LTS-5001AJR LED Display Datasheet - 0.56-inch Digit Height - Super Red Color - 2.6V Forward Voltage - English Technical Document

1. Product Overview

The LTS-5001AJR is a high-performance, low-power seven-segment numeric display designed for applications requiring clear, bright, and reliable numerical readouts. Its primary function is to visually represent digits (0-9) and some letters using individually controlled LED segments. The device is built using advanced AlInGaP (Aluminum Indium Gallium Phosphide) semiconductor technology, which is known for producing high-efficiency red light. The display features a light gray face and white segments, providing excellent contrast for enhanced readability. It is categorized based on its luminous intensity, ensuring consistency in brightness across production batches. This component is ideal for integration into a wide range of electronic equipment where space, power efficiency, and visibility are critical factors.

2. In-Depth Technical Parameter Analysis

2.1 Optical Characteristics

The optical performance is central to the display's functionality. The key parameters, measured at a standard ambient temperature of 25°C, define its visual output.

• Average Luminous Intensity (I_V): This parameter specifies the brightness of each segment. With a typical forward current (I_F) of 1mA, the intensity ranges from a minimum of 320 μcd (microcandelas) to a maximum of 700 μcd. This low-current, high-brightness characteristic is a significant advantage for battery-powered devices.
• Peak Emission Wavelength (λ_p): The light emitted has a peak wavelength of 639 nanometers, placing it firmly in the "super red" portion of the visible spectrum. This specific shade of red is often chosen for its high visibility and eye-catching properties.
• Spectral Line Half-Width (Δλ): At 20 nm, this value indicates the spectral purity of the emitted light. A narrower half-width would indicate a more monochromatic light, but this value is typical for standard LED displays and contributes to the characteristic red color.
• Dominant Wavelength (λ_d): Measured at 631 nm, this is the wavelength perceived by the human eye and is the primary descriptor for the color "super red."
• Luminous Intensity Matching Ratio (I_V-m): This ratio, specified as 2:1 maximum, ensures uniformity across the display. It means the brightness of the dimmest segment will be no less than half the brightness of the brightest segment under the same driving conditions, preventing uneven digit appearance.

2.2 Electrical Characteristics

The electrical specifications govern how the device is powered and its limits of operation.

• Forward Voltage per Segment (V_F): The voltage drop across an illuminated segment typically ranges from 2.0V to 2.6V when driven with a 1mA current. This value is crucial for designing the current-limiting circuitry.
• Reverse Current per Segment (I_R): When a reverse voltage of 5V is applied, the leakage current is a maximum of 100 μA. This is an important parameter for circuit protection.

2.3 Absolute Maximum Ratings

These are the stress limits beyond which permanent damage to the device may occur. Operation should always be maintained within these boundaries.

• Power Dissipation per Segment: 70 mW maximum.
• Peak Forward Current per Segment: 90 mA for pulsed operation (1/10 duty cycle, 0.1ms pulse width).
• Continuous Forward Current per Segment: 25 mA at 25°C. This rating derates linearly at 0.33 mA/°C above 25°C ambient temperature, meaning the allowable continuous current decreases as the environment gets hotter.
• Reverse Voltage per Segment: 5 V maximum.
• Operating & Storage Temperature Range: -35°C to +85°C.
• Solder Temperature: The device can withstand a soldering temperature of 260°C for 3 seconds at a distance of 1/16 inch (approximately 1.6mm) below the seating plane.

3. Binning System Explanation

The datasheet indicates the device is "Categorized for Luminous Intensity." This refers to a post-production sorting process, commonly known as binning. After manufacture, individual displays are tested and sorted into different groups (bins) based on their measured luminous intensity. This ensures that customers receive products with consistent brightness levels. The specified intensity range of 320-700 μcd likely represents the spread across different bins available for this part number. Designers can specify a tighter bin for applications requiring very uniform appearance.

