LTW-C181HDS5-GE SMD LED Datasheet - 1.6x0.8x0.55mm - 3.15V Max - 76mW - White - English Technical Document

1. Product Overview

This document provides the complete technical specifications for the LTW-C181HDS5-GE, a surface-mount device (SMD) LED lamp. This product belongs to a family of miniature LEDs designed for automated printed circuit board (PCB) assembly, making them ideal for applications where space is at a premium. The ultra-thin profile and compatibility with high-volume placement equipment position this component as a key solution for modern, compact electronic designs.

1.1 Features

• Compliant with the Restriction of Hazardous Substances (RoHS) directive.
• Features a super-thin package with a height of only 0.55 millimeters.
• Utilizes an ultra-bright Indium Gallium Nitride (InGaN) white light-emitting chip.
• Supplied in industry-standard 8mm tape on 7-inch diameter reels for automated handling.
• Conforms to EIA (Electronic Industries Alliance) standard package outlines.
• Input is compatible with integrated circuit (IC) logic levels.
• Designed for use with standard automatic pick-and-place assembly equipment.
• Withstands infrared (IR) reflow soldering processes commonly used in SMT assembly lines.

1.2 Applications

The LTW-C181HDS5-GE is suitable for a broad spectrum of electronic equipment. Its primary application areas include:

• Telecommunication Equipment: Status indicators on routers, modems, and handsets.
• Office Automation & Consumer Electronics: Backlighting for keypads, keyboards, and micro-displays in devices like laptops and peripherals.
• Home Appliances & Industrial Equipment: Power, mode, or fault status indicators.
• Indoor Signage & Luminaires: Small-scale signal and symbol illumination where compact size is critical.

2. Package Dimensions and Configuration

The LED is housed in a compact, rectangular SMD package. Critical dimensions are as follows:

• Package Length: 1.6 mm
• Package Width: 0.8 mm
• Package Height: 0.55 mm

Notes on Dimensions: All provided dimensions are in millimeters. The standard tolerance for these measurements is ±0.1 mm unless a specific note indicates otherwise. The device features a yellow-tinted lens which modifies the output from the internal InGaN white light source, typically resulting in a warm white or specific chromaticity point.

3. Ratings and Characteristics

All parameters are specified at an ambient temperature (Ta) of 25°C unless stated otherwise. Exceeding Absolute Maximum Ratings may cause permanent device damage.

3.1 Absolute Maximum Ratings

• Power Dissipation (Pd): 76 mW
• Peak Forward Current (I_F(peak)): 100 mA (under pulsed conditions: 1/10 duty cycle, 0.1ms pulse width)
• Continuous Forward Current (I_F): 20 mA DC
• Operating Temperature Range (T_opr): -20°C to +105°C
• Storage Temperature Range (T_stg): -40°C to +105°C
• Infrared Reflow Soldering Condition: 260°C peak temperature for a maximum of 10 seconds.

3.2 Recommended IR Reflow Profile (Pb-Free Process)

For lead-free solder assembly, a specific thermal profile must be followed to ensure reliability without damaging the LED. The recommendation includes:

• Pre-heat Temperature: 150°C to 200°C.
• Pre-heat Time: Maximum of 120 seconds.
• Peak Body Temperature: Maximum of 260°C.
• Time Above 260°C: Maximum of 10 seconds. This reflow process should not be performed more than two times.

It is crucial to note that the optimal profile can vary based on PCB design, solder paste, and oven characteristics. Board-level testing is advised.

3.3 Electrical and Optical Characteristics

These are the typical performance parameters measured under standard test conditions (I_F = 5mA, Ta=25°C).

• Luminous Intensity (I_V): 112.0 mcd (Minimum) to 224.0 mcd (Maximum). The specific bin determines the actual value.
• Viewing Angle (2θ_1/2): 130 degrees. This is the full angle at which the luminous intensity is half of the peak intensity measured at 0 degrees (on-axis).
• Chromaticity Coordinates (CIE 1931): x = 0.284, y = 0.272. These coordinates define the white point color on the CIE chromaticity diagram. A tolerance of ±0.01 applies to these coordinates.
• Forward Voltage (V_F): 2.70 V (Minimum) to 3.15 V (Maximum) at 5mA. The actual value is determined by the forward voltage bin.
• Reverse Current (I_R): 2 μA (Maximum) when a reverse voltage (V_R) of 5V is applied. Important: This device is not designed for operation in reverse bias; this parameter is for informational and testing purposes only.

Critical Notes on Testing and Handling: Luminous intensity is measured using a sensor and filter calibrated to the CIE photopic eye-response curve. The device is sensitive to Electrostatic Discharge (ESD). Proper ESD precautions, such as using grounded wrist straps and anti-static mats, are mandatory during handling. All production equipment must be correctly grounded.

4. Bin Ranking System

To ensure consistency in application, the LEDs are sorted into bins based on key parameters. The bin code is marked on the packaging.

