SMD LED LTST-010VEKT Datasheet - AlInGaP Red - 30mA - 75mW - English Technical Document

1. Product Overview

The LTST-010VEKT is a surface-mount device (SMD) light-emitting diode (LED) designed for automated printed circuit board (PCB) assembly. It utilizes an Aluminum Indium Gallium Phosphide (AlInGaP) semiconductor material to produce red light. Its miniature size makes it suitable for space-constrained applications across various electronic equipment sectors.

1.1 Core Advantages

• Miniature Footprint: The compact EIA standard package allows for high-density PCB layouts.
• Automation Compatibility: Packaged in 12mm tape on 7-inch reels, it is fully compatible with automated pick-and-place and surface-mount technology (SMT) assembly lines.
• Robust Process Compatibility: Designed to withstand standard infrared (IR) reflow soldering profiles used in lead-free (Pb-free) manufacturing processes.
• Environmental Compliance: The product meets RoHS (Restriction of Hazardous Substances) directives.
• Reliability: Components are preconditioned to JEDEC Moisture Sensitivity Level 3, ensuring reliability during the soldering process.

1.2 Target Markets and Applications

This LED is intended for a broad range of consumer, industrial, and communication electronics where reliable status indication or low-level illumination is required.

• Telecommunication Equipment: Status indicators in routers, modems, and network switches.
• Office Automation: Panel indicators in printers, scanners, and copiers.
• Consumer Appliances: Power-on/standby indicators in televisions, audio systems, and home appliances.
• Industrial Control Panels: Signal and fault indication.
• Front Panel Backlighting: Illumination for buttons and symbols.
• Indoor Signage and Symbol Luminaires.

2. In-Depth Technical Parameter Analysis

2.1 Absolute Maximum Ratings

These ratings define the limits beyond which permanent damage to the device may occur. Operation under these conditions is not guaranteed.

• Power Dissipation (Pd): 75 mW. This is the maximum amount of power the LED package can dissipate as heat at an ambient temperature (Ta) of 25°C.
• DC Forward Current (IF): 30 mA. The maximum continuous current that can be applied.
• Peak Forward Current: 80 mA. This is permissible only under pulsed conditions (1/10 duty cycle, 0.1ms pulse width) to briefly achieve higher light output.
• Reverse Voltage (VR): 5 V. Exceeding this voltage in reverse bias can cause immediate junction breakdown.
• Operating Temperature Range: -40°C to +85°C. The ambient temperature range for reliable operation.
• Storage Temperature Range: -40°C to +100°C.

2.2 Electro-Optical Characteristics

These parameters are measured at a standard test condition of Ta=25°C and IF=20mA, unless otherwise specified.

• Luminous Intensity (Iv): Ranges from 560 mcd (min) to 1120 mcd (max), with a typical value within this range. Measured using a sensor filtered to the CIE photopic eye-response curve.
• Viewing Angle (2θ½): 115 degrees (typical). This wide viewing angle indicates the light intensity is half of its peak value at ±57.5 degrees from the central axis, suitable for applications requiring wide visibility.
• Peak Emission Wavelength (λp): 639 nm (typical). The wavelength at which the spectral power output is maximum.
• Dominant Wavelength (λd): Between 617 nm and 633 nm. This is the single wavelength perceived by the human eye, defining the \"red\" color. Tolerance is ± 1nm within its bin.
• Spectral Line Half-Width (Δλ): 20 nm (typical). The spectral bandwidth where emission is at least half of the peak intensity, indicating color purity.
• Forward Voltage (VF): Between 1.6 V (min) and 2.5 V (max) at 20mA. The voltage drop across the LED when operating.
• Reverse Current (IR): 10 µA (max) when a reverse voltage of 5V is applied. This parameter is primarily for quality testing; the device is not designed for reverse operation.

3. Bin Ranking System

The LEDs are sorted into performance bins to ensure consistency in application. Designers can select bins to meet specific design requirements for brightness, voltage, or color.

