LTS-4801JG LED Display Datasheet - 0.4-inch Digit Height - AlInGaP Green - 2.6V Forward Voltage - 70mW Power Dissipation - English Technical Document

1. Product Overview

The LTS-4801JG is a single-digit, seven-segment numeric display utilizing AlInGaP (Aluminum Indium Gallium Phosphide) semiconductor technology to produce green light. It is designed as a common anode device, meaning the anodes of all LED segments are connected internally and brought out to common pins, while each segment cathode is individually accessible. This configuration is common in multiplexed display applications. The display features a gray face with white segments, which enhances contrast and readability under various lighting conditions. Its primary application is in electronic equipment where a clear, bright, single-digit numeric readout is required, such as in instrumentation panels, consumer appliances, and industrial controls.

1.1 Core Advantages

• High Brightness & Contrast: The AlInGaP material system provides high luminous efficiency, resulting in excellent brightness. The gray face/white segment design further improves contrast for superior character appearance.
• Low Power Consumption: The device operates at relatively low forward currents, making it suitable for battery-powered or energy-efficient applications.
• Solid-State Reliability: As an LED-based device, it offers long operational life, shock resistance, and fast switching times compared to legacy technologies like incandescent or vacuum fluorescent displays.
• Categorized Performance: The luminous intensity is categorized, allowing for consistent brightness matching in multi-digit displays.
• Wide Viewing Angle: The package and chip design provide a broad viewing angle, ensuring the display is legible from various positions.
• Lead-Free Package: The device is compliant with RoHS (Restriction of Hazardous Substances) directives.

1.2 Target Applications

This display is intended for use in ordinary electronic equipment. Typical applications include office automation equipment (e.g., copiers, printers), communication devices, household appliances (e.g., microwaves, ovens, washing machines), test and measurement instruments, and industrial control panels. It is not designed for applications requiring exceptional reliability where failure could jeopardize life or health (e.g., aviation, medical life-support) without prior consultation and qualification.

2. Technical Specifications Deep Dive

2.1 Absolute Maximum Ratings

These ratings define the limits beyond which permanent damage to the device may occur. Operation under or at these conditions is not guaranteed.

• Power Dissipation per Segment: 70 mW. This is the maximum power that can be dissipated by a single LED segment without causing damage.
• Peak Forward Current per Segment: 60 mA. This is allowed only under pulsed conditions (1/10 duty cycle, 0.1ms pulse width) to prevent overheating.
• Continuous Forward Current per Segment: 25 mA at 25°C. This current must be derated linearly by 0.33 mA/°C as ambient temperature (Ta) increases above 25°C.
• Operating & Storage Temperature Range: -35°C to +85°C. The device can be stored and operated within this full range.
• Solder Temperature: Maximum 260°C for 5 seconds, measured 1/16 inch (approx. 1.6mm) below the seating plane.

2.2 Electrical & Optical Characteristics

These are typical operating parameters measured at Ta=25°C, defining the device's performance under normal conditions.

• Average Luminous Intensity (I_V): 320 to 850 μcd (microcandelas) at a forward current (I_F) of 1 mA. This wide range indicates the device is categorized (binned) for intensity.
• Peak Emission Wavelength (λ_p): 571 nm (typical). This is the wavelength at which the emitted light intensity is highest, in the green region of the spectrum.
• Dominant Wavelength (λ_d): 572 nm (typical). This is the wavelength perceived by the human eye, closely matching the peak wavelength.
• Spectral Line Half-Width (Δλ): 15 nm (typical). This specifies the bandwidth of the emitted light, indicating a relatively pure green color.
• Forward Voltage per Chip (V_F): 2.05V to 2.6V at I_F=20 mA. This is the voltage drop across the LED when operating. Circuit design must account for this range.
• Reverse Current per Segment (I_R): Maximum 100 μA at a reverse voltage (V_R) of 5V. This parameter is for test purposes only; continuous reverse bias operation is not allowed.
• Luminous Intensity Matching Ratio: Maximum 2:1 for segments within the \"similar light area.\" This ensures uniformity in appearance across the digit.
• Crosstalk: Specification is less than 2.5%. This refers to unwanted illumination of a non-driven segment due to electrical leakage or optical coupling.

