SMD LED LTW-C19BZDS2-NB Datasheet - InGaN White Chip - 2.5-3.0V - 70mW - English Technical Document

1. Product Overview

This document provides the complete technical specifications for the LTW-C19BZDS2-NB, a surface-mount device (SMD) LED lamp. This component is designed for automated printed circuit board (PCB) assembly and is suitable for applications where space is a critical constraint. The LED utilizes an ultra-bright InGaN (Indium Gallium Nitride) white chip as its light source, housed within a package featuring a yellow lens and a black cap. It is compliant with the Restriction of Hazardous Substances (RoHS) directive.

1.1 Core Advantages

The primary advantages of this LED include its super-thin profile, which facilitates integration into slim devices. It is packaged on 8mm tape wound onto 7-inch diameter reels, making it fully compatible with high-speed automated pick-and-place equipment used in modern electronics manufacturing. The device is also designed to be compatible with infrared (IR) reflow soldering processes, which is the standard for surface-mount technology assembly. Its electrical characteristics are I.C. (Integrated Circuit) compatible, simplifying drive circuit design.

1.2 Target Market and Applications

This LED is targeted at a broad spectrum of electronic equipment manufacturers. Its key applications include, but are not limited to:

• Telecommunication Equipment: Status indicators on routers, modems, and handsets.
• Office Automation: Backlighting for keypads and keyboards in laptops, calculators, and control panels.
• Consumer Electronics and Home Appliances: Power status lights, function indicators.
• Industrial Equipment: Panel indicators and machine status lights.
• Microdisplays and Symbolic Luminaires: Small-scale informational lighting.

2. Technical Parameter Deep Dive

This section provides a detailed, objective interpretation of the LED's key performance parameters under standard test conditions (Ta=25°C).

2.1 Absolute Maximum Ratings

These ratings define the limits beyond which permanent damage to the device may occur. They are not intended for continuous operation.

• Power Dissipation (Pd): 70 mW. This is the maximum amount of power the LED package can dissipate as heat.
• Continuous Forward Current (IF): 20 mA DC. The maximum steady-state current that can be applied.
• Peak Forward Current: 100 mA, permissible only under pulsed conditions (1/10 duty cycle, 0.1ms pulse width) to prevent overheating.
• Electrostatic Discharge (ESD) Threshold (HBM): 2000V. This Human Body Model rating indicates a moderate level of ESD sensitivity; proper handling procedures are required.
• Operating Temperature Range: -20°C to +80°C. The ambient temperature range for reliable operation.
• Storage Temperature Range: -30°C to +100°C.
• Infrared Reflow Soldering Condition: Withstands a peak temperature of 260°C for a maximum of 10 seconds, which is standard for lead-free (Pb-free) solder processes.

2.2 Electro-Optical Characteristics

These parameters are guaranteed under the specified test conditions (typically IF = 2mA).

• Luminous Intensity (Iv): Ranges from a minimum of 11.0 mcd to a maximum of 45.0 mcd, with a typical value of 28.0 mcd. Intensity is measured using a sensor filtered to match the CIE photopic eye-response curve.
• Viewing Angle (2θ1/2): 80 degrees. This is the full angle at which the luminous intensity drops to half of its peak axial value, defining the beam spread.
• Chromaticity Coordinates (x, y): Approximately (0.31, 0.31) on the CIE 1931 chromaticity diagram. This defines the white point color of the LED. A tolerance of ±0.01 is applied to these coordinates.
• Forward Voltage (VF): Between 2.50V and 3.00V at 2mA, with a typical value of 2.70V. This is the voltage drop across the LED when conducting current.
• Reverse Voltage (VR): 5.0V to 9.0V. Important Note: This parameter is for IR test characterization only. The device is not designed for operation under reverse bias.
• Reverse Current (IR): Maximum of 10 μA when a reverse voltage of 5V is applied.

3. Bin Ranking System Explanation

The LEDs are sorted (binned) after production based on key parameters to ensure consistency. The bin code is marked on the packaging.

3.1 Forward Voltage (VF) Rank

Sorted at IF=2mA. Bin codes (10, A10, B10, B11, 12) represent increasing voltage ranges from 2.50-2.60V to 2.90-3.00V, with a ±0.1V tolerance per bin.

3.2 Luminous Intensity (Iv) Rank

Sorted at IF=2mA. Bin codes L, M, N represent intensity ranges: 11.0-18.0 mcd, 18.0-28.0 mcd, and 28.0-45.0 mcd respectively, with a ±15% tolerance per bin.