4.1 Forward Voltage (V_F) Rank

Binning at I_F = 5mA, White color. Tolerance per bin is ±0.1V.

• Bin Code A: 2.70 V (Min) – 2.85 V (Max)
• Bin Code B: 2.85 V (Min) – 3.00 V (Max)
• Bin Code C: 3.00 V (Min) – 3.15 V (Max)

4.2 Luminous Intensity (I_V) Rank

Binning at I_F = 5mA, White color. Tolerance per bin is ±15%.

• Bin Code R1: 112.0 mcd (Min) – 146.0 mcd (Max)
• Bin Code R2: 146.0 mcd (Min) – 180.0 mcd (Max)
• Bin Code S1: 180.0 mcd (Min) – 224.0 mcd (Max)

4.3 Hue (Chromaticity) Rank

Binning at I_F = 5mA. The LED is classified into specific regions on the CIE 1931 chromaticity diagram defined by (x, y) coordinate boundaries. Examples from the datasheet include:

• S1-1: Defined by the quadrilateral connecting points (x=0.274, y=0.226), (0.274, 0.258), (0.284, 0.272), (0.284, 0.240).
• S2-1: Defined by points (0.274, 0.258), (0.274, 0.291), (0.284, 0.305), (0.284, 0.272).

Tolerance on each hue bin is ±0.01 for both x and y coordinates. This precise binning allows designers to select LEDs for applications requiring tight color consistency.

5. Typical Performance Curves

The datasheet includes graphical representations of key relationships, essential for circuit design and thermal management. While the specific curves are not displayed in the provided text, they typically encompass:

• Forward Current vs. Forward Voltage (I-V Curve): Shows the non-linear relationship between current and voltage, critical for selecting current-limiting resistors or designing driver circuits.
• Luminous Intensity vs. Forward Current: Illustrates how light output increases with current, helping to optimize the drive current for desired brightness and efficiency.
• Luminous Intensity vs. Ambient Temperature: Demonstrates the decrease in light output as junction temperature rises, which is vital for thermal design in high-power or high-ambient-temperature applications.
• Relative Spectral Power Distribution: Depicts the intensity of light emitted at each wavelength, defining the color characteristics of the white light output.

6. User Guide and Assembly Information

6.1 Cleaning

If cleaning after soldering is necessary, only use specified solvents. Unspecified chemicals may damage the LED package or lens. The recommended method is to immerse the LED in ethyl alcohol or isopropyl alcohol at room temperature for less than one minute.

6.2 Recommended PCB Land Pattern

A suggested footprint for the solder pads on the printed circuit board is provided to ensure proper soldering, mechanical stability, and thermal dissipation. Adhering to this pattern helps prevent tombstoning (one end lifting during reflow) and ensures good electrical connection.

6.3 Tape and Reel Packaging Specifications

The LEDs are supplied in embossed carrier tape with a protective cover tape, wound onto 7-inch (178mm) diameter reels. Key specifications include:

• Tape Width: 8 mm.
• Pocket Pitch: Standard pitch for 8mm tape.
• Reel Quantity: 5000 pieces per full reel.
• Minimum Order Quantity (MOQ): 500 pieces for remainder quantities.
• Missing Components: A maximum of two consecutive empty pockets is allowed per the tape specification (ANSI/EIA 481).

7. Cautions and Reliability Information

7.1 Application Scope

This LED is intended for use in standard commercial and consumer electronic equipment. For applications requiring exceptional reliability where failure could risk life or health (e.g., aviation, medical life-support, transportation safety systems), a dedicated technical consultation is mandatory prior to design-in to assess suitability and potential need for additional screening or qualifications.

7.2 Storage Conditions

Proper storage is critical to maintain solderability and prevent moisture-induced damage during reflow ("popcorning").

• Sealed Moisture Barrier Bag (MBB): Store at ≤30°C and ≤90% Relative Humidity (RH). The shelf life within the sealed bag with desiccant is one year.
• After Bag Opening: The "floor life" begins. Store at ≤30°C and ≤60% RH. For this device, which is typically Moisture Sensitivity Level (MSL) 2a, it is recommended to complete the IR reflow process within 672 hours (28 days) of bag opening.
• Extended Storage (Opened): If not used within 672 hours, store in a sealed container with desiccant or in a nitrogen desiccator.
• Rebaking: Components stored out of their original packaging for more than 672 hours should be baked at approximately 60°C for at least 20 hours before assembly to remove absorbed moisture.

7.3 Soldering Guidelines

In addition to the IR reflow profile, manual soldering with a soldering iron is permissible under strict conditions:

• Iron Temperature: Maximum 300°C.
• Soldering Time: Maximum 3 seconds per solder joint.
• Frequency: Manual soldering should be performed only once. Avoid repeated heating.

