LTS-2801AJE LED Display Datasheet - 0.28-inch Digit Height - Red Color - 2.6V Forward Voltage - English Technical Document

1. Product Overview

The LTS-2801AJE is a high-performance, single-digit, seven-segment alphanumeric display module designed for applications requiring clear, bright numeric readouts. Its core function is to visually represent the digits 0-9 and some letters by selectively illuminating its seven individual LED segments (labeled A through G) and an optional decimal point (D.P.). The device utilizes advanced AS-AlInGaP (Aluminum Indium Gallium Phosphide) red LED chips, which are epitaxially grown on a Gallium Arsenide (GaAs) substrate. This material technology is chosen for its high efficiency and excellent luminous output in the red spectrum. The display features a distinctive gray faceplate with white segment markings, providing high contrast between illuminated and non-illuminated states for optimal readability under various lighting conditions.

The primary application domains for this component are industrial instrumentation, consumer electronics, test and measurement equipment, automotive dashboards (for secondary displays), and household appliances where a compact, reliable, and low-power numeric indicator is required. Its solid-state construction ensures high reliability and long operational life compared to legacy technologies like vacuum fluorescent displays (VFDs) or incandescent bulbs.

1.1 Core Advantages and Features

The LTS-2801AJE incorporates several design features that contribute to its performance and ease of use in electronic designs.

• 0.28-Inch Digit Height (7.0 mm): Offers a character size suitable for panel mounting where space is limited but readability from a moderate distance is necessary.
• Continuous Uniform Segments: The segments are designed with consistent width and illumination, ensuring a professional and cohesive appearance when characters are displayed.
• Low Power Requirement: Engineered for efficiency, it operates at standard LED drive currents, making it suitable for battery-powered or energy-conscious devices.
• Excellent Character Appearance & High Contrast: The gray-on-white design, combined with the bright red emission, creates sharp, well-defined characters that are easy to read.
• High Brightness: The AlInGaP technology delivers high luminous intensity, ensuring visibility in brightly lit environments.
• Wide Viewing Angle: The LED chip and package design provide a broad viewing cone, allowing the display to be read from various angles without significant loss of brightness or contrast.
• Solid-State Reliability: As an LED-based device, it boasts high shock and vibration resistance, instant-on capability, and a long lifespan with minimal degradation over time.
• Categorized for Luminous Intensity: Units are binned or tested to ensure consistent brightness levels, which is critical for multi-digit displays where uniformity is key.
• Lead-Free Package: The device is compliant with RoHS (Restriction of Hazardous Substances) directives, utilizing environmentally friendly materials in its construction.

2. Technical Parameters: In-Depth Objective Interpretation

This section provides a detailed, objective analysis of the key electrical and optical parameters specified in the datasheet, explaining their significance for design engineers.

2.1 Absolute Maximum Ratings

These ratings define the stress limits beyond which permanent damage to the device may occur. Operation under or at these limits is not guaranteed and should be avoided in reliable design.

• Power Dissipation per Segment (70 mW): The maximum allowable power that can be dissipated as heat by a single LED segment under continuous operation. Exceeding this can lead to overheating and accelerated degradation of the LED chip.
• Peak Forward Current per Segment (90 mA @ 1 kHz, 10% duty cycle): The maximum instantaneous current a segment can handle in a pulsed mode. The 10% duty cycle and 1 kHz frequency are critical; the average current must still be managed to stay within the continuous current rating. This rating is relevant for multiplexing schemes or PWM dimming at high peak currents.
• Continuous Forward Current per Segment (25 mA): The maximum DC current recommended for continuous illumination of a single segment. The datasheet specifies a derating factor of 0.33 mA/°C above 25°C ambient temperature (Ta). This means if the operating environment is hotter, the maximum safe continuous current decreases linearly. For example, at 85°C, the maximum current would be approximately: 25 mA - [ (85°C - 25°C) * 0.33 mA/°C ] = 25 mA - 19.8 mA = 5.2 mA. This derating is crucial for ensuring reliability in high-temperature applications.
• Reverse Voltage per Segment (5 V): The maximum voltage that can be applied in the reverse bias direction across an LED segment. Exceeding this can cause a sudden breakdown and failure of the LED junction. Circuit designs must ensure this limit is not surpassed, often using protection diodes in matrix configurations.
• Operating & Storage Temperature Range (-35°C to +85°C): Defines the environmental temperature limits for reliable operation and non-operational storage. Performance within this range is specified; operation outside it may lead to parameter drift or failure.
• Soldering Conditions (260°C for 3 seconds, 1/16 inch below seating plane): Provides guidelines for wave or reflow soldering to prevent thermal damage to the plastic package and internal wire bonds. Adherence to these conditions is essential during PCB assembly.

