SMD Chip LED Green GaP Datasheet - 3.2x2.8x1.9mm - 2.6V - 72mW - Technical Documentation

1. Product Overview

This document provides the complete technical specifications for a high-brightness, surface-mount green LED. This device is specifically designed for general indicator and backlighting applications in consumer electronics, office equipment, and communication devices. Its main advantages include: compatibility with automated placement equipment, suitability for infrared and reflow soldering processes, and compliance with lead-free (RoHS) requirements. The standard EIA package ensures broad compatibility within the industry.

2. In-depth Technical Parameter Analysis

2.1 Absolute Maximum Ratings

The operating limits of the device are defined under the condition of an ambient temperature (Ta) of 25°C. Exceeding these ratings may cause permanent damage.

• Power Dissipation (Pd):72 mW. This is the maximum power that the LED can safely dissipate as heat under continuous operation.
• Peak Forward Current (IFP):80 mA. This is the maximum current allowed under pulse conditions, specified at a duty cycle of 1/10 and a pulse width of 0.1ms. This value is much higher than the DC rating to accommodate brief, high-intensity flashes.
• Direct forward current (IF):30 mA. This is the maximum continuous forward current recommended to ensure long-term reliable operation.
• Reverse voltage (VR):5 V. Applying a reverse voltage exceeding this limit may damage the semiconductor junction of the LED.
• Operating Temperature Range:-40°C to +85°C. The device is rated for reliable operation over this wide industrial temperature range.
• Storage Temperature Range:-40°C to +100°C.

2.2 Electrical and Optical Characteristics

Key performance parameters are measured at Ta=25°C and a standard test current IF=20mA.

• Luminous Intensity (Iv):The range is from a minimum of 7.1 mcd to a typical value of 45.0 mcd. Actual intensities are binned; refer to Section 3 for details.
• Viewing Angle (2θ1/2):120 degrees. This wide viewing angle indicates it is a diffused lens, suitable for applications requiring a wide range of visibility.
• Peak Emission Wavelength (λP):565 nm. This is the wavelength at which the spectral output is strongest.
• Dominant Wavelength (λd):569 nm. This single wavelength, derived from the CIE chromaticity diagram, defines the perceived color (green) of the LED.
• Spectral Line Half-Width (Δλ):30 nm. This parameter describes the spectral purity; a narrower width indicates better monochromaticity of the light source.
• Forward Voltage (VF):The typical value is 2.6V, with a range from 2.0V to 2.6V at 20mA. The typical value has a tolerance of +/- 0.1V.
• Reverse Current (IR):Maximum 10 µA when a reverse voltage of 5V is applied.

3. Binning System Description

To ensure brightness consistency across different production lots, luminous intensity is classified into different bins. The bin code is part of the part number selection.

• Bin Code K:7.1 mcd (Min) to 11.2 mcd (Max)
• Bin Code L:11.2 mcd to 18.0 mcd
• Gear code M:18.0 mcd to 28.0 mcd
• Gear Code N:28.0 mcd to 45.0 mcd

A tolerance of +/-15% applies to each intensity gear. Designers should select the appropriate gear based on the brightness level required for their application.

4. Performance Curve Analysis

The datasheet references typical performance curves to illustrate the relationship between key parameters. Although the specific graphs are not reproduced in the text, their meaning is crucial for design.

• I-V Curve:It shows the relationship between forward current (IF) and forward voltage (VF). It is nonlinear, which is typical for diodes. This curve helps in selecting a suitable current-limiting resistor.
• Luminous intensity vs. forward current:It shows how light output increases with current, typically in an approximately linear relationship within the operating range. Operating beyond the maximum current leads to diminishing returns and generates more heat.
• Luminous Intensity vs. Ambient Temperature:It shows the derating of light output as junction temperature increases. This is crucial for thermal management in high-power or high ambient temperature applications.
• Spectral Distribution:The relationship diagram of relative intensity versus wavelength, centered at 565nm with a half-width of 30nm, confirms the green light output.

5. Mechanical and Packaging Information

5.1 Device Dimensions

Wannan LED ya yi daidai da daidaitaccen EIA SMD kunshe. Muhimman ma'auni (naúrar: millimita) sun haɗa da girman jiki kusan 3.2mm (tsayi) x 2.8mm (faɗi) x 1.9mm (tsayi). Sai dai idan an faɗi daban, saɓanin girma yawanci ±0.2mm ne. Za a yi la'akari da cikakken zanen PCB pad don daidaitaccen ƙira.

5.2 Recommended PCB Land Pattern Design

An ba da shawarar zanen pad wanda ya dace da infrared ko tururi mai sake zafi. Bin wannan shawarar zanen pad yana da mahimmanci don samun amintaccen haɗin gwiwa, daidaitaccen daidaita kai yayin sake zafi, da kuma ingantaccen sarrafa zafi. Ƙirar takan ƙunshi zanen pad na sarrafa zafi don gudanar da yanayin zafi na haɗawa.

