LTST-C19HEGBK-XM SMD LED Datasheet - 0.35mm Thin - RGB Colors - 20mA - English Technical Document

1. Product Overview

The LTST-C19HEGBK-XM is a full-color, surface-mount device (SMD) LED lamp designed for modern, space-constrained electronic applications. This component integrates three individual LED chips (Red, Green, and Blue) within an ultra-thin package, enabling vibrant color mixing and status indication in a minimal footprint. Its primary design goal is to facilitate automated assembly processes while providing reliable performance in a wide range of consumer and industrial electronics.

1.1 Core Advantages

The device offers several key advantages for designers and manufacturers. Its most notable feature is the exceptionally low profile of 0.35mm, which is critical for applications like ultra-thin displays, keypad backlighting, and modern mobile devices where z-height is a major constraint. The package conforms to EIA standard dimensions, ensuring compatibility with industry-standard automated pick-and-place equipment and tape-and-reel feeding systems. Furthermore, it is constructed using RoHS-compliant materials and is designed to withstand standard infrared (IR) reflow soldering processes, making it suitable for high-volume, lead-free manufacturing lines.

1.2 Target Market and Applications

This LED is targeted at a broad spectrum of electronic equipment manufacturers. Its typical applications include, but are not limited to, status indicators and backlighting in telecommunications devices such as cordless and cellular phones, portable computing devices like notebooks and tablets, network system equipment, various home appliances, and indoor signage or symbol illumination. The RGB capability allows for the creation of multiple colors, expanding its use in user interface feedback and decorative lighting.

2. In-Depth Technical Parameter Analysis

A thorough understanding of the electrical and optical parameters is essential for proper circuit design and performance prediction.

2.1 Absolute Maximum Ratings

These ratings define the stress limits beyond which permanent damage to the device may occur. They are specified at an ambient temperature (Ta) of 25°C. The maximum continuous DC forward current (If) is 25 mA for the Red chip and 20 mA for both the Green and Blue chips. The power dissipation ratings differ: 62.5 mW for Red and 76 mW for Green/Blue, reflecting the different efficiencies and thermal characteristics of the AlInGaP (Red) and InGaN (Green/Blue) semiconductor materials. The device can handle short pulse currents (1/10 duty cycle, 0.1ms pulse width) up to 60 mA (Red) and 100 mA (Green/Blue). The operating temperature range is from -20°C to +80°C, and storage can be from -30°C to +85°C. Critically, the device can survive IR reflow soldering with a peak temperature of 260°C for up to 10 seconds.

2.2 Electrical and Optical Characteristics

These are the typical performance parameters measured at Ta=25°C and a standard test current of 20mA. The luminous intensity (Iv) varies significantly by color: Red has a range of 71-180 mcd, Green is much brighter at 382-967 mcd, and Blue matches the Red range at 71-180 mcd. The forward voltage (Vf) also differs: Red operates between 1.6V and 2.4V, while Green and Blue require higher voltages, between 2.6V and 3.6V. This voltage disparity is crucial for designing driving circuits, especially for constant-current drivers. The viewing angle (2θ1/2) is a wide 130 degrees, typical for a lamp-style SMD LED, providing a broad emission pattern. The dominant wavelengths (λd) are: Red 617-631 nm, Green 518-528 nm, and Blue 464-474 nm. The spectral line half-width (Δλ) indicates color purity, with Red being the narrowest at 17nm (typical), followed by Blue at 26nm and Green at 35nm.

3. Binning System Explanation

To ensure color and brightness consistency in production, LEDs are sorted into performance bins. This datasheet defines bins for luminous intensity and for the dominant wavelength of Green and Blue LEDs.

3.1 Luminous Intensity Binning

The luminous output is categorized into bins with a +/-15% tolerance within each bin. For the Red and Blue LEDs, the bins are QA (71-97 mcd), QB (97-132 mcd), and RA (132-180 mcd). For the higher-output Green LED, the bins are TB (382-521 mcd), UA (521-710 mcd), and UB (710-967 mcd). Designers must specify the required bin code to guarantee the minimum brightness for their application.

3.2 Hue (Wavelength) Binning

For color-critical applications, the dominant wavelength is also binned. Green LEDs are sorted into bin P (518-523 nm) and bin Q (523-528 nm). Blue LEDs are sorted into bin C (464-469 nm) and bin D (469-474 nm). The tolerance for each wavelength bin is +/-1 nm. This allows for tighter control over the exact shade of green or blue emitted, which is important for color matching across multiple LEDs or for specific brand color requirements.

4. Mechanical and Package Information

4.1 Package Dimensions and Pinout

The LED conforms to a standard SMD footprint. The key dimensions include the overall length, width, and the critical height of 0.35mm (0.35mm Max). The pin assignment is clearly defined: Pin 1 is the anode for the Red AlInGaP chip, Pin 2 is the anode for the Green InGaN chip, and Pin 3 is the anode for the Blue InGaN chip. All cathodes are internally connected to the fourth pad (Pin 4). The dimensional tolerance is typically ±0.1mm unless otherwise noted. A detailed dimensioned drawing is essential for PCB land pattern design.

