LTS-4801KF LED Display Datasheet - 0.4-inch Digit Height - Yellow-Orange Color - 2.6V Forward Voltage - 70mW Power Dissipation - English Technical Document

1. Product Overview

The LTS-4801KF is a compact, high-performance single-digit seven-segment display designed for applications requiring clear numeric readouts. Its primary function is to provide a visual numeric output in electronic devices. The core advantage of this device lies in its utilization of advanced AlInGaP (Aluminum Indium Gallium Phosphide) LED chip technology, which offers superior brightness and efficiency compared to traditional materials. The target market includes industrial control panels, instrumentation, test equipment, consumer electronics, and any embedded system requiring a reliable, easy-to-read numeric display.

2. In-Depth Technical Parameter Analysis

2.1 Photometric and Optical Characteristics

The optical performance is central to this display's functionality. At a standard test current of 20mA, the average luminous intensity (Iv) has a typical value of 44,000 µcd (microcandelas), with a minimum specified value of 27,520 µcd. This high brightness ensures excellent visibility. The light emitted is in the yellow-orange spectrum. The peak emission wavelength (λp) is typically 611 nm, while the dominant wavelength (λd) is typically 605 nm. The spectral line half-width (Δλ) is approximately 17 nm, indicating a relatively pure, saturated color output. The display features a gray face with white segments, which contributes to a high contrast ratio for improved readability under various lighting conditions.

2.2 Electrical Parameters

The electrical specifications define the operating limits and conditions for reliable use. The absolute maximum ratings are critical for design:

• Power Dissipation per Segment: 70 mW maximum.
• Peak Forward Current per Segment: 60 mA maximum (under pulsed conditions: 1/10 duty cycle, 0.1ms pulse width).
• Continuous Forward Current per Segment: 25 mA maximum at 25°C. This rating derates linearly at 0.28 mA/°C as ambient temperature increases above 25°C.
• Reverse Voltage per Segment: 5 V maximum.
• Forward Voltage per Segment (Vf): Typically 2.6V, with a range from 2.05V to 2.6V at IF=20mA.
• Reverse Current per Segment (Ir): 100 µA maximum at VR=5V.

The luminous intensity matching ratio between segments (for similar lit areas) is specified at a maximum of 2:1, ensuring uniform brightness across the digit.

2.3 Thermal and Environmental Specifications

The device is rated for an operating temperature range of -35°C to +105°C, and a storage temperature range of -35°C to +105°C. This wide range makes it suitable for use in harsh environments. The derating of continuous forward current is a direct thermal consideration to prevent overheating and ensure long-term reliability.

3. Binning System Explanation

The datasheet indicates that the devices are categorized for luminous intensity. This implies a binning system where units are sorted and sold based on their measured light output. Typically, bins are defined by ranges of luminous intensity (e.g., Bin A: 27,520-35,000 µcd, Bin B: 35,001-44,000 µcd). This allows designers to select parts that meet specific brightness requirements for their application, ensuring consistency in production runs. While not explicitly detailed for wavelength, such categorization is also common for dominant or peak wavelength to maintain color consistency.

4. Performance Curve Analysis

While specific graphical data is referenced ("Typical Electrical / Optical Characteristic Curves"), the curves typically included in such datasheets are crucial for understanding device behavior beyond single-point specifications. These would generally include:

• Relative Luminous Intensity vs. Forward Current (I-V Curve): Shows how light output increases with current, helping to optimize drive current for desired brightness and efficiency.
• Forward Voltage vs. Forward Current: Essential for designing the current-limiting circuitry.
• Relative Luminous Intensity vs. Ambient Temperature: Demonstrates how brightness decreases as temperature rises, which is critical for high-temperature or high-power applications.
• Spectral Distribution: A graph showing the intensity of light emitted across different wavelengths, confirming the yellow-orange color characteristics.

Designers should use these curves to predict performance under non-standard conditions (different currents, temperatures) and to ensure the display meets visibility requirements throughout the product's operating life.

5. Mechanical and Package Information

The LTS-4801KF is a through-hole component with a standard 10-pin single-row configuration. The digit height is 0.4 inches (10.16mm). The package dimensions drawing provides all critical mechanical measurements. Key tolerances include: ±0.25mm (0.01") for most dimensions and a pin tip shift tolerance of +0.4mm. The pin connection diagram is essential for correct PCB layout:

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

The device uses a common anode configuration, meaning all LED segment anodes are connected internally to common pins (3 and 8). To illuminate a segment, its corresponding cathode pin must be driven low (connected to ground) while the common anode is held at a positive voltage through a current-limiting resistor.

6. Soldering and Assembly Guidelines

The datasheet specifies soldering conditions to prevent damage during assembly: the component can be subjected to wave or hand soldering with the condition that the solder temperature at 1/16 inch (approximately 1.6mm) below the seating plane does not exceed 260°C for more than 3 seconds. Alternatively, the temperature of the unit itself during assembly must not exceed its maximum temperature rating. For modern assembly, if using reflow soldering, a profile suitable for through-hole components with similar thermal limits should be used. It is a lead-free package compliant with RoHS (Restriction of Hazardous Substances) directives. Proper ESD (Electrostatic Discharge) handling procedures should be followed during storage and assembly.

