LTST-C190TGKT-2A SMD LED Datasheet - Size 1.6x0.8x0.6mm - Voltage 2.4-3.2V - Green Color - English Technical Document

1. Product Overview

The LTST-C190TGKT-2A is a surface-mount device (SMD) light-emitting diode (LED) designed for modern, space-constrained electronic applications. This component belongs to a family of ultra-thin chip LEDs, featuring a package height of just 0.8mm. It utilizes an InGaN (Indium Gallium Nitride) semiconductor chip to produce green light, offering a balance of brightness and efficiency in a miniature form factor. The device is supplied on industry-standard 8mm tape mounted on 7-inch diameter reels, making it fully compatible with high-speed automated pick-and-place assembly equipment.

1.1 Core Advantages and Target Market

The primary advantage of this LED is its exceptionally low profile, which is critical for applications where z-height is a limiting factor, such as in ultra-thin displays, mobile devices, and wearable technology. Its compatibility with infrared (IR) reflow soldering processes aligns with standard surface-mount technology (SMT) assembly lines, ensuring reliable and efficient manufacturing. The product is specified as a "Green Product," indicating compliance with environmental regulations concerning hazardous substances. Its target market includes consumer electronics, indicator lights, backlighting for small displays, and various portable devices where reliable, bright indication in a tiny package is required.

2. Technical Parameter Deep Dive

This section provides a detailed, objective analysis of the LED's key electrical, optical, and thermal characteristics as defined in the datasheet. All parameters are specified at an ambient temperature (Ta) of 25°C.

2.1 Absolute Maximum Ratings

The Absolute Maximum Ratings define the stress limits beyond which permanent damage to the device may occur. These are not operating conditions.

• Power Dissipation (Pd): 76 mW. This is the maximum amount of power the LED package can dissipate as heat without exceeding its thermal limits.
• Peak Forward Current (I_F(PEAK)): 100 mA. This current can only be applied under pulsed conditions with a 1/10 duty cycle and a pulse width of 0.1ms. It is useful for brief, high-intensity flashes but not for continuous operation.
• DC Forward Current (I_F): 20 mA. This is the recommended maximum continuous forward current for reliable long-term operation.
• Operating Temperature Range: -20°C to +80°C. The device is designed to function within this ambient temperature range.
• Storage Temperature Range: -30°C to +100°C. The device can be stored within these limits when not powered.
• Infrared Soldering Condition: Withstands 260°C for 10 seconds. This defines the peak temperature tolerance during reflow soldering processes typical for lead-free (Pb-free) solder pastes.

2.2 Electrical & Optical Characteristics

These are the typical operating parameters that define the LED's performance under normal conditions.

• Luminous Intensity (I_V): 18.0 - 112.0 mcd (millicandela) at I_F = 2mA. This wide range indicates the device is available in different brightness bins (see Section 3). The measurement uses a filter approximating the CIE photopic eye-response curve.
• Viewing Angle (2θ_1/2): 130 degrees. This is a very wide viewing angle, meaning the light output is dispersed over a broad area rather than being a narrow beam. The angle is defined where the intensity drops to half of its axial (on-center) value.
• Peak Emission Wavelength (λ_P): 530 nm (typical). This is the wavelength at which the spectral power output is highest.
• Dominant Wavelength (λ_d): 520.0 - 540.0 nm. This is the single wavelength perceived by the human eye that defines the color of the LED, derived from the CIE chromaticity diagram. Different bins cover this range.
• Spectral Line Half-Width (Δλ): 15 nm (typical). This specifies the bandwidth of the emitted light, measured as the full width at half maximum (FWHM) of the spectral peak. A value of 15nm indicates a relatively pure green color.
• Forward Voltage (V_F): 2.4 - 3.2 V at I_F = 2mA. The voltage drop across the LED when operating. It is binned into specific ranges.
• Reverse Current (I_R): 10 μA (max) at V_R = 5V. This parameter is for test purposes only. The LED is not designed to be operated in reverse bias, and applying a reverse voltage in circuit could damage it.

