1. Product Overview
This document provides the complete technical specifications for the LTST-C061VEKT, a surface-mount device (SMD) light-emitting diode (LED). This component is designed for automated printed circuit board (PCB) assembly processes and is suitable for space-constrained applications across a broad spectrum of electronic equipment.
1.1 Features
- Compliant with RoHS (Restriction of Hazardous Substances) directives.
- Packaged in 8mm tape on 7-inch diameter reels for automated handling.
- Standard EIA (Electronic Industries Alliance) package footprint.
- Input logic levels are compatible with integrated circuit (IC) outputs.
- Designed for compatibility with automated pick-and-place equipment.
- Suitable for infrared (IR) reflow soldering processes.
- Preconditioned to accelerate to JEDEC (Joint Electron Device Engineering Council) moisture sensitivity Level 3.
1.2 Applications
This LED is intended for use as a status indicator, signal luminary, or for front-panel backlighting in various sectors including telecommunications, office automation, home appliances, and industrial equipment.
2. Package Dimensions and Mechanical Information
The device features a water-clear lens with an AlInGaP (Aluminum Indium Gallium Phosphide) red light source. All dimensional drawings and tolerances are provided in the datasheet, with a standard tolerance of ±0.2mm unless otherwise specified. The package is designed for reliable surface mounting.
3. Ratings and Characteristics
3.1 Absolute Maximum Ratings
Ratings are specified at an ambient temperature (Ta) of 25°C. Exceeding these values may cause permanent damage.
- Power Dissipation (Pd): 203 mW
- Peak Forward Current (IF(PEAK)): 100 mA (pulsed, 50ms ON, 950ms OFF, Duty Cycle=0.05)
- DC Forward Current (IF): 70 mA
- Operating Temperature Range (Topr): -40°C to +85°C
- Storage Temperature Range (Tstg): -40°C to +100°C
3.2 Electrical and Optical Characteristics
Key performance parameters are measured at Ta=25°C and IF=70mA, unless stated otherwise.
- Luminous Intensity (IV): 1550 - 3600 mcd (millicandela). Measured with a filter approximating the CIE photopic eye response.
- Viewing Angle (2θ1/2): 120 degrees (typical). Defined as the full angle where intensity drops to half its axial value.
- Peak Emission Wavelength (λP): 631 nm (typical).
- Dominant Wavelength (λd): 617 - 630 nm. Tolerance is ±1nm.
- Spectral Line Half-Width (Δλ): 15 nm (typical).
- Forward Voltage (VF): 1.9 - 2.9 V. Tolerance is ±0.1V.
- Reverse Current (IR): 10 μA (maximum) at VR=5V. The device is not designed for reverse bias operation.
4. Bin Code and Sorting System
The devices are sorted (binned) based on luminous intensity measured at 70mA. This ensures consistency in brightness for production applications.
4.1 Luminous Intensity (IV) Rank
- Bin Code J1: 1550 - 2050 mcd (Luminous Flux: 5.2 - 6.8 lm)
- Bin Code J2: 2050 - 2720 mcd (Luminous Flux: 6.8 - 9.0 lm)
- Bin Code K1: 2720 - 3600 mcd (Luminous Flux: 9.0 - 12.0 lm)
Tolerance on each luminous intensity bin is ±10%. The luminous flux values in lumens (lm) are provided for reference.
5. Typical Performance Curves
The datasheet includes graphical representations of key relationships, which are essential for circuit design and thermal management.
- Forward Current vs. Forward Voltage (IF-VF Characteristic)
- Luminous Intensity vs. Forward Current (IV-IF Characteristic)
- Luminous Intensity vs. Ambient Temperature (IV-Ta Characteristic)
- Relative Spectral Power Distribution (Wavelength vs. Relative Intensity)
- Viewing Angle Characteristic (Angular Intensity Distribution)
These curves allow designers to predict performance under different operating conditions, such as derating luminous output at higher temperatures or calculating the necessary current-limiting resistor value.
6. Assembly and Handling Guidelines
6.1 Cleaning
If cleaning is required after soldering, only use specified solvents. Immerse the LED in ethyl alcohol or isopropyl alcohol at normal temperature for less than one minute. Unspecified chemicals may damage the package material.
6.2 Recommended PCB Land Pattern
A suggested printed circuit board (PCB) attachment pad layout is provided for infrared or vapor phase reflow soldering. A maximum stencil thickness of 0.10mm is recommended for solder paste application to ensure proper solder joint formation and avoid bridging.
6.3 Tape and Reel Packaging
The LEDs are supplied in embossed carrier tape on 7-inch (178mm) diameter reels. The tape width is 8mm. Detailed mechanical drawings of the tape pockets, cover tape, and reel dimensions are included, conforming to EIA-481 specifications. The standard reel contains 4000 pieces, with a minimum order quantity of 500 pieces for remnants.