3.1 Luminous Intensity (Iv) Rank

Binning ensures a minimum brightness level. Tolerance within each bin is ±11%.

• U2: 560 mcd (Min) to 710 mcd (Max)
• V1: 710 mcd (Min) to 900 mcd (Max)
• V2: 900 mcd (Min) to 1120 mcd (Max)

3.2 Forward Voltage (VF) Rank

Binning helps in designing consistent current drive circuits. Tolerance within each bin is ± 0.1V.

• G1: 1.60 V (Min) to 1.90 V (Max)
• G2: 1.90 V (Min) to 2.20 V (Max)
• G3: 2.20 V (Min) to 2.50 V (Max)

3.3 Dominant Wavelength (WD) Rank

Critical for color-critical applications. Tolerance within each bin is ± 1nm.

• R1: 617.0 nm (Min) to 621.0 nm (Max)
• R2: 621.0 nm (Min) to 625.0 nm (Max)
• R3: 625.0 nm (Min) to 629.0 nm (Max)
• R4: 629.0 nm (Min) to 633.0 nm (Max)

4. Performance Curve Analysis

While specific graphs are referenced in the datasheet, typical curves for this type of LED provide crucial design insights.

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

The I-V curve is exponential. A small increase in voltage beyond the turn-on threshold causes a large increase in current. This underscores the importance of driving LEDs with a constant current source, not a constant voltage, to prevent thermal runaway and ensure stable light output.

4.2 Luminous Intensity vs. Forward Current

Light output is approximately proportional to forward current within the rated range. Operating above the absolute maximum DC current can lead to accelerated lumen depreciation and reduced lifespan.

4.3 Luminous Intensity vs. Ambient Temperature

Luminous intensity decreases as the junction temperature increases. For AlInGaP LEDs, the light output can drop significantly at high temperatures. Effective thermal management on the PCB is essential to maintain performance in high-temperature environments.

4.4 Spectral Distribution

The emission spectrum is centered around 639 nm (peak) with a typical half-width of 20 nm, defining its saturated red color. The dominant wavelength bin determines the precise hue.

5. Mechanical and Package Information

5.1 Package Dimensions

The LED comes in a standard surface-mount package. Key dimensional notes include:

• All dimensions are in millimeters.
• Standard tolerance is ±0.1 mm unless otherwise specified.
• The lens color is water clear, while the light source color is AlInGaP red.

5.2 Polarity Identification and Recommended PCB Pad Layout

The datasheet includes a recommended land pattern for infrared or vapor phase reflow soldering. Following this pattern ensures proper solder joint formation and alignment. The cathode is typically marked on the device or indicated in the footprint diagram. Correct polarity is essential for operation.

6. Soldering and Assembly Guidelines

6.1 IR Reflow Soldering Profile

A suggested lead-free reflow profile compliant with J-STD-020B is provided. Key parameters include:

• Pre-heat: 150°C to 200°C.
• Pre-heat Time: Maximum 120 seconds.
• Peak Temperature: Maximum 260°C.
• Time Above Liquidus: Should be controlled according to solder paste specifications.
• Total Soldering Time: Maximum 10 seconds at peak temperature, with a maximum of two reflow cycles recommended.

Note: The optimal profile depends on the specific PCB assembly. The provided profile is a guideline that must be characterized for the actual production setup.

6.2 Hand Soldering (If Necessary)

• Iron Temperature: Maximum 300°C.
• Soldering Time: Maximum 3 seconds per pad.
• Frequency: One time only. Avoid repeated heating.

6.3 Cleaning

If cleaning is required after soldering, use only specified solvents to avoid damaging the plastic package. Immersion in ethyl alcohol or isopropyl alcohol at room temperature for less than one minute is acceptable. Do not use ultrasonic cleaning unless verified for compatibility.