3. Binning System Explanation

To ensure consistency in mass production, LEDs are sorted into "bins" based on key parameters. This allows designers to select parts that meet specific requirements for color, brightness, and voltage.

3.1 Forward Voltage Binning

Units are in Volts (V) measured at 2mA. Tolerance on each bin is ±0.1V.

• Bin D4: 2.4V (Min) to 2.6V (Max)
• Bin D5: 2.6V to 2.8V
• Bin D6: 2.8V to 3.0V
• Bin D7: 3.0V to 3.2V

Selecting a tighter voltage bin can help in designing more consistent current-limiting circuits, especially when driving multiple LEDs in series.

3.2 Luminous Intensity Binning

Units are in millicandela (mcd) measured at 2mA. Tolerance on each bin is ±15%.

• Bin M: 18.0 mcd to 28.0 mcd
• Bin N: 28.0 mcd to 45.0 mcd
• Bin P: 45.0 mcd to 71.0 mcd
• Bin Q: 71.0 mcd to 112.0 mcd

This binning allows for selection based on application brightness needs, from low-power indicators to brighter status lights.

3.3 Dominant Wavelength Binning

Units are in nanometers (nm) measured at 2mA. Tolerance for each bin is ±1 nm.

• Bin AP: 520.0 nm to 525.0 nm (Greener, closer to blue-green)
• Bin AQ: 525.0 nm to 530.0 nm
• Bin AR: 530.0 nm to 535.0 nm (Typical green)
• Bin AS: 535.0 nm to 540.0 nm (Yellow-green)

This is crucial for color-critical applications where a specific shade of green must be maintained across multiple units or matched with other components.

4. Performance Curve Analysis

While specific graphical curves are referenced in the datasheet (e.g., Fig.1, Fig.5), their typical behavior can be described based on standard LED physics and the provided parameters.

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

The forward voltage (V_F) has a logarithmic relationship with forward current (I_F). At the test condition of 2mA, V_F is between 2.4V and 3.2V. As current increases, V_F will increase slightly. The LED exhibits a diode-like characteristic: negligible current flows below a threshold voltage (around 2V for green InGaN), after which current increases rapidly with small increases in voltage. Therefore, LEDs must be driven by a current-limited source, not a voltage source.

4.2 Luminous Intensity vs. Forward Current

The luminous intensity (I_V) is approximately proportional to the forward current over a significant range. Operating at 2mA provides the binned intensity values. Increasing the current will increase the light output, but this relationship may become sub-linear at higher currents due to heating and efficiency droop. The maximum DC current of 20mA provides a guideline for the upper operating limit to maintain reliability.

4.3 Spectral Distribution

The LED emits light primarily in the green region of the visible spectrum. The peak wavelength is typically 530 nm, with a spectral half-width of 15 nm. This results in a relatively pure green color. The dominant wavelength (λ_d), which defines the perceived color, varies between 520 nm and 540 nm depending on the bin. The spectrum is largely independent of drive current but can experience a slight shift with junction temperature.

5. Mechanical & Packaging Information

5.1 Package Dimensions

The LED features an industry-standard "chip LED" package. Key dimensions (in millimeters) include a very low profile height of 0.8mm. The datasheet includes detailed mechanical drawings showing top, side, and bottom views with all critical dimensions and tolerances (typically ±0.10mm). The bottom view clearly shows the anode and cathode pad layout and polarity marking.

5.2 Polarity Identification

Polarity is typically indicated by a marking on the package or by an asymmetric pad design on the bottom. Correct polarity is essential for operation. Applying reverse voltage can cause immediate failure.

5.3 Suggested Soldering Pad Layout

The datasheet provides a recommended land pattern (footprint) for PCB design. Adhering to this pattern ensures proper soldering, alignment, and mechanical stability. The design typically includes thermal relief connections to manage heat during soldering and operation.

