LTS-4817CTB-P LED Display Datasheet - 0.39-inch Digit Height - InGaN Blue - 3.8V Forward Voltage - 70mW Power - English Technical Document

1. Product Overview

The LTS-4817CTB-P is a surface-mount device (SMD) designed as a single-digit numeric display. Its primary function is to provide clear, reliable alphanumeric or numeric indication in electronic equipment. The core component is the use of Indium Gallium Nitride (InGaN) semiconductor material grown on a sapphire substrate to produce blue light emission. This device is categorized as a common anode type, meaning the anodes of all LED segments are connected internally, simplifying circuit design for multiplexing. It is specifically engineered for reverse mount assembly processes.

1.1 Key Features and Advantages

• Digit Height: Features a 0.39-inch (10.0 mm) character height, offering good readability for its compact size.
• Optical Quality: Provides continuous, uniform segment illumination, excellent character appearance, high brightness, high contrast, and a wide viewing angle.
• Efficiency and Reliability: Designed for low power requirement and offers solid-state reliability inherent to LED technology.
• Quality Control: Units are categorized (binned) for luminous intensity, ensuring consistency in brightness across production batches.
• Environmental Compliance: The package is lead-free and compliant with RoHS (Restriction of Hazardous Substances) directives.

1.2 Device Identification

The part number LTS-4817CTB-P decodes the device type: a single-digit display with a right-hand decimal point, utilizing InGaN blue LED chips in a common anode configuration.

2. Mechanical and Package Information

2.1 Package Dimensions

The device conforms to a specific SMD footprint. Critical dimensional notes include: all measurements are in millimeters with a standard tolerance of ±0.25 mm unless specified otherwise. The package includes markings for the part number, date code, and LED batch. Quality specifications limit foreign material, ink contamination, bubbles within the segment area, package bending, and pin burrs to ensure proper assembly and performance.

2.2 Pin Configuration and Circuit Diagram

The display has a 10-pin configuration. The internal circuit diagram shows a common anode architecture. The pinout is as follows: Pin 1 (Cathode E), Pin 2 (Cathode D), Pin 3 (Common Anode), Pin 4 (Cathode C), Pin 5 (Cathode DP for decimal point), Pin 6 (Cathode B), Pin 7 (Cathode A), Pin 8 (Common Anode), Pin 9 (Cathode F), Pin 10 (Cathode G). Pin 8 is noted as \"No Connection\" in the provided diagram, which may be reserved or a duplicate anode connection depending on internal design.

3. Technical Parameters and Characteristics

3.1 Absolute Maximum Ratings

These are the stress limits beyond which permanent damage may occur. Ratings are specified at an ambient temperature (Ta) of 25°C.

• Power Dissipation per Segment: 70 mW maximum.
• Peak Forward Current per Segment: 50 mA (under pulsed conditions: 1/10 duty cycle, 0.1ms pulse width).
• Continuous Forward Current per Segment: 20 mA at 25°C, derating linearly at 0.21 mA/°C above 25°C.
• Operating & Storage Temperature Range: -35°C to +105°C.
• Soldering Temperature: Withstands 260°C for 3 seconds at 1/16 inch (approx. 1.6mm) below the seating plane.

3.2 Electrical and Optical Characteristics

Typical performance parameters are measured at Ta=25°C.

• Luminous Intensity (I_V): 8.4 mcd (Min), 26.8 mcd (Typ) at a forward current (I_F) of 10mA.
• Peak Wavelength (λ_p): 468 nm (Typ) at I_F=20mA.
• Spectral Half-Width (Δλ): 25 nm (Typ) at I_F=20mA.
• Dominant Wavelength (λ_d): 470 nm (Typ) at I_F=20mA.
• Forward Voltage (V_F): 3.3V (Min), 3.8V (Typ) per chip at I_F=20mA.
• Reverse Current (I_R): 100 µA (Max) at a reverse voltage (V_R) of 5V. This is a test condition, not an operating mode.
• Luminous Intensity Matching Ratio: 2:1 maximum between segments under similar conditions (I_F=10mA), ensuring uniform brightness.
• Cross-talk: Specified as ≤ 2.5%, minimizing unwanted illumination of adjacent segments.

3.3 Electrostatic Discharge (ESD) Sensitivity

LEDs are susceptible to damage from electrostatic discharge. Mandatory handling precautions include: using grounded wrist straps or anti-static gloves; ensuring all equipment, workstations, and storage are properly grounded; and employing ionizers to neutralize static charges that may accumulate on the plastic package during handling.

4. Performance Curves and Graphical Data

The datasheet includes typical characteristic curves (though not detailed in the provided text extract). These graphs are essential for design and typically illustrate the relationship between forward current and luminous intensity (I-V curve), the effect of ambient temperature on luminous intensity, and the relative spectral power distribution showing the blue light emission peak around 468-470 nm. Analyzing these curves allows designers to optimize drive current for desired brightness and understand performance trade-offs under different thermal conditions.

5. Assembly and Process Guidelines

5.1 SMT Soldering Instructions

The device is suitable for reflow soldering. Critical process limits:

• Reflow Soldering (Max 2 cycles): Pre-heat: 120-150°C for up to 120 seconds max. Peak temperature: 260°C maximum. Total soldering time should not exceed the profile limits.
• Hand Soldering (Iron, Max 1 cycle): Iron tip temperature: 300°C maximum. Contact time: 3 seconds maximum per joint.
• A mandatory cooling period to normal temperature is required between the first and second reflow process if a double-pass is necessary.

