Dual Color SMD LED LTST-C195TBJRKT-2A Datasheet - Package Dimensions - Blue 3.0V / Red 2.0V - 20mA/30mA - English Technical Document

1. Product Overview

This document details the specifications for a high-brightness, dual-color Surface-Mount Device (SMD) LED. The component integrates two distinct semiconductor chips within a single package: one emitting blue light and the other emitting red light. This design is optimized for applications requiring compact, bi-color indication or lighting solutions. The device is compliant with RoHS directives and is classified as a green product. It is supplied in industry-standard 8mm tape on 7-inch reels, facilitating compatibility with automated pick-and-place assembly equipment and high-volume manufacturing processes.

1.1 Core Features and Target Applications

The primary features of this LED include its ultra-bright output utilizing InGaN technology for the blue emitter and AlInGaP technology for the red emitter. This combination offers high luminous efficiency. The package conforms to EIA standards, ensuring broad compatibility. The device is designed to be driven by integrated circuits (I.C. compatible) and can withstand standard infrared (IR) and vapor phase reflow soldering processes, making it suitable for modern PCB assembly lines. Typical applications span consumer electronics, industrial control panels, automotive interior lighting, status indicators in communication devices, and backlighting for switches or displays where dual-color functionality is required.

2. Technical Specifications Deep Dive

2.1 Absolute Maximum Ratings

Operating the device beyond these limits may cause permanent damage. At an ambient temperature (Ta) of 25°C, the maximum power dissipation is 76 mW for the blue chip and 75 mW for the red chip. The peak forward current, permissible under pulsed conditions (1/10 duty cycle, 0.1ms pulse width), is 100 mA for blue and 80 mA for red. The maximum continuous DC forward current is 20 mA for the blue LED and 30 mA for the red LED. A linear derating factor is specified: 0.25 mA/°C for blue and 0.4 mA/°C for red, meaning the maximum allowable DC current decreases as ambient temperature rises above 25°C. The maximum reverse voltage for both colors is 5V, though continuous operation under reverse bias is prohibited. The device can be stored and operated within a temperature range of -55°C to +85°C.

2.2 Electrical and Optical Characteristics

All measurements are defined at Ta=25°C and a standard test current (IF) of 2mA. The luminous intensity (Iv) has a minimum value of 4.50 mcd for both colors. Typical values are 20.0 mcd for blue and 18.0 mcd for red. The viewing angle (2θ1/2), where intensity is half the on-axis value, is typically 130 degrees for both emitters, providing a wide beam pattern. The blue LED has a typical peak emission wavelength (λP) of 468 nm and a dominant wavelength (λd) of 470 nm. The red LED has a typical λP of 639 nm and λd of 631 nm. The spectral line half-width (Δλ) is 25 nm for blue and 20 nm for red. The forward voltage (VF) is typically 3.00V for blue (max 3.15V) and 2.00V for red (max 2.20V) at 2mA. Maximum reverse current (IR) at VR=5V is 10 µA for both.

3. Binning System Explanation

To ensure consistency in production, LEDs are sorted into performance bins. This allows designers to select components matching specific circuit requirements.

3.1 Forward Voltage Binning (Blue LED)

The blue LED chips are binned based on their forward voltage at 2mA. Bin code E6 covers 2.55V to 2.75V, E7 covers 2.75V to 2.95V, and E8 covers 2.95V to 3.15V. A tolerance of ±0.1V is applied to each bin.

3.2 Luminous Intensity Binning

Both blue and red LEDs share the same luminous intensity binning structure at 2mA. Bin code J covers 4.50 to 7.10 mcd, K covers 7.10 to 11.2 mcd, L covers 11.2 to 18.0 mcd, and M covers 18.0 to 28.0 mcd. A tolerance of ±15% is applied to each intensity bin.

4. Performance Curve Analysis

The datasheet references typical characteristic curves which are essential for understanding device behavior under varying conditions. These include the relationship between forward current (IF) and forward voltage (VF), which is exponential and differs between the blue and red chips due to their different semiconductor materials. The curves showing luminous intensity versus forward current are crucial for determining the drive current needed to achieve a desired brightness level. While not graphically detailed in the provided text, these curves typically show that intensity increases with current but may saturate at higher levels, and is also inversely affected by rising junction temperature.

5. Mechanical and Packaging Information

5.1 Package Dimensions and Pin Assignment

The device uses a standard SMD package. The pin assignment is critical for correct operation: Pins 1 and 3 are assigned to the Anode and Cathode of the blue LED chip. Pins 2 and 4 are assigned to the Anode and Cathode of the red LED chip. This configuration allows for independent control of each color. All dimensional tolerances are ±0.10 mm unless otherwise specified.

5.2 Suggested Soldering Pad Layout and Tape & Reel

A recommended land pattern (soldering pad dimensions) is provided to ensure reliable solder joint formation and proper alignment during reflow. The component is supplied on 8mm wide embossed carrier tape wound onto 7-inch (178mm) diameter reels. Each reel contains 4000 pieces. The tape and reel specifications comply with ANSI/EIA 481-1-A-1994. Key reel notes include: empty pockets are sealed with cover tape, the minimum order quantity for remnants is 500 pieces, and a maximum of two consecutive missing components are allowed per reel.

