LTL-R14FSGAJ3H79G LED Lamp Datasheet - Through Hole - Yellow/Yellow Green - 20mA - English Technical Document

1. Product Overview

The LTL-R14FSGAJ3H79G is a through-hole mounted LED lamp designed as a Circuit Board Indicator (CBI). It utilizes a black plastic right-angle holder (housing) that mates with the LED component. This product family is known for its versatility, available in configurations including top-view (spacer) or right-angle orientations, and can be arranged in horizontal or vertical arrays. The design emphasizes ease of assembly and is stackable for efficient use on printed circuit boards (PCBs).

1.1 Key Features

• Engineered for simplified circuit board assembly processes.
• Black housing material enhances the visual contrast ratio of the illuminated indicator.
• Offers low power consumption coupled with high luminous efficiency.
• Manufactured as a lead-free product and is fully compliant with RoHS (Restriction of Hazardous Substances) directives.
• Utilizes T-1 sized LED lamps. The emitted colors are generated by AlInGaP (Aluminum Indium Gallium Phosphide) semiconductor chips, specifically for yellow and yellow-green wavelengths.

1.2 Target Applications

This LED lamp is suitable for a broad range of electronic equipment and indicator applications, including but not limited to:

• Computer systems and peripherals
• Communication equipment
• Consumer electronics
• Industrial control and instrumentation panels

2. Outline Dimensions

The mechanical drawing provides the physical specifications of the component. Critical notes associated with the dimensions include:

• All linear dimensions are specified in millimeters, with equivalent values in inches provided in parentheses.
• The default dimensional tolerance is ±0.25mm (±0.010\") unless a specific note indicates otherwise.
• The holder (housing) is constructed from plastic material in black or dark gray color, rated UL 94V-0 for flammability resistance.
• The device incorporates LED1~LED3, which are bi-color (yellow/yellow green) elements paired with a white diffused lens for light dispersion.
• All specifications are subject to change without prior notice.

3. Absolute Maximum Ratings

The following ratings define the limits beyond which permanent damage to the device may occur. All values are specified at an ambient temperature (TA) of 25°C.

4. Electrical & Optical Characteristics

These parameters define the typical performance of the LED under normal operating conditions at TA=25°C.

4.1 Characteristic Notes

• Luminous intensity measurement uses a sensor and filter combination approximating the CIE photopic eye-response curve.
• Viewing angle (θ1/2) is defined as the off-axis angle where luminous intensity drops to half its axial (on-axis) value.
• Dominant wavelength (λd) is derived from the CIE chromaticity diagram, representing the perceived single wavelength of the color. Testing tolerance is ±1nm.
• Luminous intensity (Iv) guarantee includes a ±30% testing tolerance.
• Reverse current is primarily controlled by the characteristics of the semiconductor die source.
• Important: The reverse voltage (VR) condition is applied for IR testing only. This LED device is not designed for operation under reverse bias.

5. Typical Performance Curves

The datasheet includes graphical representations of key relationships, typically plotted against variables such as forward current (IF) and ambient temperature (TA). These curves are essential for design engineers to predict performance under non-standard conditions. Common curves include:

• Relative Luminous Intensity vs. Forward Current: Shows how light output scales with drive current, typically exhibiting a sub-linear relationship at higher currents due to efficiency droop.
• Relative Luminous Intensity vs. Ambient Temperature: Demonstrates the thermal quenching effect, where light output decreases as junction temperature rises.
• Forward Voltage vs. Forward Current: Illustrates the diode's I-V characteristic, crucial for designing current-limiting circuitry.
• Spectral Power Distribution: Graphs showing the relative intensity of emitted light across the wavelength spectrum for both yellow and yellow-green chips, highlighting the peak and dominant wavelengths.

These curves are generated at an ambient temperature of 25°C unless otherwise noted on the graph axes.