5.2 Recommended Soldering Pad Pattern

A land pattern design is provided to ensure reliable solder joint formation, proper self-alignment during reflow, and sufficient mechanical strength. Adherence to this pattern is crucial for manufacturing yield and long-term reliability.

6. Packaging and Handling

6.1 Packing Specifications

The devices are supplied on tape-and-reel packaging compatible with automated pick-and-place machines.

• Reel Dimensions: Details for PS6 type reel are provided, including reel diameter, hub width, and tape pocket dimensions.
• Carrier Tape: Dimensions and specifications meet EIA-481-C standards. Key parameters include pocket pitch, tape thickness (0.40±0.05mm), and camber tolerance.
• Packing Quantities: Standard reel length is 45.5 meters for a 22-inch reel, containing 800 pieces. A minimum packing quantity of 200 pieces is specified for remainder lots.
• Leader/Trailer Tape: Includes a minimum 400mm leader and 40mm trailer for machine handling.

6.2 Moisture Sensitivity and Storage

The SMD package is moisture-sensitive. Devices are shipped in moisture-proof barrier bags with desiccant.

• Storage Conditions: After opening the sealed bag, components should be stored at ≤30°C and ≤60% Relative Humidity.
• Baking Requirements: If exposed to ambient humidity beyond specifications, baking is required before reflow to prevent \"popcorn\" cracking or delamination. Approved bake conditions: 60°C for ≥48 hours (in reel), or 100°C for ≥4 hours / 125°C for ≥2 hours (in bulk). Baking should be performed only once.

7. Application Notes and Design Considerations

7.1 Typical Application Scenarios

The LTS-4817CTB-P is ideal for applications requiring compact, bright, single-digit numeric displays. Common uses include: instrument panels (multimeters, timers), consumer appliances (microwaves, coffee makers), industrial control interfaces, medical device readouts, and automotive accessory displays where blue indication is preferred for visibility or aesthetic reasons.

7.2 Circuit Design Guidelines

As a common anode display, each segment cathode is driven independently, typically by a current-limiting resistor connected to a sink-capable driver (e.g., a microcontroller GPIO pin or a dedicated LED driver IC). The forward voltage (V_F) of ~3.8V must be considered in the power supply design. The continuous current must not exceed 20mA per segment, with appropriate derating above 25°C ambient. For multiplexing multiple digits, ensure the driver's current-sinking capability and switching speed are adequate.

7.3 Thermal Management

While LEDs are efficient, power dissipation (up to 70mW per segment) generates heat. Proper PCB layout with adequate copper area for the common anode connections can act as a heat sink. Ensure the operating ambient temperature does not exceed 105°C, and consider the current derating curve for high-temperature environments.

8. Technical Comparison and Differentiation

Compared to older technologies like red GaAsP LEDs, this InGaN blue LED offers higher brightness and a distinct blue color. Within the blue SMD display segment, its key differentiators are the 0.39-inch digit height, categorized luminous intensity for uniformity, and specifications for low cross-talk and segment matching. The robust package and detailed soldering/packing specs make it suitable for high-volume, automated assembly.

9. Frequently Asked Questions (FAQ)

Q: What is the purpose of the \"No Connection\" pin (Pin 8)?
A: This pin is internally unconnected. It may exist for mechanical symmetry, package standardization, or as a placeholder. It must not be used as an electrical connection.

Q: Can I drive this display with a 5V supply?
A: Yes, but a series current-limiting resistor is mandatory for each segment cathode. The resistor value is calculated as R = (V_supply - V_F) / I_F. For a 5V supply, V_F of 3.8V, and I_F of 10mA, R ≈ (5 - 3.8) / 0.01 = 120 Ω.

Q: Why is baking necessary, and can I bake the parts more than once?
A: The plastic package absorbs moisture. During reflow, rapid heating turns this moisture to steam, potentially causing internal damage. Baking removes this moisture. The datasheet explicitly states baking should be done only once to avoid thermal aging of the materials.

Q: What does \"reverse mount assembly\" mean?
A> It indicates the device is intended to be mounted on the opposite side of the PCB from the typical component side, often for aesthetic reasons (viewing through the board). The recommended soldering pattern is designed for this.

10. Operational Principles and Technology Trends

10.1 Basic Operating Principle

An LED is a semiconductor diode. When a forward voltage exceeding its bandgap is applied across the p-n junction, electrons and holes recombine, releasing energy in the form of photons (light). The specific material, InGaN, has a bandgap that corresponds to blue light emission. The sapphire substrate provides a crystalline base for growing the InGaN epitaxial layers.

10.2 Industry Trends

The use of InGaN technology for blue (and by extension, white via phosphor conversion) LEDs represents a significant advancement in solid-state lighting. Trends in display components include continued increases in luminous efficacy (brightness per watt), further miniaturization, improved color consistency through tighter binning, and enhanced reliability for harsh environments. The move towards lead-free and RoHS-compliant packaging, as seen in this device, is a standard industry requirement.