6. Soldering and Assembly Guidelines

6.1 Reflow Soldering Profiles

Two suggested infrared (IR) reflow profiles are provided: one for standard (tin-lead) solder process and one for Pb-free (e.g., SnAgCu) solder process. The Pb-free profile requires a higher peak temperature. The general condition specified for IR and wave soldering is a peak temperature of 260°C for a maximum of 5 seconds. For vapor phase soldering, the condition is 215°C for 3 minutes. A detailed graphical profile is referenced, outlining the preheat, soak, reflow, and cooling stages with specific time and temperature constraints to prevent thermal shock.

6.2 Storage and Handling Precautions

LEDs should be stored in an environment not exceeding 30°C and 70% relative humidity. Components removed from their original moisture-barrier bag should be IR-reflowed within one week. For longer storage outside the original packaging, they must be kept in a sealed container with desiccant or in a nitrogen desiccator. If stored for more than a week outside the bag, a bake-out at 60°C for at least 24 hours is required before soldering to remove absorbed moisture and prevent \"popcorning\" during reflow.

7. Application Notes and Design Considerations

7.1 Drive Circuit Design

LEDs are current-driven devices. To ensure uniform brightness when connecting multiple LEDs in parallel, it is strongly recommended to use a individual current-limiting resistor in series with each LED (Circuit Model A). Relying on a single resistor for a parallel array (Circuit Model B) is discouraged because small variations in the forward voltage (Vf) characteristics between individual LEDs will cause significant differences in current sharing and, consequently, luminous intensity. The resistor value is calculated using Ohm's Law: R = (Vcc - Vf) / If, where Vcc is the supply voltage, Vf is the LED's forward voltage at the desired current, and If is the target forward current.

7.2 Electrostatic Discharge (ESD) Protection

The LED chips are sensitive to electrostatic discharge and voltage surges. To prevent damage, proper ESD controls must be implemented during handling and assembly. This includes the use of grounded wrist straps, anti-static gloves, and ensuring all workstations, tools, and machinery are properly grounded. The devices should be handled in ESD-protected areas.

7.3 Cleaning

If cleaning after soldering is necessary, only specified solvents should be used. Unspecified chemicals may damage the epoxy lens or package. The recommended method is to immerse the LED in ethyl alcohol or isopropyl alcohol at room temperature for less than one minute. Aggressive or ultrasonic cleaning is not advised unless specifically validated.

8. Technical Comparison and Differentiation

This dual-color LED's key differentiator is the co-packaging of high-efficiency InGaN (blue) and AlInGaP (red) chips. InGaN technology is known for high brightness in the blue/green spectrum, while AlInGaP offers superior efficiency and thermal stability in the red/amber spectrum compared to older technologies like GaAsP. Integrating both into one EIA-standard SMD package saves PCB space compared to using two separate single-color LEDs. The wide 130-degree viewing angle is suitable for applications requiring broad visibility. The specified compatibility with Pb-free reflow profiles aligns with modern environmental regulations and manufacturing trends.

9. Frequently Asked Questions (FAQ)

Q: Can I drive the blue and red LEDs simultaneously at their maximum DC current?

A: No. The power dissipation limits (76mW blue, 75mW red) and thermal considerations of the shared package must be observed. Simultaneous operation at 20mA (blue) and 30mA (red) may exceed the total package power dissipation capability depending on the forward voltages. Derating at elevated ambient temperature is also required.

Q: What is the difference between peak wavelength and dominant wavelength?

A: Peak wavelength (λP) is the wavelength at which the emission spectrum has its maximum intensity. Dominant wavelength (λd) is derived from the CIE chromaticity diagram and represents the perceived color of the light—the single wavelength that would match the LED's color to the human eye. λd is often more relevant for color-based applications.

Q: How do I interpret the bin codes when ordering?

A: You must specify the required bin codes for Voltage (for blue, e.g., E7) and Luminous Intensity (for both colors, e.g., K). This ensures you receive LEDs with electrical and optical characteristics within your desired range for consistent performance in your product.

10. Design-in Case Study

Consider a dual-status indicator for a network router: solid blue for \"operational\" and flashing red for \"error.\" Using this LED, only one PCB footprint is needed. The microcontroller drives pin 1 (blue anode) via a 150Ω resistor (for ~3V supply and 20mA target) for the steady state. The red LED (pin 2 anode) is driven via a 100Ω resistor (for ~3V supply and 30mA target) and is controlled by a different GPIO pin set to flash during an error condition. The common cathode pins (3 & 4) are connected to ground. This design minimizes component count, saves board space, and uses standard SMT assembly.

11. Operational Principle

Light emission in an LED is based on electroluminescence in a semiconductor p-n junction. 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. When these charge carriers recombine, energy is released in the form of photons (light). The specific wavelength (color) of the emitted light is determined by the bandgap energy of the semiconductor material. The blue LED uses an Indium Gallium Nitride (InGaN) compound, which has a wider bandgap suitable for shorter wavelengths (blue light). The red LED uses an Aluminum Indium Gallium Phosphide (AlInGaP) compound, which has a narrower bandgap engineered for longer wavelengths (red light). The epoxy lens serves to protect the chip, shape the light output beam, and enhance light extraction.

12. Technology Trends

The SMD LED market continues to evolve towards higher efficiency (more lumens per watt), increased power density in smaller packages, and improved color rendering. There is a strong trend towards miniaturization, with chip-scale package (CSP) LEDs becoming more prevalent. For multi-color devices, advancements include tighter binning tolerances for better color consistency and the integration of more than two chips (e.g., RGB or RGBW) into a single package for full-color tunable lighting. Furthermore, the drive towards IoT and smart devices increases demand for reliable, long-life indicator LEDs compatible with automated, high-speed assembly processes, a segment where components like this are well-positioned.