LTL17KFL5D Orange/Amber LED Lamp Datasheet - T-1 (3mm) Package - 2.4V - 75mW - English Technical Document

1. Product Overview

This document details the specifications for a through-hole LED lamp designed for status indication and general illumination in electronic equipment. The device is offered in a popular T-1 (3mm) diameter package with a diffused lens, providing a wide viewing angle suitable for various applications. The primary source color is orange/amber, achieved through specific semiconductor materials and lens properties.

1.1 Core Advantages

• Low Power Consumption & High Efficiency: The LED operates at low forward voltage and current, converting electrical energy into light with high efficacy, making it suitable for battery-powered or energy-conscious designs.
• Environmental Compliance: The product is lead-free and compliant with the Restriction of Hazardous Substances (RoHS) directive.
• Standard Package: The T-1 (3mm) form factor is a widely adopted industry standard, ensuring compatibility with existing PCB layouts and manufacturing processes.
• Design Flexibility: Available in specific luminous intensity bins and dominant wavelength bins, allowing designers to select components that meet precise brightness and color requirements for their applications.

1.2 Target Applications

This LED is versatile and finds use in numerous sectors requiring reliable, low-power status indication or backlighting. Key application areas include:

• Communication equipment (routers, modems, switches)
• Computer peripherals and internal components
• Consumer electronics (audio/video equipment, toys)
• Home appliances (control panels, displays)
• Industrial control systems and instrumentation

2. In-Depth Technical Parameter Analysis

The following parameters define the operational limits and performance characteristics of the LED under standard test conditions (TA=25°C).

2.1 Absolute Maximum Ratings

These ratings represent the stress limits beyond which permanent damage to the device may occur. Continuous operation at or near these limits is not advised.

• Power Dissipation (Pd): 75 mW. This is the maximum amount of power the device can dissipate as heat. Exceeding this can lead to overheating and reduced lifespan.
• DC Forward Current (IF): 30 mA. The maximum continuous current that can be applied to the LED.
• Peak Forward Current: 90 mA (pulse width ≤10μs, duty cycle ≤1/10). This rating allows for brief, high-current pulses, which can be useful for multiplexing or creating brighter flashes, but must be carefully controlled to avoid thermal damage.
• Operating Temperature Range: -40°C to +85°C. The ambient temperature range over which the device is guaranteed to function.
• Storage Temperature Range: -40°C to +100°C.
• Lead Soldering Temperature: 260°C for a maximum of 5 seconds, measured 2.0mm from the LED body. This defines the thermal profile the package can withstand during hand or wave soldering.

2.2 Electrical & Optical Characteristics

These are the typical performance parameters measured at a forward current (IF) of 20mA.

• Luminous Intensity (Iv): 140-680 mcd (millicandela). The axial light output is binned, with a typical value of 400 mcd. A ±15% testing tolerance is applied to the bin limits.
• Viewing Angle (2θ1/2): 50 degrees. This is the full angle at which the luminous intensity drops to half of its axial value. The diffused lens creates this wide viewing angle.
• Peak Emission Wavelength (λP): 611 nm. The wavelength at which the spectral power distribution is maximum.
• Dominant Wavelength (λd): 600-613.5 nm. This is the single wavelength perceived by the human eye that defines the color (orange/amber). It is derived from the CIE chromaticity coordinates.
• Spectral Line Half-Width (Δλ): 17 nm. This indicates the spectral purity or bandwidth of the emitted light.
• Forward Voltage (VF): 2.05V (Min), 2.4V (Typ), 2.4V (Max) at 20mA. The voltage drop across the LED when conducting current.
• Reverse Current (IR): 100 μA (Max) at a Reverse Voltage (VR) of 5V. Important: This device is not designed for reverse-bias operation; this parameter is for test purposes only.

3. Binning System Specification

To ensure consistency in brightness and color across production lots, LEDs are sorted into bins based on key parameters.

3.1 Luminous Intensity Binning

Units: mcd @ 20mA. Tolerance on each bin limit is ±15%.

• Bin GH: 140 – 240 mcd
• Bin JK: 240 – 400 mcd
• Bin LM: 400 – 680 mcd

The bin code is marked on the packaging, allowing for selective use based on application brightness requirements.

3.2 Dominant Wavelength Binning

Units: nm @ 20mA. Tolerance on each bin limit is ±1 nm.