7. Important Cautions and Application Notes
7.1 Intended Use and Reliability
This LED is designed for use in ordinary electronic equipment. It is not intended for applications where failure could directly jeopardize life or health, such as in aviation, medical life-support, or critical safety systems. For such applications, consultation with the manufacturer is required prior to design-in.
7.2 Storage Conditions
Sealed Package: Store at ≤30°C and ≤70% Relative Humidity (RH). The shelf life is one year when the moisture-proof bag with desiccant is intact.
Opened Package: Storage ambient must not exceed 30°C and 60% RH. Components removed from their original packaging should be subjected to IR reflow soldering within 168 hours (7 days). For storage beyond this period, they must be stored in a sealed container with desiccant or in a nitrogen ambient. LEDs stored out of packaging for more than 168 hours require baking at approximately 60°C for at least 48 hours before assembly to remove absorbed moisture and prevent \"popcorning\" during reflow.
7.3 Soldering Process
Reflow Soldering: A lead-free soldering profile compliant with J-STD-020B is recommended. Key parameters include a pre-heat zone (150-200°C, max 120 sec), a peak temperature not exceeding 260°C, and a time above liquidus (TAL) of 10 seconds maximum. Reflow should be performed a maximum of two times.
Hand Soldering: If necessary, use a soldering iron with a tip temperature not exceeding 300°C for a maximum of 3 seconds, and only once. The provided temperature profile is a guideline; the final profile must be characterized for the specific PCB design, components, and solder paste used.
8. Technical Deep Dive and Design Considerations
8.1 Photometric and Colorimetric Analysis
The use of AlInGaP technology results in a high-efficiency red LED with a dominant wavelength in the 617-630nm range, producing a saturated red color. The 120-degree viewing angle provides a wide emission pattern suitable for status indicators. Designers must consider the binning structure to ensure consistent brightness across multiple units in an array or product line.
8.2 Electrical Design and Thermal Management
With a maximum forward voltage of 2.9V at 70mA, a series current-limiting resistor is mandatory. The resistor value (R) can be calculated using Ohm's Law: R = (Vsupply - VF) / IF. The power dissipation of the LED itself (Pd = VF * IF) must not exceed the absolute maximum rating of 203mW, considering the derating that occurs at higher ambient temperatures, as shown in the IV-Ta curve. Adequate PCB copper area may be needed for heat sinking in high-current or high-temperature environments.
8.3 Assembly Process Compatibility
The JEDEC Level 3 moisture sensitivity and compatibility with IR reflow are critical for modern, high-volume manufacturing. Designers must follow the storage and baking guidelines meticulously to prevent moisture-induced package cracking during the high-temperature reflow process. The recommended land pattern and stencil specifications are optimized to achieve reliable solder joints while minimizing the risk of tombstoning or solder bridging.
9. Application Suggestions and Typical Use Cases
Beyond simple status indicators, this LED's brightness and viewing angle make it suitable for backlighting small symbols on front panels or providing illumination in low-light conditions for sensors. Its small form factor is ideal for portable devices like communication equipment and computing peripherals. When used in arrays, attention must be paid to current distribution and thermal coupling between adjacent LEDs.
10. Frequently Asked Questions (Based on Technical Parameters)
Q: What is the difference between peak wavelength and dominant wavelength?
A: Peak wavelength (λP) is the wavelength at which the emitted optical power is maximum. Dominant wavelength (λd) is the single wavelength of monochromatic light that matches the perceived color of the LED. λd is more relevant for color specification.
Q: Can I drive this LED with a 5V supply without a resistor?
A: No. Connecting it directly to 5V would force a current far exceeding its maximum rating, causing immediate and catastrophic failure. A current-limiting resistor or constant-current driver is always required.
Q: Why is the storage condition after opening the bag so strict?
A>SMD LED packages can absorb moisture from the air. During the high-temperature reflow soldering process, this trapped moisture rapidly turns to steam, creating internal pressure that can delaminate the package or crack the die. The 168-hour floor life and baking procedures are standardized methods to prevent this failure mode.
