LTST-C193KFKT-5A Orange SMD LED Datasheet - Dimensions 1.6x0.8x0.35mm - Voltage 1.7-2.3V - Power 75mW - English Technical Document

1. Product Overview

The LTST-C193KFKT-5A is a surface-mount device (SMD) chip LED designed for modern, space-constrained electronic applications. Its primary feature is an exceptionally low profile, with a height of just 0.35 millimeters, making it suitable for ultra-thin consumer electronics, backlighting, and indicator applications where component height is a critical design factor. The device emits a bright orange light using an AllnGaP (Aluminum Indium Gallium Phosphide) semiconductor material, known for its high efficiency and good color purity. It is packaged on 8mm tape and supplied on 7-inch reels, fully compatible with high-speed automated pick-and-place assembly equipment and standard infrared (IR) reflow soldering processes.

1.1 Key Features and Advantages

The LED offers several distinct advantages for designers. Its RoHS compliance and green product designation ensure it meets international environmental regulations. The EIA standard package footprint guarantees compatibility with a wide range of existing PCB layouts and manufacturing tooling. The device is also I.C. (Integrated Circuit) compatible, meaning it can be driven directly from typical logic-level voltages with appropriate current limiting, simplifying circuit design. The combination of ultra-thin profile, reliable performance, and manufacturing-friendly packaging positions this LED as a versatile component for mass production.

2. Absolute Maximum Ratings

Operating any electronic component beyond its absolute maximum ratings can cause permanent damage. For the LTST-C193KFKT-5A, the maximum continuous DC forward current is specified at 30 mA. Under pulsed conditions with a 1/10 duty cycle and a 0.1ms pulse width, it can handle a peak forward current of 80 mA. The maximum power dissipation is 75 mW, a critical parameter for thermal management. The device can withstand a reverse voltage of up to 5 volts. The operating ambient temperature range is from -30°C to +85°C, while the storage temperature range extends slightly wider from -40°C to +85°C. For assembly, the LED is rated for infrared reflow soldering with a peak temperature of 260°C for a maximum of 10 seconds.

3. Electro-Optical Characteristics

The performance of the LED is characterized under standard test conditions at an ambient temperature (Ta) of 25°C. The key parameters define its light output and electrical behavior.

3.1 Luminous Intensity and Viewing Angle

At a forward current (IF) of 5 mA, the luminous intensity (Iv) has a typical value within a binning range. The minimum value starts at 11.2 millicandelas (mcd), with a maximum of 45.0 mcd for the highest bin. The luminous intensity is measured using a sensor and filter combination that approximates the photopic (CIE) eye-response curve. The device features a very wide viewing angle (2θ1/2) of 130 degrees. This parameter, defined as the full angle at which the luminous intensity drops to half of its axial (on-axis) value, indicates the LED emits light over a broad area, suitable for applications requiring wide-angle visibility.

3.2 Spectral Characteristics

The spectral properties define the color of the emitted light. The peak emission wavelength (λP) is typically 611 nanometers (nm). The dominant wavelength (λd), which is the single wavelength perceived by the human eye to represent the color, is typically 605 nm at 5 mA. The spectral line half-width (Δλ), a measure of the spectral purity or how narrow the light output is around the peak wavelength, is 17 nm. These values are characteristic of high-quality orange AllnGaP LEDs.

3.3 Electrical Characteristics

The forward voltage (VF) of the LED, measured at IF=5mA, ranges from a minimum of 1.70 volts to a maximum of 2.30 volts. This range is subject to the binning process described later. The reverse current (IR) is very low, with a maximum of 10 microamperes (μA) when a reverse voltage (VR) of 5V is applied, indicating good diode characteristics.

4. Binning System

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 their application.

4.1 Forward Voltage Binning

The forward voltage is categorized into three bins: E2 (1.70V - 1.90V), E3 (1.90V - 2.10V), and E4 (2.10V - 2.30V). A tolerance of ±0.1 volt is applied to each bin. Selecting LEDs from the same voltage bin helps maintain uniform brightness when multiple LEDs are connected in parallel, as they will experience similar voltage drops.