2.2 Electrical & Optical Characteristics (Ta = 25°C)

These are the typical operating parameters measured under specified test conditions. They form the basis for circuit design.

• Average Luminous Intensity (I_V): Min: 200 µcd, Typ: 600 µcd @ I_F=1mA. This is the light output (in microcandelas) at a very low drive current. It indicates the basic efficiency of the LED. The wide range (200-600) suggests a binning process, where devices are sorted by brightness.
• Forward Voltage per Segment (V_F): Typ: 2.05V, Max: 2.6V @ I_F=20mA. This is the voltage drop across the LED when conducting the specified current. It is critical for designing the current-limiting resistor value. Using the typical value for calculation provides a nominal design, but using the maximum value ensures the resistor is sized correctly even for a high-V_F device, preventing excessive current.
• Peak Emission Wavelength (λ_p): 632 nm @ I_F=20mA. This is the wavelength at which the LED emits the most optical power. It defines the perceived color (red).
• Dominant Wavelength (λ_d): 624 nm @ I_F=20mA. This is the single wavelength perceived by the human eye to match the color of the LED's light. It is often closer to the visual perception than the peak wavelength, especially for broad-spectrum sources.
• Spectral Line Half-Width (Δλ): 20 nm @ I_F=20mA. This parameter indicates the spectral purity or bandwidth of the emitted light. A value of 20 nm is typical for a standard red AlInGaP LED, meaning the light output is spread across a range of wavelengths approximately 20 nm wide, centered around the peak wavelength.
• Reverse Current per Segment (I_R): Max: 100 µA @ V_R=5V. This is the small leakage current that flows when the LED is reverse-biased at its maximum rated voltage.
• Luminous Intensity Matching Ratio (I_V-m): 2:1 @ I_F=1mA. This specifies the maximum allowable ratio between the brightest and dimmest segment within a single device. A ratio of 2:1 means the dimmest segment will be at least half as bright as the brightest segment, ensuring visual uniformity of the displayed character.

3. Binning System Explanation

The datasheet explicitly mentions that the devices are \"Categorized for Luminous Intensity.\" This refers to a common practice in LED manufacturing known as \"binning.\" Due to inherent variations in the semiconductor epitaxial growth and fabrication process, LEDs from the same production batch can have slightly different characteristics, primarily forward voltage (V_F) and luminous intensity (I_V).

To ensure consistency for the end-user, especially in multi-digit displays where multiple units are used side-by-side, manufacturers test and sort (bin) the LEDs after production. The LTS-2801AJE is binned primarily for luminous intensity, as indicated. This means that within a given order or reel, the displays will have a guaranteed minimum brightness and a maximum variation (implied by the 2:1 matching ratio per device and the binning across devices). While not detailed in this brief datasheet, a full procurement specification would define specific bin codes for intensity (e.g., BIN 1: 200-300 µcd, BIN 2: 300-400 µcd, etc.). Designers requiring tight brightness matching across multiple displays should specify the bin code when ordering.

4. Performance Curve Analysis

The datasheet references \"Typical Electrical / Optical Characteristic Curves\" on the final page. Although the specific graphs are not provided in the text, we can infer their standard content and utility based on typical LED datasheets.

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

This graph would plot the current through an LED segment against the voltage across it. It shows the exponential relationship characteristic of a diode. The \"knee\" of this curve, typically around 1.8V-2.0V for red AlInGaP LEDs, is where conduction begins significantly. The curve allows designers to understand the V_F at currents other than the tested 20mA, which is essential for low-power or PWM-driven designs.

4.2 Luminous Intensity vs. Forward Current

This is one of the most important curves. It shows how light output (in µcd or mcd) increases with drive current. For most LEDs, this relationship is roughly linear over a significant range but will saturate at very high currents due to thermal and efficiency droop. This graph helps designers choose an operating current to achieve a desired brightness level while balancing efficiency and device lifetime.

4.3 Luminous Intensity vs. Ambient Temperature

This curve illustrates how light output decreases as the ambient temperature (T_a) increases. LED efficiency drops with rising junction temperature. This graph is critical for applications operating in non-room-temperature environments, as it quantifies the brightness loss that must be compensated for, either by design margin or thermal management.

4.4 Relative Spectral Power Distribution

This graph plots the intensity of emitted light across the wavelength spectrum. It would show a single peak around 632 nm (as per λ_p) with a width defined by Δλ (20 nm). This information is vital for optical system design, color sensing applications, or when specific spectral content is a requirement.

