SMD LED LTST-N682TWVSET Datasheet - Dual Color Yellow/White - 30mA - 102mW - Simplified Chinese Technical Documentation

1. Product Overview

This document details the specifications of the LTST-N682TWVSET, a Surface-Mount Device (SMD) Light Emitting Diode (LED). This device integrates two distinct LED chips within a single package: one emitting yellow light and the other emitting white light. It is designed for automated Printed Circuit Board (PCB) assembly processes and is suitable for high-volume production. Its compact form factor addresses the needs of space-constrained applications across various electronic fields.

1.1 Core Features and Advantages

• Dual-Color Light Source:Combines a yellow AlInGaP chip and a white LED chip in a single package, enabling multi-state indication or color mixing within an extremely small footprint.
• Automation Compatibility:Packaged in 8mm wide tape on 7-inch reels, compliant with EIA standards and compatible with high-speed automatic placement equipment.
• Robust Manufacturing Process:Compatible with infrared (IR) reflow soldering processes, the standard for modern PCB assembly. Devices are preconditioned to JEDEC Level 3 moisture sensitivity level, enhancing reliability during soldering.
• Environmental Compliance:The product complies with the RoHS (Restriction of Hazardous Substances) Directive.
• Electrical Interface:Designed to be compatible with integrated circuits (IC), it can be directly driven by typical logic-level outputs or drive circuits.

1.2 Target Applications and Market

LTST-N682TWVSET is specifically designed for a wide range of electronic devices requiring reliable and compact status indication. Its primary application areas include:

• Telecommunication Equipment:Status indicators on routers, modems, and network switches.
• Consumer Electronics & Office Automation:Power, battery, or function status lights in laptops, printers, and peripherals.
• Household appliances and industrial equipment:Operating mode indicator lights on the control panel.
• Indoor signage and front panels:Symbol backlighting or providing multi-color status illumination.

2. Package Dimensions and Mechanical Information

The outline of the LTST-N682TWVSET package is defined by the industry-standard SMD outline dimensions to ensure mechanical compatibility. Key dimension callouts indicate that all measurement units are in millimeters, with a general tolerance of ±0.2 mm unless otherwise specified. The component features a transparent lens.

2.1 Pin Assignment and Polarity

The device has four electrical terminals. The pin assignment is as follows:

• Pin 1 and 2:This isYellowAnode and cathode of AlInGaP LED chip.
• Pin 3 and 4:This isWhiteAnode and cathode of the LED chip.

To ensure correct orientation during assembly, the detailed package drawing in the specification must be consulted to determine the exact physical location of Pin 1, which is typically marked by a dot or a notch on the package.

3. Ratings and Characteristics

Operating the device within the specified limits is crucial for reliability and performance.

3.1 Absolute Maximum Ratings

These ratings define the stress limits that may cause permanent damage to the device. They are specified at an ambient temperature (Ta) of 25°C.

Parameter	White chip	Yellow Chip	Unit
Power Consumption	102	78	mW
Peak forward current (1/10 duty cycle, 0.1ms pulse)	100	100	mA
Direct forward current	30	30	mA
Operating Temperature Range	-40°C to +85°C
Storage temperature range	-40°C to +100°C

3.2 Electrical and Optical Characteristics

These are typical performance parameters measured at Ta=25°C and a standard test current (IF) of 20mA (unless otherwise specified).

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Parameter	Symbol	White chip	Yellow Chip	Unit	Condition / Remarks
Luminous intensity	Iv	Minimum: 1600, Maximum: 3200	Minimum: 710, Maximum: 1800	mcd	IF=20mA. Measured using a CIE human eye response filter.
Perspective (Half-Intensity Angle)	2θ1/2	120 (typical value)		度	The angle at which the luminous intensity drops to 50% of the axial value.
Dominant wavelength	λd	-	585 - 595	nm	Define perceived color (yellow).
Peak emission wavelength	λP	-	590 (Typical)	nm	Wavelength at the spectral output peak.
Spectral line half-width	Δλ	-	20 (typical value)	nm	Bandwidth of the emission spectrum.
Forward voltage	VF	2.6 - 3.4	1.7 - 2.6	V	IF=20mA. Tolerance is ±0.1V.
Reverse current	IR	10 (max)		μA	VRVR=5V. This device is not intended for reverse operation.

