LTS-4812CKR-PM LED Display Datasheet - 0.39-inch Digit Height - Super Red Color - 2.6V Forward Voltage - English Technical Document

1. Product Overview

The LTS-4812CKR-PM is a surface-mount device (SMD) designed as a single-digit numeric display. It utilizes advanced AlInGaP (Aluminum Indium Gallium Phosphide) semiconductor technology grown on a GaAs substrate to produce a super red color output. The display features a gray face with white segments, providing high contrast for optimal readability. Its primary application is in consumer electronics, industrial instrumentation, and control panels where a compact, reliable, and bright numeric indicator is required.

1.1 Key Features

• Digit Height: 0.39 inches (10.0 mm), offering a clear and visible character size.
• Segment Uniformity: Continuous and uniform light emission across all segments for a consistent appearance.
• Power Efficiency: Low power requirement, making it suitable for battery-powered devices.
• Optical Performance: High brightness and high contrast ratio ensure excellent visibility under various lighting conditions.
• Viewing Angle: Wide viewing angle allows for readability from different perspectives.
• Reliability: Solid-state construction ensures long operational life and resistance to shock and vibration.
• Binning: Categorized for luminous intensity, allowing for consistent brightness matching in multi-digit applications.
• Environmental Compliance: Lead-free package compliant with RoHS (Restriction of Hazardous Substances) directives.

1.2 Device Configuration

This device is configured as a common anode display. The specific part number LTS-4812CKR-PM indicates a right-hand decimal point configuration. The common anode design simplifies circuit design when interfacing with microcontroller or driver ICs that source current.

2. Technical Specifications Deep Dive

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 limits.

• Power Dissipation per Segment: 70 mW maximum.
• Peak Forward Current per Segment: 90 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 increases above 25°C.
• Operating Temperature Range: -35°C to +105°C.
• Storage Temperature Range: -35°C to +105°C.
• Soldering Temperature: Withstands iron soldering at 260°C for 3 seconds, measured 1/16 inch below the seating plane.

2.2 Electrical & Optical Characteristics

Typical performance is measured at an ambient temperature (Ta) of 25°C.

• Average Luminous Intensity (Iv): Ranges from a minimum of 201 µcd to a typical 650 µcd at a forward current (IF) of 1 mA. At 10 mA, the typical intensity is 8250 µcd.
• Peak Emission Wavelength (λp): 639 nm, defining the primary color point in the super red spectrum.
• Spectral Line Half-Width (Δλ): 20 nm, indicating the spectral purity of the emitted light.
• Dominant Wavelength (λd): 631 nm.
• Forward Voltage per Chip (VF): Typically 2.6V with a maximum of 2.6V at IF=20mA. The minimum is 2.0V.
• Reverse Current per Segment (IR): Maximum 100 µA at a reverse voltage (VR) of 5V. Note: This condition is for test purposes only; the device is not intended for continuous reverse bias operation.
• Luminous Intensity Matching Ratio: Maximum 2:1 for segments within a similar light area at IF=1mA, ensuring uniform brightness.
• Cross Talk: Specified as ≤ 2.5%, minimizing unwanted illumination of adjacent segments.

3. Binning System Explanation

The luminous intensity of the LTS-4812CKR-PM is categorized into bins to guarantee consistency. The bin code (E, F, G, H, J) corresponds to a specific range of luminous intensity measured in microcandelas (µcd). The tolerance for each bin is +/-15%.

• Bin E: 201 - 320 µcd
• Bin F: 321 - 500 µcd
• Bin G: 501 - 800 µcd
• Bin H: 801 - 1300 µcd
• Bin J: 1301 - 2100 µcd

This system allows designers to select parts with closely matched brightness for multi-digit displays, preventing uneven illumination.

4. Performance Curve Analysis

While specific graphical curves are referenced in the datasheet, the underlying relationships are critical for design.

• Forward Current vs. Forward Voltage (I-V Curve): The AlInGaP technology exhibits a characteristic forward voltage typically around 2.6V at 20mA. Designers must ensure the driving circuit can provide sufficient voltage, considering potential drops.
• Luminous Intensity vs. Forward Current: Intensity increases with current but not linearly. Operating at the recommended 10-20mA range provides optimal brightness and efficiency.
• Temperature Dependence: Like all LEDs, luminous output decreases as junction temperature rises. The derating of continuous current (0.28 mA/°C above 25°C) is crucial for thermal management in high-temperature environments.
• Spectral Distribution: The narrow half-width (20nm) around 639nm indicates a saturated, pure red color, which is less susceptible to shifts with current or temperature compared to some other LED technologies.