7. Storage and Handling Cautions

7.1 Moisture Sensitivity

The device is rated at Moisture Sensitivity Level (MSL) 3.

• Sealed Package: Store at ≤ 30°C and ≤ 70% RH. Use within one year of the pack date.
• Opened Package: If the moisture barrier bag is opened, the components must be stored at ≤ 30°C and ≤ 60% RH.
• Floor Life: Components exposed to ambient factory conditions should be soldered within 168 hours (7 days).
• Extended Storage/Baking: If exposed for more than 168 hours, a bake at 60°C for at least 48 hours is required before reflow to remove absorbed moisture and prevent \"popcorning\" damage during soldering.

7.2 Application Limits

This component is designed for standard commercial and industrial electronic equipment. It is not qualified for safety-critical applications where failure could risk life or health (e.g., aviation, medical life-support, transportation control) without prior consultation and specific qualification.

8. Packaging and Ordering Information

8.1 Standard Packaging

• Tape: 12mm wide embossed carrier tape.
• Reel: 7-inch (178mm) diameter reel.
• Quantity per Reel: 4000 pieces.
• Minimum Order Quantity (MOQ): 500 pieces for remainder quantities.
• Packaging Standard: Compliant with ANSI/EIA-481 specifications.

9. Application Design Considerations

9.1 Drive Method

LEDs are current-driven devices. The most reliable method is to use a constant current source or a current-limiting resistor in series with a voltage source.

Calculating Series Resistor (R_s):
R_s = (V_supply - V_F) / I_F
Where V_F is the forward voltage of the LED (use max value from datasheet for worst-case design), I_F is the desired forward current (e.g., 20mA), and V_supply is the source voltage.

Example: For a 5V supply, V_F(max)=2.5V, I_F=20mA.
R_s = (5V - 2.5V) / 0.020A = 125 Ω. A standard 120 Ω or 150 Ω resistor would be suitable.

9.2 Thermal Management

Although power dissipation is low (75mW), maintaining a low junction temperature is key to long-term reliability and stable light output. Ensure the PCB has adequate thermal relief, especially if multiple LEDs are used or if the ambient temperature is high. Avoid placing heat-generating components nearby.

9.3 Optical Design

The 115-degree viewing angle provides wide visibility. For applications requiring a more focused beam, secondary optics (lenses) can be used. The water-clear lens is optimal for applications where the true color of the AlInGaP chip is desired without diffusion.

10. Frequently Asked Questions (FAQs)

10.1 Can I drive this LED directly from a microcontroller GPIO pin?

It depends on the GPIO pin's current sourcing capability. Most MCU pins can source 20-25mA, which is within the LED's operating range. However, you must use a series current-limiting resistor as described in section 9.1. Never connect an LED directly between a voltage source and a GPIO pin, as this can destroy both the LED and the microcontroller pin due to excessive current.

10.2 Why is there a peak current rating (80mA) higher than the DC current rating (30mA)?

The peak current rating allows for pulsed operation, such as in multiplexed displays or for brief, high-brightness flashes. The duty cycle (1/10) and short pulse width (0.1ms) ensure the average power and junction temperature do not exceed safe limits. For continuous operation, the 30mA DC limit must be observed.

10.3 What is the difference between Peak Wavelength and Dominant Wavelength?

Peak Wavelength (λp) is the physical wavelength where the LED emits the most optical power. Dominant Wavelength (λd) is a calculated value based on human color perception (CIE chromaticity diagram); it's the wavelength of the monochromatic light that would appear to have the same color as the LED. λd is more relevant for color specification in visual applications.

10.4 How do I select the correct bin for my application?

• Choose an Iv bin (U2, V1, V2) based on the required minimum brightness.
• Choose a VF bin (G1, G2, G3) if your design is sensitive to voltage drop variations, especially when driving multiple LEDs in series.
• Choose a WD bin (R1-R4) for color-critical applications where consistent hue across multiple units or with other components is necessary.