SMD RGB LED LTST-G353CEGB7W Datasheet - 5.0x5.0x1.6mm - 5V - 94mW - White Diffused Lens - English Technical Document

1. Product Overview

The LTST-G353CEGB7W is a surface-mount device (SMD) LED designed for automated printed circuit board (PCB) assembly and applications where space is a critical constraint. This component integrates red, green, and blue (RGB) semiconductor chips along with a dedicated control circuit within a single package, forming a complete, individually addressable pixel. It is engineered for a broad spectrum of electronic equipment, including but not limited to communication devices, portable computers, network infrastructure, consumer appliances, and indoor signage or decorative lighting systems.

1.1 Core Features and Advantages

The device distinguishes itself through several key technological and packaging features that enhance its usability and performance in modern electronics manufacturing.

• Integrated Control: A significant advantage is the integration of the RGB LED chips with a 14-bit driver IC. This eliminates the need for external driver components for basic control, simplifying circuit design and reducing the overall bill of materials (BOM).
• High-Resolution Color Control: Each primary color (Red, Green, Blue) can be controlled across 1024 distinct brightness levels (10-bit PWM). This allows for the generation of over 1.07 billion (2^30) color combinations, enabling smooth color gradients and precise color mixing.
• Advanced Driver IC: The embedded driver utilizes constant current Pulse Width Modulation (PWM) control. The 14-bit control is split, with 10 bits dedicated to PWM duty cycle for brightness and 4 bits for fine-tuning the current level, offering granular control over light output and efficiency.
• Simplified Data Interface: Communication with the LED and daisy-chaining of multiple units is achieved through a single-wire serial protocol (SPI-compatible). This minimizes the number of control lines required from the host microcontroller.
• Data Integrity Feature: The device supports breakpoint continuous transmission (Bypass function). If one LED in a chain fails, the data signal can bypass it, ensuring the remaining LEDs in the sequence continue to function correctly, enhancing system reliability.
• Manufacturing Readiness: The component is supplied on 12mm tape mounted on 7-inch diameter reels, compatible with standard automated pick-and-place equipment. It is also qualified for lead-free infrared (IR) reflow soldering processes, including preconditioning to JEDEC Moisture Sensitivity Level 4.
• Environmental Compliance: The product is compliant with relevant environmental regulations.

1.2 Target Applications and Markets

The combination of small form factor, integrated intelligence, and full-color capability makes this LED suitable for diverse applications:

• Status and Indicator Lighting: Providing multi-color status feedback in telecommunications gear, office automation equipment, home appliances, and industrial control panels.
• Front Panel and Backlighting: Illuminating buttons, logos, or displays with dynamic, customizable colors.
• Decorative and Architectural Lighting: Used in LED strips, modules, soft lights, and lamps for ambient or accent lighting.
• Indoor Display Elements: Building blocks for full-color modules or irregular video displays where individual pixel control is required.

2. Technical Parameters: In-Depth Objective Interpretation

This section provides a detailed analysis of the key performance parameters specified in the datasheet.

2.1 Optical Characteristics

Optical performance is measured under standard conditions (Ta=25°C, VDD=5V). The device uses a white diffused lens to mix the light from the individual color chips, producing a uniform appearance.

• Luminous Intensity (I_V): The typical axial luminous intensity varies by color chip. The Green chip is the brightest (330-700 mcd), followed by Red (130-300 mcd), and then Blue (50-180 mcd). These values represent the light output measured through a filter simulating the photopic (human eye) response.
• Viewing Angle (2θ_1/2): The device features a wide viewing angle of 120 degrees. This is defined as the full angle at which the luminous intensity drops to half of its on-axis value, indicating good off-axis visibility.
• Dominant Wavelength (λ_d): This parameter defines the perceived color of each chip. The specified ranges are: Red: 618-630 nm, Green: 520-535 nm, Blue: 463-475 nm. The peak emission wavelength tolerance is ±1 nm, ensuring consistent color production from device to device.

