Full Color SMD LED LTST-C19HE1WT-5A Datasheet - Dimensions 3.2x1.6x0.35mm - Voltage 1.6-3.2V - Power 0.08W - English Technical Document

1. Product Overview

The LTST-C19HE1WT-5A is a full-color, surface-mount LED designed for modern electronic applications requiring compact size and multi-color indication. This device integrates red, green, and blue (RGB) LED chips within a single, ultra-thin package, enabling the creation of a wide spectrum of colors through individual or combined control of the three channels. Its primary design goal is to provide a versatile lighting solution for space-constrained, automated assembly environments.

1.1 Core Advantages and Target Market

The key advantage of this component is its combination of a miniature footprint with full-color capability. The package height is exceptionally low at 0.35mm, making it suitable for applications where vertical clearance is limited, such as in ultra-thin displays or backlighting modules for keyboards and keypads. The device is compliant with RoHS directives, ensuring it meets international environmental standards. It is packaged on 8mm tape on 7-inch diameter reels, which is compatible with standard automated pick-and-place equipment used in high-volume electronics manufacturing. The primary target markets include telecommunications equipment (e.g., cellular phones), office automation devices (e.g., notebook computers), network systems, home appliances, and indoor signage. Its I.C. compatible drive characteristics and suitability for infrared reflow soldering processes further enhance its integration into modern printed circuit board (PCB) assembly lines.

2. Technical Parameter Deep-Dive

This section provides an objective analysis of the electrical, optical, and thermal characteristics specified in the datasheet.

2.1 Absolute Maximum Ratings

Understanding the absolute maximum ratings is critical for ensuring device reliability and preventing premature failure. The ratings are specified at an ambient temperature (Ta) of 25°C. The power dissipation differs slightly between colors: 80mW for the blue and green chips, and 75mW for the red chip. This indicates a potential variance in the thermal characteristics or efficiency of the different semiconductor materials. The peak forward current, permissible under a 1/10 duty cycle with a 0.1ms pulse width, is 100mA for blue/green and 80mA for red. The continuous DC forward current rating is 20mA for blue/green and 30mA for red. The device is rated for operation between -20°C and +80°C, with a wider storage temperature range of -30°C to +100°C. A key soldering specification is the infrared reflow condition, which must not exceed 260°C for more than 10 seconds, a standard for lead-free (Pb-free) assembly processes.

2.2 Electrical and Optical Characteristics

The typical test condition for optical and key electrical parameters is at Ta=25°C with a forward current (IF) of 5mA. The luminous intensity (Iv) varies significantly by color, which is expected due to the different efficiencies of the underlying semiconductor technologies (AlInGaP for red, InGaN for green and blue). For the blue LED, the minimum luminous intensity is 11.2 mcd, with a maximum of 45.0 mcd. The green LED shows a much higher output range, from 28.0 mcd minimum to 280.0 mcd maximum. The red LED ranges from 11.2 mcd to 71.0 mcd. The viewing angle (2θ1/2) is a wide 130 degrees, typical for a diffused lens package, providing a broad, even light distribution. The peak emission wavelengths (λP) are 468nm (blue), 530nm (green), and 632nm (red). The corresponding dominant wavelengths (λd) are 470nm, 528nm, and 624nm. The spectral line half-width (Δλ) values are 26nm (blue), 35nm (green), and 17nm (red), indicating the spectral purity, with red being the narrowest. Forward voltage (VF) at 5mA ranges from 2.50V to 3.20V for blue/green and from 1.60V to 2.30V for red. The maximum reverse current (IR) at VR=5V is 10 μA for all colors.

3. Binning System Explanation

The product utilizes a binning system to categorize units based on their luminous intensity at the standard 5mA test current. This allows designers to select LEDs with consistent brightness levels for their application.

3.1 Luminous Intensity Binning

Separate bin code lists are provided for each color, reflecting their different performance ranges. Each bin has a minimum and maximum luminous intensity value, and a tolerance of +/-15% is applied within each bin. For the blue LED, bins are L (11.2-18.0 mcd), M (18.0-28.0 mcd), and N (28.0-45.0 mcd). For the green LED, the bins are N (28.0-45.0 mcd), P (45.0-71.0 mcd), Q (71.0-112.0 mcd), R (112.0-180.0 mcd), and S (180.0-280.0 mcd). For the red LED, bins are L (11.2-18.0 mcd), M (18.0-28.0 mcd), N (28.0-45.0 mcd), and P (45.0-71.0 mcd). This binning is crucial for applications requiring uniform color mixing or specific brightness levels, as it ensures predictability in the final product's appearance.

