LTST-C193KRKT-5A SMD LED Datasheet - Dimensions 1.6x0.8x0.35mm - Forward Voltage 1.7-2.3V - Red Color - 50mW Power - English Technical Document

1. Product Overview

This document provides the complete technical specifications for the LTST-C193KRKT-5A, an ultra-thin, surface-mount chip LED designed for modern, space-constrained electronic applications. The device utilizes an advanced AlInGaP (Aluminum Indium Gallium Phosphide) semiconductor material to produce a high-brightness red light output. Its primary design goals are miniaturization, compatibility with automated assembly processes, and reliable performance under standard operating conditions. The LED is supplied on industry-standard 8mm tape mounted on 7-inch reels, facilitating high-volume pick-and-place manufacturing.

2. In-Depth Technical Parameter Analysis

The performance of the LTST-C193KRKT-5A is defined by a comprehensive set of electrical, optical, and thermal parameters measured at an ambient temperature (Ta) of 25°C.

2.1 Absolute Maximum Ratings

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

• Power Dissipation (Pd): 50 mW. This is the maximum total power the package can dissipate as heat.
• Peak Forward Current (I_F(PEAK)): 40 mA. This current is permissible only under pulsed conditions with a 1/10 duty cycle and a pulse width of 0.1ms.
• Continuous Forward Current (I_F): 20 mA. This is the maximum recommended current for DC operation.
• Reverse Voltage (V_R): 5 V. Exceeding this voltage in reverse bias can cause junction breakdown.
• Operating Temperature Range: -30°C to +85°C. The device is functional within this ambient temperature range.
• Storage Temperature Range: -40°C to +85°C.
• Infrared Reflow Soldering Condition: Withstands a peak temperature of 260°C for a maximum of 10 seconds, compatible with lead-free (Pb-free) assembly processes.

2.2 Electro-Optical Characteristics

These parameters define the light output and electrical behavior under typical operating conditions (I_F = 5mA, Ta=25°C).

• Luminous Intensity (I_V): Ranges from a minimum of 7.1 mcd to a maximum of 45.0 mcd. The actual value is determined by the bin code (see Section 3). Intensity is measured using a sensor filtered to match the photopic (CIE) human eye response curve.
• Viewing Angle (2θ_1/2): 130 degrees. This wide viewing angle indicates a Lambertian or near-Lambertian emission pattern, suitable for applications requiring broad illumination rather than a focused beam.
• Peak Emission Wavelength (λ_P): 639 nm. This is the wavelength at which the spectral power distribution is at its maximum.
• Dominant Wavelength (λ_d): 631 nm. Derived from the CIE chromaticity diagram, this single wavelength best represents the perceived color (red) of the LED.
• Spectral Line Half-Width (Δλ): 20 nm. This indicates the spectral purity; a narrower width would indicate a more monochromatic light source.
• Forward Voltage (V_F): Ranges from 1.70 V to 2.30 V at 5mA. The specific range is defined by the forward voltage bin code.
• Reverse Current (I_R): Maximum 10 μA when a reverse voltage of 5V is applied.

3. Binning System Explanation

To ensure consistency in mass production, LEDs are sorted into bins based on key performance parameters. The LTST-C193KRKT-5A uses a two-dimensional binning system.

3.1 Forward Voltage Binning

Units are sorted based on their forward voltage drop at a test current of 5mA. This allows designers to select LEDs with similar electrical characteristics for uniform brightness when driven by a constant voltage source or to simplify current-limiting resistor calculations.

• Bin Code E2: V_F = 1.70V - 1.90V
• Bin Code E3: V_F = 1.90V - 2.10V
• Bin Code E4: V_F = 2.10V - 2.30V
• Tolerance within each bin is ±0.1V.

3.2 Luminous Intensity Binning

This is the primary binning parameter, categorizing LEDs by their light output at 5mA. Designers can choose a bin to meet specific brightness requirements.

• Bin Code K: I_V = 7.1 mcd - 11.2 mcd
• Bin Code L: I_V = 11.2 mcd - 18.0 mcd
• Bin Code M: I_V = 18.0 mcd - 28.0 mcd
• Bin Code N: I_V = 28.0 mcd - 45.0 mcd
• Tolerance within each bin is ±15%.

A complete part number typically includes these bin codes to specify the exact performance grade.

