SMD LED LTW-C19DZDS5-NB Datasheet - InGaN White Chip - 10mA - 36mW - English Technical Document

1. Product Overview

The LTW-C19DZDS5-NB is a surface-mount device (SMD) LED lamp designed for modern electronic applications requiring miniaturization and high reliability. It belongs to a family of components specifically engineered for automated printed circuit board (PCB) assembly processes, making it ideal for high-volume manufacturing. Its compact form factor addresses the needs of space-constrained designs prevalent in contemporary portable and embedded electronics.

1.1 Core Advantages and Features

This LED offers several key advantages that contribute to its widespread applicability. It is fully compliant with the Restriction of Hazardous Substances (RoHS) directive, ensuring it meets international environmental standards. The device utilizes an ultra-bright Indium Gallium Nitride (InGaN) semiconductor material to produce white light, offering high luminous efficiency. Its package is compatible with industry-standard EIA outlines, facilitating easy integration into existing design libraries and assembly lines. Furthermore, it is designed to be compatible with infrared (IR) reflow soldering processes, which is the standard for surface-mount technology assembly. The components are supplied on 8mm tape mounted on 7-inch diameter reels, which is the standard packaging for automated pick-and-place equipment.

1.2 Target Market and Applications

The versatility of this SMD LED makes it suitable for a broad spectrum of electronic equipment. Primary application areas include telecommunications devices such as cordless and cellular phones, computing platforms like notebook computers, and network infrastructure systems. It is also commonly used in various home appliances and consumer electronics for status indication and backlighting purposes. Specific functional uses encompass keyboard or keypad backlighting, status and power indicators, illumination for micro-displays, and general signal or symbol luminaires in indoor settings.

2. Package Dimensions and Mechanical Specifications

The LED features a yellow lens with a black cap. Precise mechanical dimensions are provided in the original datasheet drawings, with all measurements specified in millimeters. The standard tolerance for these dimensions is ±0.1 mm unless otherwise noted on the drawing. This level of precision ensures consistent placement and soldering during automated assembly. The package is designed to be a super-thin chip LED, contributing to the low profile of final products.

3. Technical Parameters: In-Depth Objective Interpretation

All ratings and characteristics are specified at an ambient temperature (Ta) of 25°C, which is the standard reference condition for semiconductor device testing.

3.1 Absolute Maximum Ratings

These ratings define the stress limits beyond which permanent damage to the device may occur. They are not intended for continuous operation. The absolute maximum ratings for the LTW-C19DZDS5-NB are as follows: The maximum power dissipation is 36 milliwatts (mW). The peak forward current, when pulsed with a 1/10 duty cycle and a 0.1ms pulse width, must not exceed 50 mA. The maximum continuous DC forward current is 10 mA. The device can withstand an electrostatic discharge (ESD) threshold of 2000 Volts using the Human Body Model (HBM). The allowable operating temperature range is from -20°C to +80°C, while the storage temperature range is wider, from -40°C to +85°C. The component can endure an infrared soldering condition with a peak temperature of 260°C for a maximum of 10 seconds.

3.2 Suggested IR Reflow Profile for Lead-Free Process

A recommended reflow soldering profile is provided to ensure reliable solder joints without damaging the LED. The profile typically includes a pre-heat stage, a thermal soak, a reflow zone with a controlled peak temperature, and a cooling period. Adherence to this profile, particularly the maximum peak temperature of 260°C and time above liquidus, is critical for maintaining device integrity and long-term reliability.

3.3 Electrical and Optical Characteristics

These parameters define the typical performance of the LED under normal operating conditions. The luminous intensity (Iv) ranges from a minimum of 18.0 millicandelas (mcd) to a maximum of 45.0 mcd when driven at a forward current (IF) of 5 mA. The viewing angle (2θ1/2), defined as the angle where intensity drops to half of its peak value, is 50 degrees. The chromaticity coordinates on the CIE 1931 diagram are typically x=0.270 and y=0.260 at 5mA. The forward voltage (VF) ranges from 2.40V (min) to 3.20V (max), with a typical value of 2.70V at IF=5mA. The reverse current (IR) is specified at a maximum of 10 microamperes (µA) when a reverse voltage (VR) of 5V is applied. It is important to note that this reverse voltage condition is for testing purposes only; the LED is not designed for operation in reverse bias.

