LTST-C195TBJRKT Dual Color SMD LED Datasheet - 0.55mm Height - Blue 3.3V / Red 2.0V - 76mW / 75mW - English Technical Documentation

1. Product Overview

This document details the specifications for a miniature, dual-color Surface-Mount Device (SMD) LED. The device is designed for automated printed circuit board (PCB) assembly and is suitable for space-constrained applications. It integrates two distinct LED chips within an ultra-thin package.

1.1 Core Advantages

• Ultra-Thin Profile: Package height is only 0.55mm, enabling use in slim devices.
• Dual-Color Source: Combines a high-brightness InGaN (Indium Gallium Nitride) blue chip and an AlInGaP (Aluminum Indium Gallium Phosphide) red chip in a single package.
• Compatibility: Designed for compatibility with automatic pick-and-place equipment and standard infrared (IR) reflow soldering processes.
• Standards Compliance: Package conforms to EIA (Electronic Industries Alliance) standards and is RoHS (Restriction of Hazardous Substances) compliant.

1.2 Target Markets and Applications

This component is intended for a broad range of consumer and industrial electronics where compact size and status indication are critical. Primary application areas include:

• Telecommunications: Status indicators in mobile phones, routers, and network equipment.
• Computer Peripherals: Backlighting for keyboards and keypads, status lights on laptops and external drives.
• Home Appliances & Industrial Equipment: Power, mode, and fault indicators.
• Display Technology: Micro-displays and symbolic illumination.

2. Technical Parameters: In-Depth Objective Interpretation

2.1 Absolute Maximum Ratings

These values represent the limits beyond which permanent damage to the device may occur. Operation under these conditions is not guaranteed.

• Power Dissipation (Pd): Blue: 76 mW, Red: 75 mW. This is the maximum power the LED can dissipate as heat at an ambient temperature (Ta) of 25\u00b0C.
• Peak Forward Current (I_FP): Blue: 100 mA, Red: 80 mA. This is the maximum allowable pulsed current (1/10 duty cycle, 0.1ms pulse width) for short-term operation.
• DC Forward Current (I_F): Blue: 20 mA, Red: 30 mA. This is the recommended maximum continuous forward current for reliable long-term operation.
• Temperature Ranges: Operating: -20\u00b0C to +80\u00b0C. Storage: -30\u00b0C to +100\u00b0C.
• Soldering Limit: The device can withstand infrared reflow soldering with a peak temperature of 260\u00b0C for a maximum of 10 seconds.

2.2 Electrical and Optical Characteristics

Measured at Ta=25\u00b0C and I_F=20mA, these are the typical performance parameters.

• Luminous Intensity (I_V): A key measure of brightness. For the Blue chip, typical value is 45.0 mcd (millicandela) with a range from 28.0 mcd (Min) to 180 mcd (Max). For the Red chip, typical is 45.0 mcd, ranging from 18.0 mcd to 112 mcd.
• Viewing Angle (2\u03b8_1/2): Typically 130 degrees. This wide viewing angle indicates a diffuse, non-directional light output suitable for status indicators viewed from various angles.
• Peak Wavelength (\u03bb_P): Blue: 468.0 nm, Red: 639.0 nm. This is the wavelength at which the spectral power distribution is maximum.
• Dominant Wavelength (\u03bb_d): Blue: 470.0 nm (465-475 nm), Red: 631.0 nm (626-638 nm). This is the single wavelength perceived by the human eye that defines the color.
• Spectral Line Half-Width (\u0394\u03bb): Blue: 25.0 nm, Red: 15.0 nm. This indicates the spectral purity; a smaller value means a more monochromatic color.
• Forward Voltage (V_F): Blue: 3.30V (2.80-3.80V), Red: 2.00V (1.80-2.40V). This is the voltage drop across the LED when operating at 20mA. The significant difference between colors is due to the different semiconductor materials.
• Reverse Current (I_R): Max 10 \u00b5A at V_R=5V. The device is not designed for reverse bias operation; this parameter is for test purposes only.

2.3 Thermal Considerations

The power dissipation ratings are directly linked to thermal management. Exceeding the maximum junction temperature will reduce luminous output and lifespan. The wide operating temperature range (-20\u00b0C to +80\u00b0C) makes it suitable for most indoor environments. Proper PCB layout, including adequate thermal relief and copper area, is essential for maintaining performance, especially when driving the LED near its maximum current rating.

3. Binning System Explanation

To ensure color and brightness consistency in production, LEDs are sorted into performance bins. This device uses a luminous intensity binning system.

