LTW-C191DS5 SMD LED Datasheet - 0.55mm Height - 3.15V Max - 72mW Power - White Color - English Technical Document

1. Product Overview

The LTW-C191DS5 is a surface-mount device (SMD) light-emitting diode (LED) designed for modern, space-constrained electronic applications. Its primary defining characteristic is an exceptionally low profile, with a package height of only 0.55 millimeters. This super-thin form factor makes it ideal for integration into slim consumer electronics, backlighting units for displays, and indicator applications where vertical clearance is limited.

Utilizing an InGaN (Indium Gallium Nitride) semiconductor material, this LED emits white light. The package conforms to EIA (Electronic Industries Alliance) standard outlines, ensuring compatibility with industry-standard automated pick-and-place machinery and tape-and-reel packaging systems. The product is specified as a Green Product and is compliant with the RoHS (Restriction of Hazardous Substances) directive, meaning it is manufactured without the use of certain hazardous materials like lead, mercury, and cadmium.

The core advantages of this component include its miniaturized footprint, compatibility with high-volume automated assembly processes, and suitability for infrared (IR) reflow soldering, which is the standard soldering method used in surface-mount technology (SMT) assembly lines.

2. Technical Specifications Deep Dive

2.1 Absolute Maximum Ratings

These ratings define the stress limits beyond which permanent damage to the device may occur. Operation under or at these limits is not guaranteed and should be avoided in reliable design.

• Power Dissipation (Pd): 72 mW. This is the maximum amount of power the LED package can dissipate as heat without exceeding its maximum junction temperature.
• DC Forward Current (IF): 20 mA. The maximum continuous forward current that can be applied.
• Peak Forward Current: 100 mA, but only under pulsed conditions (1/10 duty cycle, 0.1ms pulse width). This allows for brief, high-intensity flashes.
• Reverse Voltage (VR): 5 V. Exceeding this voltage in reverse bias can cause immediate breakdown. The datasheet explicitly notes that reverse voltage operation cannot be continuous.
• Operating Temperature Range (Topr): -30°C to +85°C. The ambient temperature range over which the device is designed to function.
• Storage Temperature Range (Tstg): -55°C to +105°C.
• Infrared Soldering Condition: Withstands 260°C peak temperature for 10 seconds, aligning with typical lead-free reflow profiles.

2.2 Electrical & Optical Characteristics

These are the typical performance parameters measured at an ambient temperature (Ta) of 25°C. Design should be based on the minimum and maximum limits, not just typical values.

• Luminous Intensity (Iv): Ranges from a minimum of 71.0 mcd to a typical 180.0 mcd at a forward current (IF) of 5 mA. Intensity is measured using a sensor filtered to match the CIE photopic eye-response curve.
• Viewing Angle (2θ1/2): 130 degrees. This wide viewing angle indicates a Lambertian or near-Lambertian emission pattern, suitable for area illumination rather than focused beams.
• Chromaticity Coordinates (x, y): Typical values are x=0.304, y=0.301 at IF=5mA, placing the white point within a specific region of the CIE 1931 color space. A tolerance of ±0.01 applies to these coordinates.
• Forward Voltage (VF): Between 2.70 V (min) and 3.15 V (max) at IF=5mA. This range is critical for driver circuit design.
• Reverse Current (IR): Maximum of 10 µA when a reverse voltage (VR) of 5V is applied.

Electrostatic Discharge (ESD) Caution: The LED is sensitive to static electricity and voltage surges. Proper ESD controls, such as grounded workstations, wrist straps, and anti-static packaging, are mandatory during handling.

3. Binning System Explanation

Due to inherent variations in semiconductor manufacturing, LEDs are sorted into performance bins. The LTW-C191DS5 uses a three-dimensional binning system:

3.1 Forward Voltage (VF) Binning

LEDs are categorized based on their voltage drop at 5 mA.
- Bin A: 2.70V - 2.85V
- Bin B: 2.85V - 3.00V
- Bin C: 3.00V - 3.15V
Tolerance: ±0.1V per bin.