6. Binning System Specification

To ensure color and brightness consistency in production, LEDs are sorted into bins based on measured parameters. The LTL-R14FSGAJ3H79G uses separate bin codes for luminous intensity and dominant wavelength for each color.

6.1 Luminous Intensity Binning (at IF=20mA)

Tolerance for each bin limit is ±30%.

6.2 Dominant Wavelength Binning (at IF=20mA)

Tolerance for each bin limit is ±1nm.

This binning system allows designers to select components that meet specific brightness and color consistency requirements for their application, particularly important in multi-indicator arrays.

7. Packaging Specification

The packing specification details how the components are supplied for automated or manual assembly. It typically includes information about:

• Carrier Tape: Dimensions of the pockets holding the LEDs, tape width, pitch (distance between pockets), and spool diameter.
• Reel Information: Standard reel quantities (e.g., 1000 pieces per reel), reel material, and orientation of components on the tape.
• Moisture Barrier Bag: If applicable, specifications for the bag used to protect moisture-sensitive devices during storage and shipping.
• Labeling: Information printed on the reel label, including part number, quantity, date code, and bin codes.

Adherence to the packing spec is crucial for ensuring compatibility with pick-and-place machinery and maintaining component integrity.

8. Assembly & Handling Guidelines

8.1 Application Scope

This LED lamp is suitable for both indoor and outdoor signage applications, as well as standard electronic equipment. The environmental sealing of the lens and the materials used determine its suitability for harsher environments.

8.2 Storage Conditions

For optimal long-term reliability, LEDs should be stored in an environment not exceeding 30°C and 70% relative humidity. Components removed from their original, sealed moisture-barrier packaging should ideally be used within three months. For extended storage outside the original packaging, it is recommended to place the LEDs in a sealed container with desiccant or in a nitrogen-purged desiccator to prevent moisture absorption, which can cause \"popcorning\" during soldering.

8.3 Cleaning

If cleaning is necessary after soldering or due to contamination, use only alcohol-based solvents such as isopropyl alcohol (IPA). Avoid using aggressive solvents, ultrasonic cleaning (which can damage the LED structure), or aqueous cleaners unless explicitly rated for the component.

8.4 Lead Forming & PCB Assembly

• Bending Point: Leads must be bent at a point at least 3mm from the base of the LED lens. Using the lead frame itself as a fulcrum during bending must be avoided to prevent stress cracks in the epoxy or internal wire bonds.
• Sequence: Lead forming must be performed before the soldering process and at room temperature.
• Clinching: During insertion into the PCB, apply the minimum clinch force required to hold the component in place. Excessive force can induce mechanical stress on the leads and the LED package.

8.5 Soldering Process

A minimum clearance of 2mm must be maintained between the base of the lens and the solder joint. Immersing the lens in molten solder must be strictly avoided. Do not apply external stress to the leads while the LED is at elevated temperature post-soldering.

8.5.1 Recommended Soldering Conditions

8.5.2 Reflow Soldering Profile

For surface-mount variants or when using compatible processes, the following reflow profile is specified:

• Preheat/Soak: Temperature range 150°C (T_smin) to 200°C (T_smax). Time (t_s) from T_smin to T_smax: 100 seconds maximum.
• Liquidous Time: Time (t_L) above 217°C (T_L): 60 to 90 seconds.
• Peak Temperature: (T_P): 250°C maximum.
• Time at Classification Temp: Time (t_P) within 5°C of the specified classification temperature (T_C=245°C): 30 seconds maximum.
• Total Ramp Time: Time from 25°C to peak temperature: 5 minutes maximum.

Critical Warning: Exceeding the recommended soldering temperature and/or time can lead to permanent deformation of the LED lens, degradation of the epoxy material, delamination, or catastrophic failure of the semiconductor die.

