LTS-10804KF LED Display Datasheet - 1.0-inch Digit Height - Yellow-Orange Color - 25mA Forward Current - English Technical Document

1. Product Overview

The LTS-10804KF is a single-digit, seven-segment alphanumeric display designed for applications requiring clear, bright numeric readouts. Its primary function is to visually represent digits (0-9) and some letters using individually controlled LED segments. The device utilizes advanced Aluminum Indium Gallium Phosphide (AlInGaP) semiconductor technology grown on a Gallium Arsenide (GaAs) substrate to produce its characteristic yellow-orange light emission. This material choice is key to its performance, offering higher efficiency and better temperature stability compared to older technologies like standard Gallium Phosphide. The display features a black faceplate with white segment markings, which significantly enhances contrast and readability under various lighting conditions, making it suitable for both indoor and outdoor applications where visibility is critical.

1.1 Core Advantages and Target Market

The LTS-10804KF offers several distinct advantages that position it well in the market for industrial and consumer electronics. Its low power requirement is a primary benefit, allowing integration into battery-powered or energy-sensitive devices without compromising brightness. The high luminous intensity, categorized for consistency, ensures uniform appearance across production batches, which is vital for multi-digit displays in instruments and panels. The solid-state reliability of LEDs translates to a long operational lifetime and resistance to shock and vibration, outperforming traditional incandescent or vacuum fluorescent displays. The wide viewing angle guarantees legibility from various positions, essential for panel meters, test equipment, and status indicators. The lead-free package ensures compliance with global environmental regulations like RoHS. This combination of features makes the display ideal for target markets including industrial control panels, automotive dashboards (for aftermarket accessories), medical instrumentation, test and measurement equipment, and consumer appliances where durable, clear, and efficient numeric display is required.

2. In-Depth Technical Parameter Analysis

A thorough understanding of the electrical and optical specifications is crucial for successful circuit design and integration.

2.1 Absolute Maximum Ratings

These ratings define the stress limits beyond which permanent damage to the device may occur. The maximum power dissipation per segment is 134 mW. The peak forward current per segment is rated at 60 mA, but this is only permissible under pulsed conditions with a 1/10 duty cycle and a 0.1 ms pulse width. For continuous operation, the maximum forward current per segment is 25 mA at 25°C, derating linearly at 0.33 mA/°C as the ambient temperature rises. This derating is critical for thermal management; exceeding the continuous current at a given temperature can lead to overheating, accelerated lumen depreciation, and eventual failure. The operating and storage temperature range is specified from -35°C to +105°C, indicating robust performance in harsh environments. The solder condition specifies a maximum temperature of 260°C for 3 seconds at a distance of 1/16 inch (approximately 1.6 mm) below the seating plane, providing clear guidelines for PCB assembly processes.

2.2 Electrical and Optical Characteristics

These are the typical operating parameters measured at Ta=25°C. The average luminous intensity (Iv) per segment ranges from 420 μcd (minimum) to 1400 μcd (typical) at a forward current (If) of 1 mA. This high brightness at low current is a hallmark of AlInGaP technology. The peak emission wavelength (λp) is 611 nm, and the dominant wavelength (λd) is 605 nm, defining the yellow-orange color point. The spectral line half-width (Δλ) is 17 nm, indicating a relatively narrow spectral bandwidth which contributes to color purity. The forward voltage (Vf) per segment has a typical range of 4.20V to 5.20V at If=20mA. Notably, the decimal point (DP) has a lower forward voltage, shown in parentheses as 2.1V to 2.6V, which must be accounted for in the driving circuit, likely indicating it uses a different chip technology (possibly standard GaP). The reverse current (Ir) is specified at a maximum of 100 μA at a reverse voltage (Vr) of 10V for segments and 5V for the DP. This parameter is for test purposes only, and the device should not be operated under reverse bias. The luminous intensity matching ratio between segments in a similar light area is 2:1 maximum at If=10mA, ensuring acceptable uniformity. Cross-talk between segments is specified to be less than 1.0%, minimizing unwanted illumination of adjacent segments.

