LTS-6775JD LED Display Datasheet - 0.56-inch Digit Height - Hyper Red - 2.6V Forward Voltage - 70mW Power Dissipation - English Technical Document

1. Product Overview

The LTS-6775JD is a high-performance, single-digit, seven-segment display module designed for applications requiring clear numeric readouts. Its core function is to visually represent the digits 0 through 9, along with a decimal point, using individual LED segments. The device is engineered for reliability and clarity in various electronic instruments and consumer devices.

The display utilizes advanced Aluminium Indium Gallium Phosphide (AlInGaP) semiconductor technology for its light-emitting elements. This material system is specifically chosen for producing high-efficiency red and hyper-red light emission. The chips are fabricated on a non-transparent Gallium Arsenide (GaAs) substrate, which helps in improving contrast by minimizing internal light scattering and reflection. The visual presentation features a gray faceplate with white segment markings, providing an excellent background for the emitted red light, thereby enhancing overall readability and aesthetic appeal.

1.1 Core Advantages and Target Market

The LTS-6775JD offers several distinct advantages that make it suitable for a range of applications. Its primary features include a digit height of 0.56 inches (14.22 mm), which offers a good balance between size and visibility. The segments are designed to be continuous and uniform, ensuring a consistent and professional appearance when illuminated. The device requires low power to operate, contributing to energy-efficient system design. It delivers high brightness and high contrast output, which is crucial for readability under various ambient lighting conditions. Furthermore, it provides a wide viewing angle, allowing the displayed information to be seen clearly from different positions relative to the display surface.

This combination of features makes the LTS-6775JD ideal for integration into a variety of electronic products. Its target market includes, but is not limited to, test and measurement equipment (e.g., multimeters, frequency counters), industrial control panels, automotive dashboard displays, consumer appliances (e.g., microwave ovens, digital clocks), and medical devices where clear, reliable numeric indication is required. The solid-state reliability of LEDs ensures a long operational lifetime with minimal maintenance.

2. Technical Parameters: In-Depth Objective Interpretation

The performance of the LTS-6775JD is defined by a set of precise electrical and optical parameters. Understanding these specifications is critical for proper circuit design and ensuring optimal display performance.

2.1 Photometric and Optical Characteristics

The optical performance is central to the display's function. The key parameter is the Average Luminous Intensity (Iv), which is specified with a minimum of 320 \u00b5cd, a typical value of 700 \u00b5cd, and no stated maximum when driven at a forward current (IF) of 1 mA. This measurement is taken using a sensor and filter that approximates the photopic (CIE) human eye response curve, ensuring the value correlates with perceived brightness. The high typical intensity ensures good visibility.

The color characteristics are defined by wavelength. The Peak Emission Wavelength (\u03bbp) is typically 650 nanometers (nm), placing the output in the hyper-red region of the spectrum. The Dominant Wavelength (\u03bbd) is specified as 639 nm. The difference between peak and dominant wavelength is normal for LEDs and relates to the shape of the emission spectrum. The Spectral Line Half-Width (\u0394\u03bb) is 20 nm, indicating the spectral purity or the spread of wavelengths emitted around the peak. A degree of variation in luminous output between segments is expected; this is quantified by the Luminous Intensity Matching Ratio (IV-m), which is specified as 2:1 maximum. This means the brightest segment will be no more than twice as bright as the dimmest segment under the same drive conditions, ensuring uniformity.

2.2 Electrical Parameters

The electrical characteristics define the interface between the display and the driving circuitry. The Forward Voltage per Segment (VF) is typically 2.1 Volts and has a maximum of 2.6 Volts when a forward current (IF) of 10 mA is applied. This voltage is relatively low, which simplifies power supply design. The Reverse Current per Segment (IR) is specified with a maximum of 100 \u00b5A when a reverse voltage (VR) of 5 V is applied, indicating the level of leakage when the LED is incorrectly biased.

2.3 Absolute Maximum Ratings and Thermal Considerations

These ratings define the limits beyond which permanent damage to the device may occur. They are not conditions for normal operation. The maximum Power Dissipation per Segment is 70 mW. The Peak Forward Current per Segment is 90 mA, but this is only permissible under pulsed conditions (1/10 duty cycle, 0.1 ms pulse width) to manage heat. The Continuous Forward Current per Segment is derated from 25 mA at 25\u00b0C down to 0 mA at 100\u00b0C, with a linear derating factor of 0.33 mA/\u00b0C. This derating is crucial for reliability, as it prevents the junction temperature from exceeding safe limits. The maximum Reverse Voltage per Segment is 5 V. The device is rated for an Operating Temperature Range of -35\u00b0C to +85\u00b0C and the same range for storage. The solder temperature must not exceed 260\u00b0C for more than 3 seconds, measured 1.6 mm below the seating plane, to prevent damage during assembly.

