SMD LED LTST-S320KRKT Datasheet - Red - 639nm Peak - 20mA - 2.4V - English Technical Document

1. Product Overview

LTST-S320KRKT wani babban haske ne, Surface Mount Device (SMD) LED mai kallon gefe wanda aka tsara don aikace-aikacen lantarki na zamani waɗanda ke buƙatar ayyukan nuni ko hasken baya masu aminci da inganci. Ta amfani da fasahar AlInGaP (Aluminum Indium Gallium Phosphide) chip na ci-gaba, wannan LED yana ba da mafi girman ƙarfin haske da tsaftar launi a cikin bakan ja. Ɗayan zanen sa na fitar da haske yana ba da damar haske ya zama layi daya da saman da aka ɗora, yana mai da shi cikakke don faranti masu haske na gefe, alamomin yanayin akan PCBs a tsaye, ko aikace-aikacen da ke da ƙarancin sarari inda hasken sama-ƙasa ba zai yiwu ba.

Manyan fa'idodin wannan ɓangaren sun haɗa da bin umarnin RoHS (Restriction of Hazardous Substances), yana rarraba shi azaman samfuri mai kore. Kunshin yana fasalta ruwa-clear lens wanda ke haɓaka fitar da haske kuma ana samar da shi akan kaset 8mm na ƙa'idar masana'antu da aka ɗora akan reels 7-inch, yana tabbatar da dacewa da kayan aikin haɗawa da sauri ta atomatik. An kuma tsara na'urar don jure daidaitattun hanyoyin siyar da infrared (IR) reflow, yana sauƙaƙa haɗawa cikin ingantattun layukan samar da fasahar Surface-mount technology (SMT).

2. Technical Parameter Deep Dive

2.1 Absolute Maximum Ratings

These ratings define the stress limits beyond which permanent damage to the device may occur. Operation under these conditions is not guaranteed and should be avoided for reliable performance.

• Power Dissipation (Pd): 75 mW. This is the maximum amount of power the LED package can dissipate as heat without exceeding its maximum junction temperature.
• Peak Forward Current (I_F(PEAK)): 80 mA. This current can be applied only under pulsed conditions, specifically at a 1/10 duty cycle with a pulse width of 0.1ms. It is useful for multiplexing or brief high-intensity flashes.
• Continuous Forward Current (I_F): 30 mA DC. This is the maximum recommended current for continuous operation, ensuring long-term reliability and stable light output.
• Reverse Voltage (V_R): 5 V. Exceeding this voltage in reverse bias can cause immediate and catastrophic failure of the LED junction.
• Operating & Storage Temperature: -30°C to +85°C and -40°C to +85°C, respectively. These ranges ensure the LED's mechanical integrity and performance across various environmental conditions.
• Soldering Condition: Withstands 260°C for 10 seconds, which aligns with typical lead-free (Pb-free) reflow soldering profiles.

2.2 Electro-Optical Characteristics

Measured at a standard ambient temperature (T_a) of 25°C and a forward current (I_F) of 20 mA, these parameters define the core performance of the LED.

• Luminous Intensity (I_V): Ranges from a minimum of 18.0 mcd to a typical value of 54.0 mcd. The actual delivered intensity is binned (see Section 3), providing predictable brightness levels for design.
• Viewing Angle (2θ_1/2): 130 degrees. This wide viewing angle is characteristic of side-looking LEDs with a diffused lens, providing a broad, even illumination pattern suitable for status indicators.
• Peak Wavelength (λ_P): 639 nm. This is the wavelength at which the spectral power output is maximum, defining the perceived hue of the red light.
• Dominant Wavelength (λ_d): 631 nm. Derived from the CIE chromaticity diagram, this is the single wavelength that best represents the color perceived by the human eye.
• Spectral Bandwidth (Δλ): 20 nm. This narrow bandwidth indicates high color purity, with most of the emitted light concentrated around the peak wavelength.
• Forward Voltage (V_F): Typically 2.4 V, with a maximum of 2.4 V at 20mA. This parameter is critical for designing the current-limiting circuitry.
• Reverse Current (I_R): Maximum 10 µA at a reverse voltage of 5V, indicating good junction quality.

