LTST-C195KFKGKT Dual-Color SMD LED Datasheet - Orange and Green - 20mA - Technical Documentation

1. Product Overview

Takardar nan tana ba da cikakken ƙayyadaddun fasaha na kayan LED mai hawa a saman mai launi biyu. Na'urar tana haɗa guntu masu haske daban-daban guda biyu a cikin daidaitaccen kayan aikin masana'antu, tana iya fitar da haske mai launin ruwan lemo da kore. Ɗaukar hotonta ya dace da tsarin haɗawa ta atomatik da fasahar walda na zamani, yana dacewa da aikace-aikacen samar da yawa kamar na'urorin lantarki na masu amfani, fitilun nuni da hasken baya.

1.1 Main Features and Product Positioning

The main features of this component include: compliance with environmental regulations, the use of high-brightness AlInGaP semiconductor technology to achieve efficient light output, and packaging optimized for tape-and-reel automated placement. Its design is compatible with infrared (IR) and vapor phase reflow soldering processes, which are standard processes for Surface Mount Technology (SMT) production lines. Compared to using two separate single-color LEDs, the dual-color function within a single package saves board space and simplifies the design.

2. Technical Parameters: In-Depth and Objective Interpretation

The following sections provide a detailed analysis of the electrical, optical, and thermal characteristics of the device as defined in the datasheet.

2.1 Absolute Maximum Ratings

These ratings define the stress limits that may cause permanent damage to the device. Operation at or near these limits is not guaranteed and should be avoided in circuit design.

• Power Dissipation (Pd):75 mW per chip (orange and green). This is the maximum power the LED can dissipate as heat when the ambient temperature (Ta) is 25°C. Exceeding this value risks thermal runaway and failure.
• Peak Forward Current (I_FP):80 mA. This is the maximum permissible instantaneous forward current, typically specified under pulse conditions (1/10 duty cycle, 0.1ms pulse width) to prevent excessive junction temperature rise.
• Continuous forward current (I_F):30 mA DC. This is the maximum recommended current for continuous operation under normal conditions.
• Current derating:From 25°C, derate linearly at 0.4 mA/°C. When the ambient temperature exceeds 25°C, the maximum allowable continuous forward current must be reduced by this factor to keep the junction temperature within a safe range.
• Reverse voltage (V_R):5 V. Applying a reverse bias exceeding this value may cause breakdown and damage the LED junction.
• Operating and Storage Temperature:-30°C to +85°C and -40°C to +85°C, respectively. These define the environmental limits for reliable operation and non-operating storage.
• Soldering Temperature Limit:The device can withstand 260°C wave soldering or infrared soldering for 5 seconds, and 215°C vapor phase soldering for 3 minutes. These parameters are crucial for defining the reflow soldering profile during PCB assembly.

2.2 Electrical and Optical Characteristics

Unless otherwise specified, these parameters are measured at Ta=25°C and I_FMeasured under standard test conditions of =20mA. They define the typical performance of the device.

• Luminous Intensity (I_V):
  • Orange Chip:Minimum 45.0 mcd, typical value not specified, maximum 280.0 mcd.
  • Green chip:Minimum 18.0 mcd, typical value not specified, maximum 71.0 mcd.

  The wide range between minimum and maximum values indicates that the device has different luminous intensity bins (see Section 3). Under the same drive current, the orange chip is significantly brighter than the green chip.

• Perspective (2θ_1/2):Both colors are 130 degrees (typical value). This wide viewing angle indicates a diffuser lens type, suitable for applications requiring wide-range illumination rather than a focused beam.
• Wavelength:
  • Orange:Peak wavelength (λ_P)~611 nm, dominant wavelength (λ_d)~605 nm.
  • Green:Peak wavelength (λ_P)~574 nm, dominant wavelength (λ_d)~571 nm.

  The dominant wavelength is the color perceived by the human eye, derived from the CIE chromaticity diagram.

• Spectral line half-width (Δλ):Approximately 17 nm for orange, and approximately 15 nm for green. This indicates the spectral purity or bandwidth of the emitted light.
• Forward voltage (V_F):For both colors at 20mA, typical 2.0V, maximum 2.4V. This low forward voltage is characteristic of AlInGaP technology and is important for calculating series resistance and power dissipation.
• Reverse current (I_R):At V_R=5V, maximum 10 µA. This is the leakage current when the LED is reverse biased.
• Capacitance (C):Typical value 40 pF at 0V, 1MHz. This parameter may be relevant for high-frequency switching applications.

3. Explanation of the Binning System

LED light intensity is graded to ensure consistency within production batches. The grading code defines specific intensity ranges.

3.1 Orange LED Light Intensity Binning

In I_FIntensity measured at =20mA. Tolerance for each bin is +/-15%.

• Bin P:45.0 - 71.0 mcd
• Bin Q:71.0 - 112.0 mcd
• Bin R:112.0 - 180.0 mcd
• Bin S:180.0 - 280.0 mcd

3.2 Green LED Light Intensity Binning

In I_FIntensity measured at =20mA. Tolerance for each bin is +/-15%.

