LTS-3361JS 0.3-Inch Yellow 7-Segment LED Display Datasheet - Digit Height 7.62mm - Forward Voltage 2.6V - Power 40mW - English Technical Document

1. Product Overview

The LTS-3361JS is a single-digit, 7-segment alphanumeric LED display module designed for applications requiring clear, bright numeric or limited alphanumeric indication. Its primary function is to provide a highly legible visual output in a compact form factor.

1.1 Core Advantages and Target Market

This device is engineered for reliability and performance in consumer electronics, industrial instrumentation, and basic digital readouts. Its core advantages, as derived from the datasheet, include a 0.3-inch (7.62mm) digit height offering a good balance between size and readability. It features continuous uniform segments for a clean, professional character appearance without visible breaks in the lit segments. The display boasts high brightness and high contrast, facilitated by the use of AlInGaP semiconductor technology on a non-transparent substrate, ensuring vivid output even in well-lit conditions. A wide viewing angle enhances visibility from various perspectives. Furthermore, it is categorized for luminous intensity, allowing for binning and consistency in production runs. The primary target markets include panel meters, household appliances, test equipment, and any device requiring a simple, efficient numeric display.

2. Technical Parameter Deep-Dive

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

2.1 Photometric and Optical Characteristics

The optical performance is central to this display's function. The device utilizes AlInGaP (Aluminum Indium Gallium Phosphide) yellow LED chips. This material system is known for its high efficiency and stability in the yellow-orange-red spectrum. The chips are fabricated on a non-transparent GaAs substrate, which helps in improving contrast by preventing light from escaping through the back of the chip, thereby directing more light forward. The package has a gray face with white segments, which further enhances contrast when the segments are unlit. Key measured parameters at Ta=25°C include:

• Average Luminous Intensity (I_V): Ranges from 200 μcd (min) to 600 μcd (max) at a forward current (I_F) of 1mA. The typical value is implied within this range. This intensity is measured using a filter approximating the CIE photopic eye-response curve.
• Peak Emission Wavelength (λ_p): Typically 588 nm, placing it in the yellow region of the visible spectrum.
• Dominant Wavelength (λ_d): Typically 587 nm, very close to the peak wavelength, indicating a relatively pure yellow color.
• Spectral Line Half-Width (Δλ): Approximately 15 nm, which defines the spectral purity or color bandwidth of the emitted light.
• Luminous Intensity Matching Ratio: Specified as 2:1 maximum. This means the intensity of the brightest segment should not be more than twice that of the dimmest segment within the same digit at the same drive current, ensuring uniformity.

2.2 Electrical Parameters

The electrical specifications define the operating limits and conditions for reliable use.

• Absolute Maximum Ratings:
  • Power Dissipation per Segment: 40 mW.
  • Peak Forward Current per Segment: 60 mA (at 1/10 duty cycle, 0.1ms pulse width).
  • Continuous Forward Current per Segment: 25 mA at 25°C, derating linearly at 0.33 mA/°C above 25°C.
  • Reverse Voltage per Segment: 5 V.
  • Operating and Storage Temperature Range: -35°C to +85°C.
  • Solder Temperature: Maximum 260°C for up to 3 seconds at 1.6mm below the seating plane.
• Electrical/Optical Characteristics at Ta=25°C:
  • Forward Voltage per Segment (V_F): Typically 2.6V, with a maximum of 2.6V at I_F=20mA. The minimum is 2.05V.
  • Reverse Current per Segment (I_R): Maximum 100 μA at V_R=5V.

2.3 Thermal Characteristics

Thermal management is indirectly addressed through the derating specification for continuous forward current. The current must be reduced by 0.33 mA for every degree Celsius above 25°C ambient temperature. This is crucial for maintaining long-term reliability and preventing accelerated lumen depreciation or catastrophic failure. The wide operating temperature range of -35°C to +85°C indicates robustness for various environmental conditions.