4. Bin Rank System Explanation

To ensure consistency in production, LEDs are sorted into performance bins based on key parameters. This allows designers to select components that meet specific requirements for their application.

4.1 Forward Voltage (VF) Rank

LEDs are binned according to their forward voltage drop at a test current of 5mA. The bin codes and their corresponding voltage ranges are: A10 (2.40V - 2.60V), A11 (2.60V - 2.80V), B10 (2.80V - 3.00V), and B11 (3.00V - 3.20V). A tolerance of ±0.1V is applied to each bin.

4.2 Luminous Intensity (IV) Rank

Components are classified based on their light output at 5mA. The defined bins are: M (18.0 mcd - 28.0 mcd) and N (28.0 mcd - 45.0 mcd). A tolerance of ±15% is applicable to each luminous intensity bin.

4.3 Hue (Chromaticity) Rank

The color point, defined by CIE 1931 (x, y) coordinates, is also binned to control color consistency. The datasheet defines several hue bins (e.g., C01, C1, C2) with specific coordinate boundaries that form quadrilaterals on the chromaticity diagram. A tolerance of ±0.01 is applied to each coordinate within a bin.

5. Performance Curve Analysis

The original datasheet includes typical characteristic curves that provide valuable insight into device behavior under varying conditions. These curves typically illustrate the relationship between forward voltage and forward current (IV curve), showing the exponential nature of the diode. They may also depict the variation of luminous intensity with forward current, and the dependence of forward voltage on ambient temperature. Analyzing these curves helps designers understand trade-offs; for example, driving the LED at a higher current increases light output but also increases power dissipation and junction temperature, which can affect longevity and color shift.

6. Mechanical, Assembly, and Handling Guidelines

6.1 Recommended PCB Attachment Pad Layout

A suggested land pattern (footprint) for the PCB is provided to ensure proper solder fillet formation and mechanical stability. Following this recommendation is crucial for achieving reliable solder joints during reflow.

6.2 Cleaning

If cleaning after soldering is necessary, only specified chemicals should be used. The datasheet recommends immersion in ethyl alcohol or isopropyl alcohol at normal temperature for less than one minute. The use of unspecified chemical liquids can damage the LED package.

6.3 Storage Conditions

Proper storage is essential to prevent moisture absorption, which can cause \"popcorning\" (package cracking) during reflow soldering. When the moisture-proof barrier bag is sealed, LEDs should be stored at ≤ 30°C and ≤ 90% Relative Humidity (RH), with a recommended use-within period of one year. Once the original packaging is opened, the storage environment should not exceed 30°C or 60% RH. For components removed from their original packaging (Moisture Sensitivity Level 3, MSL 3), it is recommended to complete IR reflow within one week. For longer storage outside the original bag, they should be kept in a sealed container with desiccant. If stored for more than a week, a bake-out at approximately 60°C for at least 20 hours is required before soldering.

6.4 Soldering Instructions

For reflow soldering, a profile with a pre-heat temperature of 150-200°C, a pre-heat time up to 120 seconds, a peak temperature not exceeding 260°C, and a time at peak of up to 10 seconds (maximum two reflow cycles) is recommended. For hand soldering with an iron, the tip temperature should not exceed 300°C, and contact time should be limited to 3 seconds maximum (one time only).

7. Packaging and Ordering Information

The standard packaging consists of LEDs placed in 8mm wide embossed carrier tape. This tape is wound onto a standard 7-inch (178mm) diameter reel. Each full reel contains 4000 pieces. For quantities less than a full reel, a minimum packing quantity of 500 pieces applies for remainder lots. The packaging follows ANSI/EIA 481 specifications. The tape uses a cover tape to seal empty component pockets, and the maximum allowed number of consecutive missing lamps on a reel is two.

8. Application Suggestions and Design Considerations

8.1 Typical Application Circuits

In a typical application, the LED is driven by a constant current source or through a current-limiting resistor connected in series with a voltage supply. The value of the current-limiting resistor (R) can be calculated using Ohm's Law: R = (V_supply - VF_LED) / IF, where VF_LED is the forward voltage of the LED at the desired current IF. Using the maximum VF from the datasheet in this calculation ensures the current does not exceed the limit even with part-to-part variation.