3. Binning System Explanation

The datasheet indicates that the luminous intensity is \"categorized.\" This typically means the devices are tested and sorted (binned) after production based on their measured light output at a standard test current (1mA in this case). The binning ensures that displays used together in a multi-digit application will have matched brightness, preventing one digit from appearing noticeably dimmer or brighter than its neighbors. Designers should specify or be aware of the intensity bin when ordering for consistency in their application.

4. Performance Curve Analysis

The datasheet references \"Typical Electrical / Optical Characteristics Curves.\" While the specific graphs are not provided in the text excerpt, such curves typically illustrate the relationship between key parameters. Based on standard LED behavior, expected curves include:

• I-V (Current-Voltage) Curve: Shows the exponential relationship between forward voltage (V_F) and forward current (I_F). The curve will show a turn-on voltage around 2V and then a relatively steep rise.
• Luminous Intensity vs. Forward Current (I_V vs I_F): Shows how light output increases with current. It is generally linear over a range but will saturate at very high currents due to thermal effects.
• Luminous Intensity vs. Ambient Temperature (I_V vs T_a): Illustrates the decrease in light output as the junction temperature rises. This is a critical consideration for high-temperature environments.
• Spectral Distribution: A plot of relative intensity versus wavelength, showing a peak around 571-572 nm with a width of approximately 15 nm at half the maximum intensity.

5. Mechanical & Package Information

5.1 Package Dimensions

The display has a digit height of 0.4 inches (10.0 mm). The detailed mechanical drawing provides all critical dimensions including overall length, width, height, segment size and spacing, and pin locations. Key notes from the drawing include:

• All dimensions are in millimeters with a general tolerance of ±0.25mm unless specified otherwise.
• Pin tip shift tolerance is ±0.40 mm.
• The recommended PCB hole diameter for the pins is 1.10 mm.
• Quality criteria are defined for foreign materials, bubbles in the segment, bending of the reflector, and surface ink contamination.

5.2 Pin Connection & Circuit Diagram

The device has a 10-pin single-row configuration. The internal circuit diagram shows a common anode structure. The pinout is as follows: Pin 1 (Cathode G), Pin 2 (Cathode F), Pin 3 (Common Anode), Pin 4 (Cathode E), Pin 5 (Cathode D), Pin 6 (Cathode Decimal Point), Pin 7 (Cathode C), Pin 8 (Common Anode), Pin 9 (Cathode B), Pin 10 (Cathode A). Note that there are two common anode pins (3 and 8), which are internally connected. This allows for flexibility in PCB layout and can help in current distribution.

6. Soldering & Assembly Guidelines

6.1 Automated Soldering Profile

For wave or reflow soldering, the condition is specified as 260°C maximum for 5 seconds, measured 1.6mm (1/16 inch) below the seating plane of the package. The component body temperature during assembly must not exceed its maximum temperature rating. Adherence to this profile is crucial to prevent damage to the plastic package or the internal wire bonds.

6.2 Manual Soldering

If hand soldering is necessary, the iron tip should be applied to the pin 1.6mm below the seating plane. The soldering temperature should be 350°C ±30°C, and the contact time must not exceed 5 seconds. Using a higher temperature for a very short time minimizes heat transfer to the sensitive LED chips.

7. Application Design Considerations

Several important cautions and recommendations are provided for reliable operation:

• Drive Circuit Protection: The circuit must protect the LEDs from reverse voltages and transient voltage spikes during power-up or shutdown, as these can cause immediate failure.
• Constant Current Drive: This is strongly recommended over constant voltage drive. A constant current source ensures consistent brightness and protects the LED from thermal runaway, as the forward voltage decreases with increasing temperature.
• Accounting for V_F Variation: The driving circuit must be designed to deliver the intended current across the full range of forward voltage (2.05V to 2.6V per chip at 20mA).
• Current Derating: The safe operating continuous current must be chosen after considering the maximum ambient temperature of the application, using the derating factor of 0.33 mA/°C above 25°C.
• Avoid Reverse Bias: Continuous reverse bias operation should be strictly avoided as it can lead to metal migration and premature device failure.

