LTW-C191TL5 White SMD LED Datasheet - Dimensions 1.6x0.8x0.55mm - Voltage 2.7-3.15V - Power 70mW - English Technical Document

1. Product Overview

The LTW-C191TL5 is a surface-mount device (SMD) light-emitting diode (LED) designed for modern, compact electronic applications. It belongs to a class of ultra-thin chip LEDs, featuring a remarkably low profile of just 0.55 mm in height. This makes it an ideal choice for applications where space constraints are critical, such as in ultra-slim displays, backlighting for mobile devices, and indicator lights in densely packed PCBs.

The core technology is based on Indium Gallium Nitride (InGaN), which enables the generation of bright white light. The LED is packaged on industry-standard 8mm tape, wound onto 7-inch diameter reels, ensuring compatibility with high-speed automated pick-and-place assembly equipment. This packaging format is essential for mass production, allowing for efficient handling and placement during the manufacturing process.

2. Technical Specifications Deep Dive

2.1 Absolute Maximum Ratings

These ratings define the limits beyond which permanent damage to the device may occur. The LTW-C191TL5 has a maximum power dissipation of 70 mW at an ambient temperature (Ta) of 25°C. The maximum continuous forward current (DC) is 20 mA. For pulsed operation, a peak forward current of 100 mA is permissible under specific conditions: a 1/10 duty cycle and a pulse width of 0.1 ms. The device can withstand a reverse voltage of up to 5V, though continuous operation under reverse bias is prohibited. The operating temperature range is from -20°C to +80°C, while the storage temperature range is wider, from -55°C to +105°C. A critical parameter for assembly is the infrared soldering condition, rated for 260°C for a maximum of 10 seconds.

2.2 Electrical and Optical Characteristics

These are the typical performance parameters measured at Ta=25°C and a forward current (IF) of 5 mA, which is a common test condition. The luminous intensity (Iv) ranges from a minimum of 45.0 millicandelas (mcd) to a typical maximum of 180.0 mcd. The viewing angle (2θ1/2) is 130 degrees, providing a wide field of illumination. The chromaticity coordinates, which define the color point of the white light on the CIE 1931 diagram, are typically x=0.31 and y=0.32. The forward voltage (VF) ranges from 2.70V to 3.15V at the test current. The reverse current (IR) is a maximum of 10 μA when a reverse voltage (VR) of 5V is applied.

3. Binning System Explanation

To ensure consistency in production, LEDs are sorted into bins based on key electrical and optical parameters. The LTW-C191TL5 uses a three-dimensional binning system.

3.1 Forward Voltage (VF) Binning

LEDs are categorized into three VF bins (A, B, C) based on their forward voltage at IF=5mA. Bin A covers 2.70V to 2.85V, Bin B covers 2.85V to 3.00V, and Bin C covers 3.00V to 3.15V. A tolerance of ±0.1V is applied to each bin.

3.2 Luminous Intensity (IV) Binning

LEDs are sorted into three IV bins (P, Q, R) based on their light output. Bin P ranges from 45.0 to 71.0 mcd, Bin Q from 71.0 to 112.0 mcd, and Bin R from 112.0 to 180.0 mcd. A tolerance of ±15% is applied to each bin.

3.3 Hue (Color) Binning

This is the most complex bin, defining the white color point. Bins are defined by quadrilaterals on the CIE 1931 chromaticity diagram. The datasheet lists coordinates for bins A0, B3, B4, B5, B6, and C0. For example, Bin B5 is defined by the coordinates (x,y): (0.296, 0.276), (0.311, 0.294), (0.307, 0.315), (0.287, 0.295). A tolerance of ±0.01 is applied to each (x, y) coordinate within a bin. The provided diagram visually plots these bins, showing their position relative to the white point region.

4. Performance Curve Analysis

While the PDF indicates the presence of typical electrical/optical characteristic curves on page 4, the specific graphs (e.g., IV curve, relative intensity vs. temperature, spectral distribution) are not included in the provided text. Typically, such curves would show the relationship between forward current and voltage, how luminous intensity decreases with increasing junction temperature, and the spectral power distribution of the emitted white light. These graphs are crucial for designers to understand the device's behavior under non-standard operating conditions.

5. Mechanical and Package Information

5.1 LED Package Dimensions

The LED has an EIA standard package footprint. Key dimensions include a body size of approximately 1.6mm in length and 0.8mm in width, with the ultra-thin height of 0.55mm being the standout feature. Detailed dimensioned drawings would specify pad locations, lens shape, and cathode/anode identification markings.

5.2 Suggested Soldering Pad Layout

A recommended land pattern (footprint) for the PCB is provided to ensure reliable solder joint formation during reflow. This pattern is slightly larger than the device itself to accommodate solder fillets.

5.3 Tape and Reel Packaging Dimensions

The device is supplied in embossed carrier tape with a width of 8mm. The tape is wound onto a standard 7-inch (178mm) diameter reel. Key specifications include: 5000 pieces per full reel, a minimum packing quantity of 500 pieces for partial reels, and a maximum of two consecutive missing components (pockets) allowed in the tape. The packaging conforms to ANSI/EIA 481-1-A-1994 standards.

6. Soldering and Assembly Guidelines

6.1 Reflow Soldering Profile

The recommended infrared (IR) reflow profile is critical. The peak temperature should not exceed 260°C, and the time above 260°C should be a maximum of 10 seconds. Pre-heating is recommended in the range of 150-200°C for up to 120 seconds to minimize thermal shock. The profile should be characterized for the specific PCB assembly.

6.2 Hand Soldering

If hand soldering is necessary, a soldering iron temperature should not exceed 300°C, and the contact time should be limited to a maximum of 3 seconds per pad. Hand soldering should be performed only once.

