LTL17KTBP5D Blue LED Lamp Datasheet - T-1 3mm Package - 3.2V - 20mA - 470nm - English Technical Document

1. Product Overview

This document details the specifications for a blue through-hole LED lamp. Through-hole LEDs are designed for status indication and illumination in a wide range of electronic applications. They are available in standard packages suitable for automated or manual insertion into printed circuit boards (PCBs).

1.1 Features

• Low power consumption and high luminous efficiency.
• Compliant with RoHS (Restriction of Hazardous Substances) directives and lead-free.
• Popular T-1 (3mm) diameter package for broad compatibility.
• Emits blue light at a peak wavelength of 470 nm with a diffused lens for wider viewing.

1.2 Applications

This LED is suitable for various applications requiring reliable and efficient status indication, including:

• Communication equipment
• Computer peripherals and motherboards
• Consumer electronics
• Home appliances
• Industrial control panels and machinery

2. Technical Parameters: In-Depth Objective Interpretation

2.1 Absolute Maximum Ratings

The following ratings define the limits beyond which permanent damage to the device may occur. Operation under these conditions is not guaranteed.

• Power Dissipation (Pd): 66 mW maximum. This is the total power the LED package can dissipate as heat.
• Peak Forward Current (I_FP): 60 mA maximum. This is permissible only under pulsed conditions (duty cycle ≤ 1/10, pulse width ≤ 10 µs).
• DC Forward Current (I_F): 20 mA maximum. This is the recommended continuous forward current for normal operation.
• Reverse Voltage (V_R): 5 V maximum. Exceeding this can cause immediate junction breakdown.
• Operating Temperature Range (T_opr): -40°C to +85°C. The ambient temperature range for reliable operation.
• Storage Temperature Range (T_stg): -40°C to +100°C.
• Lead Soldering Temperature: 260°C for a maximum of 5 seconds, measured 2.0mm from the LED body.

2.2 Electrical and Optical Characteristics

These parameters are measured at an ambient temperature (T_A) of 25°C and define the typical performance.

• Luminous Intensity (I_V): 1000 to 2200 mcd (millicandela) at I_F = 20mA. This is the perceived brightness in the primary viewing direction. A ±15% testing tolerance is applied.
• Viewing Angle (2θ_1/2): 50 degrees (typical). This is the full angle at which the luminous intensity drops to half of its axial (on-center) value. The diffused lens provides a wider, softer light pattern.
• Peak Emission Wavelength (λ_p): 468 nm (typical). The wavelength at which the spectral power output is highest.
• Dominant Wavelength (λ_d): 460 to 475 nm. This is the single wavelength that best represents the perceived color of the LED, derived from the CIE chromaticity diagram.
• Spectral Line Half-Width (Δλ): 22 nm (typical). This indicates the spectral purity; a smaller value means a more monochromatic light.
• Forward Voltage (V_F): 2.4V to 3.3V at I_F = 20mA, with a typical value of 3.2V. This is the voltage drop across the LED when operating.
• Reverse Current (I_R): 100 µA maximum at V_R = 5V. The device is not designed for operation under reverse bias; this test is for characterization only.

3. Bin Table Specification

The product is sorted into bins based on key optical parameters to ensure consistency within a production batch. The bin code is marked on the packaging.

3.1 Luminous Intensity Binning

Binned at I_F = 20mA. Tolerance for each bin limit is ±15%.

• Bin Code P: 1000 - 1200 mcd
• Bin Code Q: 1200 - 1500 mcd
• Bin Code R: 1500 - 1800 mcd
• Bin Code S: 1800 - 2200 mcd

3.2 Dominant Wavelength Binning

Binned at I_F = 20mA. Tolerance for each bin limit is ±1 nm.

• Bin Code B07: 460.0 - 465.0 nm
• Bin Code B08: 465.0 - 470.0 nm
• Bin Code B09: 470.0 - 475.0 nm

4. Performance Curve Analysis

Typical performance curves (not reproduced in text but described) illustrate the relationship between key parameters. These are essential for design analysis.

• Relative Luminous Intensity vs. Forward Current: Shows how light output increases with current, typically in a near-linear relationship within the operating range. It highlights the importance of current control for consistent brightness.
• Relative Luminous Intensity vs. Ambient Temperature: Demonstrates the thermal quenching effect, where luminous output decreases as junction temperature rises. This is critical for designs operating at high ambient temperatures.
• Forward Voltage vs. Forward Current: The I-V characteristic curve, showing the exponential relationship. The typical V_F at 20mA is a key design point for calculating series resistors.
• Spectral Distribution: A graph of relative intensity versus wavelength, showing the peak at ~468 nm and the spectral half-width of ~22 nm, defining the blue color characteristics.

5. Mechanical and Packaging Information

5.1 Outline Dimensions

The device uses a standard T-1 (3mm) round package. Key dimensions include:

• Lens diameter: Approximately 3mm.
• Lead spacing: Measured where leads emerge from the package.
• Protruded resin under the flange: Maximum 1.0mm.
• General tolerance: ±0.25mm unless otherwise specified.

5.2 Polarity Identification

The longer lead is the anode (positive). The LED body may also have a flat side near the cathode (negative) lead.

6. Soldering and Assembly Guidelines

6.1 Lead Forming

• Bend leads at a point at least 3mm from the base of the LED lens.
• Do not use the base of the lead frame as a fulcrum.
• Perform forming before soldering at room temperature.
• Use minimum clinch force during PCB assembly to avoid mechanical stress.

6.2 Soldering Conditions

Maintain a minimum clearance of 2mm from the base of the lens to the solder point. Do not immerse the lens in solder.