3.1 Luminous Intensity Binning

The luminous output at I_F=20mA is categorized into bins identified by a single-letter code. Each bin has a minimum and maximum intensity value, with a tolerance of +/-15% within each bin.

• Blue Chip Bins: N (28.0-45.0 mcd), P (45.0-71.0 mcd), Q (71.0-112.0 mcd), R (112.0-180.0 mcd).
• Red Chip Bins: M (18.0-28.0 mcd), N (28.0-45.0 mcd), P (45.0-71.0 mcd), Q (71.0-112.0 mcd).

This system allows designers to select components with guaranteed minimum brightness levels for their application. For example, an application requiring high brightness would specify bins Q or R for blue and P or Q for red.

4. Performance Curve Analysis

While specific graphical curves are referenced in the datasheet, their implications are standard for LED technology.

4.1 Forward Current vs. Forward Voltage (I-V Curve)

The I-V curve is exponential. For the blue LED (InGaN), the turn-on voltage is higher (~2.8V) compared to the red LED (AlInGaP, ~1.8V). Driving the LED requires a current-limiting mechanism (e.g., a series resistor or constant-current driver) to prevent thermal runaway, as the forward voltage decreases with increasing temperature while current increases.

4.2 Luminous Intensity vs. Forward Current

Luminous intensity is approximately proportional to forward current within the recommended operating range. However, efficiency (lumens per watt) typically peaks at a current lower than the maximum rating and decreases at higher currents due to increased heat.

4.3 Spectral Distribution

The referenced spectral plots would show the narrow emission bands characteristic of LEDs. The blue chip's emission is centered in the 468-470 nm range, and the red chip's emission is in the 631-639 nm range. The half-width values indicate the blue emission has a broader spectral spread than the red.

5. Mechanical and Package Information

5.1 Package Dimensions and Pin Assignment

The device uses a standard SMD footprint. Critical dimensions include a height of 0.55mm. The pin assignment for the dual-color function is clearly defined: Pins 3 and 1 are for the Blue LED anode and cathode, respectively. Pins 4 and 2 are for the Red LED anode and cathode, respectively. The lens is water clear to allow the true chip color to be visible.

5.2 Recommended PCB Pad Design and Polarity

The datasheet includes a recommended land pattern (footprint) for PCB design. Adhering to this pattern ensures proper soldering and mechanical stability. The polarity is indicated by the pin numbering. Correct orientation during assembly is crucial, as applying reverse voltage can damage the LED.

6. Soldering and Assembly Guidelines

6.1 IR Reflow Soldering Parameters

The device is compatible with lead-free (Pb-free) reflow processes. The maximum allowable thermal profile is defined:

• Peak Temperature: 260\u00b0C maximum.
• Time at Peak: 10 seconds maximum.
• Pre-heat: 150-200\u00b0C for up to 120 seconds to minimize thermal shock.
• Number of Cycles: Maximum of two reflow cycles are permitted.

These parameters align with JEDEC standards. The actual profile must be characterized for the specific PCB assembly, considering board thickness, component density, and solder paste type.

6.2 Hand Soldering

If manual soldering is necessary, use a temperature-controlled soldering iron set to a maximum of 300\u00b0C. The soldering time per lead should not exceed 3 seconds, and this should be performed only once.

6.3 Cleaning and Storage

• Cleaning: Only use specified solvents like ethyl alcohol or isopropyl alcohol at room temperature for less than one minute. Unspecified chemicals may damage the plastic package.
• Storage (Sealed Package): Store at \u2264 30\u00b0C and \u2264 90% Relative Humidity (RH). The shelf life in the moisture-proof bag with desiccant is one year (Moisture Sensitivity Level, MSL 3).
• Storage (Opened Package): If removed from the sealed bag, store at \u2264 30\u00b0C and \u2264 60% RH. Components should be reflowed within one week. For longer storage, use a sealed container with desiccant. If stored for more than a week, a bake-out at 60\u00b0C for 20+ hours is required before soldering to remove absorbed moisture and prevent \"popcorning\" during reflow.

7. Packaging and Ordering Information

7.1 Tape and Reel Specifications

The components are supplied on 8mm carrier tape wound onto 7-inch (178mm) diameter reels, standard for automated assembly.

• Quantity per Reel: 4000 pieces.
• Minimum Order Quantity (MOQ): 500 pieces for remainder quantities.
• Packaging Standards: Complies with ANSI/EIA-481 specifications. The tape has a cover to protect components, and a maximum of two consecutive empty pockets is allowed.

