LTS-4301KD LED Display Datasheet - 0.4-inch Digit Height - Hyper Red Color - 2.6V Forward Voltage - 70mW Power Dissipation - English Technical Documentation

1. Product Overview

The LTS-4301KD is a high-performance, single-digit numeric display module designed for applications requiring clear, bright, and reliable numerical readouts. Its core function is to visually represent a single decimal digit (0-9) along with a decimal point, utilizing advanced semiconductor technology for optimal performance.

Core Positioning: This device is positioned as a premium, high-brightness solution for industrial control panels, instrumentation, test equipment, and consumer appliances where excellent readability under various lighting conditions is paramount. It targets applications demanding long-term reliability and consistent optical performance.

Key Advantages: The primary advantages of this display stem from its use of AlInGaP (Aluminum Indium Gallium Phosphide) semiconductor material for the light-emitting chips. This technology offers superior performance compared to older technologies like standard GaAsP, particularly in terms of luminous efficiency, color purity, and high-temperature performance. The device is binned for luminous intensity, ensuring uniformity across production batches.

2. In-Depth Technical Parameter Analysis

This section provides a detailed, objective interpretation of the key technical parameters specified in the datasheet.

2.1 Photometric and Optical Characteristics

The optical performance is central to the device's function. Key parameters are measured under specific test conditions (typically at an ambient temperature Ta=25°C).

• Average Luminous Intensity (I_V): This is the measure of the light output power as perceived by the human eye. The datasheet specifies a minimum of 200 μcd, a typical value of 650 μcd, and a maximum under a forward current (I_F) of 1mA. At a higher drive current of 10mA, the typical intensity rises significantly to 9750 μcd. This non-linear relationship between current and brightness is typical for LEDs and is detailed in the characteristic curves.
• Peak Emission Wavelength (λ_p): This parameter defines the specific wavelength at which the LED emits the most optical power. For the LTS-4301KD, this is 650 nanometers (nm), which falls within the deep red portion of the visible spectrum, classified as \"Hyper Red.\"
• Dominant Wavelength (λ_d): At 639 nm, this is the wavelength perceived by the human eye, which may differ slightly from the peak wavelength due to the shape of the emission spectrum. It confirms the red color point.
• Spectral Line Half-Width (Δλ): This 20 nm value indicates the spectral purity or bandwidth of the emitted light. A narrower half-width suggests a more monochromatic, pure color.
• Luminous Intensity Matching Ratio (I_V-m): A maximum ratio of 2:1 is specified for segments within the same device under identical drive conditions (I_F=1mA). This ensures visual uniformity across all segments of the digit, preventing some segments from appearing brighter than others.

2.2 Electrical Characteristics

Understanding the electrical behavior is crucial for proper circuit design and ensuring device longevity.

• Forward Voltage per Segment (V_F): The voltage drop across an illuminated segment when driven at the specified current. The typical value is 2.6V at I_F=20mA, with a minimum of 2.1V. This parameter is vital for designing the current-limiting circuitry.
• Reverse Current per Segment (I_R): A maximum of 100 μA is specified when a reverse voltage (V_R) of 5V is applied. This indicates the level of leakage current when the LED is reverse-biased, which should be minimal.
• Continuous Forward Current per Segment: The maximum DC current that can be continuously applied to a single segment without risking damage is 25 mA.
• Peak Forward Current per Segment: For pulsed operation (at 1kHz, 10% duty cycle), a higher peak current of 90 mA is permissible. This allows for multiplexing schemes or brief over-driving for increased brightness.

2.3 Absolute Maximum Ratings and Thermal Considerations

These ratings define the operational limits beyond which permanent damage may occur. They are not conditions for normal operation.

• Power Dissipation per Segment: The maximum power that can be dissipated by a single segment is 70 mW. Exceeding this limit risks overheating and degradation.
• Forward Current Derating: The datasheet specifies a derating factor of 0.28 mA/°C from 25°C. This means for every degree Celsius above 25°C, the maximum allowable continuous forward current must be reduced by 0.28 mA to stay within safe thermal limits. This is a critical parameter for high-temperature environments.
• Operating and Storage Temperature Range: The device is rated for operation from -35°C to +105°C and can be stored within the same range. This wide range makes it suitable for harsh environments.
• Reverse Voltage per Segment: Applying more than 5V in reverse bias can cause breakdown and damage the LED.

3. Binning System Explanation

The datasheet explicitly states the device is \"BINNED FOR LUMINOUS INTENSITY.\" This is a quality control and sorting process.

After manufacture, individual displays are tested and sorted into different \"bins\" or groups based on their measured luminous intensity (typically at a standard test current like 1mA or 10mA). Devices within the same bin will have very similar brightness levels. This ensures that when multiple displays are used in a product (e.g., a multi-digit panel), all digits will have a consistent appearance, avoiding noticeable brightness variations from one digit to the next. While the datasheet does not list the specific bin codes or intensity ranges, the practice guarantees the specified minimum and typical values are met with high consistency.