• Soldering Iron: Temperature 350°C max. Time 3 seconds max (one time only).
• Wave Soldering: Pre-heat 100°C max for 60 seconds max. Solder wave 260°C max for 5 seconds max.
• Important: IR reflow is NOT suitable for this through-hole LED product. Excessive temperature or time can deform the lens or cause catastrophic failure.

6.3 Cleaning

Use alcohol-based solvents like isopropyl alcohol if cleaning is necessary.

6.4 Storage

For optimal shelf life, store in an environment not exceeding 30°C and 70% relative humidity. LEDs removed from original packaging should be used within three months. For extended storage, use a sealed container with desiccant or a nitrogen ambient.

7. Packaging and Ordering Information

7.1 Packing Specification

• Quantities per bag: 1000, 500, 200, or 100 pieces.
• 10 bags per inner carton (e.g., 10,000 pcs for 1000pc bags).
• 8 inner cartons per outer carton (e.g., 80,000 pcs total).
• The last pack in a shipping lot may be non-full.

8. Application Suggestions

8.1 Drive Method

LEDs are current-operated devices. To ensure uniform brightness when connecting multiple LEDs in parallel, it is strongly recommended to use a current-limiting resistor in series with each LED (Circuit A). Connecting LEDs directly in parallel without individual resistors (Circuit B) is not recommended due to variations in forward voltage (V_F), which can lead to significant differences in current and thus brightness between devices.

8.2 ESD (Electrostatic Discharge) Protection

This LED is susceptible to damage from electrostatic discharge. Preventive measures include:

• Use grounded wrist straps or anti-static gloves when handling.
• Ensure all equipment, workstations, and storage racks are properly grounded.
• Use ionizers to neutralize static charge that may build up on the plastic lens.
• Implement ESD training and certification programs for personnel.

8.3 Thermal Considerations

While the power dissipation is low, operating at high ambient temperatures (towards the maximum 85°C) will reduce light output as shown in the temperature characteristic curve. Ensure adequate ventilation in enclosed spaces.

9. Technical Comparison and Design Considerations

Compared to non-diffused LEDs, this device offers a wider (50°) viewing angle, making it suitable for applications where the indicator needs to be visible from a broad range of positions. The 3.2V typical forward voltage is standard for blue InGaN-based LEDs. Designers must account for the forward voltage range (2.4V-3.3V) when calculating series resistor values to ensure the current stays within the 20mA limit across all units. The high luminous intensity (up to 2200 mcd) allows it to be used in moderately bright ambient light conditions.

10. Frequently Asked Questions (Based on Technical Parameters)

10.1 Can I drive this LED with a 5V supply?

Yes, but you MUST use a series current-limiting resistor. For a 5V supply and a target current of 20mA, assuming a typical V_F of 3.2V, the resistor value would be R = (5V - 3.2V) / 0.02A = 90 Ohms. Use the maximum V_F (3.3V) to calculate the minimum safe resistor value: R_min = (5V - 3.3V) / 0.02A = 85 Ohms. A standard 91 or 100 Ohm resistor would be appropriate, also affecting the actual current slightly.

10.2 Why is a series resistor needed for each LED in parallel?

Due to natural manufacturing variations, no two LEDs have exactly the same forward voltage (V_F). If connected in parallel directly to a voltage source, the LED with the slightly lower V_F will draw disproportionately more current, potentially exceeding its ratings and failing, while the others remain dim. A series resistor for each LED helps balance the current by providing negative feedback, ensuring more uniform brightness and protecting the devices.

10.3 What does the bin code mean?

The bin code (e.g., S-B08) indicates the performance sorting. The first letter (P, Q, R, S) specifies the luminous intensity range. The alphanumeric code (B07, B08, B09) specifies the dominant wavelength (color) range. Ordering a specific bin ensures consistency in brightness and color for your application.

11. Practical Design and Usage Case

Scenario: Designing a front panel for an industrial controller with four status indicator LEDs (Power, Run, Error, Standby).

• Component Selection: This blue LED is chosen for its high brightness and wide viewing angle, ensuring visibility on a factory floor.
• Circuit Design: Each LED is connected between a microcontroller GPIO pin (sinking current) and the +5V rail via a separate current-limiting resistor. The resistor value is calculated based on the GPIO's low-level voltage and the LED's V_F to achieve ~15-18mA, balancing brightness and microcontroller load.
• PCB Layout: Holes are placed according to the LED's lead spacing. The keep-out area around the LED (2mm from body for soldering) is respected in the layout.
• Assembly: LEDs are inserted after all reflow soldering of SMD components is complete. They are wave-soldered following the specified time/temperature profile.
• Result: A reliable, consistently bright set of status indicators with uniform color and intensity.

12. Principle Introduction

A Light Emitting Diode (LED) is a semiconductor p-n junction device. When a forward voltage is applied, electrons from the n-region recombine with holes from the p-region within the active region, releasing energy in the form of photons (light). The specific wavelength (color) of the light is determined by the energy bandgap of the semiconductor materials used. This device uses an Indium Gallium Nitride (InGaN) based structure to produce blue light. The diffused epoxy lens encapsulates the semiconductor chip, provides mechanical protection, and shapes the light output beam.

13. Development Trends

While through-hole LEDs remain vital for prototyping, repair, and certain industrial applications, the broader industry trend is towards surface-mount device (SMD) LEDs for automated high-volume assembly. SMD packages offer smaller footprints, better thermal management, and higher placement density. However, through-hole components like this one continue to be valued for their mechanical robustness, ease of manual handling, and suitability for applications requiring high reliability in harsh environments where solder joint integrity is paramount. Advances in materials continue to improve the efficiency and lifetime of all LED types.