8. Application Suggestions and Design Considerations

8.1 Circuit Design

• Current Limiting: Always use a series resistor or active constant-current driver. Calculate the resistor value using R = (V_supply - V_F) / I_F. Use the typical V_F for calculation, but ensure the supply voltage is high enough to accommodate the maximum V_F.
• Driving Dual Colors: The blue and red LEDs have independent anodes and cathodes, allowing them to be driven separately. This enables individual control, color mixing (to create purple), or alternating blinking patterns.
• Microcontroller Interface: These LEDs can be directly driven from microcontroller GPIO pins, provided the pin can source/sink the required current (20-30mA). For higher currents or multiplexing many LEDs, use transistor drivers.

8.2 PCB Layout

• Follow the recommended pad layout for reliable soldering.
• Ensure sufficient clearance between the LED and other tall components to avoid shadowing or physical interference.
• For high-reliability applications, consider adding thermal vias under the LED's thermal pad (if present) to dissipate heat into inner PCB layers.

8.3 ESD (Electrostatic Discharge) Precautions

LEDs are sensitive to ESD. Handle with proper ESD precautions: use grounded wrist straps, anti-static mats, and ensure all equipment is grounded. Incorporate ESD protection diodes on sensitive signal lines if the LED is connected to external interfaces.

9. Technical Comparison and Differentiation

This device's primary differentiators in the SMD LED market are its dual-color capability in an ultra-thin 0.55mm package and its use of advanced semiconductor materials (InGaN for blue, AlInGaP for red) for high brightness. Compared to single-color LEDs, it saves board space and assembly time by replacing two components with one. Compared to thicker dual-color LEDs, it enables slimmer end-product designs. The wide 130-degree viewing angle is suitable for applications where the indicator needs to be visible from off-axis positions.

10. Frequently Asked Questions (Based on Technical Parameters)

10.1 Can I drive the blue and red LEDs simultaneously at their full 20mA/30mA?

Yes, but you must consider the total power dissipation. If both are on continuously at max current, the combined power is significant for the small package. Ensure the ambient temperature is well within limits and the PCB provides adequate heat sinking. For prolonged operation, derating the current is recommended for maximum longevity.

10.2 Why is the forward voltage so different between the blue and red LEDs?

The forward voltage is a fundamental property of the semiconductor material's bandgap energy. InGaN (blue) has a wider bandgap (~3.4 eV) than AlInGaP (red, ~2.0 eV), requiring a higher voltage to \"excite\" electrons across the gap and produce light.

10.3 What does \"I.C. Compatible\" mean?

It means the LED's input characteristics (forward voltage and current) are compatible with direct driving from standard integrated circuit (IC) outputs, such as those from microcontrollers, logic gates, or driver ICs, without requiring intermediate power transistors in many cases.

11. Practical Use Case Example

Scenario: Designing a status indicator for a portable Bluetooth speaker.

The indicator needs to show multiple states: Power Off (no light), Power On (steady blue), Pairing Mode (blinking blue), Battery Low (steady red), and Charging (pulsing red). Using the LTST-C195TBJRKT is ideal.

Design Implementation: The LED is placed on the main PCB. A microcontroller manages the states. Two GPIO pins are configured: one to control the blue LED (via a 100\u03a9 series resistor, calculated for a 3.3V supply and ~3.3V V_F), and another to control the red LED (via a 68\u03a9 resistor for ~2.0V V_F). The firmware toggles these pins to create the required lighting patterns. The ultra-thin height allows the LED to fit behind a slim grille, and the wide viewing angle ensures the status is visible from anywhere in front of the speaker.

12. Operating Principle Introduction

Light Emitting Diodes (LEDs) are semiconductor devices that emit light through electroluminescence. When a forward voltage is applied across the p-n junction, electrons from the n-type material recombine with holes from the p-type material. This recombination releases energy in the form of photons (light). The specific wavelength (color) of the emitted light is determined by the bandgap energy of the semiconductor material. InGaN is used for shorter wavelengths (blue, green), while AlInGaP is used for longer wavelengths (red, orange, yellow). The water-clear epoxy package acts as a lens, shaping the light output and providing environmental protection.

13. Technology Trends

The development of SMD LEDs continues to focus on several key areas: Increased Efficiency (lm/W) to provide more light for less power, crucial for battery-powered devices. Higher Power Density in smaller packages, enabling brighter indicators or even illumination from tiny sources. Improved Color Rendering and Consistency through tighter binning and advanced phosphor technologies for white LEDs. Integration is another trend, with LEDs incorporating built-in drivers, controllers, or even multiple colors/chips in more complex arrays, reducing the external component count for designers.