3. Binning System Explanation

The provided datasheet indicates that the devices are \"Categorized for Luminous Intensity.\" This implies a binning or sorting process based on measured light output. In typical LED manufacturing, devices from a production batch are tested and grouped into different \"bins\" according to key parameters like luminous intensity, forward voltage, and sometimes dominant wavelength. While the specific bin codes or ranges are not detailed in this document, the practice ensures that customers can select parts with consistent performance for a given application. For the LTS-6775JD, the primary binning criterion appears to be luminous intensity, guaranteeing a minimum level of brightness as specified in the electrical/optical characteristics table.

4. Performance Curve Analysis

While the specific graphs are not reproduced in the text, the datasheet references \"Typical Electrical / Optical Characteristic Curves.\" These curves are essential for detailed design work. Typically, such a datasheet would include:

• Relative Luminous Intensity vs. Forward Current (I-V Curve): This graph shows how light output increases with drive current. It is typically non-linear, with efficiency often dropping at very high currents due to heating effects.
• Forward Voltage vs. Forward Current: This shows the diode's I-V characteristic, crucial for designing current-limiting circuits.
• Relative Luminous Intensity vs. Ambient Temperature: This curve demonstrates how light output decreases as the ambient (and consequently junction) temperature rises. Understanding this derating is vital for applications operating in hot environments.
• Spectral Distribution: A plot showing the relative intensity of light emitted across different wavelengths, centered around the 650 nm peak, with a width defined by the 20 nm half-width specification.

Designers should consult these curves to optimize drive current for desired brightness while maintaining efficiency and longevity, and to account for performance changes over the intended operating temperature range.

5. Mechanical and Package Information

The LTS-6775JD comes in a standard LED display package. The Package Dimensions drawing provides the critical physical measurements for PCB footprint design and enclosure integration. All dimensions are provided in millimeters with a standard tolerance of \u00b10.25 mm unless otherwise noted. Key dimensions include the overall height, width, and depth of the package, the spacing between the pins, the diameter and position of the digit on the face, and the distance from the seating plane. Accurate interpretation of this drawing is necessary to create a correct PCB layout and ensure the display fits properly in the final product assembly.

5.1 Pin Configuration and Polarity Identification

The device has a 10-pin configuration (Pin 10 is noted as \"No Connection\"). It is configured as a Common Anode display. This means the anodes (positive terminals) of multiple LED segments are connected together internally. In this specific device, the internal circuit diagram and pin connection table show how the anodes and cathodes for the seven segments (A, B, C, D, E, F, G), the decimal point (DP), and the plus/minus signs are arranged. The common anode nodes are connected to pins 2, 4, 7, and 8 for different segment groups. The individual segment cathodes are connected to their respective pins. To illuminate a segment, its corresponding cathode pin must be driven low (connected to ground or a current sink) while the appropriate common anode pin is driven high (connected to the positive supply through a current-limiting resistor). The pinout table is the definitive reference for designing the drive circuitry.

6. Soldering and Assembly Guidelines

Proper handling during assembly is critical to reliability. The key guideline provided is for the soldering process: the maximum allowable solder temperature is 260\u00b0C, and this temperature should not be applied for more than 3 seconds. This measurement is taken at a point 1.6 mm (1/16 inch) below the seating plane of the device on the PCB. This specification is designed to prevent thermal damage to the LED chips, the internal wire bonds, and the plastic package material. For wave or reflow soldering, the entire thermal profile (preheat, soak, reflow, cooling) must be controlled to stay within these limits. Manual soldering with an iron requires careful technique to avoid localized overheating. The storage temperature range is -35\u00b0C to +85\u00b0C; devices should be kept in a dry, static-safe environment before use.