8.2 Design Considerations

Current Driving: Operating the LED at or below the recommended 10mA DC forward current is crucial for reliability. Exceeding the absolute maximum ratings, even briefly, can degrade the semiconductor material and reduce lifespan. Thermal Management: While the power dissipation is low, ensuring adequate PCB copper area around the solder pads can help dissipate heat, especially in high ambient temperature environments or when multiple LEDs are placed closely. ESD Protection: Although the device has a 2000V HBM ESD rating, standard ESD handling precautions (wrist straps, grounded workstations) should always be followed during assembly and handling to prevent latent damage. Optical Design: The 50-degree viewing angle defines the beam pattern. For applications requiring a different radiation pattern, secondary optics (lenses, light guides) may be necessary.

9. Technical Comparison and Differentiation

The LTW-C19DZDS5-NB differentiates itself through its use of InGaN technology for white light, which typically offers higher efficiency and better color rendering compared to older technologies like blue chip with yellow phosphor (though still a phosphor-converted white). Its super-thin package profile is a key advantage for ultra-slim devices. The comprehensive binning system for voltage, intensity, and chromaticity provides designers with tight control over the consistency of their end product's electrical and optical performance, which is critical in applications like backlighting arrays where uniformity is important.

10. Frequently Asked Questions Based on Technical Parameters

Q: Can I drive this LED at 20mA for higher brightness?
A: No. The absolute maximum continuous DC forward current is 10 mA. Exceeding this rating risks permanent damage and voiding any reliability specifications. For higher light output, select an LED bin with higher luminous intensity or a product rated for a higher current.

Q: The forward voltage in my circuit measures 2.5V, but the datasheet says typical is 2.7V. Is this normal?
A: Yes, this is within the expected variation. The forward voltage has a specified range (2.4V to 3.2V) and is also binned. Your measured value falls into the A10 or A11 voltage bin. Always design your current-limiting circuit for the worst-case maximum VF to ensure the current limit is never exceeded.

Q: Do I need to worry about moisture sensitivity for this component?
A: Yes. The component is rated MSL 3. Once the original sealed bag is opened, you have one week to complete the reflow soldering process under standard factory floor conditions (≤ 30°C/60% RH). If this timeline is exceeded, a bake-out is required before soldering.

Q: Can I use this LED for outdoor signage?
A: The datasheet specifies applications including \"indoor signboard applications.\" The operating temperature range is -20°C to +80°C. For outdoor use, you must ensure the environmental conditions (temperature, humidity, UV exposure) do not exceed these limits and that the assembly is properly sealed against moisture ingress, which is not covered by this component's datasheet.

11. Practical Use Case Example

Scenario: Designing a status indicator for a portable medical device. The device has a 3.3V power rail and requires a clear, bright white indicator. The design calls for a single LED driven at approximately 5mA to balance visibility with power consumption. Design Steps: 1. Select the LTW-C19DZDS5-NB for its brightness, small size, and reliability. 2. Calculate the current-limiting resistor: Using the maximum VF of 3.2V, R = (3.3V - 3.2V) / 0.005A = 20 Ohms. A standard 20-ohm resistor would be used. 3. In the PCB layout, use the recommended land pattern from the datasheet. 4. Specify components from the N luminous intensity bin and a specific hue bin (e.g., C1) to ensure consistent color and brightness across all production units. 5. In the assembly instructions, emphasize MSL 3 handling and the one-week floor life after bag opening.

12. Operating Principle Introduction

Light Emitting Diodes (LEDs) are semiconductor devices that emit light through electroluminescence. When a forward voltage is applied across the p-n junction, electrons and holes recombine in the active region (typically made of InGaN for blue/white LEDs). This recombination releases energy in the form of photons (light). The wavelength (color) of the emitted light is determined by the bandgap energy of the semiconductor material. A white LED, like the LTW-C19DZDS5-NB, typically uses a blue InGaN chip coated 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.

13. Technology Trends

The field of SMD LEDs continues to evolve towards higher efficiency (more lumens per watt), improved color rendering index (CRI) for better light quality, and increased power density in smaller packages. There is also a trend towards tighter binning tolerances for both color and flux to meet the demands of applications like high-end display backlighting and architectural lighting where uniformity is critical. Furthermore, advancements in packaging materials and designs aim to improve thermal performance, allowing for higher drive currents and longer operational lifetimes. The integration of control electronics (e.g., constant current drivers, addressability) directly into the LED package is another significant trend, simplifying system design for smart lighting applications.