5. Mechanical & Package Information

5.1 Package Dimensions

The device conforms to a standard SMD footprint. Critical dimensional notes include tolerances of ±0.25mm unless specified otherwise. Quality control criteria are defined for foreign material, ink contamination, bubbles within segments, bending of the reflector, and plastic pin burrs (max 0.1 mm).

5.2 Pin Connection and Circuit Diagram

The display has a 10-pin configuration. The internal circuit diagram shows a common anode connection for all segments. The pinout is as follows: Pin 3 and Pin 8 are Common Anodes. The remaining pins (1, 2, 4, 5, 6, 7, 9, 10) are cathodes for segments E, D, C, DP (decimal point), B, A, F, and G respectively. Pin 5 is specifically for the right-hand decimal point (DP).

5.3 Recommended Soldering Pattern

A land pattern design is provided to ensure reliable solder joint formation during reflow processes, promoting proper self-alignment and thermal and electrical connection.

6. Soldering & Assembly Guidelines

6.1 SMT Soldering Instructions

The device is rated for a maximum of two reflow soldering cycles. A complete cooling to normal temperature is mandatory between the first and second cycle.

• Reflow Soldering Profile:
  • Pre-heat: 120-150°C
  • Pre-heat Time: Maximum 120 seconds
  • Peak Temperature: Maximum 260°C
  • Time above liquidus: Maximum 5 seconds
• Hand Soldering (Iron): Maximum tip temperature of 300°C for a maximum of 3 seconds per joint.

6.2 Moisture Sensitivity and Storage

The SMD package is moisture-sensitive. Devices are shipped in moisture-proof packaging with a desiccant. They must be stored at ≤30°C and ≤60% Relative Humidity. Once the sealed bag is opened, the components begin absorbing moisture from the environment.

Baking Requirements (if exposed): If the components are not stored in a dry cabinet after bag opening, they must be baked before reflow to prevent \"popcorning\" or internal delamination during soldering.

• In Reel: 60°C for ≥48 hours.
• In Bulk: 100°C for ≥4 hours or 125°C for ≥2 hours.

Important: Baking should be performed only once to avoid degrading the plastic package.

7. Packaging & Ordering Information

7.1 Packing Specifications

The device is supplied on embossed carrier tape wound onto reels, compatible with automated pick-and-place equipment.

• Reel Dimensions: Standard reel dimensions are provided for both the component carrier and the overall reel (e.g., 13\" or 22\" reel).
• Carrier Tape: Made from black conductive polystyrene alloy. Dimensions comply with EIA-481-D standards. Key specifications include camber (within 1mm over 250mm) and thickness (0.40±0.05mm).
• Packing Quantities:
  • Components per 13\" reel: 800 pieces.
  • Packing length per 22\" reel: 44.5 meters.
  • Minimum order quantity for remnants: 200 pieces.
• Leader and Trailer Tape: The reel includes a leader (minimum 400mm) and trailer (minimum 40mm) for machine handling.

8. Application Notes & Design Considerations

8.1 Typical Application Scenarios

• Consumer Electronics: Digital clocks, microwave oven displays, audio equipment readouts.
• Industrial Controls: Panel meters, process indicators, timer displays.
• Automotive Aftermarket: Gauges and auxiliary displays (subject to additional qualification for automotive environments).
• Medical Devices: Simple numeric readouts on non-critical monitoring equipment.

8.2 Design Considerations

• Current Limiting: Always use a series current-limiting resistor for each segment or a dedicated constant-current LED driver IC. Calculate the resistor value based on the supply voltage (Vcc), the LED forward voltage (Vf ~2.6V), and the desired forward current (e.g., 10-20mA).
• Multiplexing: For multi-digit displays, a multiplexed driving scheme is common. The common anode design is well-suited for this. Ensure the peak current in multiplexed operation does not exceed the absolute maximum rating, and calculate the average current to stay within the continuous rating.
• Thermal Management: Although power dissipation is low, ensure adequate PCB layout to dissipate heat, especially in high ambient temperature applications or when driving at higher currents. Follow the current derating curve above 25°C.
• ESD Protection: Standard ESD precautions should be observed during handling and assembly, as with all semiconductor devices.