• Bin M:18.0 - 28.0 mcd
• Bin N:28.0 - 45.0 mcd
• Bin P:45.0 - 71.0 mcd

Designers should specify the required bin code when ordering to ensure the desired brightness level is obtained in their application.

4. Performance Curve Analysis

The datasheet references typical characteristic curves, which are crucial for understanding the device's behavior under various conditions. Although the specific graphs are not reproduced here, their significance is analyzed.

4.1 Current-Voltage (I-V) Curve

The I-V curve of an LED is exponential. The typical V at 20mA_FIt provides a critical operating point at 2.0V. The curve shows that a small increase in voltage beyond the knee point leads to a large (potentially destructive) increase in current. This highlights the necessity of current-limiting methods (e.g., series resistors or constant current drivers).

4.2 Light Intensity - Forward Current Relationship

The curve is typically linear within a certain range. The luminous intensity is approximately proportional to the forward current. Driving the LED at its maximum continuous current (30mA) yields higher brightness than the standard test condition of 20mA, but thermal management and lifetime considerations must be evaluated.

4.3 Temperature Dependence

LED performance is temperature-sensitive. The forward voltage (V_F) typically decreases as the junction temperature rises. More critically, luminous intensity degrades with increasing temperature. The current derating specification (0.4 mA/°C) is a direct design constraint for managing this thermal effect and maintaining reliability.

5. Mechanical and Packaging Information

This device complies with EIA standard surface-mount package dimensions.

5.1 Pin Assignment

The dual-color LED has four pins (1, 2, 3, 4). According to the datasheet:

• Pins 1 and 3 are assigned to the orange LED chip.
• Pins 2 and 4 are assigned to the green LED chip.

This configuration typically indicates an internal common-cathode or common-anode arrangement, which must be verified against the package outline drawing to ensure correct circuit connections.

5.2 Package Dimensions and Tape and Reel Packaging

The device is supplied in 8mm tape on 7-inch diameter reels, compatible with automatic placement machines. The tape and reel specifications comply with the ANSI/EIA 481-1-A-1994 standard. Key packaging details include:

• 4000 units per 7-inch reel.
• The minimum packaging quantity for remaining parts is 500 units.
• A maximum of two consecutive missing components ("LEDs") is allowed in the reel.

Recommended solder pad dimensions are provided to ensure reliable solder joints and proper alignment during the reflow soldering process.

6. Welding and Assembly Guide

6.1 Recommended Reflow Soldering Profile

Two soldering profiles are recommended:

1. Curve ya kawaida ya kulehemu kwa njia ya mionzi ya infrared:Inafaa kwa mchakato wa kawaida wa solder ya stani na risasi.
2. Curve ya kulehemu kwa njia ya mionzi ya infrared isiyo na risasi (Pb-Free):Must be used with Sn-Ag-Cu (SAC) solder paste. This profile typically has a higher peak temperature (e.g., 260°C), but the time above liquidus must be strictly controlled to prevent thermal damage to the LED's plastic lens and internal structure.

Absolute maximum conditions are: infrared/wave soldering at 260°C for 5 seconds, vapor phase soldering at 215°C for 3 minutes.

6.2 Storage and Handling Precautions

• Storage:It is recommended not to exceed 30°C and 70% relative humidity. LEDs removed from the original moisture barrier bag should be reflow soldered within one week. For longer-term storage, they should be kept in a dry, sealed environment (e.g., using desiccant or in nitrogen) and baked at approximately 60°C for 24 hours before use to remove absorbed moisture and prevent the "popcorn" phenomenon during reflow soldering.
• Cleaning:Only specified cleaning agents should be used. It is recommended to use isopropyl alcohol or ethanol at room temperature for no more than one minute. Unspecified chemicals may damage the LED package or lens.
• ESD Protection:LEDs are sensitive to electrostatic discharge. Appropriate ESD control measures must be taken during handling: use grounded wrist straps, anti-static mats, ionizers to neutralize static on the lens, and ensure all equipment is properly grounded.

7. Application Recommendations

7.1 Typical Application Scenarios

This bicolor LED is suitable for various indicator light and status display applications, including but not limited to:

• Power/status indicators on consumer electronics (e.g., routers, chargers, home appliances).
• Bicolor status lights (e.g., green for "on/normal," orange for "standby/warning").
• Backlighting for small icons or buttons.
• Automotive interior indicator lights (require proper certification).
• Industrial equipment status panels.

7.2 Circuit Design Considerations

Driving Method:LED is a current-driven device. To ensure uniform brightness, especially when multiple LEDs are connected in parallel, it is necessary toeachLED in series with a current-limiting resistor (Circuit Model A). Relying on the natural I-V characteristics to balance current in a parallel configuration without independent resistors (Circuit Model B) is not recommended, because small differences in V_Fbetween LEDs can lead to significant differences in current and brightness.

The value of the series resistor (R_s) can be calculated using Ohm's law: R_s= (V_{Power supply}- V_F) / I_F. Use the maximum V from the datasheet_Fvalue (2.4V) to ensure sufficient current under all conditions.

