LTS-3361JG 7-Segment LED Display Datasheet - Digit Height 0.3 inch (7.62mm) - Forward Voltage 2.6V - Green (572nm) - English Technical Document

1. Product Overview

The LTS-3361JG is a single-digit, 7-segment alphanumeric display module utilizing AlInGaP (Aluminum Indium Gallium Phosphide) semiconductor technology. The primary function of this device is to provide a highly legible numeric and limited alphanumeric output in electronic equipment. Its core application lies in instrumentation, consumer electronics, industrial control panels, and any device requiring a clear, bright numeric readout.

The device is characterized by a 0.3-inch (7.62 mm) digit height, which offers an excellent balance between display size and compactness. It features a gray face with white segments, a combination engineered to provide high contrast for optimal readability under various lighting conditions. The use of AlInGaP material grown on a non-transparent GaAs substrate is key to its performance, enabling high brightness and efficiency in the green wavelength spectrum.

1.1 Core Advantages & Target Market

The LTS-3361JG offers several distinct advantages that define its position in the market:

• High Brightness & Contrast: The AlInGaP chips produce a luminous intensity ranging from 200 to 800 \u00b5cd at a low drive current of 1mA, ensuring visibility even in brightly lit environments.
• Low Power Consumption: Designed for efficiency, it requires minimal power, making it suitable for battery-operated or power-sensitive applications.
• Excellent Character Appearance & Uniformity: The segments are continuous and uniform, providing a clean, professional-looking digit without gaps or irregularities.
• Wide Viewing Angle: The optical design allows for clear readability from a broad range of angles, enhancing user experience.
• Solid-State Reliability: As an LED-based device, it offers long operational life, shock resistance, and reliability superior to older technologies like filament-based displays.
• Categorized Luminous Intensity: Devices are binned for intensity, allowing designers to select parts for consistent brightness across multiple units in a product.

The target market includes designers of test and measurement equipment, automotive dashboards (secondary displays), home appliances, medical devices, and industrial control systems where a reliable, clear, and efficient numeric display is required.

2. Technical Specifications Deep Dive

This section provides a detailed, objective analysis of the key technical parameters specified in the datasheet.

2.1 Photometric & Optical Characteristics

These parameters define the light output and color properties of the display.

• Average Luminous Intensity (I_V): Ranges from 200 \u00b5cd (Min) to 800 \u00b5cd (Typ) at a forward current (I_F) of 1mA. This is the perceived brightness as measured by a sensor filtered to match the human eye's photopic response (CIE curve). The wide range indicates a binning process; designers must account for this variation or specify a tighter bin for uniform appearance.
• Dominant Wavelength (\u03bb_d): 572 nm. This is the perceived color of the light, placing it in the green region of the spectrum. It is a key parameter for color-specific applications.
• Peak Emission Wavelength (\u03bb_p): 571 nm (Typ). This is the wavelength at which the spectral power distribution is maximum, very close to the dominant wavelength, indicating a spectrally pure green output.
• Spectral Line Half-Width (\u0394\u03bb): 15 nm (Typ). This measures the spectral bandwidth. A value of 15 nm is relatively narrow, confirming good color purity for a green LED.
• Luminous Intensity Matching Ratio (I_V-m): 2:1 (Max). This is the maximum allowable ratio between the brightest and dimmest segment within a single device. A ratio of 2:1 or less ensures acceptable uniformity across the digit.

2.2 Electrical Characteristics

These parameters are critical for circuit design and power management.

