LTST-008UGVEWT SMD LED Datasheet - White Diffused Lens - Bicolor (Green/Red) - 20mA - Technical Documentation

1. Product Overview

LTST-008UGVEWT is a surface-mount device (SMD) LED specifically designed for automated printed circuit board (PCB) assembly. Its compact form factor is suitable for space-constrained applications. The device integrates two distinct light-emitting chips within a single package: one emits green light using InGaN (Indium Gallium Nitride) technology, and the other emits red light using AlInGaP (Aluminium Indium Gallium Phosphide) technology. The external lens is white diffused, which helps achieve a wider and more uniform viewing angle compared to a clear lens. This LED is designed to be compatible with standard infrared (IR) reflow soldering processes, making it ideal for high-volume production.

1.1 Features

• Compliant with the RoHS (Restriction of Hazardous Substances) Directive.
• Supplied on 12mm carrier tape wound on 7-inch diameter reels, suitable for automated pick-and-place equipment.
• Standard EIA (Electronic Industries Alliance) package outline.
• Input compatible with standard integrated circuit (IC) logic levels.
• Designed for use with automatic component placement systems.
• Capable of withstanding infrared reflow soldering temperature profiles.
• Preconditioned to accelerate attainment of JEDEC (Joint Electron Device Engineering Council) Moisture Sensitivity Level 3.

1.2 Target Applications

This LED is versatile and can be used in various electronic devices requiring status indication, backlighting, or decorative lighting. Primary application areas include:

• Communication equipment:Status indicators on routers, modems, and mobile phones.
• Office Automation:Keyboard backlighting or indicator lights on printers and scanners.
• Household Appliances:Power, mode, or function indicator lights on consumer electronics.
• Industrial Equipment:Panel indicators on machinery and control systems.
• Signage & Indoor Display:Low-brightness illumination for signage, or as components for low-resolution indoor display panels.

2. Technical Parameters: In-depth and Objective Interpretation

The performance of the LTST-008UGVEWT LED is defined by a set of electrical and optical characteristics measured under standard conditions (Ta=25°C). Understanding these parameters is crucial for proper circuit design and achieving the intended performance.

2.1 Absolute Maximum Ratings

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

• Power Dissipation (Pd):Green: 102 mW, Red: 78 mW. This is the maximum power the LED can dissipate in the form of heat.
• Peak Forward Current (I_FP):100 mA for both colors. This is the maximum instantaneous current, allowed only under pulse conditions (1/10 duty cycle, 0.1ms pulse width).
• DC Forward Current (I_F):30 mA for both colors. This is the maximum continuous current guaranteed for reliable operation.
• Operating Temperature Range:-40°C to +85°C. The ambient temperature range for normal operation.
• Storage Temperature Range:-40°C zuwa +100°C. Zazzabin ajiya a lokacin da ba a aiki ba.

2.2 Electrical and Optical Characteristics

Waɗannan sune madaidaicin sigogi na aikin na'urar a cikin sharuɗɗan aiki da aka ba da shawarar (I_F= 20mA).

• Ƙarfin haskakawa (Φ_v):Ma'aunin fitowar haske da ake ji. Kore: mafi ƙarancin 5.00 lm, mafi girma 11.00 lm. Ja: mafi ƙarancin 2.00 lm, mafi girma 4.75 lm. An auna ta amfani da firikwensin da ya dace da tacewa don dacewa da amsawar idon mutum (madaidaicin CIE).
• Kallon kusurwa (2θ_1/2):Madaidaicin darajar digiri 130. Wannan shine cikakken kusurwar da ƙarfin haske ya ragu zuwa rabin ƙimar tsakiya (digiri 0). Ruwan tabarau na hazo yana taimakawa wajen cimma wannan faɗin kusurwar kallo.
• Peak Emission Wavelength (λ_P):The wavelength at which the spectral output is strongest. Green: ~524 nm. Red: ~631 nm.
• Dominant Wavelength (λ_d):The single wavelength perceived by the human eye that defines the color. Green: 520-530 nm. Red: 617-630 nm.
• Spectral Line Half-Width (Δλ):The bandwidth of the emitted light. Green: ~33 nm. Red: ~20 nm. Indicates color purity.
• Forward Voltage (V_F):Voltage drop across the LED at a current of 20mA. Green: 2.4V to 3.4V. Red: 1.8V to 2.6V. Tolerance is ±0.1V.
• Reverse Current (I_R):At a reverse voltage (V_R) of 5V, maximum 10 µA. This device is not designed for reverse bias operation; this parameter is for test purposes only.