4.2 Polarity Identification and Mounting

Correct polarity is vital. The package has a marked polarity indicator, typically a notch or a dot near Pin 1. The recommended PCB attachment pad layout is provided to ensure proper solder fillet formation and mechanical stability during and after the reflow process. Adhering to this pad design helps prevent tombstoning (component standing up on one end) and ensures reliable electrical and thermal connection.

5. Soldering and Assembly Guidelines

5.1 IR Reflow Soldering Profile

The device is rated for lead-free (Pb-free) IR reflow processes. The suggested profile includes a pre-heat stage, a gradual ramp-up, a peak temperature zone, and a cooling phase. The absolute maximum peak body temperature is 260°C, and the time above 260°C should not exceed 10 seconds. The total number of reflow cycles should be limited to a maximum of two. It is critical to note that the optimal profile can vary based on the specific PCB design, solder paste, oven type, and other components on the board. Profiling the actual assembly process is recommended.

5.2 Hand Soldering

If hand soldering is necessary for repair or prototyping, extreme care must be taken. The soldering iron tip temperature should not exceed 300°C, and the contact time with any lead should be limited to a maximum of 3 seconds per joint. Applying excessive heat can damage the internal wire bonds or the semiconductor die itself.

6. Storage and Handling Precautions

6.1 Moisture Sensitivity and Storage

The LEDs are moisture-sensitive devices. When sealed in their original moisture-proof bag with desiccant, they should be stored at ≤30°C and ≤90% RH and used within one year. Once the original bag is opened, the components are exposed to ambient humidity. For extended storage outside the bag (more than one week), they must be stored in a sealed container with desiccant or in a nitrogen ambient. Components exposed to ambient conditions for over a week require a baking process (approximately 60°C for at least 20 hours) before soldering to remove absorbed moisture and prevent \"popcorning\" damage during reflow.

6.2 Electrostatic Discharge (ESD) Protection

LEDs are susceptible to damage from electrostatic discharge. It is strongly recommended to handle these devices in an ESD-protected area using a wrist strap or anti-static gloves. All handling equipment, including placement machines, must be properly grounded to prevent surge or static electricity from degrading the LED's performance or causing immediate failure.

7. Packaging and Ordering Information

The standard packaging for high-volume assembly is tape and reel. The components are supplied in 8mm carrier tape on 7-inch (178mm) diameter reels. Each full reel contains 4000 pieces. For smaller quantities, a minimum pack of 500 pieces is available for remnants. The tape and reel specifications follow ANSI/EIA 481 standards. The tape has a cover to protect the components, and there is a maximum allowance of two consecutive missing components in a reel.

8. Application Notes and Design Considerations

8.1 Driving Circuit Design

Due to the different forward voltages of the Red (≈2.0V) and Green/Blue (≈3.0V) chips, a simple common-anode configuration with series current-limiting resistors requires different resistor values for each color to achieve the same current, which complicates brightness matching. A more advanced approach uses a constant-current driver, often with pulse-width modulation (PWM) for dimming and color mixing. This provides stable current regardless of forward voltage variations and enables precise brightness and color control.

8.2 Thermal Management

Although power dissipation is low, proper thermal design on the PCB is still important for long-term reliability, especially when driving the LEDs at or near their maximum current. The PCB copper pad acts as a heat sink. Ensuring an adequate copper area connected to the LED's thermal pad (typically the cathode pad) helps dissipate heat and maintains lower junction temperatures, which preserves luminous output and extends operational lifetime.

8.3 Cleaning

If post-solder cleaning is required, only specified solvents should be used. Immersing the LED in ethyl alcohol or isopropyl alcohol at room temperature for less than one minute is acceptable. The use of unspecified or aggressive chemical cleaners can damage the epoxy lens or the package markings.

9. Reliability and Application Scope

The LEDs described are intended for use in standard commercial and industrial electronic equipment. For applications where failure could directly jeopardize life or health—such as in aviation, transportation, medical life-support systems, or safety devices—special qualifications and consultations are necessary. These components are not designed for reverse voltage operation; applying a reverse bias exceeding 5V can cause excessive leakage current and potential damage.

10. Technical Comparison and Positioning

The LTST-C19HEGBK-XM's primary differentiator is its combination of full RGB color in an ultra-thin 0.35mm package. Compared to single-color SMD LEDs or thicker RGB packages, it offers designers a solution for color indication in the tightest spaces. The use of high-efficiency InGaN and AlInGaP chips provides good luminous intensity, particularly for the green channel. Its compatibility with automated assembly and standard reflow processes positions it as a cost-effective choice for high-volume manufacturing, balancing performance, size, and manufacturability.