LTS-367JD LED Display Datasheet - 0.36-inch Digit Height - Hyper Red - 2.6V Forward Voltage - 70mW Power Dissipation - English Technical Document

1. Product Overview

The LTS-367JD is a compact, single-digit numeric display component designed for applications requiring clear, bright numerical readouts. Its primary function is to visually represent the digits 0-9 and some letters using a seven-segment configuration, controlled by individual anodes for each segment. The device is built using solid-state AlInGaP (Aluminum Indium Gallium Phosphide) LED technology, specifically in a Hyper Red color, which offers high brightness and efficiency. The display features a gray face with white segments, enhancing contrast and readability under various lighting conditions. It is categorized for luminous intensity, ensuring consistent brightness levels across production batches. This component is typically targeted at embedded systems, instrumentation panels, industrial controls, consumer electronics, and any device where a simple, reliable numeric indicator is needed.

2. Technical Specifications Deep Dive

2.1 Photometric and Optical Characteristics

The optical performance is central to the display's functionality. The device utilizes AlInGaP LED chips on a non-transparent GaAs substrate. The key optical parameters, measured at an ambient temperature (Ta) of 25°C, are as follows:

• Average Luminous Intensity (I_V): Ranges from a minimum of 200 µcd to a typical value of 650 µcd when driven at a forward current (I_F) of 1 mA. This parameter defines the perceived brightness of the lit segments.
• Peak Emission Wavelength (λ_p): Typically 650 nanometers (nm) at I_F=20mA, placing the output in the deep red portion of the visible spectrum.
• Dominant Wavelength (λ_d): Typically 639 nm. This is the single wavelength perceived by the human eye that best matches the color of the light emitted.
• Spectral Line Half-Width (Δλ): Typically 20 nm. This indicates the spectral purity; a narrower width means a more monochromatic (pure color) output.
• Luminous Intensity Matching Ratio (I_V-m): Maximum of 2:1 at I_F=1mA. This critical specification ensures uniformity across the display; the brightness of the dimmest segment will be no less than half the brightness of the brightest segment, preventing uneven appearance.

Luminous intensity measurements are performed using a sensor and filter combination that approximates the CIE (Commission Internationale de l'Éclairage) photopic eye-response curve, ensuring the values correlate with human visual perception.

2.2 Electrical Parameters

The electrical characteristics define the operating limits and conditions for reliable integration into a circuit.

• Forward Voltage per Segment (V_F): Typically 2.1V, with a maximum of 2.6V when I_F=10mA. This is the voltage drop across an LED segment when it is conducting current.
• Reverse Current per Segment (I_R): Maximum of 100 µA when a reverse voltage (V_R) of 5V is applied. This indicates the very small leakage current when the LED is reverse-biased.
• Continuous Forward Current per Segment: Rated at 25 mA maximum. Exceeding this value can cause permanent damage due to overheating.
• Peak Forward Current per Segment: Can withstand up to 90 mA under pulsed conditions (1/10 duty cycle, 0.1ms pulse width) for short durations, useful for multiplexing schemes to achieve higher perceived brightness.
• Power Dissipation per Segment: Maximum of 70 mW. This is the product of the forward voltage and current, representing the electrical power converted into light and heat.

2.3 Thermal and Absolute Maximum Ratings

These ratings specify the environmental and operational limits that must not be exceeded to ensure device longevity and prevent failure.

• Operating Temperature Range: -35°C to +85°C. The device is designed to function correctly within this wide ambient temperature span.
• Storage Temperature Range: -35°C to +85°C. The device can be stored safely within these limits when not powered.
• Soldering Temperature: The device can tolerate a soldering temperature of 260°C for 3 seconds at a point 1/16 inch (approximately 1.6 mm) below the seating plane of the package. This is crucial for wave or reflow soldering processes.
• Current Derating: The maximum continuous forward current must be linearly derated from its 25 mA rating at 25°C. The derating factor is 0.33 mA/°C. For example, at an ambient temperature of 85°C, the maximum allowable continuous current would be: 25 mA - [0.33 mA/°C * (85°C - 25°C)] = 25 mA - 19.8 mA = 5.2 mA. This is a critical design consideration for high-temperature environments.

3. Binning and Categorization System

The datasheet explicitly states that the device is \"Categorized for Luminous Intensity.\" This indicates a production binning process. During manufacturing, LEDs are tested and sorted (binned) based on their measured luminous intensity at a standard test current (likely 1mA or 10mA). Units are grouped into specific intensity ranges or categories. This ensures that designers and purchasers receive displays with consistent and predictable brightness levels. While the specific bin codes or categories are not detailed in this excerpt, the practice guarantees that the minimum (200 µcd) and typical (650 µcd) values are met, and units within a given order will have closely matched performance.