3. Bin System Description

To ensure production consistency, LEDs are binned according to their performance. The LTST-008UGVEWT uses two main binning criteria.

3.1 Luminous Intensity (IV) Grade

LEDs are grouped based on their light output measured at 20mA. Each bin has an 11% tolerance.

Green Chip:
G1: 5.00 - 6.50 lm
G2: 6.50 - 8.45 lm
G3: 8.45 - 11.00 lm

Red chip:
R1: 2.00 - 2.70 lm
R2: 2.70 - 3.65 lm
R3: 3.65 - 4.75 lm

3.2 Dominant Wavelength (WD) Grade

For green chips only, LEDs are binned according to their dominant wavelength to control color consistency. Tolerance is ±1 nm.

AP: 520 - 525 nm
AQ: 525 - 530 nm

4. Performance Curve Analysis

The datasheet contains typical characteristic curves, which are crucial for understanding the device's behavior under different conditions.

4.1 Current vs. Voltage (I-V) Curve

This curve shows the relationship between forward voltage (V_F) and forward current (I_F). It is nonlinear, which is typical for diodes. Compared to red chips (AlInGaP, approx. 2.0V), the curve for green chips (InGaN) will have a higher knee voltage (approx. 2.8V). Designers use this curve to calculate the required current-limiting resistor value for a given supply voltage.

4.2 Relative Luminous Intensity vs. Forward Current

This graph illustrates how light output increases with current. It is typically linear within the recommended operating range (up to 30mA). Driving the LED beyond this point results in diminishing returns in light output, while significantly increasing heat and shortening lifespan.

4.3 Spectral Distribution

Waɗannan jadawalin suna nuna ƙarfin hasken da ake fitarwa a kowane tsayin raƙuman ruwa. Cibiyar bakan na guntu kore tana kusa da 524nm, mai faɗin rabin faɗi; yayin da guntun ja yana da ƙunƙuntaccen bakan, cibiyarsa tana kusa da 631nm. Ruwan tabarau mai hazo baya canza bakan, amma yana watsa haske.

5. Mechanical and Packaging Information

5.1 Package Dimensions

Wannan LED ya dace da daidaitattun girman kunshewar SMD. Duk mahimman girma (tsayi, faɗi, tsayi, tazarar filaye) ana bayar da su a cikin milimita, tare da daidaitaccen ƙima na ±0.1mm, sai dai idan an faɗi daban. Rarraba ƙafafu an bayyana shi sarai: ƙafafu (0,1) da 2 don guntu kore, ƙafafu 3 da 4 don guntu ja, ƙafafu 5,6,7 babu kunnawa (babu haɗi).

5.2 Polarity Identification

The package includes markings or physical features (such as a notch or dot) to identify Pin 1 or the cathode. Correct orientation during assembly is crucial to ensure the target chip is powered correctly.

5.3 Recommended PCB Solder Pad Layout

It is recommended to use a pad pattern design to ensure reliable soldering. This includes the size and shape of the copper pads on the PCB, which should match the LED's terminals to form good solder fillets and provide mechanical stability.

6. Soldering and Assembly Guide

6.1 Infrared Reflow Soldering Temperature Profile

A recommended temperature profile for lead-free (Pb-free) soldering processes compliant with the J-STD-020B standard is provided. Key parameters include:
- Preheating:150-200°C, up to 120 seconds, to gradually heat the board and activate the flux.
- Peak Temperature:Maximum 260°C. The time above the liquidus (typically 217°C for SnAgCu solder) should be controlled.
- Total Soldering Time:Maximum 10 seconds at peak temperature, with a maximum of two reflow cycles allowed.