• Forward Voltage per Segment (V_F): 2.6V (Max) at I_F=20mA. The typical value is around 2.05V. This voltage drop must be considered when designing the current-limiting circuitry. The driver circuit must supply at least 2.6V to ensure proper segment illumination at the rated current.
• Continuous Forward Current per Segment (I_F): 25 mA (Max) at 25\u00b0C. This is the maximum DC current that can be applied continuously to a single segment without risking damage.
• Peak Forward Current per Segment: 60 mA (Max) under pulsed conditions (1/10 duty cycle, 0.1ms pulse width). This allows for multiplexing schemes or brief over-driving for higher perceived brightness.
• Current Derating: The maximum continuous current must be linearly derated by 0.33 mA/\u00b0C for ambient temperatures (T_a) above 25\u00b0C. This is a crucial thermal management consideration.
• Reverse Voltage per Segment (V_R): 5V (Max). Exceeding this voltage in reverse bias can permanently damage the LED junction.
• Reverse Current per Segment (I_R): 100 \u00b5A (Max) at V_R=5V. This is the leakage current when the LED is reverse-biased.
• Power Dissipation per Segment (P_D): 70 mW (Max). Calculated as V_F * I_F, this limit governs the thermal load of each segment.

2.3 Thermal & Environmental Ratings

• Operating Temperature Range: -35\u00b0C to +85\u00b0C. The device is suitable for industrial and extended commercial environments.
• Storage Temperature Range: -35\u00b0C to +85\u00b0C.
• Solder Temperature: Withstands a maximum of 260\u00b0C for up to 3 seconds, measured 1.6mm (1/16 inch) below the seating plane. This is compatible with standard lead-free reflow soldering profiles.

3. Binning System Explanation

The datasheet indicates the device is \"Categorized for Luminous Intensity.\" This implies a binning process.

• Luminous Intensity Binning: The wide I_V range (200-800 \u00b5cd) suggests LEDs are sorted into different intensity bins after production. For applications requiring consistent brightness across multiple displays (e.g., a multi-digit panel), specifying parts from the same intensity bin is essential.
• Forward Voltage Binning: While not explicitly stated as binned, the range provided (2.05V Typ, 2.6V Max) indicates natural variation. In precision applications or large arrays, voltage matching may also be a consideration for uniform current distribution.
• Wavelength Binning: The dominant wavelength is specified as a single typical value (572 nm). For this product, wavelength binning is likely very tight or not a primary sorting criterion, as a single green color is specified.

4. Performance Curve Analysis

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

• Forward Current vs. Forward Voltage (I-V Curve): This non-linear curve shows the relationship between applied voltage and resulting current. The \"knee\" voltage is around 2.0V, after which current increases rapidly with small voltage increases, necessitating constant-current drive for stable brightness.
• Luminous Intensity vs. Forward Current (I-L Curve): This curve is generally linear over a wide range. Luminous intensity is approximately proportional to forward current, allowing brightness to be controlled via PWM (Pulse Width Modulation) or analog current adjustment.
• Luminous Intensity vs. Ambient Temperature: For AlInGaP LEDs, light output typically decreases as junction temperature increases. The derating specification for forward current is directly linked to managing this thermal effect to maintain brightness and longevity.
• Spectral Distribution: A plot of relative intensity vs. wavelength, showing a peak near 571-572 nm with the stated 15 nm half-width.

5. Mechanical & Package Information

5.1 Physical Dimensions

The package is a standard single-digit 7-segment LED display outline. All dimensions are 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 digit height (7.62mm), and the spacing between segments. The exact footprint is critical for PCB (Printed Circuit Board) layout.

5.2 Pinout & Polarity Identification

The LTS-3361JG is a Common Cathode device. This means all LED segment cathodes are connected internally to common pins (Pin 1 and Pin 6), while each segment anode has its own pin. To illuminate a segment, its corresponding anode pin must be driven HIGH (positive voltage through a current-limiting resistor), and the common cathode pin(s) must be connected to GROUND (LOW).

Pin Connection:
1. Common Cathode
2. Anode F (Top-right segment)
3. Anode G (Center segment)
4. Anode E (Bottom-right segment)
5. Anode D (Bottom segment)
6. Common Cathode
7. Anode DP (Decimal Point)
8. Anode C (Bottom-left segment)
9. Anode B (Top-left segment)
10. Anode A (Top segment)

Note: Pins 1 and 6 are both common cathodes and should be connected together on the PCB to ensure even current distribution.

