LTS-4801JS LED Display Datasheet - 0.39-inch Digit Height - Yellow Color - 2.6V Forward Voltage - 70mW Power Dissipation - English Technical Document

1. Product Overview

The LTS-4801JS is a compact, high-performance single-digit seven-segment display module designed for applications requiring clear numeric readouts. Its primary function is to visually represent the digits 0-9 and some letters using individually addressable LED segments. The device is engineered for reliability and ease of integration into various electronic systems.

The core technology utilizes AlInGaP (Aluminum Indium Gallium Phosphide) semiconductor material for the LED chips, which are fabricated on a GaAs substrate. This material system is specifically chosen for its efficiency in producing high-brightness yellow light. The display features a gray faceplate with white segment markings, providing excellent contrast and readability under various lighting conditions. The device is categorized based on luminous intensity, ensuring consistent brightness levels for batch-to-batch uniformity.

2. In-Depth Technical Parameter Analysis

2.1 Optical Characteristics

The optical performance is central to the display's functionality. The key parameters are measured under standardized test conditions (typically at an ambient temperature of 25°C).

• Luminous Intensity (I_V): This parameter defines the perceived brightness of the lit segments. With a forward current (I_F) of 1mA, the typical average luminous intensity is 867 μcd (microcandelas), with a minimum specified value of 320 μcd. The measurement is performed using a sensor and filter that mimics the human eye's photopic response curve as defined by the CIE (International Commission on Illumination).
• Peak Emission Wavelength (λ_p): The wavelength at which the LED emits the maximum optical power. For the LTS-4801JS, this is typically 588 nanometers (nm), firmly in the yellow region of the visible spectrum.
• Dominant Wavelength (λ_d): This is 587 nm, which is the single wavelength perceived by the human eye that best matches the color of the emitted light. The close match between peak and dominant wavelength indicates a spectrally pure yellow color.
• Spectral Line Half-Width (Δλ): Measured at 15 nm, this value indicates the spectral purity or the spread of the emitted light's wavelengths around the peak. A narrower half-width generally corresponds to a more saturated, pure color.
• Luminous Intensity Matching Ratio (I_V-m): This ratio, specified as 2:1 maximum, ensures that the brightness difference between the dimmest and brightest segment within a single device does not exceed this factor, guaranteeing uniform appearance.

2.2 Electrical Characteristics

The electrical parameters define the operating boundaries and conditions for safe and reliable use.

• Forward Voltage per Segment (V_F): The voltage drop across an LED segment when conducting current. At a test current of 20mA, the typical forward voltage is 2.6V, with a minimum of 2.05V. This parameter is crucial for designing the current-limiting circuitry.
• Continuous Forward Current per Segment (I_F): The maximum DC current that can be continuously applied to a single segment is 25 mA at 25°C. Beyond this temperature, the rating must be derated linearly at a rate of 0.33 mA per degree Celsius increase.
• Peak Forward Current per Segment: For pulsed operation (1/10 duty cycle, 0.1ms pulse width), a higher peak current of 60 mA is permissible. This allows for multiplexing schemes or brief over-driving for increased perceived brightness.
• Reverse Voltage per Segment (V_R): The maximum voltage that can be applied in the reverse direction across an LED segment without causing damage is 5V. Exceeding this can lead to immediate or latent failure.
• Reverse Current per Segment (I_R): The leakage current when the maximum reverse voltage (5V) is applied is typically 100 μA or less.
• Power Dissipation per Segment (P_D): The maximum power that can be dissipated by a single segment is 70 mW. This is calculated as V_F * I_F and is a critical parameter for thermal management.

2.3 Thermal and Environmental Ratings

These ratings define the device's operational limits concerning temperature and soldering processes.

• Operating Temperature Range: The display is designed to function reliably within an ambient temperature range of -35°C to +85°C.
• Storage Temperature Range: The device can be stored without operation within the same range of -35°C to +85°C.
• Solder Temperature: The device can withstand a wave or reflow soldering process where the temperature at a point 1/16 inch (approximately 1.6mm) below the seating plane reaches 260°C for a duration of 3 seconds. This is a standard rating for lead-free soldering processes.

3. Binning and Categorization System

The datasheet explicitly states that the devices are "categorized for luminous intensity." This indicates a binning process where manufactured units are sorted into groups (bins) based on their measured light output at a standard test current (likely 1mA or 20mA). This ensures that customers receive displays with consistent brightness levels. While the specific bin codes are not detailed in this excerpt, designers should be aware that brightness can vary between minimum (320 μcd) and typical (867 μcd) values, and specifying a bin may be necessary for applications requiring tight brightness matching across multiple displays.