6.2 Manual Soldering (Soldering Iron)

If manual rework is required, the soldering iron tip temperature should not exceed 300°C, and the contact time per solder joint should be limited to a maximum of 3 seconds. It is recommended to perform only one rework cycle to prevent thermal damage to the plastic package and internal wire bonds.

6.3 Storage Conditions

Moisture sensitivity is a critical factor for SMD components.
- Sealed Package:Store at ≤30°C and ≤70% relative humidity (RH). Use within one year.
- Opened Package:Store at ≤30°C and ≤60% RH. If exposed to ambient air for more than 168 hours (1 week), the LEDs must be baked at approximately 60°C for at least 48 hours before soldering to remove absorbed moisture and prevent "popcorn" effect during reflow.

6.4 Cleaning

Idan ana buƙatar wanke bayan walda, ya kamata a yi amfani da kausayin barasa kawai, kamar ethanol ko isopropyl alcohol. Ya kamata a jiƙa a cikin yanayin zafi na yau da kullun na ƙasa da minti ɗaya. Yin amfani da sinadarai masu tsatsauran ra'ayi ko waɗanda ba a ƙayyade ba na iya lalata ruwan tabarau na filastik da kuma kunshe.

7. Packaging and Ordering Information

7.1 Carrier Tape and Reel Specifications

Ana samar da LED a cikin nau'in kaset ɗin ɗaukar kaya mai ɗagawa tare da kaset ɗin kariya. An ƙayyade mahimman girma na ramukan kaset ɗin ɗaukar kaya, cibiyar reel, da gefuna. Diamita na daidaitaccen reel shine inci 7, yana ɗaukar na'urori 4000. Don ƙananan adadi, mafi ƙarancin adadin oda na iya zama 500.

7.2 Reel Packaging Details

Marufi yana bin ƙa'idar ANSI/EIA-481. Ana rufe ramukan kayan da ba kowa a cikinsu. Matsakaicin adadin abubuwan da ba a samu a jere a kan reel ("Missing LEDs") shine biyu, don tabbatar da amincin ciyarwar injunan haɗawa ta atomatik.

8. Shawarar Aikace-aikace

8.1 Da'irar Aikace-aikace ta Al'ada

LED is a current-driven device. A current-limiting resistor must be connected in series. The resistor value (R_s) is calculated using Ohm's Law: R_s= (V_{Power Supply}- V_F) / I_F. For a 5V power supply and a green LED (V_F~3.0V) at 20mA, R_s= (5 - 3) / 0.02 = 100 Ω. A slightly higher value (e.g., 120 Ω) is typically used to provide margin and reduce power dissipation.

8.2 Abubuwan Tunani na Zane

• Thermal Management:Despite low power dissipation, ensure sufficient PCB copper area around the pads to aid heat dissipation, especially under high ambient temperatures or when driving near maximum current.
• Current Control:For precise brightness control or to maximize lifespan, particularly in applications with variable supply voltage, consider using a constant current driver instead of a simple resistor.
• Optical Design:White diffused lens provides wide and soft light pattern. For applications requiring a more directional beam, secondary optics (such as light pipes or external lenses) may be necessary.
• ESD Protection:While not explicitly stated as ESD-sensitive, implementing basic ESD precautions (e.g., series resistors on I/O lines) in handling and design is good practice for all semiconductor devices.

9. Kwatancen Fasaha da Bambance-bambance

The primary differentiating factors of the LTST-008UGVEWT are itsdual-color capability in a single packageand itswide viewing angle diffused lensCompared to using two separate monochromatic LEDs, this design saves PCB space, simplifies assembly (one component instead of two), and can produce mixed color effects if both chips are driven simultaneously. Compared to clear lens LEDs which typically have a more focused "hot spot," the diffused lens provides a more uniform appearance from different viewing angles. JEDEC Level 3 preconditioning indicates a moderate level of moisture resistance, suitable for most standard assembly workshop environments.