7. Packaging and Ordering Information

The part number is LTS-4801KF. The "KF" suffix likely denotes specific package or terminal finish details. While exact packaging details (reel, tube, tray) and quantities are not specified in the provided excerpt, typical packaging for such displays is in anti-static tubes or trays. The datasheet revision is C, and the effective date is 06/24/2010, which should be verified for current specifications.

8. Application Recommendations

8.1 Typical Application Scenarios

This display is ideal for any device requiring a single numeric digit. Common applications include: panel meters for voltage, current, or temperature; digital clocks and timers; scoreboards; appliance controls (ovens, microwaves); automotive dashboard indicators (e.g., gear position); and industrial equipment status displays.

8.2 Design Considerations

• Current Limiting: External current-limiting resistors are mandatory for each common anode connection. The resistor value is calculated using R = (Vsupply - Vf) / If, where Vf is the forward voltage (~2.6V) and If is the desired forward current (max 25mA continuous). Using a 5V supply, R = (5V - 2.6V) / 0.02A = 120 Ohms.
• Multiplexing: For multi-digit displays using similar components, multiplexing can be used to control multiple digits with fewer I/O pins. Since this is a common anode display, multiplexing involves sequentially enabling (powering) one digit's common anode at a time while presenting the segment data for that digit on the cathode lines.
• Viewing Angle: The wide viewing angle is beneficial for applications where the display may be viewed from off-axis positions.
• Brightness Control: Brightness can be adjusted by varying the forward current (within limits) or by using pulse-width modulation (PWM) on the drive signals.

9. Technical Comparison and Differentiation

The key differentiators of the LTS-4801KF are its use of AlInGaP technology and specific design choices. Compared to older GaAsP or GaP LED displays, AlInGaP offers significantly higher luminous efficiency, resulting in greater brightness for the same current, or equivalent brightness at lower power. The gray face/white segment combination is optimized for high contrast. Its 0.4-inch digit height fills a specific niche between smaller (0.3") and larger (0.5", 0.56") displays. The dual common anode pins (3 and 8) provide design flexibility and can help in balancing current distribution.

10. Frequently Asked Questions (FAQs)

Q: What is the difference between common anode and common cathode?
A: In a common anode display, all anodes are connected together. You apply a positive voltage to the common pin and ground the cathode of the segment you want to light. In a common cathode display, all cathodes are connected together. You ground the common pin and apply a positive voltage to the anode of the segment you want to light. The LTS-4801KF is a common anode type.

Q: Can I drive this display directly from a microcontroller pin?
A: No. A microcontroller pin cannot typically source or sink the 20-25mA required per segment (and much more if multiple segments are lit simultaneously on one common anode). You must use a driver circuit, such as a transistor array (e.g., ULN2003) to switch the common anodes and possibly the segment cathodes, with appropriate current-limiting resistors.

Q: What does "Luminous Intensity Matching Ratio 2:1" mean?
A> It means that the dimmest segment in a lit digit will be no less than half as bright as the brightest segment. This ensures visual uniformity across the displayed number.

Q: Is a heat sink required?
A> For continuous operation at the maximum continuous current (25mA/segment) and high ambient temperatures, careful consideration of the PCB layout as a heat sink is necessary due to the power dissipation derating. In most typical applications at lower currents or with multiplexing, no additional heat sink is needed.

11. Practical Application Example

Consider designing a simple digital thermometer displaying a single digit (e.g., tens place). The microcontroller reads a temperature sensor, processes the data, and determines which digit (0-9) to display. A driver IC like the MAX7219 or a discrete transistor circuit is used. The microcontroller sends a BCD (Binary-Coded Decimal) code or direct segment map to the driver. The driver, in turn, provides the correct low signals on cathode pins A-G and D.P. while supplying power to the common anode pin. A current-limiting resistor is placed in series with the common anode connection. The high brightness of the AlInGaP display ensures the temperature is readable even in a well-lit room.

12. Technical Principle Introduction

The LTS-4801KF is based on semiconductor electroluminescence. The AlInGaP (Aluminum Indium Gallium Phosphide) material is a direct bandgap semiconductor. When forward-biased (positive voltage applied to the anode relative to the cathode), electrons and holes are injected into the active region where they recombine. This recombination releases energy in the form of photons (light). The specific composition of the AlInGaP alloy determines the bandgap energy, which directly corresponds to the wavelength (color) of the emitted light—in this case, yellow-orange (~605-611 nm). The non-transparent GaAs substrate helps improve contrast by absorbing stray light. The seven segments are individual LED chips or chip arrangements wired to separate cathode pins but sharing common anode connections, allowing independent control to form numeric characters.

13. Technology Trends and Context

While seven-segment LED displays remain a robust and cost-effective solution for numeric readouts, the broader display technology landscape has evolved. Trends include a shift towards surface-mount device (SMD) packages for automated assembly, higher-density multi-digit modules, and the integration of drivers and controllers into the display package. Organic LED (OLED) and advanced liquid crystal display (LCD) technologies offer alternatives with different trade-offs in power consumption, viewing angle, and customizability. However, for applications demanding extreme reliability, wide temperature range operation, high brightness, and simplicity, discrete LED segment displays like the LTS-4801KF continue to be a preferred choice. The use of AlInGaP represents an advancement over older LED materials, offering better efficiency and color stability.