LTC-5836KR-07 LED Display Datasheet - 0.52-inch Digit Height - Super Red Color - 2.6V Forward Voltage - 70mW Power Dissipation - English Technical Document

1. Product Overview

The LTC-5836KR-07 is a high-performance, triple-digit, seven-segment LED display module. Its primary function is to provide clear, bright numeric readouts in various electronic devices and instrumentation. The core advantage of this device lies in its use of advanced AS-AlInGaP (Aluminum Indium Gallium Phosphide) semiconductor technology grown on a GaAs substrate, which delivers superior luminous efficiency and color purity in the red spectrum. This results in excellent segment uniformity, high brightness, and high contrast, making the display easily readable even under challenging lighting conditions. The device is designed with a common anode configuration and features a gray face with white segments, further enhancing contrast and visual appeal. It is binned for luminous intensity to ensure consistent performance across units, targeting applications requiring reliable, solid-state numeric indication such as industrial control panels, test equipment, consumer appliances, and automotive dashboards where low power consumption, wide viewing angles, and long-term reliability are critical.

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 1mA, the average luminous intensity per segment ranges from a minimum of 320 µcd to a typical value of 1050 µcd. This high brightness level ensures good visibility. The device emits light in the Super Red region, with a peak emission wavelength (λp) of 639 nm and a dominant wavelength (λd) of 631 nm when driven at 20mA. The spectral line half-width (Δλ) is 20 nm, indicating a relatively narrow and pure color emission. A key parameter for multi-segment displays is the luminous intensity matching ratio, which is specified at a maximum of 2:1. This means the brightness difference between the brightest and dimmest segment under identical conditions will not exceed a factor of two, ensuring a uniform appearance across all digits and segments.

2.2 Electrical Parameters

The electrical characteristics define the operating boundaries and power requirements. The forward voltage (VF) per segment is typically 2.6V with a maximum of 2.6V when a forward current (IF) of 20mA is applied. The reverse current (IR) is very low, with a maximum of 100 µA at a reverse voltage (VR) of 5V, indicating good diode characteristics. The absolute maximum ratings set the operational limits: the continuous forward current per segment is 25 mA at 25°C, derating linearly by 0.28 mA/°C as temperature increases. The peak forward current can reach 90 mA under pulsed conditions (1 kHz, 10% duty cycle). The maximum power dissipation per segment is 70 mW. Operating and storage temperature ranges are specified from -35°C to +105°C, highlighting its robustness for industrial environments.

2.3 Thermal Characteristics

While not explicitly detailed with thermal resistance parameters, the thermal management of the device is implied through its derating specifications. The linear derating of the continuous forward current from 25°C (0.28 mA/°C) is a direct instruction for thermal design. Exceeding the maximum junction temperature, which is intrinsically linked to these ratings, can lead to accelerated degradation or failure. The specified solder temperature limit of 260°C for a maximum of 3 seconds during assembly is another critical thermal consideration to prevent damage to the LED chips or package integrity.

3. Binning System Explanation

The datasheet explicitly states that the device is "BINNED FOR LUMINOUS INTENSITY." This is a quality control and sorting process. During manufacturing, slight variations in the epitaxial growth and chip processing lead to variations in the light output of individual LED segments. The binning process involves measuring the luminous intensity of each unit at a defined test current (typically 1mA or 20mA) and sorting them into specific intensity ranges or "bins." By purchasing devices from the same or a specified bin, designers ensure that all digits in a multi-digit display have nearly identical brightness, maintaining a uniform and professional appearance. The datasheet provides the intensity range (Min 320 µcd, Typ 1050 µcd), which defines the possible bins available.

4. Performance Curve Analysis

The datasheet references "TYPICAL ELECTRICAL / OPTICAL CHARACTERISTIC CURVES" on the final page. Although the specific graphs are not provided in the text, standard curves for such devices typically include: Forward Current vs. Forward Voltage (I-V Curve): This graph shows the exponential relationship, helping designers select appropriate current-limiting resistors. Luminous Intensity vs. Forward Current (I-L Curve): This shows how light output increases with current, often becoming sub-linear at higher currents due to thermal effects. Luminous Intensity vs. Ambient Temperature: This curve demonstrates the decrease in light output as the junction temperature rises, which is crucial for applications operating over a wide temperature range. Relative Spectral Power Distribution: A graph showing the intensity of emitted light across wavelengths, centered around the 639 nm peak, confirming the color purity.

