LTD-4830CKG-P LED Display Datasheet - 0.39-inch Digit Height - AlInGaP Green - 2.6V Forward Voltage - English Technical Document

1. Product Overview

The LTD-4830CKG-P is a surface-mount device (SMD) featuring a dual-digit, seven-segment LED display. The primary application is for numeric readouts in electronic equipment. Its core construction utilizes Aluminium Indium Gallium Phosphide (AlInGaP) semiconductor material epitaxially grown on a Gallium Arsenide (GaAs) substrate, which is engineered to emit green light. The display is characterized by a gray face and white segments, a combination designed to enhance contrast and readability under various lighting conditions.

1.1 Key Features and Core Advantages

• Digit Height: 0.39 inches (10.0 mm), providing clear visibility.
• Segment Design: Continuous uniform segments for excellent character appearance and legibility.
• Power Efficiency: Low power requirement, suitable for battery-powered or energy-conscious applications.
• Optical Performance: High brightness and high contrast ratio.
• Viewing Angle: Wide viewing angle ensures readability from various positions.
• Reliability: Solid-state reliability with no moving parts.
• Quality Control: Devices are categorized (binned) for luminous intensity, ensuring consistency in brightness across production batches.
• Environmental Compliance: Lead-free package compliant with RoHS (Restriction of Hazardous Substances) directives.

1.2 Device Identification and Configuration

The part number LTD-4830CKG-P specifies a Common Anode configuration with AlInGaP Green LED chips. The "Rt. Hand Decimal" notation indicates the inclusion and positioning of a right-hand decimal point for each digit.

2. Technical Parameters: In-Depth Objective Interpretation

2.1 Absolute Maximum Ratings

These ratings define the 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: 60 mA (under pulsed conditions: 1/10 duty cycle, 0.1ms pulse width).
• Continuous Forward Current per Segment: 25 mA at 25°C. This rating derates linearly at 0.28 mA/°C as ambient temperature (Ta) increases above 25°C. This is a critical design parameter for thermal management.
• Operating & Storage Temperature Range: -35°C to +105°C.
• Soldering Temperature: Iron soldering is specified at 260°C for a maximum of 3 seconds, with the iron tip positioned at least 1/16 inch below the seating plane of the component.

2.2 Electrical & Optical Characteristics

These are the typical and guaranteed performance parameters measured at Ta=25°C.

• Average Luminous Intensity (I_V): Ranges from 201 µcd (Min) to 650 µcd (Typ) at a forward current (I_F) of 1 mA. At I_F=10 mA, the typical intensity is 7150 µcd. This non-linear relationship highlights the efficiency of the LED material.
• Forward Voltage per Chip (V_F): Typically 2.6V, with a maximum of 2.6V at I_F=20 mA. The minimum is 2.05V. Circuit design must account for this range to ensure consistent current drive.
• Peak Emission Wavelength (λ_p): 571 nm (typical). This is the wavelength at which the emitted optical power is greatest.
• Dominant Wavelength (λ_d): 572 nm (typical). This is the single wavelength perceived by the human eye, defining the green color point.
• Spectral Line Half-Width (Δλ): 15 nm (typical). This indicates the spectral purity or bandwidth of the emitted light.
• Reverse Current (I_R): Maximum 100 µA at a reverse voltage (V_R) of 5V. Important Note: This parameter is for test purposes only; the device is not designed for continuous operation under reverse bias.
• Luminous Intensity Matching Ratio: Maximum 2:1 for segments within a similar light area at I_F=1mA. This ensures uniformity in brightness across the display.
• Cross Talk: Specification is ≤ 2.5%, minimizing unwanted illumination of non-driven segments.

3. Binning System Explanation

The datasheet explicitly states that devices are "Categorized for Luminous Intensity." This means the LEDs are tested and sorted (binned) based on their measured light output at a standard test current (likely 1 mA or 10 mA as per the characteristics table). This process guarantees that displays within the same order or batch will have closely matched brightness levels, which is crucial for applications requiring uniform appearance. Designers should consult the manufacturer for specific bin codes and available intensity ranges for procurement.

4. Performance Curve Analysis

While specific graphical data is referenced in the PDF ("Typical Electrical / Optical Characteristics Curves"), the textual data allows for analysis:

• IV (Current-Voltage) Relationship: The forward voltage (V_F) is specified at a specific current (20mA). In practice, V_F has a logarithmic relationship with current and a negative temperature coefficient (decreases as temperature rises).
• Luminous Intensity vs. Current: The data shows a significant increase in intensity from 1mA to 10mA (from hundreds to thousands of µcd), demonstrating the high efficiency of AlInGaP technology. The curve is typically super-linear at lower currents and may become sub-linear at very high currents due to thermal and efficiency droop.
• Temperature Dependence: The derating of continuous current (0.28 mA/°C) is a direct indicator of thermal limitations. Luminous intensity for AlInGaP LEDs generally decreases with increasing junction temperature.