9. Technical Comparison & Differentiation

The LTS-4812CKR-PM differentiates itself through its use of AlInGaP technology for the super red color.

• vs. Traditional GaAsP/GaP Red LEDs: AlInGaP offers significantly higher luminous efficiency and brightness at the same current level. It also provides better temperature stability and longer lifetime.
• vs. High-Efficiency Red LEDs: While not the absolute highest efficiency available, it provides an excellent balance of performance, cost, and reliability for standard numeric display applications.
• Key Advantage: The combination of high brightness, good contrast (gray face/white segments), wide viewing angle, and reliable SMD packaging in a 0.39-inch digit size makes it a versatile choice for many applications.

10. Frequently Asked Questions (FAQs)

10.1 What is the purpose of the binning system?

The binning system ensures brightness uniformity across different production batches and within a multi-digit display. By specifying a bin code (e.g., Bin G), you guarantee all segments will have luminous intensity within the 501-800 µcd range at 1mA, preventing one digit from appearing brighter or dimmer than another.

10.2 Can I drive this display without a current-limiting resistor?

No. LEDs are current-driven devices. Connecting them directly to a voltage source will cause current to rise uncontrollably, quickly exceeding the maximum ratings and destroying the LED. A series resistor or constant-current driver is mandatory.

10.3 Why is there a limit on the number of reflow cycles?

The plastic package and internal materials can absorb moisture. During reflow, this moisture turns to steam, potentially causing internal cracks or delamination (\"popcorning\"). The two-cycle limit, with proper baking if needed, is set to ensure package integrity remains within safe limits.

10.4 What does \"common anode\" mean for my circuit design?

In a common anode display, all the anodes (positive sides) of the LED segments are connected together internally. To illuminate a segment, you connect its cathode pin to a low voltage (ground) while applying a positive voltage to the common anode pin. This is convenient when using driver ICs that sink current (like many multiplexing drivers).

11. Practical Design Example

Scenario: Designing a 4-digit clock display using the LTS-4812CKR-PM, driven by a 5V microcontroller with limited I/O pins.

Solution: Use a multiplexing scheme with a dedicated LED driver IC (e.g., a MAX7219 or a similar multiplexing shift register).

1. Connection: Connect the four common anode pins (each digit's pins 3 & 8 tied together) to four separate driver outputs configured as current sources.
2. Segment Lines: Connect all corresponding segment cathodes (A, B, C, D, E, F, G, DP) in parallel across the four digits to the driver's segment sink outputs.
3. Current Setting: Set the driver's constant current to a value like 15mA per segment. This is within the continuous rating and provides good brightness.
4. Multiplexing: The driver will rapidly cycle through illuminating each digit one at a time. Due to persistence of vision, all four digits will appear to be lit simultaneously. Ensure the refresh rate is high enough (typically >100Hz) to avoid visible flicker.
5. Resistors: The constant-current driver eliminates the need for individual series resistors on each segment.

This approach minimizes microcontroller I/O usage while providing stable, uniform illumination.

12. Operating Principle

The LTS-4812CKR-PM is a light-emitting diode (LED) display. Each segment is composed of one or more AlInGaP semiconductor chips. When a forward bias voltage (exceeding the chip's forward voltage, ~2.6V) is applied, electrons and holes recombine in the active region of the semiconductor, releasing energy in the form of photons (light). The specific composition of the AlInGaP layers determines the wavelength of the emitted light, in this case, in the super red spectrum (~639nm peak). The gray face and white segments act as a diffuser and reflector, respectively, to shape the light output into recognizable numeric characters.

13. Technology Trends

The use of AlInGaP for red/orange/yellow LEDs represents a mature and stable technology offering high efficiency and reliability. Current trends in display technology focus on:

• Miniaturization: Even smaller digit heights and pixel pitches for higher resolution displays.
• Increased Efficiency: Ongoing material science improvements to achieve higher lumens per watt (lm/W), reducing power consumption.
• Integration: Combining the LED array, driver circuitry, and sometimes a microcontroller into a single, smart display module.
• Flexible Substrates: Research into LEDs on flexible circuits for novel form factors, though this is more relevant to newer OLED and micro-LED technologies than traditional segmented displays.

For standard, cost-effective, single-digit numeric displays, AlInGaP-based SMD components like the LTS-4812CKR-PM remain a mainstream and reliable solution.