8. Reliability Testing

The device undergoes a series of standardized reliability tests to ensure robustness. The test plan includes:

• Operating Life Test (RTOL): 1000 hours at maximum rated current under room temperature.
• Environmental Tests: High Temperature/Humidity Storage (500 hrs at 65°C/90-95% RH), High Temperature Storage (1000 hrs at 105°C), Low Temperature Storage (1000 hrs at -35°C).
• Stress Tests: Temperature Cycling (30 cycles between -35°C and 105°C) and Thermal Shock (30 cycles between -35°C and 105°C).
• Process Compatibility Tests: Solder Resistance (10 sec at 260°C) and Solderability (5 sec at 245°C).

These tests reference established military (MIL-STD), Japanese industrial (JIS), and internal standards, providing confidence in the component's durability under various storage and operating conditions.

9. Frequently Asked Questions (FAQ)

Q: Can I drive this display with a 5V microcontroller pin directly?
A: No. The forward voltage is around 2.6V max, and a series current-limiting resistor is mandatory. Connecting directly to 5V would destroy the LED due to excessive current. Calculate the resistor value using R = (V_supply - V_F) / I_F.

Q: Why are there two common anode pins?
A> They are internally connected. This design allows for more flexible PCB routing, can help balance current if driving multiple segments simultaneously, and provides mechanical stability.

Q: How do I achieve uniform brightness in a multi-digit display?
A> Use constant current drivers and ensure you use displays from the same or closely matched luminous intensity bins. Implement multiplexing with appropriate segment current and duty cycle.

Q: What is the difference between peak wavelength and dominant wavelength?
A> Peak wavelength is the physical wavelength of highest spectral power. Dominant wavelength is the perceived color point on the CIE chromaticity diagram. For a monochromatic source like this green LED, they are very close.

10. Design-in Case Study

Consider designing a simple digital thermometer display using the LTS-4801JG. The system uses a microcontroller with multiplexed output. Design steps include:

1. Driver Selection: Choose a constant current LED driver IC or design discrete transistor circuits capable of sinking the required segment current (e.g., 10-15 mA for good brightness).
2. Current Setting: Determine the operating current. For example, selecting 10 mA provides good brightness while staying well below the 25 mA maximum, allowing headroom for temperature derating.
3. Multiplexing Scheme: Configure the microcontroller to cycle through the digits rapidly. The common anodes are driven by PNP transistors (or high-side drivers) switched by the MCU, while the segment cathodes are connected to the current sink outputs of the driver IC.
4. PCB Layout: Place the display on the board, ensuring the recommended 1.10mm holes are used. Route the two common anode lines separately to balance current distribution. Keep traces for high-current segment lines short and wide.
5. Thermal Management: If the device is to be used in a high ambient temperature environment (e.g., >50°C), recalculate the maximum allowable continuous current using the derating factor: I_F(max) = 25 mA - [0.33 mA/°C * (T_a - 25°C)].

11. Technology & Principle Introduction

The LTS-4801JG is based on AlInGaP semiconductor technology grown on a non-transparent GaAs substrate. When a forward voltage is applied across the p-n junction, electrons and holes recombine, releasing energy in the form of photons. The specific composition of the AlInGaP alloy determines the bandgap energy, which in turn defines the wavelength of the emitted light—in this case, green (~572 nm). The non-transparent substrate helps improve contrast by absorbing stray light. The seven-segment format is a standardized way to represent numeric digits (0-9) and some letters by selectively illuminating seven independent LED bars (segments A-G) plus a decimal point.

12. Industry Trends

While seven-segment displays remain vital for simple numeric readouts, the industry trend is towards integration and miniaturization. There is a growing use of surface-mount device (SMD) packages for automated assembly. Furthermore, multi-digit monolithic displays and intelligent displays with integrated drivers (I2C, SPI) are becoming more common to simplify system design and reduce component count. However, discrete single-digit components like the LTS-4801JG continue to serve cost-sensitive applications, prototyping, and designs requiring specific mechanical or optical characteristics not offered by integrated modules. The move towards higher efficiency and broader color gamuts in LED technology also influences display components, though for monochromatic displays like this, efficiency and reliability are the primary drivers.