary function is to provide clear, bright numeric and limited alphanumeric character output in electronic devices. Its core application areas include instrumentation, consumer electronics, and industrial control panels that require reliable, low-current digital readouts.

This device is positioned as a solution offering excellent readability and high energy efficiency. Its core advantage stems from the use of advanced AlInGaP semiconductor material, which, compared to older technologies, can provide high brightness and good color purity at relatively low drive currents.

1.1 Core Advantages and Target Market

Key characteristics defining the product's market position include: a 0.56-inch (14.22 mm) character height, achieving a good balance between size and visibility; continuous and uniform segment patterns, ensuring aesthetically pleasing character appearance; low device power consumption, suitable for battery-powered or energy-conscious applications; provision of high brightness and high contrast, combined with a wide viewing angle, ensuring clear readability from different positions; inherent high reliability due to solid-state construction; finally, devices are graded by luminous intensity, ensuring consistent brightness matching in multi-digit numeric displays.

The target market includes designers of portable test equipment, digital multimeters, clock radios, appliance control panels, and any embedded systems requiring simple, direct drive for digital displays.

2. Detailed Technical Specifications

This section provides a detailed and objective analysis of the device's technical parameters based on the datasheet.

2.1 Photometric and Optical Characteristics

Optical performance is the core of the display function. The device utilizes AlInGaP (aluminum indium gallium phosphide) yellow LED chips. These chips are fabricated on an opaque GaAs substrate, which helps guide light forward and may improve contrast. The package features a light gray panel with white segments, a combination designed to enhance contrast when the segments are not illuminated.

• Average luminous intensity (I_V):At a forward current (I_F) of only 1mA, the range is from a minimum of 320 µcd to a typical value of 700 µcd. For such brightness, this extremely low drive current is a key specification, enabling very low system power consumption.
• Peak emission wavelength (λ_p):The typical value is 588 nm, located in the yellow region of the visible spectrum.
• Spectral line half-width (Δλ):The typical value is 15 nm, indicating a relatively narrow spectral bandwidth, which helps present a pure yellow color.
• Dominant wavelength (λ_d):The typical value is 587 nm, which is very close to the peak wavelength.
• Luminous intensity matching ratio:Specified at I_F=1mA under similar light-emitting area conditions, the maximum is 2:1. This means that the brightness difference between different segments within the same device, or between different devices, will not exceed two times, ensuring uniform appearance.

It should be noted that luminous intensity is measured using a sensor and filter that simulate the CIE photopic human eye response curve, ensuring the measurement aligns with human visual perception.

2.2 Electrical Parameters

Electrical characteristics define the interface between the display and the driving circuit.

• Forward voltage per segment (V_F):At I_F=20mA, the typical value is 2.6V, and the maximum value is 2.6V. The minimum value is 2.05V. Designers must ensure that the driving circuit can provide at least 2.6V to achieve the rated brightness at a current of 20mA.
• Reverse current per segment (I_R):At a reverse voltage (V_R) of 5V, the maximum is 100 µA. This parameter is important for circuit protection; exceeding the reverse voltage rating may damage the LED.
• Continuous forward current per segment:The absolute maximum rating is 25 mA. However, starting from 25°C, derating must be applied with a linear derating factor of 0.33 mA/°C. This means that at higher ambient temperatures, the maximum allowable continuous current must be reduced to prevent overheating and premature failure.
• Peak Forward Current:Under specific conditions (1/10 duty cycle, 0.1ms pulse width), it can be pulse-driven up to 60 mA. This allows for multiplexing schemes or brief overdrive to increase brightness.
• Power Consumption per Segment:The absolute maximum rating is 40 mW. This thermal limit, combined with current derating, is critical for reliability.

2.3 Thermal and Environmental Ratings

The operating limits of the device are defined by the temperature range.

• Operating Temperature Range:-35°C to +105°C. This wide range makes it suitable for various environments, from industrial cold storage to high-temperature equipment enclosures.
• Storage Temperature Range:-35°C to +105°C.
• Welding conditions:It is stipulated that the device body temperature must not exceed the maximum rated temperature during assembly. The guideline is soldering at 260°C for 3 seconds, with the solder joint at least 1/16 inch (approximately 1.6mm) below the package mounting plane.

3. Grading system description

The datasheet indicates that the devices are "graded by luminous intensity." This refers to a binning process. While this document does not provide specific binning codes, typical binning for such displays involves sorting manufactured units based on their luminous intensity measured at a standard test current (e.g., 1mA or 20mA).

