LTS-367KR-02 LED Display Datasheet - 0.36-inch Digit Height - Super Red Color - 2.6V Forward Voltage - English Technical Document

1. Product Overview

The LTS-367KR-02 is a single-digit, seven-segment light-emitting diode (LED) display designed for applications requiring clear, bright numeric readouts. Its primary function is to visually represent the digits 0-9 and some letters through the selective illumination of its seven individual segments (labeled A through G) and an optional decimal point. The device is constructed using advanced AS-AlInGaP (Aluminum Indium Gallium Phosphide) LED chips grown on a Gallium Arsenide (GaAs) substrate. This material technology is specifically chosen for its ability to produce high-brightness, super red light with excellent efficiency. The display features a gray faceplate, which enhances contrast, and white segment markings for optimal character definition when unlit. It is categorized for luminous intensity, meaning units are binned and tested to ensure consistent brightness levels, which is critical for multi-digit displays where uniformity is key.

1.1 Core Advantages & Target Market

The LTS-367KR-02 offers several key advantages that make it suitable for a range of industrial and consumer applications. Its high brightness and high contrast ratio ensure excellent readability even in brightly lit environments or from a distance. The wide viewing angle allows the displayed character to be seen clearly from various positions, not just head-on. The device boasts solid-state reliability, meaning it has no moving parts, is resistant to shock and vibration, and offers a long operational lifetime compared to other display technologies like incandescent or vacuum fluorescent displays (VFDs). It has a low power requirement, making it energy-efficient and suitable for battery-powered devices. The continuous, uniform segments provide a clean and professional character appearance. Its primary target markets include instrumentation panels (e.g., multimeters, frequency counters), industrial control systems, point-of-sale terminals, automotive dashboards (for auxiliary displays), medical equipment, and household appliances where clear numeric indication is required.

2. Technical Parameters Deep Objective Interpretation

2.1 Photometric & Optical Characteristics

The optical performance is defined at an ambient temperature (Ta) of 25\u00b0C. The Average Luminous Intensity (Iv) is the primary measure of brightness. The datasheet specifies a minimum of 200 \u00b5cd, a typical value of 2100 \u00b5cd, and a maximum of 750 \u00b5cd when tested at a forward current (IF) of 1mA. At a higher drive current of 10mA, the typical intensity rises significantly to 9750 \u00b5cd. This non-linear relationship between current and brightness is typical for LEDs and is detailed in the characteristic curves. The Peak Emission Wavelength (\u03bbp) is 639 nanometers (nm), which falls within the red portion of the visible spectrum. The Dominant Wavelength (\u03bbd) is 631 nm. While peak wavelength is the point of maximum spectral power, dominant wavelength is the single-wavelength perception of the color by the human eye, which is more relevant for display applications. The Spectral Line Half-Width (\u0394\u03bb) is 20 nm, indicating the spectral purity or the spread of the emitted light around the peak wavelength; a smaller value indicates a more monochromatic light. The Luminous Intensity Matching Ratio for segments within the same light area is specified as 2:1 maximum when driven at 1mA, meaning the brightest segment should not be more than twice as bright as the dimmest, ensuring visual uniformity.

2.2 Electrical Parameters

The key electrical parameter is the Forward Voltage per Segment (VF). It has a typical value of 2.6 Volts and a maximum of 2.6V when the segment is driven with a 10mA current. The minimum is noted as 2.1V. This forward voltage is crucial for designing the current-limiting circuitry. The Reverse Current per Segment (IR) is a maximum of 100 \u00b5A when a reverse bias of 5V is applied, indicating the device's leakage characteristics in the off-state. The Continuous Forward Current per Segment is rated at 25 mA under standard conditions. A derating factor of 0.33 mA/\u00b0C is provided, meaning the maximum allowable continuous current decreases by 0.33 mA for every degree Celsius the ambient temperature rises above 25\u00b0C to prevent overheating and ensure reliability.

2.3 Absolute Maximum Ratings & Thermal Characteristics

These ratings define the stress limits beyond which permanent damage may occur. The Power Dissipation per Segment must not exceed 70 mW. The Peak Forward Current per Segment can reach 90 mA, but only under pulsed conditions (1 kHz frequency, 10% duty cycle), allowing for brief periods of higher brightness without overheating. The Reverse Voltage per Segment should never exceed 5V. The device is rated for an Operating Temperature Range of -35\u00b0C to +85\u00b0C and an identical Storage Temperature Range. The Solder Temperature specification is critical for assembly: the leads can withstand 260\u00b0C for 3 seconds, measured 1/16 inch (approximately 1.59 mm) below the seating plane of the package body. Exceeding these thermal limits during soldering can damage the internal wire bonds or the LED chip itself.