4. Performance Curve Analysis

The datasheet references \"Typical Electrical / Optical Characteristic Curves.\" Although the specific graphs are not provided in the text, standard curves for such LEDs would typically include:

• Forward Current vs. Forward Voltage (I-V Curve): Shows the exponential relationship. A current-limiting resistor is always required in series with each segment to set the operating point on this curve and prevent thermal runaway.
• Luminous Intensity vs. Forward Current (I_V vs. I_F): Demonstrates how brightness increases with current, typically in a near-linear relationship within the operating range before efficiency drops at very high currents.
• Luminous Intensity vs. Ambient Temperature: Shows how light output decreases as the junction temperature of the LED increases. This is related to the current derating requirement.
• Spectral Distribution: A plot of relative intensity versus wavelength, showing the peak at ~650 nm and the 20 nm half-width, confirming the hyper-red color.

These curves are essential for advanced design, allowing engineers to optimize drive conditions for specific brightness, efficiency, and lifetime targets.

5. Mechanical and Package Information

5.1 Physical Dimensions and Drawing

The device is described as having a 0.36-inch (9.14 mm) digit height. The \"Package Dimensions\" section would contain a detailed mechanical drawing. All dimensions are specified in millimeters (mm) with standard tolerances of ±0.25 mm (0.01 inches) unless otherwise noted. This drawing is critical for PCB (Printed Circuit Board) layout, ensuring the footprint and hole patterns are correctly designed. It defines the overall length, width, and height of the package, the spacing between pins, and the position of the digit relative to the package edges.

5.2 Pin Configuration and Polarity

The LTS-367JD is a common cathode display. This means all the cathodes (negative terminals) of the individual LED segments are connected together internally. The pinout is as follows:

• Pin 1: Common Cathode (internally connected to Pin 6)
• Pin 2: Anode for Segment F
• Pin 3: Anode for Segment G
• Pin 4: Anode for Segment E
• Pin 5: Anode for Segment D
• Pin 6: Common Cathode (internally connected to Pin 1)
• Pin 7: Anode for Decimal Point (D.P.)
• Pin 8: Anode for Segment C
• Pin 9: Anode for Segment B
• Pin 10: Anode for Segment A

The internal connection between Pin 1 and Pin 6 provides mechanical redundancy for the common cathode connection, improving reliability. The \"Rt. Hand Decimal\" notation indicates the decimal point is positioned on the right-hand side of the digit when viewing the display from the front.

5.3 Internal Circuit Diagram

The referenced diagram visually represents the electrical connections described in the pinout. It shows ten pins connecting to a single digit. Seven segments (A through G) and one decimal point (DP) are represented, each as an individual LED (anode and cathode). The cathodes of all eight LEDs are shown tied together, forming the common cathode node, which is brought out to two pins (1 and 6). Each anode is connected to its respective pin. This diagram is fundamental for understanding how to drive the display: the common cathode(s) are typically connected to ground, and a logic 'high' or current source applied to an anode pin will illuminate that specific segment.

6. Soldering and Assembly Guidelines

The key assembly specification provided is the soldering temperature rating: the package can withstand 260°C for 3 seconds measured 1.6 mm (1/16\") below the seating plane. This is a standard rating for wave soldering. For reflow soldering, a profile with a peak temperature not exceeding 260°C and time above liquidus (e.g., 217°C) controlled to prevent excessive thermal stress should be used. Standard ESD (Electrostatic Discharge) precautions should be observed during handling, as LEDs are sensitive to static electricity. The wide storage temperature range (-35°C to +85°C) allows for flexibility in inventory management and shipping conditions.

7. Application Suggestions

7.1 Typical Application Circuits

The LTS-367JD is ideal for applications requiring a single, highly readable digit. Common uses include:

• Instrumentation: Panel meters, test equipment, scales.
• Industrial Controls: Counter displays, timer readouts, setting indicators on machinery.
• Consumer Electronics: Audio equipment displays, appliance controls (e.g., microwave oven, thermostat).
• Embedded Projects & Prototyping: Educational kits, hobbyist displays for Arduino, Raspberry Pi, etc.

7.2 Design Considerations and Drive Methods

Current Limiting: A series resistor is mandatory for each segment anode (or a single resistor on the common cathode if multiplexing) to limit the forward current to a safe value (e.g., 10-20 mA for full brightness). The resistor value is calculated using Ohm's Law: R = (V_supply - V_F) / I_F. For a 5V supply and a target I_F of 10mA with V_F=2.1V, R = (5 - 2.1) / 0.01 = 290 Ω. A standard 270 Ω or 330 Ω resistor would be suitable.

Drive Electronics: The segments can be driven directly from microcontroller GPIO pins if they can source/sink sufficient current (check the MCU's specifications). For higher currents or voltage differences, transistor drivers (BJTs or MOSFETs) or dedicated LED driver ICs (like 74HC595 shift registers with current limiting or MAX7219 display drivers) are recommended. Using a driver IC simplifies control, especially when multiplexing multiple digits.

Multiplexing: While this is a single-digit display, the principle applies if using multiple similar digits. By rapidly switching which digit's common cathode is active and presenting the segment data for that digit, many digits can be controlled with fewer I/O pins. The peak current rating (90mA at 1/10 duty) allows for higher instantaneous current during the brief on-time to achieve good average brightness.

Viewing Angle: The datasheet highlights a \"Wide Viewing Angle,\" which is beneficial for applications where the display may be viewed from off-axis positions.