4. Performance Curve Analysis

While specific graphical data is referenced in the datasheet, the typical relationships can be described:

• Forward Current vs. Forward Voltage (I-V Curve): The AlInGaP material exhibits a characteristic turn-on voltage around 1.7-2.3V, after which the current increases exponentially with voltage. A constant current driver is essential for stable luminous output.
• Luminous Intensity vs. Forward Current: Intensity generally increases linearly with current in the recommended operating range (up to 20mA). Exceeding the maximum current leads to efficiency droop and accelerated degradation.
• Luminous Intensity vs. Ambient Temperature: Like all LEDs, light output decreases as the junction temperature rises. Proper thermal management in the PCB design is crucial for maintaining consistent brightness and longevity.
• Spectral Distribution: The emission spectrum is centered around 639 nm (peak) with a typical half-width of 20 nm, characteristic of AlInGaP red LEDs, which offer high efficiency and good color saturation.

5. Mechanical and Package Information

5.1 Package Dimensions

The LTST-C193KRKT-5A features an extra-thin chip-scale package.

• Package Height (H): 0.35 mm maximum. This ultra-low profile is critical for applications in slim devices like smartphones, tablets, and ultra-thin displays.
• Footprint: The package conforms to EIA (Electronic Industries Alliance) standard dimensions for chip LEDs, ensuring compatibility with standard PCB land patterns and automated optical inspection (AOI) systems.

5.2 Polarity Identification and Pad Design

The datasheet includes a detailed dimensional drawing. Polarity is typically indicated by a marking on the top of the package or an asymmetric pad design (cathode pad may be larger or uniquely shaped). A suggested solder pad layout is provided to ensure reliable solder joint formation and proper alignment during reflow. The recommended stencil thickness for solder paste application is a maximum of 0.10mm.

6. Soldering and Assembly Guidelines

6.1 Reflow Soldering Profile

The LED is compatible with infrared (IR) reflow soldering processes, specifically those designed for lead-free (Pb-free) solder paste. A suggested profile is provided, which generally follows JEDEC standards:

• Pre-heat: Ramp from ambient to 150-200°C.
• Soak/Pre-heat Time: Maximum 120 seconds to activate flux and homogenize board temperature.
• Reflow (Liquidus): Peak temperature must not exceed 260°C.
• Time Above Liquidus (TAL): The duration at or above the solder melting point should be controlled, with a maximum of 10 seconds at peak temperature.
• Number of Reflow Cycles: Maximum of two times.

Because thermal profiles depend on the specific PCB design, solder paste, and oven, the provided profile should be used as a target, and board-level characterization is recommended.

6.2 Hand Soldering

If hand soldering is necessary, extreme care must be taken:

• Iron Temperature: Maximum 300°C.
• Soldering Time: Maximum 3 seconds per pad.
• Number of Times: One time only. Repeated heating can damage the LED or the solder joint.

6.3 Cleaning

Only specified cleaning agents should be used. Unspecified chemicals may damage the plastic package.

• Recommended Agents: Ethyl alcohol or isopropyl alcohol.
• Procedure: Immerse the LED at normal temperature for less than one minute if cleaning is necessary after soldering.

6.4 Storage and Handling

• ESD (Electrostatic Discharge) Precautions: LEDs are sensitive to ESD. Use wrist straps, anti-static mats, and properly grounded equipment during handling.
• Moisture Sensitivity: The package is moisture-sensitive.
  • Sealed Package: Store at ≤30°C and ≤90% RH. Use within one year.
  • Opened Package: For components removed from the moisture-proof bag, the storage ambient should not exceed 30°C / 60% RH. It is recommended to complete IR reflow within 672 hours (28 days).
  • Extended Storage/Baking: If exposed for more than 672 hours, a bake at approximately 60°C for at least 20 hours is required before soldering to prevent "popcorning" during reflow.

7. Packaging and Ordering Information

7.1 Tape and Reel Specifications

The product is supplied for automated assembly.

• Carrier Tape Width: 8 mm.
• Reel Diameter: 7 inches.
• Quantity per Reel: 5000 pieces.
• Minimum Order Quantity (MOQ): 500 pieces for remainder quantities.
• Packing Standard: Complies with ANSI/EIA-481 specifications. Empty pockets are sealed with cover tape.
• Quality: The maximum number of consecutive missing components in the tape is two.