5. Mechanical and Package Information

5.1 Package Dimensions

The device is housed in an SMD package. Critical dimensional tolerances are ±0.25 mm unless otherwise specified. Key quality notes include limits on foreign material, ink contamination, bubbles within the segment area, and plastic pin burrs, all aimed at ensuring optical quality and reliable solderability.

5.2 Pin Connection and Polarity Identification

The display has a 20-pin configuration. It features a Common Anode architecture. Each digit has its own common anode pin (pins 3, 8, 13, 18), and individual segment cathodes (A-G, DP) are shared across digits according to the pinout table. Correct identification of the common anode pins is essential for proper circuit design, as they will be connected to the positive supply voltage through current-limiting resistors.

5.3 Internal Circuit Diagram & Recommended Soldering Pattern

The internal diagram shows the interconnection of the LED chips within the package. The recommended soldering pattern (land pattern) is provided to ensure proper solder joint formation, mechanical stability, and thermal relief during the reflow process.

6. Soldering and Assembly Guidelines

6.1 SMT Reflow Soldering Instructions

• Process Limit: The component may undergo reflow soldering a maximum of two times. A complete cooling cycle to normal ambient temperature is mandatory between the first and second reflow process.
• Profile: A recommended reflow profile is provided:
  • Pre-heat: 120–150°C.
  • Pre-heat Time: Maximum 120 seconds.
  • Peak Temperature: Maximum 260°C.
  • Time Above Liquidus: Maximum 5 seconds.
• Hand Soldering: If using a soldering iron, the tip temperature should not exceed 300°C, and contact time should be limited to 3 seconds maximum.

6.2 Moisture Sensitivity and Storage

The components are shipped in moisture-proof packaging. They must be stored at ≤30°C and ≤60% Relative Humidity (RH). Once the sealed bag is opened, the components begin to absorb moisture from the environment. If exposed to ambient conditions beyond the specified limits, they must be baked before reflow to prevent "popcorning" or internal delamination caused by rapid vapor expansion during soldering.

• Baking Conditions:
  • Components on reel: 60°C for ≥48 hours.
  • Components in bulk: 100°C for ≥4 hours or 125°C for ≥2 hours.
• Important: Baking should be performed only once.

7. Packaging and Ordering Information

7.1 Packing Specifications

The device is supplied on tape-and-reel for automated assembly.

• Reel Dimensions: Standard 13-inch reel.
• Quantity per Reel: 550 pieces.
• Minimum Order Quantity (MOQ) for Remainders: 200 pieces.
• Carrier Tape: Dimensions for the pocket that holds the component are specified.
• Leader and Trailer Tape: Minimum lengths of 400mm and 40mm, respectively, are required for machine feeding.

8. Application Suggestions and Design Considerations

8.1 Target Applications

This display is intended for ordinary electronic equipment including, but not limited to, office equipment, communication devices, household appliances, instrumentation panels, and consumer electronics where numeric readouts are required.

8.2 Critical Design Considerations

• Drive Method: Constant current driving is strongly recommended over constant voltage to ensure consistent luminous intensity across units and over temperature variations. The circuit must be designed to accommodate the full V_F range (2.05V to 2.6V) to deliver the intended current to all devices.
• Current Limiting: The safe operating current must be selected after considering the absolute maximum ratings, especially the derating with temperature. Exceeding these limits will cause severe light output degradation or premature failure.
• Reverse Voltage Protection: The driving circuit must incorporate protection against reverse voltages and transient voltage spikes during power-up or shutdown sequences, as LEDs have very low reverse breakdown voltages.
• Thermal Management: Adequate PCB layout for heat dissipation is necessary, especially when operating near maximum ratings or in elevated ambient temperatures, due to the current derating specification.

8.3 Cautions and Reliability

The datasheet includes explicit cautions regarding use in safety-critical applications (aviation, medical, transportation). For such applications, consultation with the manufacturer is required prior to design-in. The manufacturer is not liable for damage resulting from operation outside the specified absolute maximum ratings or misuse of the product.

9. Technical Comparison and Differentiation

The LTD-4830CKG-P differentiates itself through several key attributes common to modern SMD LED displays:

• Material Technology (AlInGaP): Offers higher efficiency and better temperature stability compared to older technologies like standard GaP, resulting in higher brightness and more consistent color.
• SMD Package: Enables automated pick-and-place assembly, reducing manufacturing costs and improving reliability over through-hole designs.
• Intensity Binning: Provides guaranteed brightness uniformity, which is a significant advantage for multi-digit displays where visual consistency is paramount.
• RoHS Compliance: Meets global environmental regulations, making it suitable for a wide market.