2.2 Electrical and Absolute Maximum Ratings

Adherence to these ratings is critical for reliable operation and preventing permanent damage.

• Absolute Maximum Ratings:
  • Power Dissipation (P_D): 94 mW. Exceeding this can lead to overheating.
  • Supply Voltage (V_DD): +4.2V to +5.5V. The internal IC is designed for a 5V nominal supply.
  • Total Forward Current (I_F): 17 mA. This is the maximum total current for all three chips combined.
  • Operating Temperature: 0°C to +85°C.
  • Storage Temperature: -40°C to +100°C.
• Electrical Characteristics (Typical @ V_DD=5V):
  • IC Output Current per Color: Typically 5 mA per individual R, G, or B channel. This constant current drive ensures stable color output regardless of minor voltage fluctuations.
  • Logic Input Levels: High-level input voltage (V_IH) is 0.7*V_DD (typically 3.3V at 5V supply). Low-level input voltage (V_IL) is 0.3*V_DD. This makes it compatible with both 5V and 3.3V microcontroller logic.
  • IC Quiescent Current: Approximately 0.2 mA when all LED outputs are off, indicating low power consumption in standby.

2.3 Thermal Considerations

While not explicitly detailing thermal resistance, the datasheet provides crucial thermal management guidelines through the soldering profile and storage conditions. The maximum power dissipation of 94 mW and the operating temperature range define the thermal operating window. Proper PCB layout with adequate thermal relief is necessary to maintain the junction temperature within safe limits during continuous operation, especially at maximum brightness and current.

3. Binning System Explanation

The datasheet includes a CIE (Commission Internationale de l'Eclairage) chromaticity binning table to ensure color consistency.

• Color Binning: The LEDs are sorted into bins (A, B, C, D) based on their measured chromaticity coordinates (x, y) on the CIE 1931 color space diagram. Each bin is defined by a quadrilateral on the chart. The tolerance for placement within a bin is ±0.01 in both x and y coordinates. This binning process groups LEDs with nearly identical perceived color, which is vital for applications where multiple LEDs are used side-by-side to avoid visible color mismatches.
• Interpretation: Bins A and B cover a specific region of the color space for the mixed white light (through the diffused lens), while bins C and D cover an adjacent region. Designers can specify a bin code to guarantee a tighter color match for their production run.

4. Performance Curve Analysis

The datasheet references typical performance curves which graphically represent key relationships. While the specific graphs are not reproduced in the provided text, their standard content is analyzed below.

• Relative Luminous Intensity vs. Forward Current (I-V Curve): This curve would show how light output increases with the forward current supplied to each LED chip. Due to the integrated constant current driver, this relationship is primarily managed internally, but the curve would illustrate the efficiency of the chip/driver combination.
• Relative Luminous Intensity vs. Ambient Temperature: This is a critical curve showing the derating of light output as the ambient (or junction) temperature rises. LED efficiency decreases with temperature, so this graph helps designers understand the thermal performance and potential light loss in warm environments.
• Spectral Power Distribution: This graph would display the intensity of light emitted across the wavelength spectrum for each color chip, showing the narrow emission peaks characteristic of LEDs and the specific dominant wavelengths.

5. Mechanical and Package Information

5.1 Package Dimensions and Configuration

The device conforms to an industry-standard SMD footprint. Key dimensions are approximately 5.0mm in length, 5.0mm in width, and 1.6mm in height (tolerance ±0.2mm). A detailed dimensional drawing is provided in the original datasheet for precise PCB land pattern design.

5.2 Pin Configuration and Function

The 6-pin device has the following pinout:

1. VCC: Power supply input for the internal IC. Can be connected to VDD.
2. VDD: Main DC power input (4.2-5.5V).
3. DOUT: Control data signal output for daisy-chaining to the next LED's DIN.
4. DIN: Control data signal input from a microcontroller or previous LED.
5. VSS: Ground connection.
6. FDIN: Auxiliary data signal input (functionality may be specific to certain control modes).