3. Binning System Explanation

The datasheet explicitly states that the device is categorized for luminous intensity. This is a binning process where manufactured LEDs are tested and sorted into groups (bins) based on their measured light output at a specific test current. This ensures that designers sourcing multiple displays for a single product receive units with closely matched brightness, preventing uneven or patchy-looking multi-digit readouts. While the specific bin codes are not detailed in this public datasheet, they are typically provided in separate documentation or available upon request for high-volume orders. The dominant wavelength of 631 nm is also a key color parameter that would be controlled within a certain tolerance during manufacturing, though a formal wavelength binning scheme is not mentioned here.

4. Performance Curve Analysis

The datasheet references Typical Electrical/Optical Characteristic Curves. While the specific graphs are not provided in the text, standard curves for such a device would typically include: 1. Relative Luminous Intensity vs. Forward Current (I-V Curve): This graph would show how light output increases with drive current, initially linearly at low currents and then tending to saturate at higher currents due to thermal effects and efficiency droop. 2. Forward Voltage vs. Forward Current: This shows the exponential relationship, critical for designing constant-current drivers. 3. Relative Luminous Intensity vs. Ambient Temperature: This curve demonstrates the thermal derating of light output; as temperature increases, luminous intensity generally decreases for AlInGaP LEDs. 4. Spectral Distribution: A plot showing the relative power emitted across wavelengths, centered around the 639 nm peak with a 20 nm half-width. These curves are essential for understanding the device's behavior under non-standard conditions (different currents, temperatures) and for optimizing the design for performance and longevity.

5. Mechanical & Package Information

The device is supplied in a standard through-hole package with 10 pins on a 0.1-inch (2.54 mm) pitch. The overall package dimensions are provided in a drawing (not fully detailed in text, but notes indicate all dimensions are in millimeters with a general tolerance of \u00b10.25 mm). A specific note mentions that the pin tip's shift tolerance is \u00b1 0.4 mm, which is important for PCB hole placement and wave soldering processes. The Internal Circuit Diagram shows that this is a Common Cathode configuration. All the cathodes of the LED segments (and the decimal point) are connected internally and brought out to two pins: Pin 1 and Pin 6, which are also internally connected to each other. This means to illuminate a segment, its corresponding anode pin must be driven high (with a current-limiting resistor) while the common cathode pin(s) are connected to ground. The decimal point is located on the right-hand side of the digit.

6. Soldering & Assembly Guidelines

The primary guideline is the soldering temperature profile: 260\u00b0C maximum for 3 seconds, measured at a point 1/16 inch (1.59 mm) from the bottom of the package body. This is typically achieved using a controlled wave soldering or selective soldering process. For hand soldering, extreme care must be taken to apply heat briefly and avoid touching the package body directly with the iron tip. The use of a heat sink on the lead between the joint and the package is recommended. The device is specified as a lead-free package (according to RoHS), meaning it is compatible with lead-free solder alloys which generally have higher melting points than traditional tin-lead solder, making adherence to the temperature limit even more critical. After soldering, cleaning may be required to remove flux residues, but care should be taken with solvent selection to avoid damaging the plastic lens or markings.

7. Packaging & Ordering Information

The part number is LTS-367KR-02. The naming convention likely breaks down as follows: LTS (product family/display type), 367 (possibly indicating 0.36-inch size and 7-segment), KR (likely denoting color: Super Red, and perhaps package style), and -02 (a revision or variant code). The device is typically supplied in anti-static tubes or trays to protect the pins from damage and prevent electrostatic discharge (ESD). Reel packaging for automated assembly is also common for high-volume orders, but the specific tape width, pocket size, and reel diameter would be specified in a separate packaging specification document. The label on the packaging should clearly state the part number, quantity, date code, and possibly the luminous intensity bin code.

8. Application Suggestions

8.1 Typical Application Scenarios

This display is ideal for any application requiring a single, highly legible digit. Examples include: Test and Measurement Equipment: As a range indicator or mode indicator on handheld multimeters. Industrial Controls: Displaying setpoints, counters, or error codes on control panels. Consumer Electronics: Displaying channel numbers on older audio/video equipment, timer readouts on appliances. Automotive Aftermarket: Auxiliary gauges for voltage, temperature, or boost pressure. Medical Devices: Simple parameter displays on monitors or diagnostic tools where reliability is paramount.

8.2 Design Considerations

Current Limiting: Each segment anode must be driven through a series current-limiting resistor. The resistor value is calculated using R = (Vcc - VF) / IF, where VF is the forward voltage (typ. 2.6V) and IF is the desired forward current (e.g., 10mA for high brightness). Using a constant-current driver IC can provide better uniformity and brightness control, especially across temperature. Multiplexing: For multi-digit displays, a multiplexing scheme is used where digits are illuminated one at a time rapidly. The LTS-367KR-02's common cathode design is well-suited for this, as the cathode can be switched to ground for the active digit while the anodes for the desired segments are driven. The peak current rating allows for higher pulsed currents during multiplexing to compensate for the reduced duty cycle. Viewing Angle: The wide viewing angle should be considered when positioning the display in the final product enclosure to ensure the intended audience can see it clearly.