4. Performance Curve Analysis

While the PDF references typical characteristic curves, the provided text does not include the specific graphs. Based on standard LED behavior, these curves would typically illustrate the following relationships, which are critical for detailed circuit design:

• Forward Current (I_F) vs. Forward Voltage (V_F): This exponential curve shows how voltage increases with current. It is used to determine the necessary driving voltage for a desired brightness level.
• Luminous Intensity (I_V) vs. Forward Current (I_F): This generally linear relationship (within operating limits) shows how brightness scales with current. It confirms the high efficiency at low currents (1mA) as mentioned in the features.
• Luminous Intensity vs. Ambient Temperature: This curve would show how brightness decreases as the junction temperature of the LED increases. Understanding this derating is essential for designs operating in elevated temperature environments.
• Spectral Distribution: A graph showing the relative light output across wavelengths, peaking at 639 nm with the specified 20 nm half-width.

5. Mechanical and Packaging Information

5.1 Physical Dimensions

The device is described as a 0.56-inch (14.22 mm) digit height display. A detailed mechanical drawing would typically be included, showing the overall package length, width, and height, segment dimensions, and the spacing between digits if it were a multi-digit unit. The drawing notes that all dimensions are in millimeters with standard tolerances of ±0.25 mm unless otherwise specified. This information is critical for PCB (Printed Circuit Board) footprint design and ensuring proper fit within the end product's enclosure.

5.2 Pin Configuration and Polarity

The LTS-5001AJR is a common anode display. This means the anodes (positive terminals) of all LED segments are connected internally and brought out to common pins (Pin 3 and Pin 8). The cathodes (negative terminals) for each segment (A, B, C, D, E, F, G, and Decimal Point) are brought out to individual pins. To illuminate a segment, its corresponding cathode pin must be connected to a lower voltage (typically ground) while the common anode pin(s) are supplied with a positive voltage through a current-limiting resistor. The pinout is as follows: Pin 1 (E Cathode), Pin 2 (D Cathode), Pin 3 (Common Anode), Pin 4 (C Cathode), Pin 5 (DP Cathode), Pin 6 (B Cathode), Pin 7 (A Cathode), Pin 8 (Common Anode), Pin 9 (F Cathode), Pin 10 (G Cathode).

6. Soldering and Assembly Guidelines

The absolute maximum ratings provide the key soldering parameter: the device can withstand a peak temperature of 260°C for 3 seconds, measured 1.6mm below the package body. This is compatible with standard lead-free reflow soldering profiles. Designers should ensure the thermal profile of their reflow oven does not exceed this limit. Standard ESD (Electrostatic Discharge) precautions should be observed during handling. For storage, the specified range of -35°C to +85°C in a dry environment should be maintained.

7. Application Recommendations

7.1 Typical Application Scenarios

This display is suited for a multitude of applications including, but not limited to: test and measurement equipment (multimeters, oscilloscopes), industrial control panels, medical devices, consumer electronics (audio amplifiers, clock radios), automotive aftermarket displays, and instrumentation panels. Its low power requirement makes it ideal for portable, battery-operated devices.

7.2 Design Considerations

• Current Limiting: Always use a series resistor for each common anode connection to limit the current through the segments. The resistor value is calculated using the formula: R = (V_supply - V_F) / I_F. For a 5V supply, a V_F of 2.2V, and a desired I_F of 5mA, the resistor would be (5 - 2.2) / 0.005 = 560 Ω.
• Multiplexing: For driving multiple digits, a multiplexing technique is commonly used. This involves rapidly cycling power to each digit's common anode while presenting the corresponding segment data for that digit. This greatly reduces the number of required microcontroller I/O pins.
• Viewing Angle: The "wide viewing angle" feature means the display remains readable when viewed from sharp off-axis angles, which is important for panel-mounted devices.
• Heat Management: While the device is low power, adhering to the current derating specification above 25°C is crucial for long-term reliability, especially in enclosed or high-temperature environments.