3. Binning System Explanation

The datasheet explicitly states the device is \"categorized for luminous intensity.\" This refers to a binning or sorting process post-manufacturing. Due to inherent variations in the semiconductor epitaxial growth and chip fabrication, LEDs from the same production batch can have slightly different optical outputs. Binning involves measuring the luminous intensity of each unit and grouping them into specific intensity ranges (bins). This allows designers to select displays with consistent brightness levels for their application, ensuring a uniform appearance across multiple digits in a multi-digit display. The datasheet provides the overall min (200 μcd) and max (600 μcd) range; specific bin codes would typically be defined in separate documentation or ordering information.

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:

• I-V (Current-Voltage) Curve: Showing the relationship between forward voltage (V_F) and forward current (I_F). This curve is non-linear, with a turn-on voltage around 2V for AlInGaP, after which the current increases rapidly with small increases in voltage. This highlights the importance of current-limiting resistors or constant-current drivers.
• Luminous Intensity vs. Forward Current (I_V vs. I_F): This curve shows how light output increases with drive current. It is generally linear over a range but will saturate at very high currents due to thermal and efficiency droop.
• Luminous Intensity vs. Ambient Temperature: This curve would show the decrease in light output as the junction temperature rises, emphasizing the need for proper thermal design, especially when operating near maximum ratings.
• Spectral Distribution: A plot of relative intensity versus wavelength, centered around 587-588 nm with a ~15 nm half-width, confirming the yellow color point.

5. Mechanical and Package Information

5.1 Dimensions and Outline

The package is a standard single-digit 7-segment LED display. The datasheet includes a \"PACKAGE DIMENSIONS\" drawing (details not fully extracted here). Critical notes state that all dimensions are in millimeters and tolerances are ±0.25 mm (0.01\") unless otherwise specified. This tolerance is important for PCB footprint design to ensure proper fit and alignment.

5.2 Pinout and Polarity Identification

The device has a common cathode configuration. This means all the cathodes (negative terminals) of the LED segments are connected together internally. The pin connection is clearly defined:

1. Common Cathode
2. Anode F
3. Anode G
4. Anode E
5. Anode D
6. Common Cathode (Note: Pins 1 and 6 are both common cathode, likely for layout flexibility or lower resistance)
7. Anode DP (Decimal Point)
8. Anode C
9. Anode B
10. Anode A

The internal circuit diagram shows the common cathode connection to pins 1 & 6, with individual anodes for segments A-G and DP. The \"RT. HANDE DECIMAL\" note in the part number description suggests a right-hand decimal point placement.

6. Soldering and Assembly Guidelines

The datasheet provides a critical soldering specification: the package can withstand a maximum soldering temperature of 260°C for a maximum of 3 seconds, measured at 1.6mm (1/16 inch) below the seating plane. This is a standard reflow soldering profile constraint. Designers must ensure their PCB assembly process, whether wave or reflow soldering, adheres to this limit to prevent damage to the internal LED chips, wire bonds, or the plastic package. The storage temperature range (-35°C to +85°C) should also be observed before and after assembly.

7. Application Suggestions

7.1 Typical Application Scenarios

This display is ideal for applications requiring a single, highly visible digit: voltage/current readouts on power supplies, temperature displays on thermostats or ovens, timer counters, simple scoreboards, or status indicators on network equipment and appliances.

7.2 Design Considerations

• Drive Circuitry: As a common cathode device, the cathodes (pins 1/6) should be connected to ground or a current sink. Each segment anode must be driven through a current-limiting resistor. The resistor value is calculated based on the supply voltage (V_CC), the LED forward voltage (V_F, use max 2.6V for reliability), and the desired forward current (I_F). For example, with a 5V supply and targeting I_F=10mA: R = (V_CC - V_F) / I_F = (5V - 2.6V) / 0.01A = 240 Ω. A 220 Ω or 270 Ω resistor would be suitable.
• Multiplexing: For multi-digit displays, this digit can be multiplexed. Since it has independent anodes and a common cathode, it is well-suited for multiplexed designs where the cathodes of different digits are switched rapidly.
• Brightness Control: Brightness can be adjusted by varying the forward current (within absolute limits) or by using pulse-width modulation (PWM) on the drive signals.
• Viewing Angle: The wide viewing angle should be considered during mechanical enclosure design to ensure the display is visible to the end-user.