4.2 Luminous Intensity Binning

The luminous intensity is binned into three categories: L (11.2 - 18.0 mcd), M (18.0 - 28.0 mcd), and N (28.0 - 45.0 mcd). A tolerance of ±15% applies to each intensity bin. This binning is crucial for applications requiring consistent brightness levels across multiple indicators or backlighting elements.

5. Package and Mechanical Information

The physical dimensions and handling of the component are critical for PCB design and assembly.

5.1 Package Dimensions

The LED has a very compact footprint. Detailed dimensioned drawings in the datasheet specify the length, width, height (0.35mm), and the placement of the cathode identifier. All dimensions are in millimeters with a standard tolerance of ±0.10 mm unless otherwise noted. The package follows EIA standard outlines for compatibility.

5.2 Suggested Soldering Pad Layout

A recommended land pattern (solder pad design) for the PCB is provided. This layout is optimized for reliable solder joint formation during reflow soldering. The datasheet suggests a maximum stencil thickness of 0.10mm for solder paste application to prevent bridging or excessive solder.

5.3 Tape and Reel Packaging

The LEDs are supplied in embossed carrier tape with a width of 8mm, wound onto 7-inch (178mm) diameter reels. Each reel contains 5000 pieces. The packaging conforms to ANSI/EIA 481-1-A-1994 specifications. Empty component pockets are sealed with a top cover tape. Specific rules are noted, such as a maximum of two consecutive missing components and a minimum packing quantity of 500 pieces for remainder reels.

6. Assembly and Handling Guidelines

Proper handling is essential to maintain reliability and performance.

6.1 Soldering Process

The LED is fully compatible with infrared (IR) reflow soldering processes, which is the standard for SMD assembly. A detailed reflow profile suggestion is provided for lead-free (Pb-free) solder processes. Key parameters include a pre-heat zone, a controlled ramp-up, a peak temperature not exceeding 260°C, and a time above liquidus (TAL) as per the profile. The total time at peak temperature should be a maximum of 10 seconds. For manual rework with a soldering iron, the tip temperature should not exceed 300°C, and contact time should be limited to 3 seconds, for one time only. The datasheet emphasizes that the final profile should be characterized for the specific PCB design, components, and solder paste used.

6.2 Cleaning

If cleaning after soldering is necessary, only specified solvents should be used. Unspecified chemicals may damage the LED epoxy package. The recommended method is to immerse the LED in ethyl alcohol or isopropyl alcohol at normal room temperature for less than one minute. Aggressive or ultrasonic cleaning is not advised unless specifically tested and qualified.

6.3 Storage Conditions

Strict storage conditions are defined to prevent moisture absorption, which can cause \"popcorning\" (package cracking) during reflow. When the original moisture-proof bag with desiccant is sealed, LEDs should be stored at ≤30°C and ≤90% RH and used within one year. Once the bag is opened, the \"floor life\" begins. LEDs should be stored at ≤30°C and ≤60% RH and are recommended to be IR-reflowed within 672 hours (28 days). For longer storage out of the original bag, they should be kept in a sealed container with desiccant or in a nitrogen ambient. If the floor life exceeds 672 hours, a bake-out at approximately 60°C for at least 20 hours is required before assembly to drive out moisture.

7. Application Information and Design Considerations

Understanding the operational principles and design constraints is key to a successful implementation.

7.1 Drive Circuit Design

An LED is a current-operated device. Its light output is primarily a function of forward current, not voltage. Therefore, driving it with a constant voltage source is not recommended as it can lead to thermal runaway and destruction. The datasheet strongly recommends using a current-limiting resistor in series with the LED when connected to a voltage source. This resistor sets the operating current according to Ohm's Law: R = (V_supply - VF_LED) / I_desired. This practice is especially critical when connecting multiple LEDs in parallel to ensure current sharing and uniform brightness, as the forward voltage (VF) can vary slightly from device to device.