8. Technical Comparison and Differentiation

The LTS-367JD's key differentiators are its use of AlInGaP (Hyper Red) technology and its specific form factor. Compared to older GaAsP or GaP red LEDs, AlInGaP offers significantly higher luminous efficiency, resulting in greater brightness for the same input current. The \"gray face with white segments\" enhances contrast compared to all-red or all-green packages. The 0.36-inch digit height is a standard size, offering a good balance between readability and board space. Its common cathode configuration is typical and interfaces easily with most microcontroller circuits which sink current more easily than they source it. The categorization for luminous intensity is a mark of quality control, ensuring performance consistency.

9. Frequently Asked Questions (FAQ)

Q1: What is the purpose of having two common cathode pins (1 and 6)?

A1: This provides mechanical and electrical redundancy. It allows for a more robust connection to ground on the PCB (using two solder pads/vias), improving reliability. Electrically, they are the same node.

Q2: Can I drive this display directly from a 3.3V microcontroller?

A2: Possibly, but you must check the forward voltage (V_F). With a typical V_F of 2.1V, there is 1.2V headroom (3.3V - 2.1V). A current-limiting resistor is still needed. Calculate R = (3.3 - 2.1) / I_F. For 10mA, R = 120 Ω. Ensure the microcontroller pin can source ~10mA.

Q3: What does \"Hyper Red\" mean compared to standard red?

A3: Hyper Red LEDs have a longer dominant/peak wavelength (typically 640-660 nm) compared to standard red (620-630 nm). They appear as a deeper, more \"true\" red color and often have higher luminous efficiency.

Q4: How do I calculate the total power consumption of the display?

A4: If all 7 segments and the decimal point are lit continuously at, for example, 10mA each with V_F=2.1V, the total current is 80mA. Power = V_F * Total I_F = 2.1V * 0.08A = 0.168W or 168 mW. This is below the per-segment dissipation limit but must be considered for the power supply and heat.

Q5: Why is current derating necessary?

A5: LED efficiency decreases and the risk of catastrophic failure increases as the junction temperature rises. At higher ambient temperatures, the same electrical power input creates a higher junction temperature. Derating the current reduces the electrical power input (heat generated), keeping the junction temperature within safe limits.

10. Practical Design and Usage Example

Scenario: Building a Simple Counter Display with an Arduino.

The goal is to display a count from 0 to 9, incrementing every second.

Components: Arduino Uno, LTS-367JD display, 8x 330Ω resistors (one for segments A-G and DP).

Wiring:

1. Connect the common cathode pins (1 & 6) of the display to Arduino GND.

2. Connect each segment anode (Pins 2,3,4,5,7,8,9,10) to a separate Arduino digital pin (e.g., 2 through 9) via a 330Ω current-limiting resistor.

Software Logic:

The code would define an array that maps digits (0-9) to the combination of segments that need to be lit (e.g., '0' = segments A,B,C,D,E,F). In the loop, it would:

1. Determine which digit to display.

2. Look up the segment pattern for that digit.

3. Set the corresponding Arduino pins HIGH (to light the segment) or LOW (to turn it off) according to the pattern.

4. Wait one second, then increment the digit and repeat.

Design Note: The total current from the Arduino's 5V pin, if all segments are on, would be ~8 * (5V-2.1V)/330Ω ≈ 8 * 8.8mA = 70.4mA. This is within the capability of the Arduino's voltage regulator for a single display but should be considered if powering other components.

11. Technology Principle Introduction

The LTS-367JD is based on AlInGaP (Aluminum Indium Gallium Phosphide) semiconductor material grown on a non-transparent GaAs (Gallium Arsenide) substrate. When a forward voltage exceeding the material's bandgap energy is applied across the p-n junction, electrons and holes recombine, releasing energy in the form of photons (light). The specific composition of the AlInGaP alloy determines the bandgap energy, which directly dictates the wavelength (color) of the emitted light—in this case, hyper red (~639-650 nm). The non-transparent substrate helps direct more of the generated light out through the top of the device, improving external quantum efficiency compared to some older designs with absorbing substrates. The individual segments are formed by patterning the semiconductor layers and metal contacts. The gray face filter absorbs ambient light, improving contrast, while the white segment markings diffuse the LED's point-source light to create a uniformly lit segment appearance.

12. Technology Trends and Context

While single-digit seven-segment LED displays like the LTS-367JD represent mature technology, they remain highly relevant due to their simplicity, reliability, low cost, and excellent readability, especially in high-ambient-light or wide-viewing-angle situations. The underlying AlInGaP material technology represents a significant advancement over earlier red LED materials (like GaAsP), offering superior efficiency and brightness. Current trends in display technology focus on higher integration (multi-digit modules, dot matrix displays) and interfaces (I2C, SPI drivers). However, discrete single-digit components are perfect for applications where only one or a few digits are needed, minimizing complexity and cost. There is also a trend towards higher efficiency, allowing displays to be driven at lower currents for reduced power consumption and heat generation, which aligns with the derating principles outlined in this datasheet. The core principles of current limiting, thermal management, and drive circuitry detailed here are fundamental and apply to virtually all LED-based indicator designs.