4. Performance Curve Analysis

The datasheet references typical performance curves which graphically represent the relationship between various parameters. While the specific graphs are not detailed in the provided text, standard curves for such devices typically include the forward current vs. forward voltage (I-V curve) for each color, which is non-linear and differs between the red (lower Vf) and blue/green (higher Vf) chips. Luminous intensity vs. forward current curves would show how light output increases with current, potentially nearing saturation at higher currents. Relative luminous intensity vs. ambient temperature curves are critical for understanding brightness degradation at elevated operating temperatures. Spectral distribution graphs would visually depict the peak wavelength and spectral half-width for each color. Analyzing these curves allows designers to optimize drive currents for desired brightness and efficiency while managing thermal effects and power consumption.

5. Mechanical and Package Information

5.1 Package Dimensions and Pin Assignment

The device features an industry-standard SMD package. The lens color is white diffused, which helps blend the individual colored light sources to create a uniform mixed-color appearance. The pin assignment is clearly defined: Pin 1 is the anode for the AlInGaP red chip, Pin 2 is the anode for the InGaN green chip, and Pin 3 is the anode for the InGaN blue chip. The cathodes for all three chips are internally connected to a common terminal (typically the thermal pad or a designated cathode pin, as implied by standard RGB LED configurations, though the exact common connection point should be verified from the dimensional drawing). All dimensional tolerances are ±0.1mm unless otherwise specified.

5.2 Recommended PCB Attachment Pad

A recommended land pattern (footprint) for the printed circuit board is provided to ensure proper soldering and mechanical stability. Adhering to this recommended pattern is essential for achieving reliable solder joints, managing heat dissipation, and preventing tombstoning during the reflow process.

6. Soldering and Assembly Guide

6.1 IR Reflow Soldering Parameters

For Pb-free assembly processes, a specific reflow profile is suggested. The peak temperature must not exceed 260°C, and the time at or above this peak temperature must be limited to a maximum of 10 seconds. A pre-heat stage is also recommended. The datasheet emphasizes that because board designs, pastes, and ovens vary, the provided profile is a guideline, and board-specific characterization should be performed. The component is verified to withstand JEDEC-standard reflow profiles.

6.2 Storage and Handling Conditions

The LEDs are sensitive to electrostatic discharge (ESD). Handling precautions such as using wrist straps and grounded equipment are mandatory. For storage, unopened moisture-proof bags (with desiccant) should be kept at ≤30°C and ≤90% RH, with a recommended use-within period of one year. Once the original packaging is opened, the storage environment should be ≤30°C and ≤60% RH. Components removed from their packaging should be reflow-soldered within one week (Moisture Sensitivity Level 3, MSL 3). If stored longer out of the bag, they require baking (e.g., 60°C for 20 hours) before soldering to prevent popcorning during reflow.

6.3 Cleaning

If cleaning is necessary after soldering, only specified solvents should be used. Immersing the LED in ethyl alcohol or isopropyl alcohol at normal temperature for less than one minute is acceptable. Unspecified chemicals may damage the package material.

7. Packaging and Ordering Information

The device is supplied in a tape-and-reel format compatible with automated assembly. The tape width is 8mm, wound on a standard 7-inch (178mm) diameter reel. Each reel contains 4000 pieces. For smaller quantities, a minimum packing quantity of 500 pieces is available for remnants. The packaging follows ANSI/EIA 481 specifications. The tape uses a top cover to seal empty pockets, and the maximum allowed number of consecutive missing components in the tape is two.

8. Application Suggestions

8.1 Typical Application Scenarios

This LED is well-suited for a variety of applications: Status Indicators: Multi-color capability allows a single LED to indicate multiple system states (e.g., power on=green, standby=blue, fault=red). Backlighting: Ideal for keypad, keyboard, or small decorative panel backlighting, where color-changing effects are desired. Micro-Displays: Can be used in arrays to form simple full-color graphic or symbolic displays. Consumer Electronics: Found in phones, laptops, and home appliances for aesthetic and functional lighting.