3. Binning System Explanation

The datasheet indicates that the device is \"Categorized for Luminous Intensity.\" This implies a binning system is in place, although specific bin codes are not detailed here. In practice, manufacturers often sort LEDs into bins based on key parameters like luminous intensity and forward voltage to ensure consistency within a single production run or order. Designers should consult the manufacturer for detailed binning information if tight intensity matching across multiple displays is required for their application. The typical intensity range provided (420-1400 μcd) gives an indication of the possible spread.

4. Performance Curve Analysis

While the PDF references \"Typical Electrical / Optical Characteristics Curves,\" the specific graphs are not included in the provided content. Typically, such curves for an LED display would include: Forward Current vs. Forward Voltage (I-V Curve): This graph shows the nonlinear relationship between current and voltage. The knee voltage is where the LED begins to emit light significantly. The curve helps in selecting the appropriate current-limiting resistor or designing constant-current drivers. Luminous Intensity vs. Forward Current (L-I Curve): This shows how light output increases with current. It is generally linear over a range but will saturate at high currents due to thermal effects. Luminous Intensity vs. Ambient Temperature: This curve demonstrates the reduction in light output as the junction temperature increases, highlighting the importance of thermal management. Spectral Power Distribution: A graph plotting relative intensity against wavelength, showing the peak at ~611 nm and the shape defined by the 17 nm half-width.

5. Mechanical and Package Information

5.1 Package Dimensions and Tolerances

The display has a digit height of 1.0 inch (25.4 mm). All primary dimensions have a tolerance of ±0.25 mm (0.01\"). Key mechanical notes include limits on foreign materials or bubbles within a segment (≤20 mils), bending of the reflector (≤1% of its length), and surface ink contamination (≤20 mils). The pin tip shift tolerance is ±0.40 mm. The recommended PCB hole diameter for the pins is 1.00 mm, which is important for ensuring proper mechanical fit and solder joint reliability during wave or reflow soldering.

5.2 Pin Configuration and Polarity

The LTS-10804KF is a common anode display. The internal circuit diagram shows all segment anodes connected together to common anode pins (pin 4 and pin 11). Each segment cathode (A-G and DP) has its own dedicated pin. To illuminate a segment, the corresponding common anode pin must be connected to a positive voltage (through a current-limiting resistor or driver), and the segment's cathode pin must be pulled low (sinked to ground). Pins 3, 7, 10, and 13 are noted as \"No Connection\" (N/C). The pinout is: 1:E, 2:D, 3:N/C, 4:Common Anode, 5:C, 6:DP, 7:N/C, 8:B, 9:A, 10:N/C, 11:Common Anode, 12:F, 13:N/C, 14:G.

6. Soldering and Assembly Guidelines

The absolute maximum ratings specify the solder condition: the component body temperature must not exceed its maximum rating during assembly, with a guideline of 260°C for 3 seconds at 1/16 inch below the seating plane. This is typical for wave soldering. For reflow soldering, a standard lead-free profile with a peak temperature around 260°C would be applicable, but the exposure time above liquidus should be controlled. Designers must ensure the PCB layout provides adequate thermal relief to prevent overheating the LED chips through the leads. Prior to soldering, components should be stored within the specified -35°C to +105°C range in dry conditions to prevent moisture absorption, which could cause \"popcorning\" during reflow.

7. Application Recommendations

7.1 Typical Application Circuits

The display requires external current-limiting resistors for each segment or a dedicated LED driver IC. For a simple multiplexed design with a microcontroller, the common anode pins would be switched via PNP transistors or high-side drivers, while the segment cathodes would be connected to microcontroller pins or a shift register with current-sinking capability. The different forward voltage of the decimal point (DP) necessitates a separate current-limiting resistor calculation. A constant current driver is recommended for applications requiring precise brightness control and stability over temperature.

7.2 Design Considerations

• Current Limiting: Always use series resistors or constant-current drivers. Calculate resistor values based on the supply voltage, LED forward voltage (use max Vf for a safe design), and desired forward current (stay well below the 25mA continuous maximum, e.g., 10-15mA for good brightness and longevity).
• Thermal Management: Although power dissipation is low per segment, multi-digit displays or high ambient temperatures require attention. Ensure adequate airflow and consider the derating curve. Avoid placing the display near other heat sources.
• Viewing Angle: The wide viewing angle is beneficial, but for optimal readability, position the display perpendicular to the primary line of sight of the user.
• ESD Protection:** LEDs are sensitive to electrostatic discharge. Implement standard ESD handling procedures during assembly.