3. Binning System Explanation

To ensure consistency in brightness across production batches, the LTST-S320KRKT employs a luminous intensity binning system. Each LED is tested and sorted into a specific bin code based on its measured intensity at 20 mA.

• Lambar Kwandon M: 18.0 - 28.0 mcd
• Lambar Kwandon N: 28.0 - 45.0 mcd
• Bin Code P: 45.0 - 71.0 mcd
• Bin Code Q: 71.0 - 112.0 mcd
• Bin Code R: 112.0 - 180.0 mcd

A tolerance of +/-15% is applied to each intensity bin. Designers should select the appropriate bin based on their application's brightness requirements. For example, high-visibility indicators may require Bin R or Q, while less critical status lights may use Bin M or N. This system allows for predictable performance and simplifies inventory management for manufacturers.

4. Performance Curve Analysis

While specific graphical curves are referenced in the datasheet (e.g., Fig.1, Fig.6), their implications are standard for AlInGaP LEDs. Designers can expect the following general relationships:

• I-V (Current-Voltage) Curve: The forward voltage (V_F) exhibits a logarithmic relationship with current. It remains relatively stable around the typical 2.4V within the recommended operating current range but increases with higher currents and temperature.
• Luminous Intensity vs. Forward Current: Intensity is approximately proportional to forward current up to the maximum rated current. However, efficiency (lumens per watt) typically peaks at a current lower than the absolute maximum and decreases thereafter due to thermal effects.
• Temperature Dependence: AlInGaP LEDs luminous intensity has a negative temperature coefficient. As junction temperature increases, light output decreases. Forward voltage also slightly decreases with rising temperature. Proper thermal management is crucial for maintaining consistent brightness.
• Spectral Distribution: The emission spectrum is a Gaussian-like curve centered at 639 nm (peak) with a half-width of 20 nm. The dominant wavelength (631 nm) may shift slightly (typically towards longer wavelengths) with increased junction temperature and drive current.

5. Mechanical & Package Information

The LED conforms to EIA (Electronic Industries Alliance) standard package dimensions for side-looking SMD LEDs. Key mechanical features include:

• Package Type: Standard side-view SMD package.
• Lens: Water clear, non-diffused (for the KRKT variant), maximizing light output.
• Termination: Tin (Sn) plating on the leads, providing good solderability and compatibility with lead-free processes.
• Polarity Identification: Cathode typically identified by marking on package, such as notch, dot, or trimmed lead. Datasheet includes diagram showing suggested soldering pad layout and orientation to ensure correct placement.
• Tape and Reel: Packaged in 8mm wide embossed carrier tape on 7-inch (178mm) diameter reels. Standard reel quantity is 3000 pieces. This packaging compliant with ANSI/EIA-481 specifications for automated handling.

6. Soldering & Assembly Guidelines

6.1 Reflow Soldering Profile

A suggested infrared (IR) reflow profile for Pb-free assembly is provided. Key parameters include:

• Preheat: 150-200°C for a maximum of 120 seconds to gradually heat the board and components, minimizing thermal shock.
• Peak Temperature: Maximum of 260°C. The component is rated for 10 seconds at this peak temperature.
• Time Above Liquidus (TAL): The profile should be characterized to ensure proper solder joint formation without overheating the LED. The example profile is based on JEDEC standards.

6.2 Hand Soldering

If hand soldering is necessary, use a temperature-controlled iron set to a maximum of 300°C. Limit the contact time to 3 seconds per lead, and perform this operation only once to prevent damage to the plastic package and the internal wire bonds.