• Bin H23: 600.0 – 603.0 nm
• Bin H24: 603.0 – 606.5 nm
• Bin H25: 606.5 – 610.0 nm
• Bin H26: 610.0 – 613.5 nm

This binning ensures precise color matching within a defined orange/amber hue range.

4. Performance Curve Analysis

While specific graphical curves are referenced in the datasheet (Fig.1, Fig.6), their general implications are critical for design.

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

The relationship is exponential. A small increase in forward voltage leads to a large increase in current. This underscores why LEDs must be driven by a current-limited source, not a constant voltage source, to prevent thermal runaway.

4.2 Luminous Intensity vs. Forward Current

Light output is approximately proportional to forward current within the operating range. However, efficiency may drop at very high currents due to increased heat.

4.3 Spectral Distribution

The emitted light spectrum is centered around 611 nm (peak) with a half-width of 17 nm, defining the orange/amber color. The dominant wavelength (λd) is the metric used for color binning as it correlates with human perception.

4.4 Viewing Angle Characteristic

The intensity distribution pattern is Lambertian-like, smoothed by the diffused lens to provide a consistent 50-degree viewing angle where intensity is half the peak value.

5. Mechanical & Packaging Information

5.1 Outline Dimensions

The LED uses a standard T-1 (3mm) round package. Key dimensional notes include:

• All dimensions are in millimeters (inches).
• Tolerance is ±0.25mm (.010") unless otherwise specified.
• Maximum resin protrusion under the flange is 1.0mm (.04").
• Lead spacing is measured where leads emerge from the package body.

5.2 Polarity Identification

Typically, the longer lead denotes the anode (positive), and the shorter lead denotes the cathode (negative). The cathode may also be indicated by a flat spot on the lens rim or a notch in the flange. Always verify polarity before installation to prevent reverse bias.

5.3 Packaging Specifications

LEDs are supplied in anti-static packing bags. Standard packing quantities are:

• 1000, 500, 200, or 100 pieces per bag.
• 10 bags are packed into an inner carton (total 10,000 pcs).
• 8 inner cartons are packed into an outer shipping carton (total 80,000 pcs).

6. Soldering & Assembly Guidelines

6.1 Storage Conditions

For optimal shelf life, store LEDs in an environment not exceeding 30°C and 70% relative humidity. If removed from the original sealed, moisture-barrier bag, use within three months. For longer storage outside the original packaging, use a sealed container with desiccant or a nitrogen-filled desiccator.

6.2 Cleaning

If cleaning is necessary, use only alcohol-based solvents like isopropyl alcohol. Avoid harsh or abrasive chemicals.

6.3 Lead Forming

Bend leads at a point at least 3mm away from the base of the LED lens. Do not use the lens base as a fulcrum. Perform all lead forming at room temperature and before soldering. Use minimal force during PCB insertion to avoid mechanical stress on the epoxy lens.

6.4 Soldering Process

Critical Rule: Maintain a minimum distance of 2mm from the base of the epoxy lens to the solder point. Never immerse the lens in solder.

• Hand Soldering (Iron): Maximum temperature 350°C. Maximum soldering time 3 seconds per lead. Apply heat to the lead, not the component body.
• Wave Soldering: Maximum preheat temperature 100°C for up to 60 seconds. Maximum solder wave temperature 260°C. Maximum contact time 5 seconds. Ensure the PCB is designed so the LED does not dip more than 2mm into the solder wave.
• IR Reflow: This process is not suitable for through-hole LED lamps. Excessive heat can cause lens deformation or catastrophic failure.

7. Application & Design Considerations

7.1 Drive Circuit Design

LEDs are current-operated devices. To ensure uniform brightness and prevent damage:

• Always use a current-limiting resistor in series with each LED. This is the recommended method (Circuit A). The resistor value is calculated using Ohm's Law: R = (Vsupply - VF) / IF.
• Avoid connecting multiple LEDs directly in parallel without individual resistors (Circuit B). Small variations in the forward voltage (VF) characteristic between LEDs can cause significant current imbalance, leading to uneven brightness and potential overcurrent in one device.

7.2 Thermal Management

While power dissipation is low (75mW max), proper PCB layout can help. Ensure adequate copper area around the leads to act as a heat sink, especially when operating near maximum current or at high ambient temperatures.