Key Measurement Description:

• Luminous intensity measurement follows the CIE standard photopic human eye response curve.
• Dominant wavelength is derived from CIE chromaticity coordinates.
• Reverse voltage test is for information/quality purposes only; in application, the LED should not be operated under reverse bias.

4. Bin System Description

To ensure color and brightness consistency in production, LEDs are binned according to their performance. The LTST-N682TWVSET employs independent binning for white and yellow chips.

4.1 Luminous Intensity (Iv) Grading

White Chip:Divided into two groups based on the minimum luminous intensity at 20mA.

• W1:1600 mcd to 2265 mcd.
• W2:2265 mcd to 3200 mcd.

Yellow chip:Divided into three groups.

• U:710 mcd to 965 mcd.
• V:965 mcd to 1315 mcd.
• W:1315 mcd to 1800 mcd.

The tolerance within each intensity grade is ±11%.

4.2 Yellow Chip Wavelength (WD) Binning

Sort the dominant wavelength of yellow chips to control the hue.

• J:585 nm to 590 nm.
• K:590 nm to 595 nm.

The tolerance within each wavelength bin is ±1 nm.

4.3 White Chip Chromaticity (CIE) Binning

The color point of a white LED is defined by its CIE 1931 (x, y) chromaticity coordinates. The datasheet provides a table containing multiple bin codes (A1, A2, A3, B1, B2, B3, C1, C2, C3), each representing a quadrilateral area on the chromaticity diagram defined by four (x, y) coordinate points. This allows for precise selection of white color temperature and hue. The tolerance for (x, y) coordinates within a bin is ±0.01.

5. Performance Curve Analysis

The datasheet references typical performance curves, which graphically represent key relationships. Analyzing these curves is crucial for design.

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

This curve illustrates the exponential relationship between the current flowing through the LED and the voltage drop across it. As shown in the Electrical Characteristics table, for a given current, the forward voltage (VF) of the yellow AlInGaP chip will be lower than that of the white chip. Designers use this curve to select appropriate current-limiting resistors or constant-current drive settings to achieve the desired brightness within power constraints._F5.2 Luminous Intensity vs. Forward Current

The graph shows how light output increases with drive current. It is typically linear within a certain range but saturates at higher currents. Operating at the recommended 20mA DC ensures optimal efficiency and lifetime. The 100mA peak pulse current rating allows for brief, high-intensity flashes without damaging the device.

5.3 Spectral Distribution

For the yellow chip, the spectral distribution curve will show a relatively narrow peak at approximately 590nm (typical), with a half-width of about 20nm, confirming its monochromatic yellow light output. The spectrum of a white LED is much broader, typically resulting from a blue LED chip combined with phosphor to produce broad-spectrum emission across the visible range.

6. Assembly and Application Guide

6.1 Welding Process

This device is specifically designed for lead-free (Pb-free) soldering processes. The recommended IR reflow profile should comply with the J-STD-020B standard. Key parameters include:

Preheat:

• Ramp up to 150-200°C.Preheating time:
• Maximum 120 seconds.Peak temperature:
• Should not exceed 260°C.Akoko ti o wa loke ila-omi:
• A gbọdọ ṣe idiwọ, akoko lapapo ti a fi sin gbigbọn ni ori iwọn otutu giga ko gbọdọ ju awọn iṣẹju 10 lọ, ati pe a le ṣe atunṣe iṣan lẹẹmeji nikan.Fun gbigbọn ọwọ ti a lo irin irin, iwọn otutu ori irin irin ko gbọdọ ju 300°C lọ, akoko ifọwọkan gbọdọ diwọ si awọn iṣẹju 3, ati pe a le ṣe ẹẹkan nikan.