Units are grouped into bins with defined minimum and maximum intensity values. This allows customers to select a bin based on their application, ensuring brightness uniformity across all digits in a multi-digit display. For example, a designer might specify that all displays must come from a bin where the luminous intensity I at 1mA current_Vfalls between 500 µcd and 600 µcd. The specified 2:1 intensity matching ratio is the worst-case variation allowed within a single device or possibly within a standard bin.

4. Performance Curve Analysis

The datasheet references "Typical Electrical/Optical Characteristic Curves." Although the specific charts are not detailed in the provided text, we can infer their standard content and importance.

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

This fundamental curve shows the relationship between the current flowing through an LED segment and the voltage across it. It is nonlinear. The typical V at 20mA current_F2.6V shine a wuri a kan wannan lanƙwasa. Wannan lanƙwasa yana taimaka wa mai zane ya zaɓi madaidaicin resistor na iyakancewar kwarara, kuma ya fahimci buƙatun ƙarfin lantarki na tsarin tuƙi, musamman a cikin yanayin multiplexing inda matsakaicin kwarara ya bambanta da kwarara na ɗan lokaci.

4.2 Luminous Intensity vs. Forward Current

Wannan jadawali yana da mahimmanci ga sarrafa haske. Yana nuna yadda fitar da haske ke ƙaruwa tare da ƙaruwar kwarara. Yawanci yana da alaƙa ta layi a cikin wani iyaka, amma a cikin babban kwarara mai ƙarfi zai cika. Ikon tuƙi sashi na lamba da kwarara har zuwa 1mA shine muhimmin sifa, wannan lanƙwasa zai nuna wannan batu dangane da haske na dangi a ƙarƙashin tuƙi na 20mA na yau da kullun.

4.3 Luminous Intensity vs. Ambient Temperature

The light output of an LED decreases as its junction temperature increases. This curve quantifies this derating. For applications operating in high-temperature environments, it is crucial to ensure that the display maintains sufficient brightness throughout its entire operating range.

4.4 Spectral Distribution

This chart shows the relative light intensity across wavelengths, centered at a 588 nm peak with a 15 nm half-width. This defines the exact yellow hue.

5. Mechanical and Packaging Information

5.1 Package Dimensions and Drawings

This device uses a standard 10-pin single-digit seven-segment display package. The datasheet includes detailed dimensioned drawings. Key notes indicate that, unless otherwise specified, all dimensions are in millimeters with a standard tolerance of ±0.25 mm. A special note mentions a pin tip offset tolerance of +0.4 mm, which is important for PCB hole layout and wave soldering processes.

5.2 Pin Connections and Polarity Identification

The device employsCommon cathodeconfiguration. This means the cathodes (negative terminals) of the individual LED segments are internally connected together. There are two common cathode pins (pins 3 and 8), which are internally connected. This dual-pin design aids in current distribution and PCB layout. The anodes (positive terminals) for each segment (A, B, C, D, E, F, G, and the decimal point) are on separate pins. The specific pin definitions are: 1:E, 2:D, 3:Common cathode, 4:C, 5:Decimal point, 6:B, 7:A, 8:Common cathode, 9:F, 10:G.

5.3 Internal Circuit Diagram

The provided diagram visually confirms the common-cathode architecture, showing that the anodes of all segment LEDs are located on their respective pins, while their cathodes are connected to pins 3 and 8.

6. Soldering and Assembly Guide

The Absolute Maximum Ratings section provides critical assembly data. The specified soldering conditions are industry standard for through-hole components: a maximum soldering iron temperature of 260°C for no more than 3 seconds, with the solder joint located at least 1.6mm below the package body to minimize heat transfer to the LED chip and internal bond wires. During any assembly process involving heat, such as wave soldering or manual rework, the temperature of the display unit itself must not exceed its maximum storage temperature rating. Proper handling to avoid Electrostatic Discharge (ESD) is also a standard precaution for LED devices, though not explicitly stated.

7. Application Recommendations

7.1 Typical Application Circuit

For common cathode displays, the driving circuit typically connects the common cathode pin to ground. Each segment anode pin is connected to the positive supply voltage (V_CC). The resistance value is calculated using the formula R = (V_CC - V_F) / I_F Calculation. For example, using a 5V power supply, V_Fis 2.6V, the desired I_Fis 10mA, then the resistor is (5 - 2.6) / 0.01 = 240 ohms. If the microcontroller's I/O pin can supply the required current (e.g., 10-20mA per segment), the display can be driven directly, but when multiplexing multiple digits, external driver transistors or a dedicated LED driver IC are typically required.