7.3 Electrostatic Discharge (ESD) Protection

The LED is sensitive to electrostatic discharge. Implement the following in the handling and assembly area:

• Use grounded wrist straps and anti-static mats.
• Ensure all equipment (soldering irons, workstations) is properly grounded.
• Store and transport LEDs in conductive or anti-static packaging.
• Consider using an ionizer to neutralize static charge that may build up on the plastic lens.

8. Technical Comparison & Differentiation

Compared to non-diffused or narrower-angle LEDs, this device offers superior viewing characteristics, making it ideal for applications where the indicator needs to be visible from a wide range of angles. Its specific orange/amber color and defined binning structure provide better color consistency for multi-LED arrays than unbinned or broadly binned alternatives. The T-1 package offers a balance between size and light output, being smaller than 5mm LEDs but typically brighter than surface-mount alternatives of similar cost for through-hole applications.

9. Frequently Asked Questions (FAQ)

9.1 What resistor value should I use with a 5V supply?

Using the typical forward voltage (VF=2.4V) and desired current (IF=20mA): R = (5V - 2.4V) / 0.02A = 130 Ohms. The nearest standard value is 130Ω or 150Ω. Always calculate based on the maximum VF from the datasheet to ensure the current does not exceed the limit under worst-case conditions.

9.2 Can I pulse this LED for higher brightness?

Yes, but strictly within the Absolute Maximum Ratings. You can apply a peak current of 90mA, but the pulse width must be ≤10μs and the duty cycle ≤1/10 (e.g., 10μs on, 90μs off). This allows for brighter flashes in multiplexed displays or alert signals.

9.3 Why is there a minimum distance for soldering?

The 2mm minimum distance from the lens base prevents molten solder from wicking up the lead and contacting the epoxy lens. The thermal shock and physical stress from hot solder can crack the lens or damage the internal die bond, leading to immediate or latent failure.

9.4 How do I interpret the bin codes for ordering?

Specify both the luminous intensity bin (e.g., JK for 240-400 mcd) and the dominant wavelength bin (e.g., H24 for 603.0-606.5 nm) when ordering to ensure you receive LEDs with consistent brightness and color for your application.

10. Practical Design Example

Scenario: Designing a status indicator panel with four uniformly bright orange LEDs powered from a 12V rail.

1. Current Selection: Choose a standard operating point of IF = 20mA for good brightness and longevity.
2. Resistor Calculation (Worst-Case): Use maximum VF = 2.4V. R = (12V - 2.4V) / 0.02A = 480 Ohms. Use a standard 470Ω resistor. Power dissipation in the resistor: P_R = (12V-2.4V)^2 / 470Ω ≈ 0.196W. A 1/4W (0.25W) resistor is sufficient.
3. Circuit Topology: Use four independent circuits, each with one LED and one 470Ω resistor, all connected in parallel to the 12V supply. This ensures uniform brightness regardless of VF variations between individual LEDs.
4. PCB Layout: Place the LEDs with at least 3mm of straight lead before any bend. Ensure solder pads are more than 2mm from the LED body outline on the PCB silkscreen.
5. Binning: For best visual consistency, specify all LEDs from the same luminous intensity bin (e.g., JK) and the same dominant wavelength bin (e.g., H24).

11. Operating Principle

This LED is a semiconductor photonic device. When a forward voltage exceeding its characteristic threshold is applied, electrons and holes recombine within the active region of the semiconductor chip (typically based on materials like Gallium Arsenide Phosphide - GaAsP). This recombination process releases energy in the form of photons (light). The specific composition of the semiconductor layers determines the peak wavelength of the emitted light, in this case, within the orange/amber spectrum (600-613.5 nm). The diffused epoxy lens encapsulates the chip, providing mechanical protection, shaping the light output beam, and scattering the light to create a wide viewing angle.

12. Technology Trends

While through-hole LEDs remain vital for prototyping, repair, and certain industrial applications, the broader industry trend is toward surface-mount device (SMD) packages for automated, high-volume assembly. SMD LEDs offer smaller footprints, lower profiles, and better suitability for reflow soldering. However, through-hole components like the T-1 LED continue to be relevant due to their robustness, ease of manual handling, and superior single-point luminous intensity for their size, making them a persistent choice for status indicators where high visibility from multiple angles is required. Advances in materials continue to improve the efficiency and longevity of all LED types.