5.3 Internal Circuit Diagram

The internal diagram shows ten pins connecting to the eight LED elements (segments A-G plus DP). The two common cathode pins (1 & 6) are tied together internally. This configuration is standard for a common-cathode, single-digit display.

6. Soldering & Assembly Guidelines

• Reflow Soldering: Compatible with standard SMT reflow processes. The maximum rated solder temperature is 260\u00b0C for 3 seconds. A standard lead-free profile with a peak temperature between 245-250\u00b0C is recommended to stay within this limit.
• Hand Soldering: If manual soldering is necessary, use a temperature-controlled iron set to a maximum of 350\u00b0C and limit contact time to less than 3 seconds per pin to prevent thermal damage to the plastic package and internal wire bonds.
• Cleaning: Use only cleaning agents compatible with LED epoxy and plastic materials. Avoid ultrasonic cleaning unless verified to be safe for the specific package.
• ESD (Electrostatic Discharge) Precautions: Although not explicitly stated, LEDs are generally sensitive to ESD. Handle with appropriate ESD precautions (grounded workstations, wrist straps).
• Storage Conditions: Store in a dry, anti-static environment within the specified temperature range (-35\u00b0C to +85\u00b0C).

7. Application Suggestions

7.1 Typical Application Circuits

The most common drive method is multiplexing. For multi-digit displays, a microcontroller sequentially activates each digit's common cathode while outputting the segment pattern for that digit on the common anode lines. This reduces the required number of driver pins significantly. A constant-current driver IC or transistor array is often used to source sufficient current for the segments.

Current-Limiting Resistor Calculation: Essential for direct drive. Formula: R = (V_supply - V_F) / I_F. Example: For a 5V supply, V_F=2.2V, and I_F=10mA: R = (5 - 2.2) / 0.01 = 280 \u03a9. Use the nearest standard value (e.g., 270 \u03a9 or 330 \u03a9). One resistor is needed per segment anode if driving directly.

7.2 Design Considerations

• Brightness Control: Use PWM on the cathode or anode drivers to dim the display. This is more effective and efficient than varying the DC current.
• Viewing Angle: Position the display considering its wide viewing angle to ensure optimal visibility for the end-user.
• Thermal Management: Adhere to current derating guidelines for high ambient temperature applications. Ensure adequate PCB copper area or ventilation if driving at or near maximum currents.
• Decoupling: Place a small ceramic capacitor (e.g., 100nF) near the display's power pins to suppress noise, especially in multiplexed designs.

8. Technical Comparison & Differentiation

Compared to older technologies like Red GaAsP LEDs, the AlInGaP-based LTS-3361JG offers significantly higher brightness and efficiency for a given current. Compared to some modern white or blue LEDs with phosphor, it provides a pure, saturated green color without the complexity and efficiency loss of phosphor conversion.

Its primary differentiation lies in its specific combination: 0.3-inch digit height, common cathode configuration, pure green AlInGaP emission, and characterized intensity bins. Competing products might use different chip technologies (e.g., InGaN for blue/green), have different package colors (e.g., black face), or be common anode.

9. Frequently Asked Questions (Based on Technical Parameters)

Q1: Can I drive this display directly from a 3.3V microcontroller pin?
A: Possibly, but with caution. The typical V_F is 2.05V, and a GPIO pin's output high voltage (V_OH) might be as low as 2.64V at 3.3V supply. The voltage headroom (3.3V - 2.6V = 0.7V) is minimal for a current-limiting resistor. It's safer to use a transistor or driver IC to interface the microcontroller.

Q2: Why are there two common cathode pins (1 and 6)?
A: This is for mechanical symmetry and improved current distribution. Connecting both pins to ground on your PCB helps balance the current load, potentially improving segment brightness uniformity and long-term reliability.

