LTS-4801JR 0.39-inch Super Red LED Display Datasheet - Digit Height 10.0mm - Forward Voltage 2.6V - Power 70mW - English Technical Document

1. Product Overview

The LTS-4801JR is a single-digit, seven-segment alphanumeric display module. It features a digit height of 0.39 inches (10.0 millimeters), making it suitable for applications requiring clear, medium-sized numeric readouts. The device utilizes advanced AlInGaP (Aluminum Indium Gallium Phosphide) semiconductor technology to produce a super red color output. The package presents a gray face with white segment markings, providing high contrast for excellent character legibility. This display is designed as a common anode type, which is a common configuration for simplifying drive circuitry in multiplexed applications.

1.1 Key Features and Advantages

• 0.39 Inch Digit Height: Offers a balanced size for good visibility without excessive power consumption.
• Continuous Uniform Segments: Ensures consistent light emission across each segment for a professional appearance.
• Low Power Requirement: Efficient AlInGaP technology allows for bright output at relatively low forward currents.
• High Brightness & High Contrast: The super red AlInGaP chips combined with the gray face/white segment design deliver excellent readability in various lighting conditions.
• Wide Viewing Angle: Provides consistent luminosity and color across a broad viewing range.
• Categorized for Luminous Intensity: Units are binned for intensity, allowing for consistent brightness in multi-digit displays.
• Lead-Free Package (RoHS Compliant): Manufactured in accordance with environmental regulations restricting hazardous substances.
• Solid-State Reliability: LEDs offer long operational life, shock resistance, and vibration tolerance compared to other display technologies.

1.2 Target Applications and Market

This display is intended for use in ordinary electronic equipment. Typical application areas include instrumentation panels, consumer electronics, industrial control readouts, test and measurement equipment, and household appliances where a clear numeric display is required. It is suitable for applications where reliability, readability, and low-power operation are key considerations. The datasheet explicitly cautions against using this device in safety-critical systems (e.g., aviation, medical life-support) without prior consultation, indicating its primary market is commercial and industrial electronics.

2. Technical Specifications and Objective Interpretation

2.1 Absolute Maximum Ratings

These ratings define the limits beyond which permanent damage to the device may occur. Operating the display continuously at or near these limits is not recommended.

• Power Dissipation per Segment: 70 mW. This is the maximum power that can be safely dissipated as heat by a single LED segment.
• Peak Forward Current per Segment: 90 mA. This is allowed only under pulsed conditions (1/10 duty cycle, 0.1ms pulse width) for multiplexing.
• Continuous Forward Current per Segment: 25 mA at 25°C. This current derates linearly by 0.33 mA/°C as ambient temperature (Ta) increases above 25°C. For example, at 50°C, the maximum continuous current would be approximately 25 mA - (0.33 mA/°C * 25°C) = 16.75 mA.
• Operating & Storage Temperature Range: -35°C to +85°C. The device can withstand and operate within this broad temperature range.
• Solder Temperature: 260°C max for 5 seconds, measured 1/16 inch (≈1.6mm) below the seating plane.

2.2 Electrical & Optical Characteristics

These are typical performance parameters measured at an ambient temperature (Ta) of 25°C.

• Average Luminous Intensity (I_V): 200 ucd (Min), 520 ucd (Typ) at I_F=1mA. This is the light output per segment. The 2:1 matching ratio ensures that within a batch, the brightest segment is no more than twice as bright as the dimmest, which is important for uniform appearance.
• Peak Emission Wavelength (λ_p): 639 nm (Typ). This is the wavelength at which the spectral power output is highest, defining the \"super red\" color.
• Dominant Wavelength (λ_d): 631 nm (Typ). This is the single wavelength perceived by the human eye, which may differ slightly from the peak wavelength.
• Spectral Line Half-Width (Δλ): 20 nm (Typ). This indicates the color purity; a smaller value means a more monochromatic light.
• Forward Voltage per Chip (V_F): 2.10V (Min), 2.60V (Typ) at I_F=20mA. This is the voltage drop across an LED when operating. Circuit design must account for this range.
• Reverse Current (I_R): 100 µA (Max) at V_R=5V. This parameter is for test purposes only; the device should not be operated under continuous reverse bias.
• Cross Talk: < 2.5%. This specifies the minimum amount of light leakage from an unlit segment adjacent to a lit one.

3. Binning and Grading System

The datasheet indicates that the LTS-4801JR is \"Categorized for Luminous Intensity.\" This implies a binning process where displays are sorted based on their measured light output at a standard test current (typically 1mA or 20mA). This ensures that when multiple digits are used side-by-side, their brightness appears uniform to the user. Designers should specify if tight intensity matching is required for their application. The document does not specify detailed bin codes or thresholds for wavelength (color) or forward voltage, suggesting primary sorting is based on luminous intensity.