LED Specification Terminology
Complete explanation of LED technical terms
Photoelectric Performance
| Term | Unit/Representation | Simple Explanation | Why Important |
|---|---|---|---|
| Luminous Efficacy | lm/W (lumens per watt) | Light output per watt of electricity, higher means more energy efficient. | Directly determines energy efficiency grade and electricity cost. |
| Luminous Flux | lm (lumens) | Total light emitted by source, commonly called "brightness". | Determines if the light is bright enough. |
| Viewing Angle | ° (degrees), e.g., 120° | Angle where light intensity drops to half, determines beam width. | Affects illumination range and uniformity. |
| CCT (Color Temperature) | K (Kelvin), e.g., 2700K/6500K | Warmth/coolness of light, lower values yellowish/warm, higher whitish/cool. | Determines lighting atmosphere and suitable scenarios. |
| CRI / Ra | Unitless, 0–100 | Ability to render object colors accurately, Ra≥80 is good. | Affects color authenticity, used in high-demand places like malls, museums. |
| SDCM | MacAdam ellipse steps, e.g., "5-step" | Color consistency metric, smaller steps mean more consistent color. | Ensures uniform color across same batch of LEDs. |
| Dominant Wavelength | nm (nanometers), e.g., 620nm (red) | Wavelength corresponding to color of colored LEDs. | Determines hue of red, yellow, green monochrome LEDs. |
| Spectral Distribution | Wavelength vs intensity curve | Shows intensity distribution across wavelengths. | Affects color rendering and quality. |
Electrical Parameters
| Term | Symbol | Simple Explanation | Design Considerations |
|---|---|---|---|
| Forward Voltage | Vf | Minimum voltage to turn on LED, like "starting threshold". | Driver voltage must be ≥Vf, voltages add up for series LEDs. |
| Forward Current | If | Current value for normal LED operation. | Usually constant current drive, current determines brightness & lifespan. |
| Max Pulse Current | Ifp | Peak current tolerable for short periods, used for dimming or flashing. | Pulse width & duty cycle must be strictly controlled to avoid damage. |
| Reverse Voltage | Vr | Max reverse voltage LED can withstand, beyond may cause breakdown. | Circuit must prevent reverse connection or voltage spikes. |
| Thermal Resistance | Rth (°C/W) | Resistance to heat transfer from chip to solder, lower is better. | High thermal resistance requires stronger heat dissipation. |
| ESD Immunity | V (HBM), e.g., 1000V | Ability to withstand electrostatic discharge, higher means less vulnerable. | Anti-static measures needed in production, especially for sensitive LEDs. |
Thermal Management & Reliability
| Term | Key Metric | Simple Explanation | Impact |
|---|---|---|---|
| Junction Temperature | Tj (°C) | Actual operating temperature inside LED chip. | Every 10°C reduction may double lifespan; too high causes light decay, color shift. |
| Lumen Depreciation | L70 / L80 (hours) | Time for brightness to drop to 70% or 80% of initial. | Directly defines LED "service life". |
| Lumen Maintenance | % (e.g., 70%) | Percentage of brightness retained after time. | Indicates brightness retention over long-term use. |
| Color Shift | Δu′v′ or MacAdam ellipse | Degree of color change during use. | Affects color consistency in lighting scenes. |
| Thermal Aging | Material degradation | Deterioration due to long-term high temperature. | May cause brightness drop, color change, or open-circuit failure. |
Packaging & Materials
| Term | Common Types | Simple Explanation | Features & Applications |
|---|---|---|---|
| Package Type | EMC, PPA, Ceramic | Housing material protecting chip, providing optical/thermal interface. | EMC: good heat resistance, low cost; Ceramic: better heat dissipation, longer life. |
| Chip Structure | Front, Flip Chip | Chip electrode arrangement. | Flip chip: better heat dissipation, higher efficacy, for high-power. |
| Phosphor Coating | YAG, Silicate, Nitride | Covers blue chip, converts some to yellow/red, mixes to white. | Different phosphors affect efficacy, CCT, and CRI. |
| Lens/Optics | Flat, Microlens, TIR | Optical structure on surface controlling light distribution. | Determines viewing angle and light distribution curve. |
Quality Control & Binning
| Term | Binning Content | Simple Explanation | Purpose |
|---|---|---|---|
| Luminous Flux Bin | Code e.g., 2G, 2H | Grouped by brightness, each group has min/max lumen values. | Ensures uniform brightness in same batch. |
| Voltage Bin | Code e.g., 6W, 6X | Grouped by forward voltage range. | Facilitates driver matching, improves system efficiency. |
| Color Bin | 5-step MacAdam ellipse | Grouped by color coordinates, ensuring tight range. | Guarantees color consistency, avoids uneven color within fixture. |
| CCT Bin | 2700K, 3000K etc. | Grouped by CCT, each has corresponding coordinate range. | Meets different scene CCT requirements. |
Testing & Certification
| Term | Standard/Test | Simple Explanation | Significance |
|---|---|---|---|
| LM-80 | Lumen maintenance test | Long-term lighting at constant temperature, recording brightness decay. | Used to estimate LED life (with TM-21). |
| TM-21 | Life estimation standard | Estimates life under actual conditions based on LM-80 data. | Provides scientific life prediction. |
| IESNA | Illuminating Engineering Society | Covers optical, electrical, thermal test methods. | Industry-recognized test basis. |
| RoHS / REACH | Environmental certification | Ensures no harmful substances (lead, mercury). | Market access requirement internationally. |
| ENERGY STAR / DLC | Energy efficiency certification | Energy efficiency and performance certification for lighting. | Used in government procurement, subsidy programs, enhances competitiveness. |