3.2 Luminous Intensity (Iv) Binning

LEDs are sorted by their light output at 5 mA.
- Bin Q: 71.0 mcd - 112.0 mcd
- Bin R: 112.0 mcd - 180.0 mcd
Tolerance: ±15% per bin.

3.3 Hue (Color) Binning

This is the most complex bin, defining the color coordinates on the CIE 1931 diagram. Six bins (S1 through S6) are defined by quadrilaterals specifying the (x,y) coordinate boundaries. The provided diagram visually maps these bins. The typical chromaticity point (x=0.304, y=0.301) falls within the S3/S4 region. Tolerance on hue is ±0.01 in both x and y coordinates.

This binning allows designers to select LEDs with tightly controlled electrical and optical properties for consistent performance in their application, especially important in multi-LED arrays where color and brightness uniformity are critical.

4. Mechanical and Packaging Information

4.1 Package Dimensions

The datasheet includes detailed dimensioned drawings of the LED package. Key features include the 0.55mm maximum height and the EIA-standard footprint for automated handling. All dimensions are in millimeters with a standard tolerance of ±0.10mm unless otherwise specified.

4.2 Suggested Soldering Pad Layout

A recommended land pattern (footprint) for the PCB is provided. Following this design is crucial for achieving reliable solder joints, preventing tombstoning (one end lifting), and ensuring proper alignment during reflow.

4.3 Tape and Reel Packaging

The LEDs are supplied in embossed carrier tape, sealed with a cover tape, and wound onto 7-inch (178mm) diameter reels. Standard reel quantity is 5,000 pieces. Packaging complies with ANSI/EIA 481-1-A-1994 standards. Key tape and reel dimensions are provided for feeder setup in assembly machines.

5. Assembly, Handling, and Reliability Guidelines

5.1 Soldering Process

The component is fully compatible with infrared reflow soldering processes. A suggested reflow profile is provided, with key parameters:
- Pre-heat: 150-200°C
- Pre-heat Time: Max 120 seconds
- Peak Temperature: Max 260°C
- Time above 260°C: Max 10 seconds
- Number of reflow cycles: Maximum two times.
The datasheet references JEDEC standards for profile development and emphasizes that the final profile must be characterized for the specific PCB design, components, and solder paste used.

For manual rework with a soldering iron, the tip temperature must not exceed 300°C, and contact time should be limited to 3 seconds, for one time only.

5.2 Cleaning

If cleaning after soldering is necessary, 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. The use of unspecified chemicals can damage the LED package.

5.3 Storage and Moisture Sensitivity

LEDs are moisture-sensitive devices. Strict storage conditions are outlined:
- Sealed Bag: Store at ≤30°C and ≤90% RH. Use within one year of bag opening.
- After Bag Opening: Store at ≤30°C and ≤60% RH. It is recommended to complete IR reflow within 672 hours (28 days).
- Extended Storage (Opened): Store in a sealed container with desiccant or in a nitrogen desiccator.
- Exposure >672 hours: A bake-out at approximately 60°C for at least 20 hours is required before soldering to remove absorbed moisture and prevent \"popcorning\" (package cracking during reflow).

6. Application Notes and Design Considerations

6.1 Typical Applications

The LTW-C191DS5 is intended for ordinary electronic equipment, including:
- Status indicators on consumer electronics (phones, tablets, routers).
- Backlighting for LCD displays, keypads, or panels in slim devices.
- Decorative lighting in appliances.
- General purpose indicator lights.

Important Application Limitation: The datasheet explicitly states that this LED is not designed for applications where failure could jeopardize life or health (e.g., aviation, medical life-support, transportation safety systems). For such high-reliability applications, consultation for a specialized product is required.

6.2 Circuit Design

1. Current Limiting: An LED is a current-driven device. A series current-limiting resistor or a constant-current driver circuit is essential to prevent exceeding the maximum DC forward current (20 mA), even if the power supply voltage fluctuates. The design must account for the forward voltage bin (A, B, or C).
2. Reverse Voltage Protection: As the maximum reverse voltage is only 5V, care must be taken in circuit design to avoid exposing the LED to reverse bias, especially in AC or bipolar signal applications. A protection diode in parallel (cathode-to-cathode) may be necessary.
3. Thermal Management: While the power dissipation is low (72mW), ensuring adequate PCB copper area or thermal vias under the LED's thermal pad (if applicable) helps maintain lower junction temperature, which is critical for long-term luminous output stability and lifespan.