5.3 Recommended PCB Attachment Pad

A suggested solder pad layout is provided to ensure reliable soldering and mechanical stability. This layout typically includes thermal relief connections to manage heat during soldering and operation, and correctly sized pads for the gull-wing or similar leads.

6. Soldering, Assembly, and Handling Guidelines

6.1 IR Reflow Soldering Profile

A detailed reflow profile for lead-free soldering is provided, conforming to J-STD-020B. This profile specifies critical parameters:

• Preheat: A gradual ramp to activate flux and minimize thermal shock.
• Soak Zone: A temperature plateau to ensure uniform heating of the component and board.
• Reflow Zone: A peak temperature typically between 240°C and 260°C, with time above liquidus (TAL) carefully controlled to form reliable solder joints without damaging the LED package or internal components.
• Cooling Rate: A controlled cool-down to solidify the solder and minimize stress.

6.2 Storage and Moisture Sensitivity

The device is moisture-sensitive. When sealed in its original moisture-proof bag with desiccant, it has a shelf life of one year when stored at ≤30°C and ≤70% RH. Once opened, components should be stored at ≤30°C and ≤60% RH. For extended storage outside the original bag, use a sealed container with desiccant. Components exposed to ambient air for more than 96 hours require a baking procedure (approx. 60°C for 48 hours) before reflow to prevent \"popcorning\" or delamination during soldering.

6.3 Cleaning

If cleaning after soldering is necessary, only use specified solvents. Immersion in ethyl alcohol or isopropyl alcohol at room temperature for less than one minute is recommended. Harsh or unspecified chemicals can damage the plastic lens and package.

7. Packaging and Ordering Information

• Standard Packaging: The components are supplied on 12mm wide embossed carrier tape, wound onto 7-inch (178mm) diameter reels.
• Quantity per Reel: 1500 pieces per full reel.
• Minimum Order Quantity (MOQ): For partial quantities, a minimum of 500 pieces is available.
• Packaging Standards: Complies with ANSI/EIA-481 specifications. Empty pockets in the tape are covered with a protective top cover tape.

8. Application Design Considerations

8.1 Typical Application Circuits

The primary application involves daisy-chaining multiple LEDs. A single data line from a microcontroller connects to the DIN of the first LED. Its DOUT connects to the DIN of the next, and so on. A 5V power supply (with appropriate local decoupling capacitors, e.g., 100nF) must be provided to all LEDs, ensuring the voltage remains within the 4.2-5.5V range, especially at the end of long chains where IR drop may occur. A series resistor on the data line may be needed for impedance matching in long chains or noisy environments.

8.2 Data Transmission Protocol

Communication uses a high-speed, single-wire, reset-based protocol. Each bit is transmitted as a high pulse within a 1.2µs (±160ns) period.

• Logic '0': T_0H (high time) = 300ns ±80ns, T_0L (low time) = 900ns.
• Logic '1': T_1H = 900ns ±80ns, T_1L = 300ns.
• Data Frame: 42 bits per LED (presumably 14 bits for each R, G, and B channel).
• Reset: A low signal on the data line for longer than 50µs (RES) latches the received data into the output registers and prepares the IC to receive a new frame for the first LED in the chain.

8.3 Thermal and Power Management

Designers must calculate the total power dissipation. At the typical 5mA per color and 5V supply, one LED with all three colors at full white could dissipate up to 75mW (5V * 15mA), which is below the 94mW maximum. However, in dense arrays, the aggregate heat can be significant. Adequate PCB copper area for heat sinking, possible airflow, and derating brightness at high ambient temperatures are essential considerations for long-term reliability.