8. Technical Comparison and Differentiation

Compared to older technologies like standard GaP or GaAsP LEDs, the AlInGaP technology in the LTS-3361JS offers significantly higher luminous efficiency and brightness. Compared to some white or blue LEDs that use phosphor conversion, AlInGaP provides a pure, saturated color directly from the semiconductor, often with better stability over time and temperature. The non-transparent substrate is a key differentiator from cheaper displays that may use a transparent substrate, leading to poorer contrast as light escapes in all directions. The categorization (binning) for intensity is a mark of a quality component aimed at applications requiring consistency.

9. Frequently Asked Questions (Based on Technical Parameters)

Q: What is the purpose of having two common cathode pins (1 and 6)?
A: This provides design flexibility for PCB routing. It can help reduce the current density through a single pin if driving all segments at high current simultaneously, and it can make board layout easier by offering two ground connection points.

Q: Can I drive this display directly from a microcontroller pin?
A: Yes, but with important caveats. A typical MCU pin can source/sink up to 20-25mA, which is within the continuous current rating. However, you MUST use a series current-limiting resistor for each segment. Do not connect the LED directly to the pin. Also, ensure the total current from the MCU's power supply or ground pin does not exceed its package limits when multiple segments are lit.

Q: The forward voltage is listed as \"2.05 2.6 V\". What does this mean?
A: This indicates the forward voltage range. The minimum expected V_F is 2.05V, and the maximum is 2.6V when measured at I_F=20mA. You should design your driving circuit assuming the worst-case (highest) V_F to ensure sufficient voltage headroom to achieve the desired current across all units.

Q: What does \"categorized for luminous intensity\" mean for my design?
A: It means you can request parts from a specific brightness bin when ordering. If you are building a multi-digit instrument, specifying the same bin code for all displays will ensure they all have nearly identical brightness, resulting in a professional, uniform appearance.

10. Operational Principle Introduction

The operational principle is based on semiconductor electroluminescence. The AlInGaP chip consists of multiple epitaxial layers forming a p-n junction. When a forward bias voltage exceeding the junction's turn-on voltage (~2V) is applied, electrons and holes are injected across the junction. When these charge carriers recombine in the active region of the semiconductor, energy is released in the form of photons (light). The specific composition of the AlInGaP alloy determines the bandgap energy, which directly corresponds to the wavelength (color) of the emitted light—in this case, yellow (~587 nm). The non-transparent GaAs substrate absorbs rather than transmits light, improving overall forward light extraction and contrast. The light emitted from the chip passes through the encapsulating epoxy lens, which is shaped to enhance the viewing angle, and illuminates the white segment pattern printed on the gray face, creating the recognizable 7-segment character.

11. Development Trends

While this is a mature product, trends in display technology continue to evolve. There is a general move towards higher density and full-matrix addressable displays (like dot matrix or OLED) for greater information content. However, for simple numeric readouts, 7-segment LEDs remain popular due to their simplicity, robustness, low cost, and excellent readability. Future iterations of such devices may focus on even higher efficiency, allowing lower power consumption for battery-operated devices, or integration of driver ICs within the package (\"intelligent displays\"). The use of advanced materials like GaN-on-Si or improved phosphors could also broaden the available color gamut and efficiency for single-color displays. Nevertheless, the fundamental design and application of common-cathode, AlInGaP-based 7-segment displays like the LTS-3361JS are expected to remain relevant in cost-sensitive, high-reliability applications for the foreseeable future.