3.3 Hue (Color) Rank

Defined by chromaticity coordinates (x, y) on the CIE 1931 diagram at IF=2mA. Bin codes S1, S2, S3, S5 define specific quadrilateral regions on the color chart, ensuring LEDs within a bin have a consistent white color. A tolerance of ±0.01 is applied to the coordinates.

4. Performance Curve Analysis

While specific graphical curves are referenced in the datasheet (Fig.1, Fig.5), the following analysis is based on the provided tabular data and standard LED behavior.

4.1 Forward Current vs. Forward Voltage (I-V Curve)

The forward voltage (VF) is specified at a low test current of 2mA. For a typical InGaN LED, the VF exhibits a logarithmic relationship with current. Operating at the maximum continuous current of 20mA will result in a higher VF than the 2.70V typical value listed at 2mA. Designers must refer to or derive the complete I-V curve to calculate the correct series resistor or constant-current drive voltage.

4.2 Luminous Intensity vs. Forward Current

Luminous intensity (Iv) is highly dependent on forward current. The specified Iv values are at 2mA. Intensity typically increases super-linearly with current before potentially saturating at higher currents due to thermal and efficiency droop. The 20mA maximum continuous current rating suggests the device can be driven harder than the test condition for higher output, but this will increase power dissipation and junction temperature, potentially affecting lifetime and color stability.

4.3 Temperature Dependence

The operating temperature range is -20°C to +80°C. Like all LEDs, the performance of this device is temperature-sensitive. Typically, forward voltage (VF) decreases with increasing temperature (negative temperature coefficient). More critically, luminous output (Iv) generally decreases as junction temperature rises. For applications requiring stable light output, thermal management of the PCB and consideration of the LED's operating environment are essential.

5. Mechanical and Package Information

5.1 Package Dimensions

The datasheet includes a detailed dimensional drawing. Key notes: all dimensions are in millimeters, and the standard tolerance is ±0.1 mm unless otherwise specified. The physical footprint is designed to be an EIA standard package for compatibility.

5.2 Recommended PCB Attachment Pad Layout

A suggested land pattern (pad geometry) for the PCB is provided to ensure reliable soldering and proper alignment during the reflow process. Adhering to this recommendation helps achieve good solder fillets and mechanical strength.

5.3 Polarity Identification

The datasheet drawing indicates the cathode and anode markings on the device. Correct polarity must be observed during assembly, as applying reverse voltage can damage the LED.

6. Soldering and Assembly Guidelines

6.1 IR Reflow Soldering Parameters (Pb-Free Process)

A detailed reflow profile is suggested. Key parameters include a pre-heat zone (150-200°C), a pre-heat time (max 120 seconds), a peak temperature not exceeding 260°C, and a time above 260°C limited to a maximum of 10 seconds. The LED can withstand this profile a maximum of two times. It is crucial to note that the optimal profile depends on the specific PCB assembly; board-level characterization is recommended.

6.2 Hand Soldering

If hand soldering is necessary, it should be performed with a soldering iron tip temperature not exceeding 300°C, and the soldering time should be limited to a maximum of 3 seconds. This should be done only once.

6.3 Storage and Handling Conditions

ESD Precautions: The device has an ESD threshold of 2000V (HBM). Handling with anti-static wrist straps and on properly grounded equipment is mandatory to prevent damage from electrostatic discharge.
Moisture Sensitivity: The LEDs are packaged in a moisture-barrier bag with desiccant. Once the original sealed bag is opened, the components have a limited floor life (MSL 3). It is recommended to complete IR reflow within one week of exposure. For longer storage after opening, bake at 60°C for at least 20 hours before soldering, or store in a sealed, dry environment (e.g., with desiccant or nitrogen).
Storage Environment: Unopened packages should be stored at ≤30°C and ≤90% RH. Opened packages or components should be stored at ≤30°C and ≤60% RH.

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 package material.

7. Packaging and Ordering Information

7.1 Tape and Reel Specifications

The LEDs are supplied on 8mm wide embossed carrier tape wound onto 7-inch (178mm) diameter reels. Standard reel quantity is 4000 pieces. A minimum packing quantity of 500 pieces is available for remainder orders. The packaging conforms to ANSI/EIA 481 specifications. The tape has a cover tape to seal the component pockets.

7.2 Part Number Interpretation

The part number LTW-C19BZDS2-NB contains coded information about the product family, color, and specific bin selections (likely for intensity and color). The exact decoding is proprietary, but it identifies this specific variant with a yellow lens/black cap and InGaN white chip.

8. Application Suggestions and Design Considerations

8.1 Typical Application Circuits

The most common drive method is a simple series resistor to limit current. The resistor value (R) is calculated as R = (Vsupply - VF) / IF, where VF is the forward voltage at the desired operating current (IF). For stable current over varying VF or supply voltage, a constant current driver (linear or switching) is recommended, especially for applications requiring consistent brightness.