7.3 Thermal Management

Although the power consumption is low (75mW per chip), proper PCB layout contributes to thermal performance. Ensure sufficient copper area is connected to the LED's thermal pad (if available) or surrounds the solder pad to act as a heat sink, especially when operating near maximum ratings or in high ambient temperatures.

8. Technical Comparison and Differentiation

The primary differentiating factor of this component is itsDual-color functionality within a single SMD packageand the orange emitter employsAlInGaP technology。

• Compared to monochromatic LEDs:Saves PCB space, reduces component count, and simplifies assembly compared to installing two separate LEDs.
• AlInGaP compared to other technologies:AlInGaP (Aluminum Indium Gallium Phosphide) is renowned for its high efficiency and stability in the red, orange, and yellow wavelength regions, typically offering higher brightness and better temperature performance than older technologies such as GaAsP.
• Wide Viewing Angle (130°):It provides an ideal diffused light pattern, suitable for wide-area indication, as opposed to narrow-angle LEDs used for focused illumination.

9. Frequently Asked Questions (Based on Technical Parameters)

9.1 Can I drive this LED directly with a 5V or 3.3V microcontroller pin?

No, it cannot be driven directly.LEDs require current control. Connecting them directly to a voltage source like an MCU pin (MCU pins typically have current limiting, but are not designed for driving LEDs) may damage the LED and the microcontroller output. Always use a series current-limiting resistor or a dedicated LED driver circuit.

9.2 Peak wavelength and dominant wavelength, what is the difference?

Peak wavelength (λ_P)It is the wavelength at which the spectral power distribution reaches its maximum value.Dominant Wavelength (λ_d)is the wavelength of monochromatic light that matches the LED color perceived by the human eye, calculated based on CIE chromaticity coordinates. λ_dis more relevant for color specifications in human-centric applications.

9.3 Why is current derating necessary?

Yayin da yanayin zafi ya ƙaru, ga wani ƙayyadaddun ƙarfin aiki, zafin haɗin LED zai tashi. Mafi girman zafin haɗin zai hanzarta hanyoyin lalacewa, ya rage rayuwar LED, kuma yana iya haifar da gazawar bala'i. Rage ƙarfin lantarki yana rage yawan amfani da wutar lantarki, don haka yana rage zafin haɗin, yana tabbatar da dogon lokacin aminci.

10. Practical Design Case Study

Scene:Design a dual-color status indicator for devices using a 5V power rail. The indicator should display green during "normal operation" and orange during "charging/warning".

Design Steps:

1. Circuit Topology:Use two microcontroller GPIO pins. Each pin drives one color of the LED through an independent current-limiting resistor. Configure internal connections (common anode/cathode) correctly according to the package diagram.
2. Resistor Calculation (for 20mA drive):
   • Assuming V_F(max) = 2.4V, V_{Power supply}= 5V, I_F= 20mA.
   • R = (5V - 2.4V) / 0.020A = 130 ohms.
   • Select the closest standard value (e.g., 130Ω or 120Ω). A 120Ω resistor will result in a slightly higher current (approximately 21.7mA), which is acceptable as it is below the maximum of 30mA.
3. PCB Layout:Place the LED and its series resistor together. Provide adequate copper pour around the LED pads for heat dissipation. Follow the recommended soldering pad layout in the datasheet.
4. Software:Implementation logic: Open the green GPIO in normal state, and open the orange GPIO in warning state. Ensure they are not turned on simultaneously unless a mixed color is required, while also considering the total drive current limit of the package.

11. Introduction to Working Principle

A light-emitting diode (LED) is a semiconductor device that emits light through electroluminescence. When a forward voltage is applied across the p-n junction, electrons and holes are injected into the active region where they recombine. The energy released during recombination is emitted in the form of photons (light). The specific wavelength (color) of the light is determined by the bandgap energy of the semiconductor material used in the active region. In this device, orange light is generated by an AlInGaP chip, and green light is generated by another chip (likely based on InGaN technology, though the technology for the green chip is not explicitly stated here). Both chips are co-packaged in an epoxy encapsulation with a diffused lens that shapes the light output into a wide viewing angle.

12. Technology Development Trends

The LED technology field continues to develop, with several clear trends related to such components:

• Efficiency Improvement:Continuous advancements in materials science and chip design lead to higher luminous efficacy (more light output per watt of electrical input), enabling brighter indicator lights or lower power consumption.
• Miniaturization:The drive for smaller electronic devices is pushing the continuous reduction in LED package sizes while maintaining or improving optical performance.
• Enhanced Reliability and Lifespan:Improvements in packaging materials, die-attach methods, and phosphor technology (for white LEDs) continue to extend operational lifespan and stability under harsh conditions.
• Integration:Beyond multicolor, the trend is to integrate control electronics—such as constant-current drivers or PWM controllers—directly with the LED chip or within the package, creating "smart LED" modules that simplify system design.
• Environmental Compliance:The transition to lead-free (Pb-Free) soldering and halogen-free materials has now become standard, as reflected in the independent soldering profile provided in this specification.