5.3 Polarity Identification

The cathode is typically marked on the device, for example, with a notch, a green dot, or a cut corner on the lens or package. The diagram in the datasheet must be consulted to confirm the exact marking scheme, ensuring correct orientation during assembly.

6. Welding and Assembly Guide

6.1 Reflow Soldering Temperature Profile

This device is compatible with lead-free (Pb-free) reflow soldering processes. It references the recommended temperature profile compliant with the J-STD-020B standard. Key parameters include:

• Preheat temperature:150°C to 200°C.
• Preheat time:Maximum 120 seconds.
• Peak temperature:Maximum 260°C.
• Time above liquidus:According to the solder paste specification recommended duration.
• Ramp-up/Ramp-down rate:It must be controlled to prevent thermal shock.

Key Consideration: The optimal temperature profile depends on the specific PCB design, solder paste, and reflow oven. Component-level and board-level verification is recommended.

6.2 Manual Soldering

If manual soldering is required, use a soldering iron with a temperature not exceeding 300°C. The contact time for each solder joint should be limited to a maximum of 3 seconds and should be performed only once to avoid damaging the plastic package or internal bonding wires.

6.3 Cleaning

If cleaning is required after soldering, only specified solvents may be used. Immersing the LED in ethanol or isopropyl alcohol at room temperature for no more than one minute is acceptable. Unspecified chemicals may damage the epoxy lens or package.

6.4 Storage and Moisture Sensitivity

LEDs are moisture sensitive. When stored in the original sealed moisture barrier bag (with desiccant), they should be kept at ≤30°C and ≤70% relative humidity and used within one year. Once the bag is opened, the storage environment should not exceed 30°C and 60% relative humidity. Components exposed to ambient air for more than 168 hours should be baked at approximately 60°C for at least 48 hours before reflow soldering to prevent "popcorn" effect (package cracking due to vapor pressure).

7. Packaging and Ordering Information

7.1 Tape and Reel Specifications

The device is supplied in 8mm carrier tape, wound on 7-inch (178mm) diameter reels, compatible with standard automated placement equipment.

• Quantity per reel: 2000.
• Minimum Order Quantity (MOQ):Remaining quantity, minimum order starts from 500 pieces.
• Cover Tape:Empty slots are sealed with top cover tape.
• Missing parts:According to the specification (EIA-481-1-B), a maximum of two consecutive missing lights is allowed.

7.2 Part Number Structure

Part number LTST-M670GKT encodes key attributes:

• LTST:Possibly indicates product series or family.
• M670:Possibly refers to a specific chip/die type or optical design.
• G:Indicates lens color (colorless and transparent).
• K:Represents the luminous intensity grade code (e.g., K grade: 7.1-11.2 mcd).
• T:Iya nufin kunnawa da na'urar nadi a cikin kundi.

Zaɓi ƙarshen da ya dace (lambar ma'auni) yana da mahimmanci don samun matakin haske da ake so.

8. Application Recommendations

8.1 Typical Application Scenarios

This LED is suitable for a wide range of applications requiring bright, reliable green indicator lights, including:

• Status indicators on consumer electronics (routers, modems, audio equipment).
• Backlighting for membrane switches and panels.
• Illumination for instrumentation and control panels.
• General signage and decorative lighting where a wide viewing angle is beneficial.

8.2 Drive Circuit Design

LED is a current-driven device.To maintain uniform brightness, especially when driving multiple LEDs in parallel,Strongly recommendedUse a series current-limiting resistor for each LED (Circuit Model A). It is not recommended to drive LEDs directly in parallel from a voltage source (Circuit Model B), as slight variations in the forward voltage (VF) characteristics among individual LEDs will lead to severe current imbalance, resulting in uneven brightness. The series resistor value can be calculated using Ohm's Law: R = (Vcc - VF) / IF, where Vcc is the supply voltage, VF is the LED forward voltage (use the maximum value for reliability), and IF is the desired forward current.

8.3 Thermal Management

Although the power consumption is relatively low (maximum 72mW), proper thermal design can extend lifespan and maintain stable light output. Ensure the PCB pad design provides sufficient heat dissipation. Avoid operating the LED for extended periods at or near its absolute maximum current and temperature ratings.

8.4 ESD (Electrostatic Discharge) Protection

Like most semiconductor devices, LEDs are sensitive to electrostatic discharge. Standard ESD handling procedures should be followed during assembly and operation, including the use of grounded workbenches, wrist straps, and conductive containers.