5. Mechanical and Package Information

The device features a standard dual in-line package (DIP) format suitable for through-hole PCB mounting. The package dimensions are provided in millimeters with a general tolerance of ±0.25 mm. The digit height is a key mechanical specification, stated as 0.52 inches (13.2 mm). The pin connection diagram is essential for PCB layout. It is a 30-pin device with a specific arrangement for three common-anode digits. The internal circuit diagram shows that each digit is a common anode configuration, meaning all the anodes for the segments (A-G, DP) of a single digit are connected internally to one common pin. The cathodes of each segment are brought out to individual pins. This configuration is typically driven by multiplexing, where the common anode of each digit is powered sequentially at a high frequency, while the appropriate segment cathodes are grounded to illuminate the desired pattern.

6. Soldering and Assembly Guidelines

The datasheet provides a critical parameter for the assembly process: the maximum allowable solder temperature. It specifies that the device can withstand a peak temperature of 260°C for a maximum duration of 3 seconds, measured at a point 1.6 mm (1/16 inch) below the seating plane of the package. This is a standard guideline for wave soldering or hand soldering of through-hole components. Exceeding this time-temperature profile can cause thermal stress on the epoxy package, potentially leading to cracking, delamination, or damage to the internal wire bonds and semiconductor die. Proper handling to avoid electrostatic discharge (ESD) is also implied, as LEDs are generally sensitive to voltage spikes.

7. Packaging and Ordering Information

The primary ordering code is LTC-5836KR-07. The part number breakdown can be inferred: 'LTC' likely denotes the product family, '5836' is the specific model, 'K' may indicate the color (Super Red), 'R' could denote the right-hand decimal point placement, and '-07' might be a revision or variant code. The device is typically supplied in anti-static tubes or trays to protect the pins and prevent ESD damage during shipping and handling. The packaging would include labels specifying the part number, quantity, lot code, and potentially the luminous intensity bin code.

8. Application Recommendations

Typical Application Scenarios: This display is ideal for any application requiring a clear, multi-digit numeric readout. This includes digital multimeters, frequency counters, process timers, weighing scales, automotive instrument clusters (e.g., clock, odometer), medical devices, and household appliances like ovens or microwaves. Its wide operating temperature range makes it suitable for industrial environments.

Design Considerations: 1. Drive Circuitry: Use a multiplexing driver circuit to efficiently control the three digits. This requires microcontroller GPIO pins or a dedicated display driver IC (like a MAX7219 or HT16K33) capable of sinking the segment current and sourcing the digit current. 2. Current Limiting: External current-limiting resistors are mandatory for each segment cathode (or integrated into the driver) to set the desired forward current (e.g., 10-20 mA for full brightness). The resistor value is calculated using R = (Vcc - VF) / IF. 3. Power Dissipation: Ensure the calculated power per segment (VF * IF) does not exceed 70 mW, especially at high ambient temperatures. 4. Viewing Angle: The wide viewing angle allows for flexible mounting positions, but the optimal contrast is achieved when viewed head-on.

9. Technical Comparison and Differentiation

The key differentiating advantage of the LTC-5836KR-07 is its use of AlInGaP (Aluminum Indium Gallium Phosphide) technology for the red emission. Compared to older technologies like standard GaAsP (Gallium Arsenide Phosphide) red LEDs, AlInGaP offers significantly higher luminous efficiency. This means it produces more light (higher brightness) for the same amount of electrical current, or it can achieve the same brightness at a lower current, leading to reduced power consumption and less heat generation. Furthermore, AlInGaP LEDs generally have better performance retention at elevated temperatures and offer superior color saturation and purity, resulting in a more vibrant and consistent red color. The gray face/white segment design is another feature that enhances contrast compared to displays with black faces or diffused segments.