7.2 Design Considerations and Precautions

• Current Limiting:Always use a series resistor. Do not connect the LED directly to a voltage source.
• Multiplexing:To drive multiple digits, a multiplexing scheme is required, where each digit is rapidly illuminated one at a time. The peak current can be higher (up to 60mA nominal) to compensate for the lower duty cycle, thereby maintaining the perceived brightness.
• Viewing Angle:A wide viewing angle is beneficial, but the expected user position must be considered when installing the display.
• Brightness Matching:For multi-digit display, use devices from the same luminous intensity bin, or if the difference is significant, use PWM for software brightness calibration.
• Low Power Design:For battery-sensitive applications, utilize its 1mA drive capability. The brightness at 1mA (minimum 320 µcd) is usually sufficient for indoor use.

8. Technical Comparison and Differentiation

LTS-5703AJS primarily achieves this through itsAlInGaP technology和Extremely low current operating characteristicsAchieve differentiation. Compared to older red GaAsP or GaP LEDs, AlInGaP offers higher efficiency, enabling higher brightness at the same current or equivalent brightness at lower current. Compared to contemporary high-brightness red LEDs, yellow may provide better visibility or lower visual fatigue in certain applications. Its lower V_F(compared to blue or white LEDs) is also an advantage in low-voltage systems. Luminous intensity binning provides an advantage for applications requiring uniformity, superior to simple unbinned commodity displays.

9. Frequently Asked Questions (Based on Technical Specifications)

Q: Can I drive this display with 3.3V logic levels?
A: Yes. The typical V_Fis 2.6V, so a 3.3V supply provides sufficient margin. Calculate the series resistor accordingly: for example, for 10mA, R = (3.3 - 2.6) / 0.01 = 70 ohms.

Q: What is the purpose of setting two common cathode pins?
A: They are internally connected. Setting two pins helps distribute the total cathode current (i.e., the sum of the currents of all lit segments) across two PCB traces and two solder joints, thereby improving reliability and potentially reducing voltage drop.

Q: The datasheet shows a maximum continuous current of 25mA, but the test condition for V_Fis 20mA. Which value should be used in the design?
A: The figure of 20mA is the standard test condition for reporting typical characteristics (such as V_Fand wavelength). To ensure long-term reliable operation, it is prudent to design for a continuous current of 20mA or less, especially when the ambient temperature is expected to be above 25°C, following the derating curve.

Q: If I multiplex 4 digits, how to achieve the same brightness?
A: At a 1/4 duty cycle, you need to multiply the instantaneous segment current by 4 to obtain the same average current, thereby achieving similar perceived brightness. If you want the average current per segment to be 5mA, you should drive each segment with a 20mA pulse. Ensure this pulse current (20mA) and the resulting instantaneous power dissipation are within the absolute maximum ratings (peak 60mA, 40mW).

10. Practical Use Case Example

Design Case: 4-digit Portable Digital Thermometer.
Design goals are long battery life and clear readability. The microcontroller has limited I/O and power budget.
Implementation Plan:Four LTS-5703AJS displays are connected in a multiplexed configuration. All corresponding segment anodes (A, B, C...) of the four digits are tied together. The common cathode of each digit is controlled by a separate NPN transistor driven by a microcontroller pin. The microcontroller cycles through, turning on the cathode of one digit at a time while outputting that digit's segment pattern on the common anode lines. To save power, the drive current is set to an average of 5mA. Using 1/4 duty cycle multiplexing, the instantaneous current per segment is set to 20mA (5mA * 4). This is within the 60mA peak rating. Perceived brightness will be good, and the average power consumption per segment is very low, significantly extending battery life compared to using displays requiring 10-20mA continuous current per segment.

11. Introduction to Technical Principles

LTS-5703AJS is based on growth onGaAs (Gallium Arsenide)substrateAlInGaP (Aluminum Indium Gallium Phosphide)Semiconductor material. In LEDs, when a forward voltage is applied across the p-n junction, electrons and holes recombine, releasing energy in the form of photons (light). The specific composition of the AlInGaP alloy determines the bandgap energy, which directly defines the wavelength (color) of the emitted light. Yellow emission (approximately 587-588 nm) is achieved through specific ratios of aluminum, indium, and gallium. The opaque GaAs substrate absorbs stray light, improving contrast by preventing internal reflections that could illuminate unlit segments. The common-cathode configuration simplifies the driving circuit by allowing a single switch (e.g., a transistor) to control the on/off state of an entire digit during multiplexing.