6.2 Recommended PCB Pad Layout

The datasheet contains the recommended PCB land pattern (footprint). Using this recommended design ensures good solder joint formation, mechanical stability, and heat dissipation during and after soldering. Following this land pattern is crucial for successful automated assembly and reliability.

6.3 Cleaning

If post-soldering cleaning is required, only specified solvents may be used. It is acceptable to immerse the LED in ethanol or isopropyl alcohol at room temperature for no more than one minute. The use of unspecified or corrosive chemicals may damage the LED package or lens.

7. Storage and Handling Precautions

7.1 Moisture Sensitivity

LED packages are sealed in moisture barrier bags with desiccant to prevent absorption of atmospheric moisture, which can cause "popcorn" effect (package cracking) during reflow soldering. In sealed condition, they should be stored at ≤30°C and ≤70% relative humidity, and used within one year.

Once the bag is opened, the "floor life" begins. Components should be stored at ≤30°C and ≤60% relative humidity. It is strongly recommended to complete the IR reflow soldering process within 168 hours (7 days) after opening the bag.

If the component exposure time exceeds 168 hours, "baking" (dehydration) must be performed before soldering, baking at approximately 60°C for at least 48 hours to remove absorbed moisture.

7.2 Application Considerations

These LEDs are suitable for standard commercial and industrial electronic equipment. For applications requiring extremely high reliability where failure could endanger safety (e.g., aviation, medical life support, traffic control), specific qualification and consultation are required before design adoption.

8. Packaging and Ordering Information

8.1 Tape and Reel Specifications

Components are supplied in 8mm wide embossed carrier tape and sealed with cover tape. The carrier tape is wound on standard 7-inch (178mm) diameter reels. Each full reel contains 2000 pieces. For quantities less than a full reel, the minimum packaging quantity is 500 pieces. Packaging complies with EIA-481-1-B specification.

8.2 Part Number Interpretation

The part number LTST-N682TWVSET follows the manufacturer's internal coding system, where "TWVSET" may indicate a specific color combination (T=?, W=White, V=?, SET=Dual-color?). For accurate ordering, the complete part number along with any required binning code selections (e.g., for intensity or color) must be specified.

9. Design Considerations and Typical Application Circuit

9.1 Current Limiting

LED ni kifaa kinachotumia mkondo wa umeme. Njia rahisi na ya kawaida ya kuendesha ni kutumia upinzani wa mfululizo. Thamani ya upinzani (RS) inaweza kuhesabiwa kwa kutumia sheria ya Ohm: RS = (V chanzo - VF) / IF. Kwa mfano, kuendesha chipi ya manjano kutoka kwa chanzo cha 5V kwa 20mA, kwa kudhania VF ya kawaida ni 2.2V: RS = (5V - 2.2V) / 0.020A = 140 Ω. Upinzani wa kawaida wa 150 Ω utakuwa unaofaa. Nguvu ya upinzani inapaswa kukaguliwa: P = IF² * RS = (0.02)² * 150 = 0.06W, kwa hivyo upinzani wa 1/8W (0.125W) utatosha.

9.2 Independent Drive vs. Common Drive_sKwa kuwa chipi za manjano na nyeupe zina anode na cathode zilizojitegemea (pini 4 kwa jumla), zinaweza kudhibitiwa kikamilifu kwa kujitegemea. Hii inaruhusu hali tatu za kuona: manjano pekee, nyeupe pekee, au zote mbili zinawaka wakati mmoja (kutegemea na nguvu, zinaweza kuonekana kama rangi iliyochanganywa). Kwa sababu ya kutolingana kwa VF inayoweza kutokea, hazipaswi kuunganishwa moja kwa moja kwa sambamba kwa kiendeshi kimoja._s9.3 Thermal Management_{Although the power consumption is low (white maximum 102mW, yellow maximum 78mW), correct PCB design helps to extend the lifespan. Using the recommended pad pattern helps conduct heat from the LED junction to the PCB copper layer. Operating at or below the recommended DC current and within the specified temperature range ensures the LED maintains its rated lifespan and color stability.}10. Technical Comparison and Differentiation_FThe primary differentiating factor of the LTST-N682TWVSET is its dual-color, single-package design. Compared to using two separate SMD LEDs, this solution offers significant advantages:_FSpace Saving:PCB footprint reduction of approximately 50% is crucial for miniaturized designs.Assembly Efficiency:_FPicking, placing, and soldering only one component instead of two increases assembly throughput and reduces potential placement errors._sOptical Alignment:²Two light sources are fixed within the package in a known and consistent spatial relationship, which may be important for light guide or lens coupling.²Performance matching:

Although independently binned, chips from the same production lot may exhibit more consistent thermal characteristics when packaged together.