7. Application Recommendations

7.1 Typical Application Circuits

The LTS-6775JD, being a common anode display, is typically driven by a microcontroller or a dedicated display driver IC (like a BCD-to-7-segment decoder/driver). The common anode pins are connected to the positive supply rail (Vcc), each through a current-limiting resistor if multiplexing is not used. If multiplexing multiple digits, the common anodes are switched by transistors. The cathode pins for each segment are connected to the driver outputs, which sink current to ground. The value of the current-limiting resistor is calculated using the formula: R = (Vcc - VF) / IF, where VF is the forward voltage of the segment (use max value for worst-case design, e.g., 2.6V) and IF is the desired forward current (e.g., 10 mA for typical brightness). For a 5V supply: R = (5V - 2.6V) / 0.01A = 240 Ohms. A standard 220 or 270 Ohm resistor would be suitable.

7.2 Design Considerations and Notes

• Current Limiting: Always use external current-limiting resistors. Driving the LEDs directly from a voltage source or a microcontroller pin without a resistor will cause excessive current flow, leading to immediate failure or significantly reduced lifespan.
• Multiplexing: To control multiple digits with fewer I/O pins, multiplexing is used. This involves rapidly cycling power to each digit's common anode while presenting the corresponding segment data on the shared cathode lines. The persistence of vision makes all digits appear lit simultaneously. The peak current during the short ON time can be higher than the DC rating, but the average current must not exceed the continuous forward current rating, considering the duty cycle.
• Viewing Angle: The wide viewing angle is beneficial, but for optimal readability, the display should be oriented so the primary viewing direction is roughly perpendicular to its face.
• ESD Protection: While not explicitly stated, LEDs are sensitive to electrostatic discharge (ESD). Standard ESD handling precautions should be observed during assembly.

8. Technical Comparison and Differentiation

Compared to older technologies like incandescent or vacuum fluorescent displays (VFDs), the LTS-6775JD offers significant advantages: lower power consumption, higher reliability (no filament to burn out), faster response time, and better shock/vibration resistance. Within the LED display segment, the use of AlInGaP technology for hyper-red offers higher efficiency and potentially better color stability over time and temperature compared to older GaAsP or GaP red LEDs. The 0.56-inch digit height places it in a common size category, competing with other similar displays primarily on specifications like brightness (luminous intensity), forward voltage (affecting power supply design), viewing angle, and overall package quality/reliability.

9. Frequently Asked Questions (Based on Technical Parameters)

Q: What is the purpose of the \"plus sign\" and \"minus sign\" cathodes (pins 9 and 1)?
A: These are dedicated LED segments for displaying a \"+\" or \"-\" symbol, typically used to indicate polarity (e.g., for a voltmeter reading) or sign for a numeric value. They are controlled independently from the main digit segments.

Q: Can I drive this display with a 3.3V microcontroller system?
A: Yes, but you must recalculate the current-limiting resistor. Using the typical VF of 2.1V and a target IF of 10 mA: R = (3.3V - 2.1V) / 0.01A = 120 Ohms. The lower supply voltage provides less headroom, so brightness consistency might be more sensitive to variations in VF.

Q: The maximum continuous current is 25 mA at 25\u00b0C. Can I run it at 20 mA for higher brightness?
A: While possible, operating near the absolute maximum rating reduces the design margin and may impact long-term reliability, especially if the ambient temperature is high. It is generally better practice to operate at or below the typical test condition of 10 mA for a balance of brightness, efficiency, and lifespan.

Q: What does \"Common Anode\" mean for my circuit design?
A: It means you supply voltage to the common pin(s) and sink current from the segment pins to turn them on. Your driver circuit (microcontroller, driver IC) must be configured to sink current (provide a low logic level or ground connection) to activate a segment.

10. Operational Principles

The fundamental principle behind the LTS-6775JD is electroluminescence in a semiconductor p-n junction, specifically using AlInGaP materials. When a forward voltage exceeding the diode's turn-on voltage (approximately 2.1V) is applied, electrons from the n-type region and holes from the p-type region are injected into the active region where they recombine. In a direct bandgap semiconductor like AlInGaP, a significant portion of this recombination event releases energy in the form of photons (light). The specific composition of the AlInGaP layers determines the bandgap energy, which in turn dictates the wavelength (color) of the emitted light\u2014in this case, hyper-red at around 650 nm. Each of the seven segments (A-G) and the decimal point is a separate LED or a group of LED chips, wired internally according to the circuit diagram. By selectively applying power to these individual segments, the pattern for a specific digit (0-9) or character is formed.