9. Technical Comparison and Differentiation

Compared to discrete RGB LEDs requiring external constant current drivers and multiplexing circuits, this device offers significant integration, reducing design complexity, component count, and board space. Versus other addressable LEDs (e.g., those using a different protocol like APA102 or older WS2812), the LTST-G353CEGB7W's 14-bit control (10-bit PWM + 4-bit current) provides finer color resolution and grayscale control than typical 8-bit (256 levels) alternatives. The integrated bypass function for fault tolerance is also a distinguishing reliability feature not found in all addressable LEDs.

10. Frequently Asked Questions (Based on Technical Parameters)

Q1: What is the difference between VCC and VDD pins?
A1: Both are power inputs for the internal IC. They can be connected together. The datasheet suggests they are internally similar, providing design flexibility, possibly for noise isolation in sensitive applications.

Q2: Can I drive this LED with a 3.3V microcontroller?
A2: Yes, for the data input (DIN). The V_IH minimum is 0.7*V_DD. With V_DD=5V, V_IH min is 3.5V. A 3.3V output might be at the lower edge. It may work, but for reliability, a level shifter to 5V for the data line is recommended. The power supply V_DD must still be 4.2-5.5V.

Q3: How many LEDs can I daisy-chain?
A3: The limit is primarily determined by the data refresh rate and power supply. Each LED requires 42 bits of data. For a long chain, the time to transmit data for all LEDs before the desired refresh rate (e.g., 60Hz) may limit the number. Electrically, the DOUT can drive the DIN of the next LED directly. Power must be distributed robustly to avoid voltage drop along the chain.

Q4: What is the purpose of the FDIN pin?
A4: The datasheet lists it as an auxiliary data input. Its exact function may be for advanced control modes, factory testing, or compatibility with specific controller features. For standard single-wire daisy-chaining, it is typically left unconnected or tied to VDD or VSS as specified in application notes.

11. Practical Design and Usage Examples

Example 1: Status Indicator Panel: A cluster of 10 LEDs can be used on a network router. Each can be assigned a unique color to indicate link status, traffic activity, or system alerts. The single data line control simplifies wiring compared to multiplexing 30 discrete LEDs (10 RGB).

Example 2: Decorative LED Strip Prototype: For a custom lighting project, 50 LEDs can be soldered onto a flexible PCB strip. A small microcontroller (e.g., ESP32) can generate the data stream, allowing animations, color washes, and music visualization. The wide viewing angle ensures even illumination.

Example 3: Instrument Cluster Backlighting: In a low-volume industrial device, these LEDs can provide customizable backlighting for gauges or buttons, allowing the end-user to select color themes. The constant current drive ensures consistent brightness regardless of the selected color.

12. Operational Principle Introduction

The device operates on a straightforward principle. An external microcontroller sends a serial data stream containing brightness information for the red, green, and blue channels. The integrated driver IC receives this data, stores it in internal registers, and then uses constant current sources to drive each LED chip. The brightness of each chip is controlled by rapidly switching its current on and off (PWM) at a frequency high enough to be imperceptible to the human eye (>200Hz). The duty cycle of this PWM (the proportion of 'on' time) determines the perceived brightness. The 4-bit current adjustment allows scaling the maximum current for each color, enabling white point calibration. The light from the three monochromatic chips mixes within the white diffused lens, producing the final composite color.

13. Technology Trends and Context

The LTST-G353CEGB7W represents a mature stage in the evolution of SMD LEDs, specifically in the category of \"intelligent\" or \"addressable\" LEDs. The trend in this field is towards higher integration, greater control resolution (moving from 8-bit to 16-bit or higher per channel), improved power efficiency (lower forward voltages, higher luminous efficacy), and enhanced communication protocols that are faster and more robust to noise. There is also a drive towards miniaturization while maintaining or increasing light output, and the development of LEDs with wider color gamuts for more vivid displays. This device, with its integrated 14-bit driver and reliable single-wire interface, aligns with the industry's push for simpler, higher-performance, and more reliable lighting solutions for smart and connected devices.