10. Frequently Asked Questions (FAQ) Based on Technical Parameters

10.1 What is the purpose of the "Common Anode" configuration?

In a common anode display, all the anodes of the LEDs for a digit are connected together to a single pin (the common anode), which is connected to the positive supply. Individual segments are turned ON by applying a low (ground) signal to their respective cathode pins through a current-limiting resistor. This configuration often simplifies multiplexing circuits in microcontroller-based designs.

10.2 Why is constant current drive recommended?

LEDs are current-driven devices. Their light output is proportional to forward current, not voltage. The forward voltage (V_F) has a tolerance and varies with temperature. A constant current source ensures that the desired brightness is maintained regardless of variations in V_F from device to device or due to temperature changes, leading to more uniform and predictable performance.

10.3 How do I calculate the current-limiting resistor value?

For a simple resistor drive with a common anode connected to V_CC, the resistor value (R) for each segment cathode is calculated as: R = (V_CC - V_F - V_OL) / I_F. Where V_CC is the supply voltage, V_F is the forward voltage of the LED (use max value for worst-case current calculation), V_OL is the output low voltage of the driving IC (e.g., microcontroller), and I_F is the desired forward current (must be ≤ the maximum continuous current rating, considering derating).

10.4 What happens if I exceed the maximum soldering temperature or time?

Excessive heat during soldering can cause irreparable damage to the internal wire bonds, the LED chip itself, or the plastic package, leading to immediate failure or significantly reduced long-term reliability. Always adhere to the specified reflow profile and hand-soldering limits.

11. Practical Design and Usage Case

Scenario: Designing a dual-digit temperature readout for a consumer appliance.

1. Selection: The LTD-4830CKG-P is chosen for its 0.39" digit size (good visibility), green color (often associated with "on" or "normal" status), and SMD package for automated assembly.
2. Schematic Design: The four common anode pins (for two digits) are connected to GPIO pins on a microcontroller configured as open-drain or with series transistors. Each of the 7 segment cathodes (plus two decimal points) is connected to other GPIO pins through individual current-limiting resistors. The resistor value is calculated based on a 3.3V or 5V system voltage and a target I_F of 10-15 mA for adequate brightness.
3. PCB Layout: The recommended soldering pattern from the datasheet is used in the PCB footprint. Adequate copper pour around the pads aids in heat dissipation.
4. Firmware: The display is multiplexed. The firmware rapidly cycles between enabling Digit 1 (setting its common anode high/turning on its transistor) while driving the correct cathode pattern for Digit 1's value, then disabling Digit 1, enabling Digit 2, and driving Digit 2's pattern. This happens faster than the human eye can perceive, creating the illusion of both digits being lit simultaneously.
5. Manufacturing: Components are stored in a dry cabinet after the reel is opened. The PCB undergoes a single reflow process adhering to the specified temperature profile.

12. Operating Principle Introduction

Light Emitting Diodes (LEDs) are semiconductor p-n junction devices. When a forward voltage is applied, electrons from the n-type region and holes from the p-type region are injected into the junction region (the active layer). Here, electrons recombine with holes, releasing energy in the form of photons (light). The specific wavelength (color) of the emitted light is determined by the energy bandgap of the semiconductor material used in the active layer. The LTD-4830CKG-P uses AlInGaP (Aluminium Indium Gallium Phosphide), which has a bandgap corresponding to green light (~572 nm). The seven-segment format is created by arranging multiple individual LED chips (or chip segments) within a single plastic package, with their electrical connections routed to the external pins.

13. Technology Trends and Context

AlInGaP LED technology represents a mature and highly efficient solution for red, orange, amber, and green LEDs. Key trends in the display segment include:

• Miniaturization: Continued reduction in digit height and package size for higher-density displays and smaller devices.
• Higher Efficiency: Ongoing material and process improvements yield higher luminous efficacy (more light output per watt of electrical input), enabling brighter displays or lower power consumption.
• Enhanced Reliability: Improvements in packaging materials, wire bonding, and encapsulation techniques lead to longer operational lifetimes and better performance in harsh environments (temperature, humidity).
• Integration: While discrete segment displays remain vital, there is a parallel trend towards integrated driver-and-display modules and dot-matrix graphic panels offering greater flexibility, though often at a higher cost and complexity.

The LTD-4830CKG-P sits within this landscape as a reliable, high-performance component for applications where dedicated numeric readouts provide the optimal balance of cost, simplicity, and clarity.