4. Performance Curve Analysis

While the provided text excerpt references \"Typical Electrical / Optical Characteristics Curves,\" the specific graphs are not included in the text. Typically, such a datasheet would include the following essential curves for design analysis:

• Forward Current vs. Forward Voltage (I-V Curve): Shows the nonlinear relationship, crucial for designing current-limiting circuits.
• Luminous Intensity vs. Forward Current (I-L Curve): Demonstrates how light output increases with current, often showing a near-linear relationship within the operating range.
• Luminous Intensity vs. Ambient Temperature: Shows the derating of light output as temperature increases, which is critical for high-temperature environment applications.
• Relative Spectral Power Distribution: A graph plotting intensity against wavelength, showing the peak at ~639nm and the spectral width.

Designers should consult the full PDF for these graphs to make accurate predictions about performance under specific operating conditions.

5. Mechanical and Package Information

5.1 Package Dimensions

The display has a standard through-hole DIP (Dual In-line Package) form factor. Key dimensional notes include:

• All dimensions are in millimeters with a general tolerance of ±0.25mm unless specified otherwise.
• Pin tip shift tolerance is ±0.40 mm, which must be considered for PCB hole placement.
• The recommended PCB hole diameter is 1.0 mm for reliable soldering.
• Quality specifications limit foreign materials, bubbles in the segment, bending of the reflector, and surface ink contamination to ensure optical clarity and aesthetic quality.

5.2 Pin Configuration and Circuit Diagram

The LTS-4801JR is a 10-pin device with a common anode configuration. The internal circuit diagram shows all seven segments (A-G) and the decimal point (DP) with their cathodes connected to individual pins. The anodes for all segments are connected together internally and brought out to two pins (Pin 3 and Pin 8), which are also internally connected. This allows for flexibility in PCB layout and power connection.

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

6. Soldering and Assembly Guidelines

6.1 Automated Soldering (Wave/Reflow)

The recommended condition is 260°C for 5 seconds, measured 1.6mm (1/16 inch) below the seating plane of the package. The temperature of the component body itself must not exceed its maximum rating during this process.

6.2 Manual Soldering

For hand soldering, a temperature of 350°C ±30°C can be used, but the soldering time must be limited to 5 seconds per pin, again measured from 1.6mm below the seating plane. Care must be taken to avoid prolonged heat exposure.

6.3 Storage Conditions

While not explicitly stated for storage, the operating and storage temperature range is -35°C to +85°C. It is good practice to store components in a dry, controlled environment to prevent moisture absorption which can cause \"popcorning\" during soldering.

7. Reliability Testing

The device undergoes a comprehensive suite of reliability tests based on military (MIL-STD), Japanese (JIS), and internal standards. This ensures robustness under various environmental stresses.

• Operating Life Test (RTOL): 1000 hours at maximum rated current under room temperature.
• Environmental Stress Tests: Includes High Temperature/Humidity Storage (65°C/90-95% RH for 500h), High Temperature Storage (105°C for 1000h), Low Temperature Storage (-35°C for 1000h), Temperature Cycling (-35°C to 105°C for 30 cycles), and Thermal Shock.
• Mechanical/Solderability Tests: Solder Resistance (260°C for 10s) and Solderability (245°C for 5s) tests verify the integrity of the pins during assembly processes.

8. Application Notes and Design Considerations

8.1 Critical Application Cautions

• Absolute Maximum Ratings: Exceeding the ratings for current, power, or temperature will cause severe light output degradation or catastrophic failure.
• Drive Circuit Protection: The circuit must protect the LEDs from reverse voltages and voltage transients during power-up/down sequences. A series resistor is insufficient for this; diode clamps or integrated driver ICs with protection features are recommended.
• Constant Current Drive: For consistent brightness and longevity, driving the segments with a constant current source is strongly recommended over a simple voltage source with a series resistor, especially in environments with varying temperature.
• Forward Voltage Range: The driver circuit must be designed to provide the required current over the entire V_F range (2.10V to 2.60V at 20mA).
• Thermal Management: The maximum continuous current must be derated based on the actual operating ambient temperature. Adequate ventilation or heatsinking may be necessary in enclosed or high-temperature environments.
• Avoid Reverse Bias: Continuous reverse bias can cause metal migration within the semiconductor, leading to premature failure.

8.2 Typical Application Circuits

For a common anode display like the LTS-4801JR, the anodes (Pins 3 & 8) are connected to a positive supply voltage (V_CC). Each cathode pin is connected to a current sink. This can be achieved using:

1. Transistor Sinks: NPN transistors or N-channel MOSFETs controlled by a microcontroller.
2. Integrated Driver ICs: Dedicated LED driver chips or microcontroller port pins with sufficient sink current capability (remembering the 25mA per segment limit). A current-limiting resistor is typically placed in series with each segment or in the common anode path when using a voltage source, but a constant current circuit is superior.

For multiplexing multiple digits, the common anodes of different digits are switched sequentially at a high frequency, while the appropriate cathode patterns are displayed for each digit. This reduces the number of required I/O pins.