6.3 Storage and Handling

The LEDs are moisture-sensitive. In their original sealed moisture barrier bag (with desiccant), they should be stored at ≤30°C and ≤90% RH and used within one year. Once the bag is opened, the storage environment should be ≤30°C and ≤60% RH. Components exposed to ambient air for more than 672 hours (4 weeks) should be baked at approximately 60°C for at least 20 hours before reflow to remove absorbed moisture and prevent \"popcorning\" damage during soldering. For extended storage outside the original bag, use a sealed container with desiccant or a nitrogen desiccator.

6.4 Cleaning

If cleaning after soldering 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. Unspecified chemicals may damage the epoxy lens or package.

7. Packaging and Ordering Information

The standard packaging hierarchy is: LEDs on tape → tape on 7\" reel → reel(s) in a moisture barrier bag (with desiccant) → bag(s) in an inner carton → inner carton(s) in a master carton. A maximum of 3 barrier bags can be in one inner carton, and a maximum of 21 inner cartons can be in one master carton. The part number LTW-C191TL5 follows the manufacturer's internal naming convention, where \"LTW\" likely indicates a white LED, and \"C191\" denotes the package type and series.

8. Application Suggestions

8.1 Typical Application Scenarios

The ultra-thin profile makes this LED ideal for: backlighting in ultra-slim LCD displays for smartphones, tablets, and monitors; status indicators in wearable devices and ultra-portable electronics; decorative lighting in thin consumer products; and panel indicators in networking and communication equipment where board real estate is limited.

8.2 Design Considerations

Current Limiting: Always use a series resistor or constant current driver to limit the forward current to a maximum of 20mA DC. Operating at the typical test current of 5mA will provide longer life and better stability.
Thermal Management: Although small, the LED generates heat. Ensure adequate thermal relief in the PCB pad design, especially if operating near maximum current or in high ambient temperatures. The derating factor of 0.25 mA/°C above 25°C must be considered.
ESD Protection: The device is sensitive to electrostatic discharge (ESD). Implement ESD-safe handling procedures, including the use of grounded wrist straps and workstations, during assembly and installation.
Optical Design: The wide 130-degree viewing angle provides diffuse illumination. For focused light, external lenses or light guides may be necessary.

9. Technical Comparison and Differentiation

The primary differentiating advantage of the LTW-C191TL5 is its 0.55mm height, which is significantly lower than many standard SMD LEDs (e.g., 0603 or 0805 packages which are often >0.8mm tall). This allows for design in increasingly thinner end products. The use of InGaN technology provides high efficiency and good color rendering for a white LED. The comprehensive binning system offers designers the ability to select LEDs for consistent color and brightness in their applications, which is critical for multi-LED arrays in backlighting or signage.

10. Frequently Asked Questions (Based on Technical Parameters)

Q: Can I drive this LED at 20mA continuously?
A: Yes, 20mA is the maximum rated continuous DC current. However, for optimal longevity and efficiency, driving it at a lower current like 5-10mA is recommended.

Q: What is the purpose of the different VF and IV bins?
A: Binning allows you to select LEDs with very similar electrical and optical characteristics. This is vital for applications using multiple LEDs where uniform brightness and color are required, preventing visible differences between individual LEDs.

Q: How do I interpret the Hue bin coordinates?
A: The (x,y) coordinates place the LED's white point on the CIE chromaticity diagram. Bins like B5 or C0 represent different regions of \"white,\" ranging from cooler (bluer) to warmer (yellower) tones. You should choose a bin that matches your product's color temperature requirements.

Q: My reflow oven profile peaks at 250°C. Is that acceptable?
A: Yes, a peak of 250°C is within the specification (max 260°C). Always ensure the time above the liquidus temperature of your solder paste is sufficient for proper joint formation.

11. Practical Design and Usage Case

Case: Designing a Status Indicator for a Slim Smartwatch.
The primary constraint is Z-height. The 0.55mm profile of the LTW-C191TL5 allows it to fit beneath a thin diffuser layer without increasing the overall thickness of the watch casing. The designer selects LEDs from Bin R for high brightness and Bin B5 for a consistent, neutral white color. A constant-current LED driver IC is used to supply 8mA to the LED, providing ample brightness while conserving battery life and keeping junction temperature low. The PCB pad layout follows the datasheet recommendation. During assembly, the watch PCB undergoes IR reflow with a carefully profiled peak of 245°C for 8 seconds. The wide viewing angle ensures the indicator light is visible from various angles when the user glances at their wrist.

12. Technology Principle Introduction

The LTW-C191TL5 is based on InGaN (Indium Gallium Nitride) semiconductor technology. In a white LED, the active region typically emits blue light. Part of this blue light is then converted to longer wavelengths (yellow, red) by a phosphor coating applied over the semiconductor chip. The mixture of the remaining blue light and the phosphor-converted yellow/red light is perceived by the human eye as white. The specific ratios of indium and gallium in the InGaN alloy, along with the composition and thickness of the phosphor layer, determine the final color temperature and chromaticity coordinates of the emitted white light. The ultra-thin package is achieved through advanced chip-scale packaging techniques that minimize the amount of encapsulating material around the semiconductor die.

13. Industry Trends and Developments

The trend in SMD LEDs for consumer electronics is relentlessly towards miniaturization and higher efficiency. The 0.55mm height of this device represents a step in the ongoing reduction of package profiles. Future developments may focus on further reducing the footprint (e.g., chip-scale packages with no visible package) while increasing luminous efficacy (lumens per watt). There is also a strong trend towards improved color consistency and higher Color Rendering Index (CRI) values, especially for lighting applications. Furthermore, integration of control circuitry (like PWM dimming) within the LED package is an emerging area. The drive for RoHS compliance and green manufacturing, as noted in this LED's features, remains a fundamental industry standard.