10. Frequently Asked Questions (Based on Technical Parameters)

Q: What is the purpose of the luminous intensity binning?
A: Binning guarantees visual uniformity across all segments and digits in a multi-unit display. Without binning, one digit might appear noticeably brighter or dimmer than its neighbors, which is visually distracting and unprofessional.

Q: How do I drive this three-digit display with a microcontroller that has limited pins?
A: You must use multiplexing. A microcontroller would need at least 11 I/O pins (7 segments + decimal point + 3 digit commons) if driven directly, but it's more efficient to use a dedicated serial-interfaced LED driver IC. This IC handles the multiplexing and current control, requiring only 2-3 pins from the microcontroller (e.g., SPI or I2C).

Q: Why is the forward current derated with temperature?
A> As the LED's junction temperature increases, its ability to dissipate heat decreases. To prevent the junction temperature from exceeding its maximum safe limit (which would cause rapid failure), the maximum allowable continuous current must be reduced. The derating factor (0.28 mA/°C) provides the guideline for this reduction.

Q: Can I use this display in an outdoor application?
A: The operating temperature range (-35°C to +105°C) suggests it can handle harsh environments. However, for direct outdoor use, consider additional factors not covered in the datasheet: the package is not inherently waterproof, and prolonged exposure to UV sunlight may degrade the plastic epoxy over time, potentially causing discoloration. A protective cover or conformal coating would be advisable.

11. Practical Design and Usage Case

Case: Designing a Digital Bench Power Supply Readout
A designer is building a variable bench power supply and needs a clear, 3-digit voltage display (e.g., 0.0V to 30.0V). The LTC-5836KR-07 is selected for its brightness, readability, and right-hand decimal point (perfect for showing tenths of a volt). The design uses a microcontroller with an ADC to measure the output voltage. The microcontroller communicates via I2C with an LED driver chip. The driver chip handles the multiplexing of the three digits: it cycles power to the common anode of Digit 1, Digit 2, and Digit 3 in rapid succession. Simultaneously, it grounds the cathodes of the segments that need to be lit for the digit currently powered. The refresh rate is set high enough (e.g., >100 Hz) to eliminate visible flicker. Current-limiting resistors are placed on the driver's segment outputs to set the forward current to 15 mA per segment, providing a good balance of brightness and power consumption. The gray face provides excellent contrast against the metal panel of the power supply.

12. Technical Principle Introduction

The fundamental operating principle is based on electroluminescence in a semiconductor p-n junction. The AlInGaP epitaxial layers are engineered to have a specific bandgap energy. When a forward voltage exceeding the junction's threshold (approximately 2.0V) is applied, electrons from the n-region and holes from the p-region are injected across the junction. When these charge carriers recombine in the active region, they release energy in the form of photons (light). The wavelength (color) of this light is directly determined by the bandgap energy of the AlInGaP material, which is tuned to produce red light around 639 nm. The seven-segment format is a standardized pattern where individual LED segments (labeled A through G) can be selectively illuminated to form any numeric digit from 0 to 9. The common anode configuration simplifies the driving circuitry for multiplexed displays.

13. Technology Trends and Developments

While discrete seven-segment LED displays remain relevant for specific applications, the broader trend in display technology is moving towards integrated solutions. These include: Dot-Matrix and Alphanumeric Displays: Offering more flexibility to show letters, symbols, and custom characters. OLED and Micro-LED Displays: Providing higher resolution, better contrast, and thinner form factors, though often at a higher cost and with different driving requirements. Integrated Driver Displays: Modules that combine the LED array with the controller/driver IC on the same PCB, simplifying interface design (often just a serial connection). For the specific niche of high-brightness, rugged, and simple numeric readouts, AlInGaP-based displays like the LTC-5836KR-07 continue to offer an optimal balance of performance, reliability, and cost. Future developments may focus on even higher efficiency, broader temperature ranges, and surface-mount package alternatives to through-hole designs.