7.2 Thermal Management

Although the power dissipation is low (75 mW max), proper thermal design is still important for long-term reliability and stable light output. The LED's performance, particularly forward voltage and luminous intensity, is temperature-dependent. Ensuring adequate PCB copper area around the solder pads can help dissipate heat. Operating the LED at or near its maximum current rating will generate more heat and may require additional thermal considerations.

7.3 Application Scope and Cautions

The datasheet specifies that this LED is intended for ordinary electronic equipment such as office equipment, communication devices, and household appliances. For applications requiring exceptional reliability where failure could jeopardize life or health (e.g., aviation, medical devices, transportation safety systems), consultation with the manufacturer is required prior to design-in. This is a standard disclaimer for commercial-grade components.

8. Technical Deep Dive and Performance Analysis

Beyond the basic specifications, several underlying principles and performance trends are important for advanced design.

8.1 Relationship Between Current, Voltage, and Intensity

The performance curves (implied in the datasheet) would typically show that luminous intensity increases approximately linearly with forward current in the normal operating range. However, efficiency (lumens per watt) may peak at a certain current and then decrease due to increased thermal effects. The forward voltage has a negative temperature coefficient, meaning it decreases slightly as the junction temperature increases.

8.2 Material Technology: AllnGaP

The use of Aluminum Indium Gallium Phosphide (AllnGaP) as the active semiconductor material is significant. AllnGaP LEDs are known for their high efficiency in the red, orange, and yellow wavelength regions compared to older technologies like GaAsP. They offer good color stability over time and operating current, and relatively low forward voltage. The 605-611 nm orange light produced is vibrant and easily visible.

8.3 Optical Design and Viewing Angle

The 130-degree viewing angle is achieved through the chip design and the shape of the epoxy lens. A wide viewing angle is ideal for status indicators that need to be seen from various angles. For applications requiring a more focused beam, secondary optics would be necessary.

9. Comparison and Selection Guidance

When selecting an LED for a design, engineers must compare key parameters.

Key Differentiators of this LED: The primary differentiator is its ultra-low 0.35mm height. Compared to standard 0.6mm or 1.0mm tall chip LEDs, this enables thinner end products. The wide 130-degree viewing angle is another advantage for wide-area illumination. The AllnGaP technology provides good efficiency and color for orange light.

Selection Criteria: Designers should prioritize based on application needs: height constraints, required brightness (luminous intensity bin), color point (dominant wavelength), drive current compatibility, and thermal/power limits. The binning system allows for cost optimization by selecting the appropriate performance grade.

10. Frequently Asked Questions (FAQ)

Q: Can I drive this LED directly from a 3.3V or 5V microcontroller pin?

A: No, not directly. You must use a series current-limiting resistor. For example, with a 3.3V supply, a typical VF of 2.0V, and a desired current of 5mA, the resistor value would be (3.3V - 2.0V) / 0.005A = 260 Ohms. A 270 Ohm standard value resistor would be suitable.

Q: What happens if I exceed the 10-second limit at 260°C during reflow?

A: Exceeding the time/temperature limits can cause several issues: degradation of the epoxy lens (yellowing), damage to the internal wire bonds, or excessive thermal stress on the semiconductor die, potentially leading to immediate failure or reduced long-term reliability.

Q: Why is the storage and floor life so strictly defined?

A: The epoxy packaging material can absorb moisture from the air. During the high-temperature reflow soldering process, this trapped moisture rapidly turns to steam, creating high internal pressure. This can delaminate the package or even crack it open, a phenomenon known as \"popcorning.\" The storage and baking procedures control moisture content to prevent this.

Q: How do I identify the cathode on the LED?

A: The datasheet package drawing indicates the cathode marking. Typically, for such chip LEDs, the cathode is marked by a green stripe, a dot, or a chamfered corner on the top or bottom of the component. Always refer to the mechanical drawing for the specific marking.