6.3 Optical Design

The wide 130-degree viewing angle provides a broad, diffuse light pattern. For applications requiring a more directed beam, secondary optics (lenses, light guides) would need to be designed and placed over the LED. The super-thin profile is advantageous when integrating into tight optical assemblies or behind thin light guide plates (LGPs).

7. Technical Comparison and Positioning

The LTW-C191DS5's primary differentiator is its 0.55mm height. Compared to standard 0603 or 0402 package LEDs which are typically 0.8-1.0mm tall, this represents a significant reduction in Z-height. This allows for thinner end products. Its InGaN technology provides a modern, efficient white light source compared to older technologies. The comprehensive binning structure offers better consistency for quality-sensitive applications than unbinned or broadly binned LEDs. Its compatibility with standard SMT processes makes it a drop-in replacement for thicker LEDs in many designs, offering a straightforward path to product miniaturization.

8. Frequently Asked Questions (Based on Technical Parameters)

Q: Can I drive this LED at 20mA continuously?
A: Yes, 20mA is the maximum continuous DC forward current rating. For optimal longevity and to account for thermal effects, driving it at a lower current (e.g., 10-15 mA) is often recommended.

Q: What is the difference between the Iv bins Q and R?
A: Bin R LEDs have a higher minimum luminous intensity (112 mcd vs. 71 mcd) at the same 5mA test current. Selecting Bin R ensures brighter output but may come at a slightly higher cost.

Q: Why is the storage humidity so critical after opening the bag?
A: The LED package can absorb moisture from the air. During the high-temperature reflow soldering process, this trapped moisture rapidly turns to steam, potentially causing internal delamination or cracking of the plastic package (\"popcorning\"). The specified storage conditions and bake requirements prevent this failure mode.

Q: How do I interpret the Hue binning diagram?
A: The CIE 1931 diagram plots color. The six labeled quadrilaterals (S1-S6) represent the acceptable color coordinate regions for LEDs in that hue bin. An LED's measured (x,y) coordinates must fall within the polygon of its assigned bin. This ensures all LEDs labeled with the same hue bin will appear the same color to the human eye under standard conditions.

9. Design and Usage Case Study

Scenario: Designing a status indicator for a ultra-thin Bluetooth tracker.
The product's industrial design allows only 0.6mm of internal height for the indicator LED assembly. A standard LED would not fit.
Solution: The LTW-C191DS5, with its 0.55mm height, is selected. The designer uses the package dimensions to create a PCB cutout, allowing the LED to sit flush with the board, saving crucial tenths of a millimeter. A constant-current driver IC set to 5mA is used to ensure consistent brightness regardless of battery voltage drop. LEDs from Bin R and Hue Bin S3 are specified in the Bill of Materials to guarantee bright, uniform white light across all production units. The assembly house follows the recommended reflow profile and the 672-hour floor life rule, resulting in high manufacturing yield and reliable performance in the field.

10. Technology Introduction and Trends

InGaN Technology: Indium Gallium Nitride is the semiconductor material used in this white LED. Typically, a blue-emitting InGaN chip is combined with a yellow phosphor coating inside the package. The blue light excites the phosphor, which re-emits yellow light; the mix of blue and yellow is perceived by the human eye as white. This is a highly efficient method for producing white light from solid-state devices.

Industry Trends: The push for miniaturization in electronics continues unabated. Components like the LTW-C191DS5 represent the ongoing trend of reducing the Z-height (thickness) of passive and active components to enable ever-thinner smartphones, tablets, wearables, and IoT devices. Furthermore, the emphasis on precise binning reflects the market's demand for higher quality and visual consistency in consumer products. The integration of RoHS compliance and compatibility with lead-free, high-temperature reflow processes is now a baseline requirement, driven by global environmental regulations.