Q3: What is the difference between Peak Emission and Dominant Wavelength?
A: Peak Emission Wavelength (\u03bb_p) is the physical peak of the light spectrum emitted. Dominant Wavelength (\u03bb_d) is the single wavelength perceived by the human eye that matches the color of the light source. For a monochromatic source like this green LED, they are very close.

Q4: How do I achieve consistent brightness in a multi-digit design?
A: 1) Use a constant-current driver circuit. 2) Implement software calibration or PWM adjustment per digit if needed. 3) Most importantly, specify and use LEDs from the same luminous intensity bin from your supplier.

10. Design-in Case Study

Scenario: Designing a simple 4-digit voltmeter display.

1. Component Selection: Four LTS-3361JG displays are selected for their readability and green color, which is often associated with \"on\" or \"normal\" status.
2. Drive Scheme: A multiplexing scheme is chosen. A microcontroller with 12 I/O pins (8 for segment anodes A-G, DP, and 4 for digit cathodes) can drive the entire display.
3. Circuit Design: The segment anode lines are connected in parallel across all four digits. Each digit's common cathode pins (1 & 6) are connected together and then to an NPN transistor sink. The microcontroller turns on one transistor (digit) at a time while outputting the corresponding 7-segment code on the anode lines. The refresh rate is set above 60 Hz to avoid flicker.
4. Current Calculation: For a multiplexed display, the instantaneous current per segment can be higher to achieve the same average brightness. If the duty cycle is 1/4 (4 digits), to get an average I_{F_avg} of 5mA, the instantaneous current during its active time should be I_{F_inst} = I_{F_avg} / Duty Cycle = 5mA / 0.25 = 20mA. This is within the continuous rating but must be checked against the peak rating for the chosen multiplexing frequency.
5. PCB Layout: The displays are placed with precise spacing according to the dimensional drawing. Traces for the common cathode connections are made wider to handle the cumulative segment current when a digit is fully lit (e.g., number '8').

11. Technology Principle Introduction

The LTS-3361JG is based on AlInGaP (Aluminum Indium Gallium Phosphide) semiconductor material. This is a III-V compound semiconductor where aluminum, indium, gallium, and phosphorus atoms are arranged in a crystal lattice. When forward-biased, electrons and holes recombine in the active region of the PN junction, releasing energy in the form of photons (light). The specific ratio of Al, In, Ga, and P in the crystal determines the bandgap energy, which directly dictates the wavelength (color) of the emitted light. For green emission around 572 nm, a precise composition is required.

The chips are fabricated on a non-transparent GaAs (Gallium Arsenide) substrate. This substrate absorbs some of the generated light, but the AlInGaP material system itself is highly efficient. The light is emitted from the top surface of the chip. The gray face and white segment diffuser of the package help to enhance contrast by absorbing ambient light and efficiently scattering the emitted green light from the chip, respectively.

12. Technology Trends

While this specific product uses mature and reliable AlInGaP technology, the broader LED display market trends include:

• Higher Efficiency: Ongoing material science research aims to improve the internal quantum efficiency (IQE) and light extraction efficiency (LEE) of all LED colors, reducing power consumption for the same brightness.
• Miniaturization: There is a trend towards smaller pixel pitches and higher-density displays, although for standalone 7-segment devices, the 0.3-inch size remains a popular standard for legibility.
• Integration: More displays are integrating the driver IC directly into the module package, simplifying external circuitry for designers.
• Alternative Technologies: For full-color or high-resolution applications, technologies like MicroLED and advanced OLEDs are evolving. However, for simple, robust, bright, and low-cost single-digit numeric displays, AlInGaP and InGaN-based LEDs remain dominant due to their reliability, longevity, and simplicity.

The LTS-3361JG represents a well-optimized solution within its niche, balancing performance, cost, and reliability based on established semiconductor physics and packaging techniques.