8. Application Notes and Design Considerations

8.1 Typical Application Scenarios

The ultra-thin profile and high brightness make this LED suitable for:

• Backlighting: Keypad, icon, or small display backlighting in mobile phones, remote controls, and portable consumer electronics.
• Status Indicators: Power, charge, connectivity, and operational status indicators in a wide range of devices.
• Panel Indicators: Illumination of buttons, switches, and symbols on control panels.
• Consumer Electronics: General illumination and signaling in appliances, office equipment, and communication devices.

Important Note: The datasheet specifies that these LEDs are intended for ordinary electronic equipment. For applications requiring exceptional reliability where failure could jeopardize life or health (aviation, medical, safety systems), consultation with the manufacturer is required prior to design-in.

8.2 Drive Method and Circuit Design

An LED is a current-operated device. To ensure uniform luminous intensity and prevent damage, it must be driven by a controlled current, not a voltage.

• Constant Current Drive: The preferred method. Use a dedicated LED driver IC or a simple current-limiting circuit.
• Current-Limiting Resistor: When using a voltage source (V_CC), a series resistor (R_S) is mandatory. Calculate it using Ohm's Law: R_S = (V_CC - V_F) / I_F. Use the maximum V_F from the bin to ensure I_F does not exceed the limit even with unit-to-unit variation.
• PWM Dimming: For brightness control, Pulse Width Modulation (PWM) is effective. Ensure the frequency is high enough to avoid visible flicker (typically >100Hz).

8.3 Thermal Management

Although power dissipation is low (50mW max), proper thermal design extends lifespan and maintains color stability.

• PCB Layout: Use thermal relief pads connected to a copper pour to help dissipate heat.
• Avoid Overdriving: Operating at or near the maximum DC current (20mA) will generate more heat. Derating the operating current (e.g., to 10-15mA) significantly improves longevity and reliability.

9. Technology and Material Overview

9.1 AlInGaP Semiconductor Technology

The LTST-C193KRKT-5A uses an AlInGaP (Aluminum Indium Gallium Phosphide) chip. This material system is renowned for producing high-efficiency LEDs in the amber, red, and orange wavelength ranges. Compared to older technologies like GaAsP, AlInGaP offers significantly higher luminous efficacy (more light output per electrical watt), better temperature stability, and superior long-term reliability. The "water clear" lens material allows the true color of the chip to be seen, resulting in a saturated red appearance.

10. Frequently Asked Questions (FAQ)

10.1 What is the difference between Peak Wavelength and Dominant Wavelength?

Peak Wavelength (λ_P): The single wavelength where the LED emits the most optical power. It's a physical measurement from the spectrum.
Dominant Wavelength (λ_d): A calculated value from the CIE color coordinates that represents the perceived color. For a monochromatic source, they are identical. For LEDs with a spectral width, λ_d is what the human eye perceives as the color, and it's the standard parameter used for color binning.

10.2 Can I use a 3.3V supply to drive this LED directly?

No, you must not connect it directly. With a typical V_F of ~2.0V, connecting it to 3.3V without a current-limiting resistor would cause excessive current to flow, destroying the LED almost instantly. Always use a series resistor or constant-current driver.

10.3 Why is there a 672-hour (28-day) floor life after opening the bag?

The plastic LED package absorbs moisture from the air. During the high-temperature reflow soldering process, this trapped moisture can rapidly vaporize, creating internal pressure that may crack the package ("popcorning"). The 672-hour limit is the time the component can be exposed to ambient factory conditions (≤30°C/60% RH) before this risk becomes unacceptable. Beyond this time, baking is required to remove the moisture.

10.4 How do I select the correct Bin Code?

Selection depends on your application's requirements:

• For uniform brightness in an array: Specify the same Luminous Intensity Bin (K, L, M, N) for all units. You may also want to specify the same Forward Voltage Bin (E2, E3, E4) if using a simple resistor drive scheme.
• For cost-sensitive applications: A wider bin (e.g., K-N) may be acceptable and cheaper.
• For precise color requirements: Ensure the Dominant Wavelength specification meets your needs. The datasheet provides a typical value; for critical color applications, consult the manufacturer for detailed chromaticity binning information.