Compared to older technologies such as GaAsP, the selection of AlInGaP material for yellow chips offers high luminous efficiency and excellent color purity (narrow spectrum)._F mismatch.

11. Frequently Asked Questions (FAQ) Based on Technical Parameters

Q1: Can I use the same current-limiting resistor to drive both yellow and white LEDs?

A1:

No. They have different forward voltage characteristics (yellow: approx. 1.7-2.6V, white: approx. 2.6-3.4V). Connecting them in parallel with a single resistor will cause uneven current distribution, potentially overdriving one chip and underdriving the other. They require independent current-limiting circuits.Q2: What is the purpose of the Peak Forward Current rating (100mA, 1/10 duty cycle)?A2:

• This rating allows for pulsed operation at higher currents for short durations, such as in blinking or strobing applications, to achieve higher instantaneous brightness. Low duty cycle and short pulse width ensure that average power and junction temperature remain within safe limits.Q3: Why are the storage and baking procedures so specific?
• A3:SMD plastic packages absorb moisture from the air. During high-temperature reflow soldering, this trapped moisture rapidly turns to steam, generating high internal pressure that can cause package delamination or chip cracking ("popcorn" effect). Moisture sensitivity labels and baking procedures are key industry practices to prevent this failure mode.
• Q4: How to interpret the CIE binning code for white LEDs?A4:
• CIE bin codes (A1, B2, C3, etc.) define a small area on the CIE chromaticity diagram. Designers select specific bin codes to ensure all white LEDs in their product have a consistent color appearance (same white point, avoiding yellowish or bluish tints). For most applications, specifying a bin is necessary for color uniformity.12. Practical Application Examples

Scenario: Dual-state indicator light for network equipment.

A network router design requires an indicator light to display two states:

Power On/Network Activity
和System Error

Design Selection:
Use LTST-N682TWVSET.Implementation:

The white LED is connected to a GPIO pin of the main microcontroller via a 150Ω series resistor and to the 3.3V power rail. When the system is operating normally, the firmware gently blinks this LED to indicate network activity.
The yellow LED is connected to another GPIO pin via a 100Ω series resistor (as an alarm, with slightly higher brightness). The firmware drives this LED in a steady-on or fast-blinking mode only when a system error is detected.Results:

A single compact component on the PCB provides clear, distinct visual feedback for both operational states, simplifying front-panel design and user interface.
13. Working PrincipleLight emission in an LED is based on electroluminescence in a semiconductor p-n junction. When a forward voltage is applied, electrons and holes are injected into the junction region. When these charge carriers recombine, they release energy in the form of photons (light). The color (wavelength) of the emitted light is determined by the bandgap energy of the semiconductor material.

Yellow chip (AlInGaP):

E fa'aaogaina le semiconductor alumini-indium-gallium-phosphorus. O le va o le va o lenei faiga mea e fetaui ma le fa'aosoina o le malamalama i le vaega samasama/amber/moli/mumu o le fusi o alaleo. E lauiloa i le maualuga o le lelei ma le mautu lelei o le vevela.
White Chip:O le LED pa'epa'e sili ona taatele o se chip LED lanumoana ua valiina i le phosphor samasama (e masani lava ona fa'avae i luga o le semiconductor InGaN). O se vaega o le malamalama lanumoana e liua e le phosphor i le malamalama samasama. O le fefiloi o le malamalama lanumoana totoe ma le malamalama samasama ua liua e iloa e mata o le tagata o le malamalama pa'epa'e. O le "lanu" tonu o le pa'epa'e (malulu pa'epa'e, le faaituau pa'epa'e, mafanafana pa'epa'e) e pulea e le tuufaatasiga ma le mafiafia o le phosphor.14. Technical Trends and BackgroundLTST-N682TWVSET, SMD LED pazarında olgunlaşmış ve optimize edilmiş bir ürünü temsil etmektedir. Bu alandaki süregelen önemli trendler şunları içerir:.