4. Performance Curve Analysis

The datasheet references "Typical Electrical / Optical Characteristic Curves" on the final page. While the specific graphs are not provided in the text, standard curves for such devices typically include:

• Relative Luminous Intensity vs. Forward Current (I-V Curve): This graph shows how light output increases with forward current, usually in a sub-linear fashion, highlighting the importance of current regulation over voltage regulation for consistent brightness.
• Forward Voltage vs. Forward Current: Illustrates the diode's exponential I-V relationship.
• Relative Luminous Intensity vs. Ambient Temperature: Shows the decrease in light output as the junction temperature rises, a key consideration for high-temperature or high-current applications.
• Spectral Distribution: A plot of relative intensity versus wavelength, showing the peak at ~588nm and the 15nm half-width.

These curves are essential for detailed design work, allowing engineers to predict performance under non-standard conditions.

5. Mechanical and Package Information

5.1 Physical Dimensions

The display features a 0.39-inch (10.0 mm) digit height, which refers to the physical size of the individual numeric characters. A detailed dimensioned drawing is provided in the datasheet (Page 2). All dimensions are specified in millimeters (mm) with a standard tolerance of ±0.25mm (0.01 inches) unless otherwise noted. This drawing is critical for PCB (Printed Circuit Board) layout, ensuring the footprint and cutout are designed correctly.

5.2 Pin Configuration and Polarity

The LTS-4801JS is a 10-pin device with a common anode configuration. This means the anodes (positive terminals) of all LED segments are connected together internally and brought out to specific pins, while each segment's cathode (negative terminal) has its own dedicated pin.

Pin Connection Details:

1. Pin 1: Cathode for segment G
2. Pin 2: Cathode for segment F
3. Pin 3: Common Anode (internally connected to Pin 8)
4. Pin 4: Cathode for segment E
5. Pin 5: Cathode for segment D
6. Pin 6: Cathode for Decimal Point (D.P.)
7. Pin 7: Cathode for segment C
8. Pin 8: Common Anode (internally connected to Pin 3)
9. Pin 9: Cathode for segment B
10. Pin 10: Cathode for segment A

Important Note: Pins 3 and 8 are internally connected, providing two connection points for the common anode, which can be useful for PCB routing or redundancy. Pin 6 is dedicated to the right-hand decimal point. The internal circuit diagram visually confirms this common anode architecture, showing all segment LEDs with their anodes tied together.

6. Soldering and Assembly Guidelines

The primary guideline provided is the absolute maximum rating for solder temperature: the device can withstand 260°C for 3 seconds at a point 1.6mm below the seating plane. This aligns with standard lead-free reflow soldering profiles (IPC/JEDEC J-STD-020).

Design Considerations:

• Current Limiting: LEDs are current-driven devices. Each segment must have a series current-limiting resistor (or be driven by a constant current source) to prevent exceeding the maximum continuous forward current (25mA). The resistor value is calculated using Ohm's Law: R = (V_supply - V_F) / I_F, where V_F is the typical forward voltage (2.6V).
• Thermal Management: Ensure the total power dissipation (number of lit segments * V_F * I_F) does not cause excessive heating, especially near the upper limit of the operating temperature range.
• ESD Protection: AlInGaP LEDs can be sensitive to electrostatic discharge (ESD). Standard ESD handling precautions should be observed during assembly.
• Storage: Store devices in a dry, temperature-controlled environment within the specified -35°C to +85°C range.

7. Application Suggestions

7.1 Typical Application Scenarios

The LTS-4801JS is suitable for a wide range of applications requiring a single, highly readable numeric digit:

• Test and Measurement Equipment: Digital multimeters, frequency counters, power supplies, sensor readouts.
• Consumer Electronics: Kitchen appliance timers, bathroom scales, audio equipment level meters.
• Industrial Controls: Panel meters, process control indicators, timer displays.
• Automotive Aftermarket: Gauges and displays for performance monitoring (where environmental specs are suitable).
• Prototyping and Educational Kits: Due to its simplicity and common anode configuration, it is an excellent component for learning about digital electronics and microcontroller interfacing.

7.2 Design Considerations and Interfacing

Microcontroller Interfacing: Driving a common anode display with a microcontroller typically involves:

1. Connecting the common anode pin(s) to a positive voltage source (e.g., 3.3V or 5V) through a transistor or directly if the MCU's GPIO can source sufficient current for multiple segments.
2. Connecting the individual segment cathode pins to the microcontroller's GPIO pins, usually through current-limiting resistors.
3. To light a segment, the corresponding MCU pin is driven LOW (sinking current) while the anode is HIGH.

Multiplexing: While this is a single-digit display, the principle applies if using multiple digits. Multiplexing involves rapidly cycling power between digits, lighting only one digit at a time. This greatly reduces the number of required driver pins. The peak forward current rating (60mA) allows segments to be briefly driven harder during their multiplexed "on" time to compensate for the reduced duty cycle and maintain brightness.