6.3 Storage & Handling

• ESD (Electrostatic Discharge) Sensitivity: LEDs are susceptible to ESD. Use proper anti-static precautions like grounded wrist straps, conductive mats, and ESD-safe packaging during handling.
• Moisture Sensitivity: Yayin da rufaffen reel ke ba da kariya, abubuwan da aka cire daga marufi na asali yakamata a yi amfani da su cikin mako guda. Don ajiya mai tsawo, ajiye su a cikin yanayi mai bushewa (\u003c 30°C, \u003c 60% RH) ko a cikin akwati mai rufi tare da desiccant. Idan an adana ba tare da buɗewa ba fiye da mako guda, ana ba da shawarar gasa a 60°C na sa'o'i 20+ kafin a yi amfani da solder don hana "popcorning" (fashewar fakitin saboda tururin danshi yayin reflow).
• Tsaftacewa: Idan ana buƙatar tsaftacewa bayan solder, yi amfani da kawai takamaiman kaushi kamar isopropyl alcohol (IPA) ko ethyl alcohol a cikin dakin zafi na ƙasa da minti ɗaya. Guji sinadarai masu ƙarfi ko waɗanda ba a bayyana ba waɗanda zasu iya lalata ruwan tabarau na epoxy ko fakitin.

7. Shawarwarin Aikace-aikace

7.1 Typical Application Scenarios

• Consumer Electronics: Power, battery, or function status indicators on smartphones, tablets, routers, and audio equipment.
• Industrial Controls: Panel-mounted indicators for machine status, fault alarms, or operational modes.
• Automotive Interior: Backlighting for buttons, switches, or minor status displays (subject to specific automotive-grade qualification which this standard part may not have).
• Instrumentation: Indicator lights on test equipment, medical devices (for non-critical functions), and communication hardware.

7.2 Design Considerations

• Current Limiting: Always drive the LED with a constant current source or a current-limiting resistor in series with a voltage source. Calculate the resistor value using R = (V_source - V_F) / I_F. For a 5V supply and a target I_F of 20mA with V_F=2.4V: R = (5 - 2.4) / 0.02 = 130 Ω. Use the nearest standard value (e.g., 120Ω or 150Ω) and check the actual current.
• Thermal Management: Although power dissipation is low, ensure adequate PCB copper area or thermal vias around the solder pads to conduct heat away from the LED junction, especially when operating near maximum current or in high ambient temperatures.
• Optical Design: The side-emitting nature requires the design to incorporate a light guide or a properly positioned viewing window to channel the light to the desired location on the product housing.

8. Technical Comparison & Differentiation

LTST-S320KRKT ina tofautisha yenyewe katika soko kupitia vipengele kadhaa muhimu:

• Teknolojia ya Chip: Matumizi ya AlInGaP, ikilinganishwa na GaAsP ya zamani au GaP ya kawaida, hutoa ufanisi mkubwa wa mwanga na uthabiti bora wa joto, na kusababisha mwanga mwekundu mkali na thabiti zaidi.
• Side-Looking Package: Offers a design alternative to top-emitting LEDs, solving specific layout challenges where light needs to travel parallel to the PCB.
• High Brightness Binning: Availability of bins up to 180 mcd (Bin R) allows for applications requiring very high visibility.
• Robust Process Compatibility: Explicit compatibility with IR reflow and automatic placement streamlines manufacturing, reducing assembly cost and complexity compared to through-hole alternatives.

9. Frequently Asked Questions (FAQ)

Q: Can I drive this LED directly from a microcontroller GPIO pin?
A: It depends on the GPIO's current sourcing capability. Many MCU pins can source only 10-25mA. At 20mA, you are likely at or above the limit. It is safer to use the GPIO to control a transistor (e.g., a MOSFET) that switches the higher LED current.

Q: Why is there a difference between Peak Wavelength (639nm) and Dominant Wavelength (631nm)?
A: The peak wavelength is the physical maximum of the emission spectrum. The dominant wavelength is a calculated value based on human color perception (CIE chart). The human eye's sensitivity (photopic response) causes this shift, making the "apparent" color correspond to 631nm.