9. Technical Comparison and Differentiation

Compared to older through-hole LED technology, this SMD device offers significant advantages:

• Size and Form Factor:The compact 3.2x2.8mm footprint and low profile (1.9mm) contribute to the miniaturization of end products.
• Manufacturability:Fully compatible with high-speed, automated SMT assembly lines, reducing production costs and improving reliability compared to manual insertion.
• Optical Performance:The combination of high brightness (up to 45 mcd) and a 120-degree wide viewing angle provides excellent visibility.
• Reliability:The package design is suitable for robust infrared/reflow soldering processes and provides a wide operating temperature range (-40°C to +85°C).

The use of GaP (Gallium Phosphide) substrate technology is a mature and reliable process for producing green LEDs with stable color and performance.

10. Frequently Asked Questions (FAQ)

Q1: What is the difference between Peak Wavelength (λP) and Dominant Wavelength (λd)?
A1: Peak wavelength (565 nm) is the physical wavelength at which the LED emits its strongest optical power. Dominant wavelength (569 nm) is a value calculated based on colorimetry, representing a single wavelength that defines the perceived color. For monochromatic light sources like this green LED, the two are typically very close.

Q2: Can I operate this LED continuously at 30mA?
A2: Yes, 30mA is the maximum rated DC forward current. For the highest reliability and lifetime, it is generally recommended to operate slightly below this maximum, for example at 20mA (the standard test condition), which also provides sufficient brightness for most indicator applications.

Q3: Even if my power supply is current-limited, why do I still need a series resistor?
A3: A dedicated series resistor provides a simple, cost-effective, and robust method for setting the current. It also helps absorb minor variations in the power supply voltage and the LED forward voltage, ensuring stable operation. This is considered best practice for most general-purpose LED circuits.

Q4: How critical is the 168-hour floor life after opening the moisture barrier bag?
A4: This is very important for process reliability. Exceeding this time without baking increases the risk of package damage due to moisture during high-temperature reflow soldering, which may lead to immediate failure or reduced long-term reliability.

11. Design Case Study

Scenario:Design a status indicator panel for a network switch with 24 identical green port activity LEDs.
Design Steps:

1. Brightness Selection:For a viewing distance of 1-2 meters for indoor equipment, medium brightness is sufficient. Select the gear code L (11.2-18.0 mcd) from the ordering information.
2. Drive circuit:The system uses a 3.3V power rail. Using a maximum VF of 2.6V and a target IF of 20mA, calculate the series resistor: R = (3.3V - 2.6V) / 0.020A = 35 ohms. Choose the nearest standard value of 33 ohms or 39 ohms, which will slightly adjust the current.
3. PCB layout:Use the pad layout recommended in the datasheet. Route the 3.3V and GND traces to all 24 LEDs. Place the current-limiting resistor close to the anode of each LED.
4. Thermal Considerations:Each of the 24 LEDs draws approximately 20mA, resulting in a relatively low total power (about 1.5W). No special heat dissipation is required, but ensure general airflow within the enclosure.
5. Assembly:Follow the recommended reflow soldering temperature profile. After opening the reel, plan to complete SMT assembly for all PCBs within the 168-hour window, or implement a baking plan.

This method ensures uniform brightness, reliable soldering, and long-term performance.

12. Technical Principle Introduction

This LED is based on gallium phosphide (GaP) semiconductor material. When a forward voltage is applied across the p-n junction, electrons and holes are injected into the active region where they recombine. In GaP, this recombination process releases energy in the form of photons (light), with a wavelength corresponding to the material's bandgap energy. For this specific composition, it produces green light (approximately 565-569 nm). The "colorless transparent" lens is made of epoxy resin, designed to diffuse the light, creating a wide viewing angle of 120 degrees. The SMD package encapsulates the semiconductor chip, bonding wires, and lead frame, providing mechanical protection as well as thermal/electrical connections.

13. Industry Trends and Development

The optoelectronics industry continues to evolve. While this GaP-based green LED represents a mature and highly reliable technology, the trends include:

• Efficiency Enhancement:Ongoing development of new materials (e.g., InGaN for wider color gamut) and chip designs to achieve higher lumens per watt (lm/W), thereby reducing power consumption for a given light output.
• Miniaturization:Develop smaller package sizes (e.g., 0201, 01005) for space-constrained applications, such as wearable devices and ultra-compact consumer electronics.
• Integrated Solutions:LEDs with built-in drivers (constant current ICs), protection diodes (for ESD/reverse voltage), or multi-color (RGB) in one package are increasingly common, simplifying circuit design.
• High Reliability Requirements:The expansion of applications in automotive, industrial, and medical fields drives the demand for wider temperature ranges, higher vibration resistance, and longer operational life (often rated as L70 or L90, which refers to the time until the luminous flux degrades to 70% or 90% of its initial brightness).

The device described in this specification is firmly positioned in a mature, high-volume market segment, favored for its proven performance, cost-effectiveness, and ease of integration.