8.6 Drive Circuit Design

LEDs are current-operated devices, not voltage-operated. Their forward voltage (VF) has a tolerance and a negative temperature coefficient (decreases as temperature increases). To ensure uniform brightness when driving multiple LEDs in parallel, it is essential to incorporate a current-limiting resistor in series with each LED or each parallel string. Driving LEDs directly from a voltage source without current regulation will lead to uneven brightness and potential thermal runaway, as the LED with the lowest VF will draw more current, heat up, lower its VF further, and draw even more current, potentially leading to failure.

9. Design Considerations & Application Notes

9.1 Thermal Management

While the through-hole design offers some heat sinking via the leads to the PCB, the maximum power dissipation is 52mW. In high ambient temperature environments or when driven near the maximum DC current (20mA), ensure the PCB layout does not trap heat around the component. Using a PCB with thermal relief patterns or additional copper pour connected to the LED's cathode/anode pads can help dissipate heat.

9.2 Optical Design

The device features a white diffused lens providing a wide 120-degree viewing angle. This makes it ideal for applications where the indicator needs to be visible from a broad range of viewing positions. The black housing significantly improves contrast by absorbing ambient light, making the illuminated LED appear brighter and more saturated against the background.

9.3 Bi-Color Functionality

The inclusion of both yellow and yellow-green chips in a single package (LED1~LED3) allows for dual-state indication (e.g., status OK vs. warning, power on vs. standby) using only one physical component footprint on the PCB. The drive circuit must be designed to independently control the current to each color chip.

9.4 Material Compliance

Compliance with RoHS and being lead-free are critical for products sold in many global markets. The UL 94V-0 rating of the housing material indicates it is self-extinguishing, a key safety requirement for enclosures and components.

10. Comparison with Alternative Technologies

The T-1 through-hole LED lamp offers distinct advantages and trade-offs compared to other indicator technologies:

• vs. Surface-Mount Device (SMD) LEDs: Through-hole components are generally easier for prototyping, manual assembly, and repair. They often have higher mounting strength and better heat dissipation via leads. SMD LEDs offer a smaller footprint, lower profile, and are better suited for fully automated, high-volume assembly.
• vs. Incandescent Lamps: LEDs are vastly superior in terms of power efficiency, lifetime (typically tens of thousands of hours vs. hundreds/thousands), shock/vibration resistance, and switching speed. They also generate significantly less heat.
• vs. Other Through-Hole LED Packages: The right-angle holder of this product allows the light to be emitted parallel to the PCB surface, which is ideal for edge-lit panels or displays, compared to standard radial LEDs that emit perpendicularly.

11. Frequently Asked Questions (FAQs)

11.1 Can I drive this LED at 30mA for higher brightness?

No. The Absolute Maximum Rating for DC Forward Current is 20mA. Exceeding this rating, even intermittently, will significantly reduce the LED's lifespan and may cause immediate failure due to overheating of the semiconductor junction.

11.2 Why is a current-limiting resistor necessary if my power supply is 2.0V and the LED's typical VF is 2.0V?

The typical VF is just an average. The actual VF for any given LED can range from 1.7V to 2.5V at 20mA. A 2.0V supply connected directly to an LED with a VF of 1.7V would attempt to drive it with excessive current, potentially damaging it. The resistor ensures a controlled current regardless of VF variations.

11.3 What is the difference between Peak Wavelength (λP) and Dominant Wavelength (λd)?

Peak Wavelength (λP) is the single wavelength at which the emission spectrum has its maximum intensity. Dominant Wavelength (λd) is the single wavelength of monochromatic light that would appear to have the same color (hue) as the LED's light to the human eye, calculated from the CIE chromaticity coordinates. λd is often more relevant for color specification in indicator applications.

11.4 How do I interpret the bin codes when ordering?

You can specify the required bin codes for luminous intensity (A, B, C) and dominant wavelength (1, 2) for each color based on your application's consistency requirements. For example, ordering all parts in Bin C/1 for yellow would give you the brightest yellow LEDs within the tightest yellow color range. Check with the supplier for availability of specific bin combinations.