8.2 Design Considerations

Designers must consider several factors: Current Limiting: Each color channel must have its own current-limiting resistor or be driven by a constant-current source, as the forward voltages differ. Color Mixing: Achieving a specific white point or mixed color requires careful calibration of the drive currents for each chip, considering the binning variations. Thermal Management: Despite its low power, ensuring the maximum junction temperature is not exceeded is vital for longevity, especially in enclosed spaces. ESD Protection: Incorporating ESD protection on signal lines driving the LED anodes may be necessary in sensitive environments.

9. Technical Comparison and Differentiation

The primary differentiation of the LTST-C19HE1WT-5A lies in its ultra-thin 0.35mm profile combined with full RGB functionality in a single EIA-standard package. Compared to discrete single-color LEDs or larger RGB packages, it offers significant space savings on the PCB. The use of advanced InGaN and AlInGaP chip technologies provides good luminous efficiency. Its compatibility with standard IR reflow and tape-and-reel packaging makes it a drop-in solution for modern SMT lines, reducing assembly complexity compared to manually placing three separate LEDs.

10. Frequently Asked Questions (Based on Technical Parameters)

Q: Can I drive all three colors from a single 5V supply? A: Yes, but you will need separate current-limiting resistors for each channel. Calculate the resistor value using R = (Vcc - Vf) / If, where Vf is the forward voltage of the specific color at your desired current. Note that Vf for red is lower than for blue/green.

Q: Why is the luminous intensity range for green so much wider than for red or blue? A: This reflects the higher typical efficiency of the InGaN-based green chip technology used in this product and the binning structure implemented to categorize parts across this wide performance spread.

Q: What is the meaning of the \"Dominant Wavelength\" vs. \"Peak Wavelength\"? A: Peak wavelength (λP) is the single wavelength at which the emission spectrum has its maximum power. Dominant wavelength (λd) is derived from the color coordinates on the CIE chromaticity diagram and represents the perceived color of the light; it is the single wavelength that would match the LED's color sensation to the human eye.

Q: Is this LED suitable for outdoor use? A: The operating temperature range is -20°C to +80°C. While it could function in some outdoor conditions, the datasheet does not specify ingress protection (IP) ratings against moisture and dust. For harsh outdoor environments, a product with appropriate environmental sealing should be selected.

11. Practical Use Case

Scenario: Designing a Status Indicator for a Network Router. A designer needs a single LED to show network activity (blinking green), connection type (solid blue for 5GHz, solid cyan for 2.4GHz), and error state (solid red). The LTST-C19HE1WT-5A is chosen for its small size and three-in-one functionality. The designer uses a microcontroller with PWM-capable outputs to drive each channel through small current-limiting resistors. The firmware is programmed to control the LEDs: rapid green blinking for activity, a mix of blue and green (at specific PWM ratios to achieve cyan) for the 2.4GHz band, and solid red for errors. The wide viewing angle ensures the indicator is visible from various angles. The ultra-thin profile allows it to fit behind a slim fascia panel.

12. Principle Introduction

Light Emitting Diodes (LEDs) are semiconductor devices that emit light when an electric current passes through them. This phenomenon, called electroluminescence, occurs when electrons recombine with electron holes within the device, releasing energy in the form of photons. The color of the emitted light is determined by the energy band gap of the semiconductor material. The LTST-C19HE1WT-5A uses two primary material systems: Indium Gallium Nitride (InGaN) for the blue and green chips, and Aluminum Indium Gallium Phosphide (AlInGaP) for the red chip. By independently controlling the current to these three primary-color chips, a vast array of secondary colors, including white (when all three are appropriately balanced), can be produced through additive color mixing.

13. Development Trends

The general trend in SMD LED technology continues towards higher efficiency (more lumens per watt), smaller package sizes, and improved color rendering and consistency. There is also a drive towards higher reliability and longer operational lifetimes. For multi-color LEDs like the LTST-C19HE1WT-5A, trends include tighter binning tolerances for more predictable color mixing, integrated driver ICs within the package (making \"smart LEDs\"), and even thinner profiles for next-generation flexible and foldable displays. The underlying semiconductor materials are also being refined to improve efficiency, particularly for green LEDs, which have traditionally lagged behind red and blue in performance.