Q: What happens if I operate the LED at 30mA continuously?
A: While this is the maximum DC rating, operating at the absolute maximum will generate more heat, reduce luminous efficiency over time, and potentially shorten the LED's lifespan. For optimal reliability, derating to 15-20mA is recommended for most applications.

Q: Yaya za a fassara lambar bin lokacin yin oda?
A: Ka saka lambar bin ƙarfin haske da ake buƙata (misali, \"P\") a cikin odar siyayyarka don tabbatar da cewa za ka karɓi LEDs masu haske a cikin kewayon 45-71 mcd. Wannan yana tabbatar da daidaito a cikin bayyanar samfurinka.

10. Design-in Case Study

Scenario: Designing a status indicator for a compact IoT sensor module. The PCB is densely populated, and the indicator must be visible from the side of the enclosed unit.

Implementation: LTST-S320KRKT an zaɓe saboda kaddarorin fitarwa ta gefe. An sanya shi a gefen PCB. Ana haɗa resistor mai iyakancewar ƙarfin 120Ω a jere zuwa layin 3.3V, wanda ke haifar da kusan ƙarfin gaba na (3.3V - 2.4V)/120Ω = 7.5mA. Wannan yana ba da isasshiyar haske don amfani a cikin gida yayin da ake rage yawan amfani da wutar lantarki, wani muhimmin al'amari na na'urorin IoT masu amfani da baturi. Faɗin kusurwar kallon LED yana tabbatar da ganuwa ko da idan mahangar mai amfani ba ta daidaita daidai ba. Ana sanya kayan aikin ta amfani da daidaitaccen taron SMT, kuma an daidaita bayanin sake kwararar IR don tsayawa cikin iyakar 260°C na tsawon sakan 10, yana tabbatar da haɗin gwiwa mai aminci ba tare da lalacewar zafi ba.

11. Gabatarwar Ka'idar Fasaha

LTST-S320KRKT ya dogara ne akan fasahar semiconductor na AlInGaP. Wannan kayan wani semiconductor ne mai haɗaka daga rukunin III-V. Lokacin da ake amfani da ƙarfin lantarki na gaba a kan mahaɗin p-n, electrons daga yankin n-type da ramuka daga yankin p-type ana shigar da su cikin yankin aiki. A nan, suna sake haɗuwa, suna sakin makamashi a cikin nau'in photons (haske). Takamaiman abun da ke ciki na Aluminum, Indium, Gallium, da Phosphide a cikin Layer mai aiki yana ƙayyade ƙarfin bandgap na semiconductor, wanda kai tsaye yana ƙayyade tsawon zango (launi) na fitowar haske. Ga wannan LED ja, an ƙera bandgap don samar da photons tare da makamashi daidai da kusan 639 nm. Ruwan-ruwan epoxy lens yana rufe guntu, yana ba da kariya ta injiniya, yana siffanta tsarin fitar da haske (kusurwar kallo digiri 130), da haɓaka fitar da haske daga kayan semiconductor.

12. Trends na Masana'antu

Yarjejeniyar a cikin LEDs masu nuna alama kamar LTST-S320KRKT na ci gaba da zuwa ga mafi inganci, ƙananan fakitoci, da mafi girman haɗin kai. Yayin da AlInGaP ya kasance babban fasaha don jan LED da amber masu inganci, fasahar InGaN (Indium Gallium Nitride) ta ci gaba don rufe cikakken bakan na gani tare da inganci, ciki har da kore, shuɗi, da fari. Ci gaba na gaba na iya ganin ƙarin ƙananan fakitocin kallon gefe da ƙara amfani da guntu-sikelin fakitin (CSP) LEDs, waɗanda ke kawar da fakitin filastik na al'ada don mafi ƙaramin ƙafa da yuwuwar ingantaccen aikin zafi. Bugu da ƙari, ana ƙara mai da hankali kan daidaita launi da matsewa don biyan buƙatun aikace-aikace kamar cikakkun launi masu nuna alama da ƙwararrun hanyoyin sadarwa na mutum-mutumi inda daidaitaccen launi da haske suka fi mahimmanci.