12. Technical Trends and Background

While seven-segment LED displays remain crucial in specific applications, broader trends in display technology have shifted towards dot-matrix formats (for alphanumeric and graphics) and integrated controller-based modules (such as OLED or TFT). However, a niche market persists for simple, rugged, low-cost, low-power, high-brightness, and directly driven numeric displays. Evolution within this niche focuses on materials science (e.g., AlInGaP replacing older materials for higher efficiency), lower operating voltages and currents, improved packaging for greater reliability and wider temperature ranges, and surface-mount versions for automated assembly. The LTS-5703AJS represents a mature point in this evolution, offering a balance of performance and practicality for its intended use. Future developments may integrate current-limiting resistors or simple logic internally, but for many simple applications, the simplicity of the basic component remains a key advantage.

Detailed Explanation of LED Specification Terminology

Complete Explanation of LED Technical Terminology

I. Core Indicators of Optoelectronic Performance

Terminology	Units/Notation	Popular Explanation	Why It Is Important
Luminous Efficacy	lm/W (lumens per watt)	The luminous flux emitted per watt of electrical power; the higher the value, the more energy-efficient it is.	Directly determines the energy efficiency rating and electricity cost of the lighting fixture.
Luminous Flux	lm (lumen)	The total amount of light emitted by a light source, commonly known as "brightness".	Determines whether a light fixture is bright enough.
Viewing Angle	° (degrees), such as 120°	The angle at which light intensity drops to half, determining the beam width.	Affects the illumination range and uniformity.
Correlated Color Temperature (CCT)	K (Kelvin), e.g., 2700K/6500K	The warmth or coolness of light color; lower values are yellowish/warm, higher values are whitish/cool.	Determines the lighting atmosphere and suitable application scenarios.
Color Rendering Index (CRI / Ra)	Unitless, 0–100	The ability of a light source to restore the true color of an object, Ra≥80 is recommended.	Affects color authenticity, used in high-demand places such as shopping malls and art galleries.
Color Tolerance (SDCM)	MacAdam Ellipse Steps, e.g., "5-step"	A quantitative indicator of color consistency; a smaller step number indicates higher color consistency.	Ensure no color difference among the same batch of luminaires.
Dominant Wavelength	nm (nanometer), e.g., 620nm (red)	The 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	Display the intensity distribution of light emitted by the LED across various wavelengths.	Affect color rendering and color quality.

II. Electrical Parameters

Terminology	Symbol	Popular Explanation	Design Considerations
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; 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 (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	The maximum reverse voltage that an LED can withstand; exceeding it may cause breakdown.	The circuit must be protected against reverse polarity or voltage surges.
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 more robust heat dissipation design; otherwise, the junction temperature will increase.
ESD Immunity	V (HBM), e.g., 1000V	The higher the ESD immunity rating, the more resistant the device is to electrostatic damage.	Anti-static measures must be taken during production, especially for high-sensitivity LEDs.

III. Thermal Management and Reliability

Terminology	Key Metrics	Popular Explanation	Impact
Junction Temperature	Tj (°C)	The actual operating temperature inside the LED chip.	For every 10°C reduction, lifespan may double; excessively high temperatures cause 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.	Directly defines the "service 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	Deterioration 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	Characteristics and Applications
Packaging Type	EMC, PPA, Ceramic	The housing material that protects the chip and provides optical and thermal interfaces.	EMC tahan panas baik, biaya rendah; keramik pendinginan unggul, umur panjang.
Struktur chip	Face-up, 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	Planar, Microlens, Total Internal Reflection	Optical structure on the encapsulation surface, controlling light distribution.	Determine the beam angle and light distribution curve.

V. Quality Control and Binning

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

VI. Testing and Certification

Terminology	Standards/Testing	Popular Explanation	Significance
LM-80	Lumen Maintenance Test	Record brightness attenuation data under constant temperature conditions over an extended period.	Used to estimate LED lifetime (in conjunction with TM-21).
TM-21	Lifespan Projection Standard	Estimating lifespan under actual use conditions based on LM-80 data.	Provide scientific life prediction.
IESNA Standard	Illuminating Engineering Society Standard	Covers optical, electrical, and thermal testing methods.	Industry-recognized basis for testing.
RoHS / REACH	Environmental Certification	Ensure products are free from hazardous substances (e.g., lead, mercury).	Market access requirements for entering 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.