8. Technical Comparison and Differentiation

Compared to older red GaAsP or standard green GaP LED displays, the AlInGaP technology in the LTS-10804KF offers superior luminous efficacy, meaning brighter output for the same current, or equivalent output at lower power. The yellow-orange color provides excellent visibility and is often subjectively perceived as brighter than red. Compared to dot-matrix displays, a seven-segment device is simpler to drive and decode, requiring fewer I/O pins for a single digit, making it cost-effective for applications that only need to show numbers. Its main trade-off is the limitation to alphanumeric characters rather than full graphics.

9. Frequently Asked Questions (Based on Technical Parameters)

Q: Why are there two different forward voltage ranges listed (for segments and DP)?
A: The decimal point likely uses a different semiconductor material (e.g., standard GaP for red) with a lower bandgap, resulting in a lower forward voltage. This must be considered when designing the driving circuit.

Q: Can I drive this display with a 5V supply?
A: Yes, but careful calculation of the current-limiting resistor is needed. For a segment with Vf(max)=5.2V at 20mA, a 5V supply is insufficient to overcome the forward voltage. You must either operate at a lower current (where Vf is lower, see typical curves) or use a supply voltage higher than the maximum Vf, such as 6V or 12V, with an appropriate resistor.

Q: What does \"luminous intensity matching ratio 2:1\" mean?
A: It means the measured intensity of the dimmest segment compared to the brightest segment in a similar area (e.g., all \"A\" segments) will not be worse than a 1:2 ratio. The brightest segment will be no more than twice as bright as the dimmest one under the same test conditions.

10. Practical Application Example

Case: Designing a Digital Voltmeter Readout
A designer is creating a 3-digit DC voltmeter. They select three LTS-10804KF displays. The microcontroller has limited I/O, so they use a multiplexing scheme. The three common anode pins (one per digit) are connected to the collector of three PNP transistors, whose emitters are tied to a 12V rail. The microcontroller drives the transistor bases through resistors to switch each digit on sequentially. The segment cathodes (A-G) of all three displays are connected in parallel to the outputs of a single BCD-to-7-segment decoder/driver IC (e.g., 74HC4511). This driver sinks current for the active segments. Separate current-limiting resistors are placed between the driver outputs and the display cathodes. The decimal point for the middle digit (to show tenths of a volt) is driven directly by a microcontroller pin with its own dedicated resistor, calculated for the DP's lower Vf. The multiplexing is fast enough (e.g., 100Hz per digit) to appear continuous to the human eye. This design minimizes component count while providing a clear, bright readout.

11. Operating Principle

A seven-segment LED display is an assembly of light-emitting diodes arranged in a figure-eight pattern. Each of the seven segments (labeled A through G) is a separate LED or a series/parallel combination of LED chips. An additional LED is used for the decimal point (DP). In a common anode configuration like the LTS-10804KF, the anodes of all segments are connected together to one or more common pins. The cathode of each segment is brought out to an individual pin. Light is emitted when a forward bias is applied: the common anode is set to a positive voltage relative to the cathode of the target segment, causing current to flow through that segment's LED(s) and produce photons via electroluminescence in the AlInGaP semiconductor material. By selectively energizing different combinations of segments, the numerals 0-9 and some letters can be formed.

12. Technology Trends

The use of AlInGaP represents a mature and efficient technology for amber, orange, and red LEDs. Current trends in display technology include a shift towards higher-density, full-color solutions like OLEDs and micro-LEDs for complex graphics. However, for simple, low-cost, high-reliability, and high-brightness numeric and alphanumeric indications, segmented LED displays remain highly relevant, especially in industrial, automotive, and outdoor applications. Future developments may focus on further efficiency gains, even wider viewing angles, integration of onboard drivers or controllers (smart displays), and miniaturization while maintaining or increasing digit height for visibility. The drive towards IoT and smart devices may also see these displays used in more connected applications, though their core function as a robust human-machine interface remains constant.