9. Technical Comparison and Differentiation

The LTS-4801JR differentiates itself through several key attributes:

• Material Technology (AlInGaP): Compared to older GaAsP or GaP LEDs, AlInGaP offers significantly higher efficiency and brightness, especially in the red/orange/amber spectrum, resulting in lower power consumption for the same light output.
• Super Red Color: The 631-639 nm dominant/peak wavelength provides a vibrant, deep red color that is highly saturated and visible.
• Intensity Binning: Not all displays offer guaranteed luminous intensity matching, which is critical for multi-digit applications to avoid uneven brightness.
• Wide Temperature Range: The -35°C to +85°C operating range is robust for industrial and automotive (non-safety-critical) applications.

10. Frequently Asked Questions (Based on Technical Parameters)

Q: Can I drive this display directly from a 5V microcontroller pin?
A: Not directly for sinking current. A microcontroller pin can typically sink 20-25mA, which is at the absolute maximum for one segment. This leaves no safety margin and risks damaging both the LED and the microcontroller. It is always better to use a transistor or driver IC. For sourcing current (to the common anode), a pin may not supply enough current for all segments lit simultaneously (7*20mA=140mA).

Q: Why are there two common anode pins (3 and 8)?
A> They are internally connected. This provides layout flexibility, allows for connecting the anode from both sides of the PCB for lower resistance, and can help in heat dissipation by using both pins.

Q: What is the difference between Peak Wavelength and Dominant Wavelength?
A: Peak Wavelength (λ_p) is the physical peak of the light emission spectrum. Dominant Wavelength (λ_d) is calculated based on the human eye's color response (CIE curve) and represents the perceived color. They are often close but not identical.

Q: How do I calculate the series resistor value?
A> If using a simple voltage source (V_supply), the formula is R = (V_supply - V_F) / I_F. Use the maximum V_F from the datasheet (2.60V) to ensure minimum current is met. For example, with a 5V supply and desired I_F of 20mA: R = (5V - 2.6V) / 0.02A = 120 Ohms. Always recalculate for different supply voltages and currents.

11. Practical Design and Usage Example

Scenario: Designing a 4-digit voltmeter readout.

1. Component Selection: Use four LTS-4801JR displays. Ensure they are from the same intensity bin if uniform brightness is critical.
2. Drive Method: Implement multiplexing. Connect all corresponding segment cathodes (A, B, C,... DP) together across the four displays. Use four NPN transistors (e.g., 2N3904) to control the common anode of each digit individually.
3. Current Control: Place a single current-limiting resistor in the common path of the transistor collectors (before the anodes). Since only one digit is lit at a time, the resistor value is calculated for the total current of one digit (e.g., 8 segments * 5mA each = 40mA). Alternatively, use a constant current driver IC for each cathode line for better accuracy.
4. Microcontroller Interface: Use 7-8 microcontroller pins for the segment patterns (cathodes) and 4 pins to control the digit select transistors (anodes).
5. Software: In the main loop, sequentially turn on one digit transistor, output the segment pattern for that digit, wait a short time (1-5ms), then move to the next digit. The refresh rate should be above 60Hz to avoid flicker.
6. Protection: Add small-value resistors (e.g., 100Ω) in series with the base of each transistor and the microcontroller pins to limit current. Ensure the power supply is clean and free of spikes.

12. Operating Principle

A Light Emitting Diode (LED) is a semiconductor p-n junction diode. When a forward voltage exceeding the diode's threshold (V_F) is applied, electrons from the n-type material recombine with holes from the p-type material in the depletion region. This recombination event releases energy. In standard diodes, this energy is primarily thermal. In LED materials like AlInGaP, the bandgap energy of the semiconductor is such that the released energy is in the form of photons (light). The specific wavelength (color) of the light is directly determined by the bandgap energy of the semiconductor material. AlInGaP has a bandgap that produces photons in the red to amber part of the visible spectrum. The seven-segment display simply packages multiple such LED chips (one per segment and the decimal point) into a standard arrangement, with their electrical connections brought out to pins for external control.

13. Technology Trends

The use of AlInGaP represents an advancement over earlier LED materials for red/orange colors. Current trends in display technology relevant to such components include:

• Increased Efficiency: Ongoing material science research aims to improve the internal quantum efficiency (IQE) and light extraction efficiency of LEDs, leading to higher brightness at lower currents.
• Miniaturization: While 0.39-inch is a standard size, there is a trend towards smaller, high-density displays using surface-mount device (SMD) packages rather than through-hole DIP packages for automated assembly.
• Integration: Driver electronics are increasingly being integrated either into the display module itself (intelligent displays) or into more sophisticated, multi-channel constant current driver ICs that simplify system design.
• Broader Color Gamut: While this is a monochromatic display, the underlying material technology development for red LEDs also benefits full-color RGB displays, pushing for purer and more saturated colors.
• Focus on Reliability and Standardization: As LEDs penetrate more demanding applications, standardized testing (as seen in the reliability section) and more detailed lifetime specifications (L70, L90 ratings) are becoming common.

Despite these trends, discrete seven-segment displays like the LTS-4801JR remain highly relevant for applications requiring simple, reliable, low-cost, and highly readable numeric output where a full graphic display is unnecessary.