8. Technical Comparison and Differentiation

The primary differentiators of the LTS-5001AJR are its use of AlInGaP technology and its optimized low-current performance. Compared to older GaAsP or GaP LED displays, AlInGaP offers significantly higher luminous efficiency, resulting in brighter output at the same current or equivalent brightness at much lower current. The specific design for excellent low-current characteristics (down to 1mA per segment) sets it apart from displays that require higher drive currents to achieve usable brightness, making it a superior choice for power-sensitive designs. The continuous uniform segments and high contrast ratio contribute to a more professional and legible appearance compared to displays with visible segment joints or poor contrast.

9. Frequently Asked Questions (Based on Technical Parameters)

Q: Can I drive this display directly from a microcontroller pin?
A: No. A microcontroller pin cannot typically source or sink enough current (25mA max continuous) safely for all segments lit simultaneously and does not provide voltage regulation. You must use the microcontroller to control transistors (for the common anodes) and/or driver ICs (like a 74HC595 shift register or a dedicated LED driver) that handle the higher current.

Q: What is the difference between peak wavelength and dominant wavelength?
A: Peak wavelength is the single wavelength where the LED emits the most optical power. Dominant wavelength is the single wavelength of monochromatic light that would appear to have the same color as the LED's output to the human eye. For LEDs, they are often close but not identical.

Q: The forward voltage has a range (2.0V-2.6V). How does this affect my design?
A: You should design your current-limiting circuit for the maximum V_F (2.6V) to ensure sufficient voltage is available to drive the current even for a high-V_F unit. If you design for the typical 2.2V, a unit with 2.6V V_F will be dimmer because the voltage drop across the fixed resistor will be smaller, resulting in lower current.

10. Design and Usage Case Study

Scenario: Designing a low-power digital thermometer. The LTS-5001AJR is an excellent choice. The system is powered by a 3.3V microcontroller and a 3V coin cell battery. A temperature sensor provides data. The microcontroller uses 4 I/O pins in a multiplexed configuration to drive two 7-segment digits (for tens and ones of degrees). Current-limiting resistors are calculated for an I_F of 2mA per segment to maximize battery life while maintaining good visibility (V_supply=3.3V, V_F=2.2V, R = (3.3-2.2)/0.002 = 550Ω). The display's low current requirement allows the thermometer to operate for several months on a single battery. The high contrast and wide viewing angle ensure the temperature is easily readable in various lighting conditions.

11. Technical Principle Introduction

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. By selectively illuminating specific combinations of these segments, all decimal digits (0-9) and some letters can be formed. The underlying technology, AlInGaP, is a III-V semiconductor compound. When a forward voltage is applied across the p-n junction of the LED, electrons and holes recombine, releasing energy in the form of photons (light). The specific bandgap energy of the AlInGaP material determines the wavelength (color) of the emitted light, in this case, red. The "super red" designation indicates a specific, deeper shade of red with high luminous efficacy. The common anode configuration simplifies driving circuitry when using sinking current drivers (like many microcontrollers and logic ICs).

12. Technology Trends

The evolution of seven-segment displays continues alongside general LED technology. While the basic form factor remains, trends include: 1) Higher Efficiency: Ongoing material science improvements (like more advanced InGaN and AlInGaP structures) yield brighter displays at lower currents, further reducing power consumption. 2) Miniaturization: Displays with smaller digit heights and finer pitch are being developed for compact devices. 3) Integration: Driver electronics are increasingly being integrated into the display module itself, simplifying the interface for the host system to simple digital communication (I2C, SPI). 4) Color Options: While red remains popular for its visibility and efficiency, full-color RGB seven-segment displays are available for more dynamic applications. 5) Alternative Technologies: In some applications, especially where ultra-low power or sunlight readability is paramount, segmented LCDs or OLEDs may be considered, though they often lack the inherent brightness and robustness of LEDs.