6. Soldering & Assembly Guidelines

6.1 Reflow Soldering Profile

The device is compatible with infrared (IR) reflow soldering processes using lead-free (Pb-free) solder paste. A suggested profile is provided, which generally follows JEDEC standards. Key parameters include:

• Pre-heat: 120-150°C range.
• Pre-heat Time: Maximum 120 seconds to allow for paste flux activation and temperature stabilization.
• Peak Temperature: Maximum 260°C.
• Time Above Liquidus: The profile should limit the time the LED's leads are above the solder melting point to about 10 seconds maximum.

The profile is characterized to prevent thermal shock and ensure reliable solder joints without damaging the LED's internal structure or epoxy lens.

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.
• Frequency: Should be performed only once. Repeated heating increases the risk of damage.

A fine-tip soldering iron and appropriate flux are recommended.

6.3 Cleaning

Only specified cleaning agents should be used. Recommended solvents include ethyl alcohol or isopropyl alcohol at normal temperature. The LED should be immersed for less than one minute. Unspecified chemicals may damage the plastic package or lens.

6.4 Storage Conditions

Proper storage is critical for SMD components:

• Sealed Package: Store at ≤30°C and ≤90% Relative Humidity (RH). Use within one year of opening the moisture barrier bag.
• Opened Package: For components removed from their original dry-pack, the ambient should not exceed 30°C / 60% RH. It is recommended to complete IR reflow within one week.
• Extended Storage (Opened): Store in a sealed container with desiccant or in a nitrogen desiccator.
• Baking: LEDs stored out of original packaging for more than one week should be baked at approximately 60°C for at least 20 hours before assembly to remove absorbed moisture and prevent "popcorning" during reflow.

7. Packaging & Ordering Information

7.1 Tape and Reel Specifications

The product is supplied for automated assembly:

• Tape Width: 8mm.
• Reel Diameter: 7 inches (178mm).
• Quantity per Reel: 4000 pieces.
• Minimum Order Quantity (MOQ): 500 pieces for remainder quantities.
• Pocket Sealing: Empty pockets are sealed with top cover tape.
• Missing Components: A maximum of two consecutive missing lamps is allowed per the specification.
• Standard: Packaging conforms to ANSI/EIA-481-1-A-1994 specifications.

8. Application Suggestions

8.1 Typical Application Scenarios

• Status Indicators: Power, connectivity, or activity lights in consumer electronics (routers, chargers, smart home devices).
• Backlighting: Edge-lighting for small LCD displays or icons in thin devices.
• Portable & Wearable Devices: Indicator lights in smartphones, fitness trackers, and hearables where thickness is critical.
• Panel Indicators: Clustered indicators on control panels and instrumentation.

8.2 Design Considerations

• Current Driving: Always use a series current-limiting resistor or a constant-current driver circuit. Calculate the resistor value using R = (V_supply - V_F) / I_F. Use the maximum V_F from the bin to ensure minimum current is met if V_supply is at its minimum.
• Thermal Management: While power dissipation is low, ensure adequate PCB copper area or thermal vias under the pads if operating near maximum current, especially in high ambient temperatures.
• ESD Protection: The LED is sensitive to electrostatic discharge (ESD). Implement ESD-safe handling procedures (wrist straps, grounded workstations) during assembly and design. Consider adding transient voltage suppression (TVS) diodes or resistors on sensitive lines if the application environment is prone to ESD.
• Optical Design: The 130-degree viewing angle provides wide dispersion. For directed light, an external lens or light guide may be necessary.

9. Technical Comparison & Differentiation

The LTST-C190TGKT-2A differentiates itself primarily through its ultra-thin 0.8mm profile. Compared to standard 1.0mm or 1.2mm height LEDs, this allows for design in thinner end products. The use of InGaN technology provides higher efficiency and brighter output compared to older technologies like AlGaInP for green, though at a typically higher forward voltage. The comprehensive binning system offers designers fine control over color and brightness consistency, which is an advantage over LEDs supplied with wider, unspecified parameter spreads.