10. Frequently Asked Questions (Based on Technical Parameters)

10.1 Can I drive green and red chips simultaneously?

Yes, they are electrically independent. You need two separate current-limiting circuits (resistor or driver), one for the anode/cathode pair of the green chip and another for the pair of the red chip. When driving them simultaneously at full current (20mA each), you must ensure the total power dissipation (Pd_Green + Pd_Red) and the local thermal conditions on the PCB are within acceptable limits.

10.2 What is the difference between peak wavelength and dominant wavelength?

Peak Wavelength (λ_P)is the physical wavelength at which the LED emits its maximum optical power.Dominant Wavelength (λ_d)is a value calculated based on the CIE chromaticity diagram, corresponding to the color perceived by the human eye. For such monochromatic LEDs, they are usually close, but λ_dIt is a more relevant parameter for color specifications in applications.

10.3 Why is the maximum DC current (30mA) lower than the peak pulse current (100mA)?

This is due tothermal limitations.Continuous current generates continuous heat. The 30mA DC rating ensures the junction temperature remains within safe limits for long-term reliability. The 100mA pulse rating allows for short, high-intensity pulses (as in multiplexed displays or communications) because the duty cycle is only 10%, resulting in much lower average power and heat generation.

10.4 Yaya ake fassara lambar rarrabawa lokacin yin oda?

To achieve consistent visual performance across production batches, specify the required luminous intensity (IV) and wavelength (WD) binning codes. For example, ordering "LTST-008UGVEWT, G2, AP" requests an LED with a green chip luminous intensity between 6.50-8.45 lm and a dominant wavelength between 520-525 nm. If not specified, you will receive components from the standard production binning.

11. Misalin amfani na ainihi

Scenario: Dual-state indicator light for network equipment.
Network router designers require two status LEDs (power and internet connection), but front panel space is limited. Using LTST-008UGVEWT, they can design a single LED location to display:
- Solid green:Power on, internet connected (green chip only).
- Solid red:Power on, no internet connection (red chip only).
- Flashing green:Startup/System Activity.
- Flashing Red:Error Status.
This is achieved by connecting the green and red anodes to different GPIO pins of the microcontroller, each with its own series resistor. The microcontroller firmware controls the status and color. The 130-degree wide viewing angle ensures the status is visible from almost any angle in the room.

12. Ayyukan ka'ida

Light emission in an LED is based onElectroluminescence. When a forward voltage is applied across the p-n junction, electrons from the n-type region recombine with holes from the p-type region. This recombination releases energy in the form of photons (light). The specific wavelength (color) of the light is determined by the energy band gap of the semiconductor material.InGaNYana da faɗin tazara, yana haifar da ƙarin ƙarfin haske, ana ganinsa a matsayin kore/blue.AlInGaPYana da ƙaramin tazara, yana haifar da ƙarancin ƙarfin haske, ana ganinsa a matsayin ja/lemu. Gilashin hazo fari an yi shi da epoxy ko siliki mai ɗauke da barbashi masu watsawa, waɗanda ke bazuwar hanyar fitar da haske, suna haifar da yanayin fitarwa mai kama da Lambert.

13. Trends na fasaha

Kasuwar SMD LED tana ci gaba da tafiya zuwa ga:
1. Mafi inganci (lm/W):Ci gaba da inganta girma na epitaxial da ƙirar guntu, yana ba da ƙarin fitarwa na haske daga shigarwar wutar lantarki iri ɗaya, don haka rage amfani da wutar lantarki da nauyin zafi.
2. Improved Color Consistency and Binning:Stricter production control and more complex binning strategies (e.g., multi-parameter binning covering luminous intensity, wavelength, and sometimes forward voltage) enable better color matching in applications requiring multiple LEDs.
3. Miniaturization:Packages continue to shrink (e.g., 0402, 0201 metric sizes) to enable higher-density designs, especially in portable consumer electronics.
4. Enhanced Reliability:Advancements in packaging materials (molding compounds, leadframes) and die-attach technologies have improved resistance to thermal cycling, moisture, and other environmental stresses.
5. Integrated Solution:The growing integration of LEDs with built-in drivers (constant current ICs), protective components (ESD, surge), and even microcontrollers for "smart LED" applications reduces the number of external components required.