8. Design Considerations and Technical Analysis

8.1 Driving the LED

The LED must be driven with a constant current source or via a current-limiting resistor in series with a voltage source. Using a resistor is the simplest method. The resistor value (R_limit) can be calculated using Ohm's Law: R_limit = (V_supply - V_F) / I_F. It is critical to use the maximum V_F from the bin (e.g., 3.15V for Bin C) in this calculation to ensure the current does not exceed the desired I_F (e.g., 20mA) under worst-case conditions. Exceeding the absolute maximum current rating will drastically reduce lifetime and can cause immediate failure.

8.2 Thermal Management

Although the power dissipation is low (76mW max), effective thermal management is still important for longevity and stable light output. The luminous intensity decreases as the LED's junction temperature increases. To minimize temperature rise:

• Use the recommended PCB land pattern to provide adequate copper area for heat sinking.
• Avoid placing the LED near other heat-generating components.
• Ensure adequate ventilation in the end-product enclosure.
• Operate the LED at the lowest practical forward current that meets the brightness requirement.

8.3 Optical Design

The wide 130-degree viewing angle makes this LED suitable for applications requiring broad, diffuse illumination rather than a focused beam, such as backlighting or status indicators that need to be visible from various angles. For more directional light, secondary optics (lenses or light guides) would be required. The yellow lens acts as a color filter, shifting the chromaticity coordinates from the native blue-pump + phosphor white of the InGaN chip to the specified (x, y) values, often yielding a warmer white tone.

9. Comparison and Selection Guidance

The LTW-C181HDS5-GE's key differentiators are its ultra-thin 0.55mm height and standard 1.6x0.8mm footprint. When selecting an SMD LED, engineers should compare:

• Package Size/Height: This device is among the thinnest, crucial for ultra-slim products.
• Brightness (Luminous Intensity): The S1 bin offers high brightness for its size.
• Viewing Angle: A 130-degree angle is very wide, ideal for area illumination.
• Color Consistency: The multi-parameter binning (V_F, I_V, Hue) allows for tight matching in applications using multiple LEDs.
• Reliability and Compatibility: RoHS compliance and IR reflow compatibility are standard for modern SMD LEDs.

For applications not requiring the minimal height, other package sizes (e.g., 3528, 5050) may offer higher light output or better thermal performance.

10. Frequently Asked Questions (FAQ)

Q1: What is the purpose of the different bin codes?
A1: Manufacturing variations cause slight differences in V_F, brightness, and color. Binning sorts LEDs into groups with nearly identical characteristics, allowing designers to source parts that will perform consistently in their circuit, especially when using multiple LEDs in an array.

Q2: Can I drive this LED directly from a 5V or 3.3V microcontroller pin?
A2: No. You must always use a series current-limiting resistor. Connecting it directly to a voltage source will cause excessive current to flow, destroying the LED instantly. Calculate the resistor value based on your supply voltage and desired forward current.

Q3: How do I interpret the chromaticity coordinates (x=0.284, y=0.272)?
A3: These coordinates plot a point on the CIE 1931 chromaticity diagram, which is the standard for defining color. This specific point corresponds to a white color with a slight shift, often perceived as a "cool white" or "neutral white," influenced by the yellow lens. The exact perceived color also depends on the correlated color temperature (CCT), which can be derived from these coordinates.

Q4: Why are the storage conditions so strict after opening the bag?
A4: SMD packages can absorb moisture from the air. During the high heat of reflow soldering, this trapped moisture can vaporize rapidly, creating internal pressure that can crack the package or delaminate internal layers—a failure known as "popcorning." The MSL rating and storage guidelines prevent this.

11. Technology Introduction and Trends

11.1 InGaN LED Technology

The LTW-C181HDS5-GE utilizes an Indium Gallium Nitride (InGaN) semiconductor chip. InGaN is the material of choice for producing high-efficiency blue, green, and white LEDs. A white LED is typically created by coating a blue InGaN chip with a yellow phosphor. Some of the blue light is converted by the phosphor to yellow light, and the mixture of blue and yellow light is perceived by the human eye as white. This method, known as phosphor-converted white (pc-white), is highly efficient and allows for tuning the white color point by adjusting the phosphor composition.

11.2 Industry Trends

The trend in SMD LEDs for indicator and backlight applications continues toward:

• Miniaturization: Even smaller and thinner packages like the 0.55mm height of this device to enable slimmer end products.
• Higher Efficiency: More lumens per watt (lm/W), reducing power consumption for the same light output.
• Improved Color Rendering and Consistency: Tighter binning tolerances and new phosphor technologies to produce more natural and consistent white light.
• Enhanced Reliability: Improved materials and packaging techniques to withstand higher soldering temperatures and harsher operating environments.
• Integration: The emergence of LEDs with built-in current-limiting resistors or IC drivers within the same tiny package.

This datasheet represents a component designed for the mainstream demands of compactness, automated assembly, and reliable performance in a wide range of consumer and industrial electronics.