10. Frequently Asked Questions (FAQ)

10.1 Can I drive this LED at 20mA continuously?

Yes, 20mA is the maximum recommended DC forward current. For longest lifetime and reliability, operating at a lower current such as 10-15mA is often advisable, as it reduces thermal stress. Always refer to the derating curves if available.

10.2 What resistor do I need for a 5V supply?

Using the formula R = (V_supply - V_F) / I_F. For a target I_F of 5mA and a maximum V_F of 3.2V (Bin D7): R = (5V - 3.2V) / 0.005A = 360 Ohms. For a target of 10mA: R = (5V - 3.2V) / 0.01A = 180 Ohms. Always choose the next higher standard resistor value and consider power rating (P = I²R).

10.3 Why is there a reverse current specification if I shouldn't apply reverse voltage?

The I_R specification at V_R=5V is a quality and leakage test parameter performed during manufacturing. It verifies the integrity of the semiconductor junction. In an actual circuit, you should never subject the LED to a reverse bias, as even a small reverse voltage beyond the device's low reverse breakdown voltage can cause immediate and catastrophic failure.

10.4 How do I interpret the bin codes in an order?

A full order code might specify bins for V_F, I_V, and λ_d (e.g., D5-N-AR). This would specify LEDs with a forward voltage of 2.6-2.8V, luminous intensity of 28-45 mcd, and a dominant wavelength of 530-535 nm. Consult the manufacturer for exact ordering syntax.

11. Practical Design Case

Scenario: Designing a low-battery indicator for a portable device powered by a 3.7V Li-ion battery. The indicator should be clearly visible but minimize power consumption. Design Steps:

1. Current Selection: Choose I_F = 5mA for a good balance of brightness and low power.
2. Voltage Consideration: Battery voltage ranges from ~4.2V (full) to ~3.0V (low). Use the minimum system voltage (3.0V) for worst-case resistor calculation to ensure the LED still turns on.
3. Resistor Calculation (Worst-case): Assume using a V_F Bin D7 LED (max V_F = 3.2V). At low battery (3.0V), there is insufficient voltage to forward bias the LED (3.0V < 3.2V). Therefore, select a lower V_F bin (e.g., D4: max 2.6V) or use a charge pump/LED driver for consistent performance across the battery range. If using Bin D4 with max V_F=2.6V at low battery: R = (3.0V - 2.6V) / 0.005A = 80 Ohms. At full charge (4.2V): I_F = (4.2V - 2.4V_min) / 80 = 22.5mA (exceeds 20mA max). This shows the challenge of driving LEDs directly from a varying voltage source. A constant-current circuit or a more sophisticated driver is recommended for optimal performance and LED safety.

12. Operating Principle Introduction

Light-emitting diodes are semiconductor devices that convert electrical energy directly into light through a process called electroluminescence. The LTST-C190TGKT-2A uses an InGaN (Indium Gallium Nitride) compound semiconductor. When a forward voltage is applied across the p-n junction, electrons from the n-type region and holes from the p-type region are injected into the active region. When these charge carriers recombine, they release energy in the form of photons (light). The specific wavelength (color) of the emitted light is determined by the bandgap energy of the semiconductor material. InGaN materials are used to produce light in the blue, green, and ultraviolet parts of the spectrum. The green color of this LED is a result of the specific composition of indium, gallium, and nitrogen in its active layer.

13. Technology Trends

The development of LEDs like the LTST-C190TGKT-2A follows several key industry trends. There is a continuous drive toward miniaturization, enabling thinner and smaller end products. Efficiency improvements in InGaN materials are leading to higher luminous efficacy (more light output per electrical watt), which is crucial for battery-powered devices. Another trend is the refinement of binning and tighter parameter control, allowing for more consistent performance in mass production and enabling applications with stringent color or brightness uniformity requirements. Finally, enhanced reliability and compatibility with lead-free, high-temperature soldering processes are essential to meet global environmental regulations and modern manufacturing standards.