4. Performance Curve Analysis

The datasheet references \"Typical Electrical / Optical Characteristic Curves.\" While the specific graphs are not detailed in the provided text, standard curves for such a device would typically include:

• Forward Current (I_F) vs. Forward Voltage (V_F) Curve: This shows the exponential relationship typical of a diode. The \"knee\" voltage is around the typical V_F of 2.6V. Designers use this to set appropriate drive voltages.
• Relative Luminous Intensity vs. Forward Current (I_F): This curve demonstrates how light output increases with current. It is generally linear over a range but will saturate at very high currents. The data points (200 μcd @1mA, 9750 μcd @10mA) indicate a highly efficient, super-linear response.
• Relative Luminous Intensity vs. Ambient Temperature: This curve shows the decrease in light output as the junction temperature rises. The derating factor (0.28 mA/°C) is directly related to the slope of this characteristic. AlInGaP technology generally has better high-temperature performance than older materials, but light output still decreases with heat.
• Spectral Distribution Curve: A plot of relative intensity versus wavelength, showing a peak at 650 nm (λ_p) and a width of 20 nm (Δλ) at half the maximum intensity.

5. Mechanical and Package Information

The LTS-4301KD uses a standard single-digit LED package with through-hole pins for mounting on a printed circuit board (PCB).

• Digit Height: 0.4 inches (10.16 mm), which defines the physical size of the displayed number.
• Package Appearance: The device features a gray face (the background of the display) with white segments. This color combination provides high contrast when the red segments are illuminated.
• Pin Configuration: The device has 10 pins in a dual-in-line package. The internal circuit diagram and pin connection table show it is a Common Cathode type. This means all the cathodes (negative terminals) of the individual LED segments (A-G and DP) are connected together internally to two common pins (pin 3 and pin 8). Each segment anode (positive terminal) has its own dedicated pin. This configuration is common and simplifies multiplexing in multi-digit displays.
• Dimensions and Tolerances: All dimensions are provided in millimeters. General tolerances are ±0.25mm, with a specific pin tip shift tolerance of ±0.4mm to account for variations during the lead forming process.

6. Soldering and Assembly Guidelines

The datasheet provides specific soldering conditions to prevent thermal damage during assembly.

• Wave or Hand Soldering: The recommended condition is to solder at 260°C for a maximum of 3 seconds, with the condition that the soldering iron tip must be at least 1/16 inch (approximately 1.6 mm) below the seating plane of the package body. This prevents excessive heat from traveling up the leads and damaging the internal semiconductor die and wire bonds.
• General Thermal Precautions: The temperature of the unit during the entire assembly process must not exceed the maximum temperature rating specified in the Absolute Maximum Ratings section. Prolonged exposure to high temperatures, even below the soldering temperature, should be avoided.
• Storage Conditions: Devices should be stored in their original moisture-barrier bags in an environment within the specified storage temperature range (-35°C to +105°C) and at low humidity to prevent oxidation of the leads.

7. Application Suggestions

Typical Application Scenarios:

• Industrial Instrumentation: Panel meters, process controllers, timer displays.
• Test and Measurement Equipment: Digital multimeters, frequency counters, power supplies.
• Consumer Appliances: Microwave ovens, washing machines, audio equipment displays.
• Automotive Aftermarket: Gauges and readouts (where environmental specs are suitable).

Design Considerations:

• Current Limiting: ALWAYS use a series current-limiting resistor for each segment or a constant-current driver circuit. The resistor value can be calculated using Ohm's Law: R = (V_supply - V_F) / I_F. For a 5V supply, typical V_F of 2.6V, and desired I_F of 10mA: R = (5 - 2.6) / 0.01 = 240 Ohms.
• Multiplexing: For multi-digit displays, a common cathode configuration is ideal for multiplexing. By sequentially enabling the common cathode of one digit while driving the anodes for the desired segments, many digits can be controlled with fewer I/O pins. The peak current rating (90mA @ 10% duty) allows for this.
• Viewing Angle: The datasheet claims a \"wide viewing angle,\" which is beneficial for applications where the display may be viewed from the side.
• Thermal Management: In high ambient temperature applications or when driving at high currents, consider the current derating factor. Ensure adequate spacing on the PCB for heat dissipation.

8. Technical Comparison and Differentiation

The primary differentiator of the LTS-4301KD is its use of AlInGaP (Aluminum Indium Gallium Phosphide) technology for the LED chips, compared to older displays using GaAsP or standard red GaP.

• vs. Traditional Red GaAsP/GaP LEDs: AlInGaP offers significantly higher luminous efficiency, meaning brighter output at the same drive current. It also provides better color saturation (a deeper, more pure red at 650nm vs. ~630nm for standard red) and superior performance stability over temperature and time.
• vs. Other Colors/Sizes: Within a manufacturer's lineup, this 0.4\" Hyper Red device would be compared to other digit heights (e.g., 0.3\\

  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°	Angle where light intensity drops to half, determines beam width.	Affects illumination range and uniformity.
  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"	Color consistency metric, smaller steps mean more consistent color.	Ensures uniform color across same batch of 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	Design Considerations
  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: better heat dissipation, higher efficacy, for high-power.
  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.	Ensures uniform brightness in same batch.
  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	Ensures no harmful substances (lead, mercury).	Market access requirement internationally.
  ENERGY STAR / DLC	Energy efficiency certification	Energy efficiency and performance certification for lighting.	Used in government procurement, subsidy programs, enhances competitiveness.