5. Mechanical and Packaging Information

5.1 Package Dimensions and Drawing

The datasheet includes a detailed dimensional drawing (referenced as \"PACKAGE DIMENSIONS\"). Key specifications from such a drawing typically include:

• Overall height, width, and depth of the display module.
• Digit height and segment dimensions.
• Precise lead (pin) spacing, diameter, and length.
• Location of the decimal point relative to the digit.
• Any mounting hole or peg locations.
• All dimensions are provided in millimeters with a standard tolerance of ±0.25 mm unless otherwise noted. This drawing is essential for creating the PCB footprint, designing the front panel cutout, and ensuring proper mechanical fit.

5.2 Pin Connection and Internal Circuit Diagram

The device has a 10-pin single-row configuration. The pinout is clearly defined:

1. Cathode E
2. Cathode D
3. Common Anode
4. Cathode C
5. Cathode D.P. (Decimal Point)
6. Cathode B
7. Cathode A
8. Common Anode
9. Cathode G
10. Cathode F

The internal circuit diagram shows that it is a Common Anode configuration. This means the anodes of all LED segments (and the decimal point) are connected internally to two common pins (Pin 3 and Pin 8, which are likely connected internally). To illuminate a segment, its corresponding cathode pin must be driven to a low logic level (ground or a current sink) while a positive voltage is applied to the common anode pin(s). This configuration is common and often interfaces easily with microcontroller GPIO pins configured as open-drain or with external current-sinking driver ICs.

6. Soldering and Assembly Guidelines

The datasheet provides specific soldering conditions: 260°C for 3 seconds, with the solder wave or reflow heat applied 1/16 inch (approximately 1.6 mm) below the seating plane of the package. This is a critical process parameter.

• Purpose: To ensure sufficient heat reaches the solder joints on the pins to form a reliable connection without exposing the main plastic body of the display to excessive temperature, which could cause warping, discoloration, or internal damage to the wire bonds connecting the LED chips to the pins.
• Design Implication: When designing the PCB, the pad layout should allow the solder to flow and wet correctly while respecting the thermal mass of the pins. The recommended distance below the seating plane helps process engineers set up their wave soldering machine or reflow oven profile correctly.
• Storage Conditions: While not explicitly stated beyond the storage temperature range (-35°C to +85°C), it is standard practice to store moisture-sensitive components in dry packaging. If the device is exposed to ambient humidity, a baking process may be required before soldering to prevent \"popcorning\" (internal delamination caused by rapid vapor expansion during reflow).

7. Application Suggestions and Design Considerations

7.1 Typical Application Circuits

For a common anode display like the LTS-2801AJE, the basic drive circuit involves:

1. Current-Limiting Resistors: A resistor must be placed in series with each cathode pin (or each segment group if multiplexing). The resistor value (R_limit) is calculated using Ohm's Law: R_limit = (V_supply - V_F) / I_F. Using the maximum V_F (2.6V) ensures safe operation. For a 5V supply and a desired I_F of 20mA: R = (5V - 2.6V) / 0.02A = 120 Ω. A standard 120Ω or 150Ω resistor would be suitable.
2. Driver Circuitry: The cathodes can be driven directly by microcontroller pins if they can sink the required current (e.g., 20mA per segment). For multi-digit multiplexing or higher current, dedicated driver ICs (like the classic 7447 BCD-to-7-segment decoder/driver or modern constant-current LED driver ICs) are recommended. These simplify software control and provide better current regulation.
3. Multiplexing: To control multiple digits with fewer pins, a multiplexing technique is used. The common anodes of different digits are switched on one at a time at a high frequency, while the corresponding cathode patterns for that digit are applied. The human eye perceives all digits as continuously lit due to persistence of vision. This requires the peak current per segment to be higher to maintain average brightness (staying within the 90mA peak rating) and careful timing in software/firmware.

7.2 Design Considerations

• Viewing Angle: Position the display so the primary viewing direction is within its wide viewing cone, typically perpendicular to the face.
• Brightness Control: Brightness can be adjusted by varying the drive current (via resistor value) or by using Pulse Width Modulation (PWM) on the cathode or anode. PWM is more efficient and provides a linear dimming control.
• ESD Protection: LEDs are susceptible to Electrostatic Discharge (ESD). Handle with appropriate ESD precautions during assembly. In harsh environments, consider adding transient voltage suppression on the input lines.
• Thermal Management: While the device itself dissipates little heat, operating at high ambient temperatures requires current derating as specified. Ensure adequate ventilation if multiple displays or other heat-generating components are in close proximity.

8. Technical Comparison and Differentiation

While this datasheet is for a specific part, the LTS-2801AJE can be objectively compared to other display technologies:

• vs. Larger/Smaller Seven-Segment LEDs: The 0.28\" digit is a mid-size option. Smaller digits (0.2\") save space but are harder to read from a distance. Larger digits (0.5\\

  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.