8.2 Thermal Management

With a maximum power dissipation of 70mW, thermal design is important for reliability. Ensure the PCB has adequate copper area connected to the LED pads to act as a heat sink. Avoid operating at maximum current in high ambient temperatures without evaluating the resulting junction temperature.

8.3 Optical Design

The 80-degree viewing angle provides a wide, diffuse beam suitable for indicator lights and backlighting where even illumination over an area is needed. For more focused light, secondary optics (lenses) would be required.

9. Technical Comparison and Differentiation

This LED's key differentiators in its class are its combination of an InGaN white chip (typically offering higher efficiency and better color rendering than older phosphor-on-blue technologies in some aspects), its specific yellow lens/black cap package for aesthetic or optical filtering purposes, and its detailed binning structure for color and intensity consistency. The 70mW power rating and 20mA current capability are standard for small SMD LEDs, positioning it for general-purpose indicator use.

10. Frequently Asked Questions (Based on Technical Parameters)

Q: Can I drive this LED with 3.3V logic?
A: Yes. With a typical VF of 2.7V at 2mA, a simple series resistor can be used with a 3.3V supply. Calculate the resistor value based on your desired operating current.

Q: What is the difference between the Iv bins (L, M, N)?
A: They represent different guaranteed minimum light output levels. Bin N offers the highest intensity (28-45 mcd), while Bin L is the lowest (11-18 mcd). Select based on your application's brightness requirement.

Q: Is a reverse protection diode necessary?
A: While the LED can withstand a small reverse current (10 μA max at 5V), it is not designed for reverse operation. In circuits where reverse voltage is possible (e.g., AC coupling, inductive loads), an external protection diode in parallel with the LED (cathode to anode) is strongly recommended.

Q: How do I interpret the Hue Bin coordinates?
A: The S1, S2, S3, S5 bins define regions on the CIE color chart. LEDs within the same bin will have a visually similar white color. For applications where color matching between multiple LEDs is critical, specifying a tight hue bin is essential.

11. Practical Use Case Example

Scenario: Designing a status indicator for a consumer router.
The LED needs to indicate \"power on\" and \"network activity.\" A steady green light is often used for power, but this white LED could be used behind a colored diffuser or for a modern white-light aesthetic.
Design Steps:
1. Drive Circuit: Use the router's 3.3V rail. Target an operating current of 10mA for good visibility without excessive power draw. Assuming a VF of 2.8V (conservative estimate), calculate series resistor: R = (3.3V - 2.8V) / 0.01A = 50 Ohms. Use a standard 51-ohm resistor.
2. Thermal: Power dissipation: Pd = VF * IF = 2.8V * 0.01A = 28mW, well below the 70mW maximum.
3. PCB Layout: Follow the recommended pad layout from the datasheet. Add a small amount of copper pour around the pads for heat dissipation.
4. Component Selection: Order from Bin M or N for adequate brightness. Specify a consistent Hue Bin (e.g., S2) if multiple units are used across different router models to ensure color matching.

12. Operational Principle Introduction

This LED is based on a semiconductor chip made of InGaN (Indium Gallium Nitride). When a forward voltage is applied across the p-n junction of this material, electrons and holes recombine, releasing energy in the form of photons (light). The specific composition of the InGaN layers is engineered to emit light in the blue or near-ultraviolet spectrum. To create white light, this primary emission is combined with a phosphor coating inside the package. The phosphor absorbs some of the blue light and re-emits it at longer wavelengths (yellow, red), mixing with the remaining blue light to produce the perception of white. The yellow lens may further modify the spectral output or provide diffusion.

13. Technology Trends and Context

InGaN-based white LEDs represent a significant advancement in solid-state lighting. Key industry trends relevant to this component include:
Increased Efficiency: Ongoing materials science research aims to improve the internal quantum efficiency (IQE) of the chip and the conversion efficiency of the phosphor, leading to higher lumens per watt (lm/W).
Color Quality: Development of multi-phosphor blends and novel phosphor materials to improve the Color Rendering Index (CRI), making white light appear more natural.
Miniaturization: The drive for thinner and smaller consumer electronics continues to push for LEDs with ever-smaller footprints and lower profiles, like the \"super thin\" characteristic of this device.
Reliability and Lifetime: Improvements in packaging materials and thermal management are extending the operational lifetime of SMD LEDs, making them suitable for more demanding applications. The detailed storage and handling guidelines in this datasheet reflect the industry's focus on maintaining reliability through the supply chain.