• Entegrasyonun Artması:From dual-color to RGB (Red-Green-Blue) or RGBW (Red-Green-Blue-White) packages within a single SMD package, enabling full-color programmability for indicator lights and micro-displays.
• Higher efficiency:
  1. Continuous improvements in the internal quantum efficiency of semiconductor materials (such as AlInGaP and InGaN) and phosphors result in higher light output (lumens) per unit of electrical input power (watts), thereby reducing energy consumption and thermal load.Miniaturization:The pursuit of even smaller devices continues, with the emergence of Chip Scale Package (CSP) LEDs that eliminate traditional plastic packaging, further reducing size and enhancing optical design flexibility.
  2. Improved Color Consistency:Advances in manufacturing and binning processes allow for tighter tolerances on wavelength and chromaticity, enabling designers to control the final visual appearance of their products more precisely.Smart Features:
• By directly integrating control circuits (such as constant current drivers or simple logic) into the LED package, "smart" LED modules are created, thereby simplifying system design.For cost-effective, reliable, and space-saving status indication applications that do not require advanced color control or programmability, devices like the LTST-N682TWVSET remain highly relevant.

. Operational Principle

Light emission in LEDs is based on electroluminescence in a semiconductor p-n junction. When a forward voltage is applied, electrons and holes are injected across the junction. When these charge carriers recombine, they release energy in the form of photons (light). The color (wavelength) of the emitted light is determined by the bandgap energy of the semiconductor material.

• Yellow Chip (AlInGaP):Yana amfani da semiconductor na Aluminum Indium Gallium Phosphide. Wannan tsarin kayan yana da bandgap wanda yayi daidai da fitar da haske a cikin sashi na rawaya/amber/lemu/ja na bakan. An san shi da ingantacciyar aiki da kwanciyar hankali na zafin jiki.
• Farin Chip:Mafi yawanci, farin LED shine blue LED chip (yawanci bisa InGaN semiconductor) wanda aka lullube da rawaya phosphor. Wasu daga cikin hasken blue suna canzawa ta hanyar phosphor zuwa hasken rawaya. Cakuda sauran hasken blue da canza hasken rawaya ana ganinsu ta idon mutum a matsayin fari. Tabbataccen "inuna" na fari (sanyi, tsaka-tsaki, dumi) ana sarrafa su ta hanyar abun da ke ciki da kauri na phosphor.

. Trends na Fasaha da Mahallin

The LTST-N682TWVSET represents a mature and optimized product within the SMD LED market. Key ongoing trends in this sector include:

• Increased Integration:Moving beyond dual-color to RGB (Red-Green-Blue) or RGBW (Red-Green-Blue-White) packages in a single SMD footprint, enabling full-color programmability for indicators and micro-displays.
• Higher Efficiency:Continuous improvement in the internal quantum efficiency of semiconductor materials (like AlInGaP and InGaN) and phosphors, leading to higher luminous output (lumens) per unit of electrical input power (watts), reducing energy consumption and thermal load.
• Miniaturization:The drive for smaller devices continues, with chip-scale package (CSP) LEDs that have no traditional plastic package, further reducing size and improving optical design flexibility.
• Improved Color Consistency:Advances in manufacturing and binning processes allow for tighter tolerances on wavelength and chromaticity, giving designers more precise control over the final visual appearance in their products.
• Smart Features:Integration of control circuitry (like constant-current drivers or simple logic) directly into the LED package, creating "intelligent" LED modules that simplify system design.

Devices like the LTST-N682TWVSET remain highly relevant for cost-effective, reliable, and space-efficient status indication where advanced color control or programmability is not required.