Viewing Angle: The datasheet highlights a "wide viewing angle," which is beneficial for applications where the display may be viewed from off-axis positions.

8. Technical Comparison and Differentiation

The key differentiating factors of the LTS-4801JS are its material technology and specific performance characteristics:

• AlInGaP vs. Traditional Materials: Compared to older technologies like standard GaP (Gallium Phosphide) yellow LEDs, AlInGaP offers significantly higher luminous efficiency and brightness. This results in better readability, especially in well-lit ambient conditions, and potentially lower power consumption for a given light output.
• Color Quality: The specified 587-588nm dominant/peak wavelength produces a pure, saturated yellow, which is often preferred for indicators and displays due to its high visibility and contrast against dark backgrounds.
• Gray Face/White Segments: This combination provides high contrast when the display is off (white on gray) and maintains excellent contrast when lit (bright yellow on gray), enhancing overall readability compared to displays with black faces or other color combinations.
• Reliability: As a solid-state device with no moving parts or fragile filaments, it offers high reliability and long operational lifetime under proper electrical and thermal conditions.

9. Frequently Asked Questions (Based on Technical Parameters)

Q1: What is the purpose of having two common anode pins (3 and 8)?

A1: They are internally connected. This provides design flexibility for PCB layout, allowing the power connection to be routed from either side of the package. It can also help in distributing current if driving all segments simultaneously at high current.

Q2: How do I calculate the correct current-limiting resistor value?

A2: Use the formula R = (V_supply - V_F) / I_F. For a 5V supply, a target segment current of 20mA, and a typical V_F of 2.6V: R = (5 - 2.6) / 0.02 = 120 Ohms. Always use the maximum supply voltage and minimum V_F for a conservative design to avoid over-current: R_min = (5 - 2.05) / 0.025 = 118 Ohms. A standard 120Ω or 150Ω resistor is appropriate.

Q3: Can I drive this display directly from a microcontroller's GPIO pin?

A3: It depends on the MCU. You can sink current (connect cathodes to GPIO set LOW) easily, as a typical MCU GPIO can sink 20-25mA. However, sourcing current for the common anode (setting a pin HIGH) for multiple lit segments may exceed a single pin's source capability. It is common to use a small NPN/PNP transistor or a dedicated driver IC (like a 74HC595 shift register with constant-current outputs) to control the anode power.

Q4: What does "categorized for luminous intensity" mean for my design?

A4: It means displays are tested and sorted by brightness. If your application uses multiple displays and requires them all to have identical brightness, you should specify that you need units from the same intensity bin. For a single display, it ensures you get a device that meets the minimum brightness specification.

10. Practical Design and Usage Example

Scenario: Building a Simple Digital Counter with an Arduino.

1. Hardware Connection: Connect pins 3 and 8 (common anode) to the Arduino's 5V pin through a 100Ω resistor (optional, for extra protection). Connect each of the cathode pins (1,2,4,5,6,7,9,10) to individual Arduino digital pins (e.g., D2 through D9), each via a 150Ω current-limiting resistor.
2. Software Logic: In the Arduino code, define which segments (A-G, DP) are needed to form each digit (0-9). This is typically stored in a byte array (a segment map). To display a number, the code looks up the pattern, sets the Arduino pins connected to the required segment cathodes to LOW (to turn them on), and the others to HIGH. Since the anode is constantly at 5V, this completes the circuit for the selected segments.
3. Consideration: The total current if all segments plus the decimal point are lit would be ~9 segments * 20mA = 180mA sourced from the 5V rail. Ensure your power supply can handle this.

11. Operating Principle

The device operates on the principle of electroluminescence in a semiconductor p-n junction. When a forward voltage exceeding the diode's threshold (approximately 2.05V) is applied across an LED segment, electrons from the n-type AlInGaP layer recombine with holes from the p-type layer within the active region. This recombination event releases energy in the form of photons (light). The specific composition of the AlInGaP alloy determines the bandgap energy of the semiconductor, which directly dictates the wavelength (color) of the emitted photons—in this case, yellow light around 588nm. The seven segments (A through G) and the decimal point (DP) are individual LED chips that can be independently controlled by applying forward bias to their respective cathode-anode paths.

12. Technology Trends and Context

AlInGaP technology represents a significant advancement in visible LED performance, particularly for red, orange, amber, and yellow colors. It largely superseded older GaAsP and GaP technologies due to its superior efficiency and brightness. The trend in display technology has moved towards higher integration—such as multi-digit modules, dot-matrix displays, and eventually full graphical OLED or TFT-LCD screens—which offer greater flexibility but often at higher complexity and cost. However, discrete seven-segment LEDs like the LTS-4801JS remain highly relevant for applications where cost, simplicity, reliability, extreme readability of a single number, or high brightness in ambient light are paramount. They serve as a fundamental, robust solution in a world of increasingly complex display technologies.