9. Technical Comparison

Compared to older red GaAsP (Gallium Arsenide Phosphide) LED displays, the AlInGaP technology in the LTS-367KR-02 offers significantly higher brightness and efficiency, allowing for lower drive currents to achieve the same visibility or much greater visibility at similar currents. It also provides a more saturated, \"super red\" color. Compared to Vacuum Fluorescent Displays (VFDs), this LED display is more rugged, has a much longer lifetime, operates at lower voltages, and does not require a dedicated high-voltage power supply. However, VFDs can offer a wider viewing angle and a different aesthetic. Compared to modern OLED displays, this seven-segment LED is far simpler, more reliable in extreme temperatures, and much more cost-effective for applications that only need to display numbers. Its simplicity also translates to lower microcontroller overhead for driving.

10. Frequently Asked Questions (Based on Technical Parameters)

Q: Can I drive this display with a 5V microcontroller pin directly? A: No. The typical forward voltage is 2.6V, and a microcontroller pin outputting 5V would need a series resistor to limit the current to a safe value (e.g., 10-20mA). The resistor value would be approximately (5V - 2.6V) / 0.01A = 240 Ohms.

Q: Why are there two common cathode pins (1 and 6)? A: They are internally connected. This provides design flexibility (e.g., connecting to ground in two places for better current distribution) and redundancy in case one pin connection fails during soldering.

Q: What does \"categorized for luminous intensity\" mean for my design? A: It means you can order parts from the same intensity bin to ensure all digits in your multi-digit display have uniform brightness. If uniformity is critical, you should specify the bin code when ordering.

Q: Can I use this display outdoors? A: The operating temperature range extends to -35\u00b0C to +85\u00b0C, which covers many outdoor conditions. However, the plastic package may degrade with prolonged exposure to direct UV sunlight, and the display is not inherently waterproof. An appropriate protective cover or conformal coating would be necessary for harsh outdoor use.

11. Practical Design & Usage Case

Case: Designing a Simple Digital Counter. A designer needs a 3-digit counter for an industrial production line. They select three LTS-367KR-02 displays. They design a PCB with the displays in a row. A microcontroller (e.g., an ATmega328) is used to count pulses from a sensor. The microcontroller drives the displays in a multiplexed configuration. It uses 7 I/O pins connected to the segment anodes (A-G) of all three displays via current-limiting resistors (e.g., 220\u03a9 for ~10mA from a 5V supply). Three additional I/O pins are used to control NPN transistors (or a dedicated driver IC like a ULN2003) that switch the common cathode lines of each digit to ground in sequence. The firmware illuminates each digit for a few milliseconds, cycling rapidly to create the illusion of all three being on simultaneously. The high brightness ensures the count is visible on the factory floor. The categorized luminous intensity of the displays, requested in the same bin, guarantees that all three digits appear equally bright to the operator.

12. Principle Introduction

The operational principle is based on electroluminescence in a semiconductor p-n junction. The AlInGaP semiconductor material has a specific bandgap energy. When a forward voltage exceeding the junction's threshold (approximately 2.1-2.6V) is applied, electrons from the n-type region and holes from the p-type region are injected into the active region where they recombine. This recombination releases energy in the form of photons (light). The wavelength (color) of the emitted light is directly determined by the bandgap energy of the AlInGaP material, which is engineered to produce red light around 631-639 nm. Each of the seven segments (and the decimal point) is a separate LED with its own anode connection, but they share a common cathode connection, forming the electrical circuit shown in the datasheet.

13. Development Trends

While discrete seven-segment LED displays like the LTS-367KR-02 remain vital for simple, reliable, and cost-effective numeric readouts, the broader trend in display technology is towards integration and flexibility. This includes: Integrated Driver Displays: Modules that include the LED digits, current-limiting resistors, and even a simple microcontroller or driver IC (like those with I2C or SPI interfaces) to reduce the component count and microcontroller I/O requirements for the system designer. Higher Density & Multi-Function: Clusters of digits with additional icons or symbols in a single package. Advancing LED Technology: Ongoing improvements in AlInGaP and InGaN (for other colors) materials continue to push efficiency (lumens per watt) and brightness higher, allowing for lower power consumption or increased visibility. However, the fundamental through-hole, common-cathode seven-segment display continues to serve as a robust, well-understood, and highly reliable solution for countless applications where its simplicity is an advantage over more complex graphic or dot-matrix displays.