LTL17KCBP5D Blue LED Datasheet - T-1 5mm Package - 3.2V 20mA - 680mcd - English Technical Document

1. Product Overview

The LTL17KCBP5D is a high-efficiency, through-hole LED designed for status indication and illumination in a wide range of electronic applications. It features a popular T-1 (5mm) diameter package with a blue diffused lens, providing a wide viewing angle and uniform light distribution. The device is constructed using InGaN technology to emit light at a dominant blue wavelength of 470 nm.

1.1 Key Features

• Low power consumption and high luminous efficiency.
• Compliant with RoHS and lead-free manufacturing standards.
• Standard T-1 (5mm) form factor for easy integration into existing designs.
• Blue diffused lens for wide-angle, soft light emission.

1.2 Target Applications

This LED is suitable for various sectors requiring reliable and efficient visual indicators. Primary application areas include:

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

2. Technical Specifications Deep Dive

This section provides a detailed analysis of the electrical, optical, and thermal parameters that define the LED's performance.

2.1 Absolute Maximum Ratings

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

• Power Dissipation (Pd): 108 mW maximum.
• Peak Forward Current (I_F(PEAK)): 100 mA for pulses with a duty cycle ≤ 1/10 and width ≤ 10µs.
• Continuous Forward Current (I_F): 30 mA DC maximum.
• Current Derating: Linear derating of 0.4 mA per °C above an ambient temperature (T_A) of 30°C.
• Operating Temperature Range (T_opr): -30°C to +85°C.
• Storage Temperature Range (T_stg): -40°C to +100°C.
• Lead Soldering Temperature: 260°C maximum for 5 seconds, measured 1.6mm from the LED body.

2.2 Electrical & Optical Characteristics

These parameters are measured at an ambient temperature of 25°C and represent typical operating performance.

• Luminous Intensity (I_V): Ranges from 310 mcd (min) to 1500 mcd (max), with a typical value of 680 mcd at a forward current (I_F) of 20 mA. A ±15% testing tolerance is applied to guaranteed values.
• Viewing Angle (2θ_1/2): 50 degrees. This is the full angle at which the luminous intensity drops to half of its axial (center) value.
• Peak Wavelength (λ_p): 468 nm.
• Dominant Wavelength (λ_d): Ranges from 460 nm to 475 nm, with a typical value of 470 nm. This is the single wavelength perceived by the human eye.
• Spectral Bandwidth (Δλ): 22 nm, indicating the spectral purity of the emitted blue light.
• Forward Voltage (V_F): Ranges from 2.7V (min) to 3.6V (max), with a typical value of 3.2V at I_F = 20 mA.
• Reverse Current (I_R): 10 µA maximum at a reverse voltage (V_R) of 5V. The device is not designed for operation under reverse bias.

3. Binning System Specification

The LEDs are sorted into bins based on key optical parameters to ensure consistency within a production batch. This allows designers to select parts that meet specific color and brightness requirements.

3.1 Luminous Intensity Binning

Binning is performed at a test current of 20 mA. Each bin has a tolerance of ±15% at its limits.

• Bin KL: 310 mcd (Min) to 520 mcd (Max)
• Bin MN: 520 mcd (Min) to 880 mcd (Max)
• Bin PQ: 880 mcd (Min) to 1500 mcd (Max)

3.2 Dominant Wavelength Binning

Binning is performed at a test current of 20 mA.

• Bin B07: 460.0 nm (Min) to 465.0 nm (Max)
• Bin B08: 465.0 nm (Min) to 470.0 nm (Max)
• Bin B09: 470.0 nm (Min) to 475.0 nm (Max)

4. Performance Curve Analysis

While specific graphical curves are not detailed in the provided text, typical performance trends for such LEDs can be described based on standard semiconductor physics.

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

The LED exhibits a non-linear I-V characteristic typical of a diode. The forward voltage shows a positive temperature coefficient, meaning it decreases slightly as junction temperature increases for a given current.

4.2 Luminous Intensity vs. Forward Current

The luminous output is approximately proportional to the forward current in the normal operating range (e.g., up to 30 mA). Exceeding the maximum current leads to super-linear efficiency drop and potential damage.

4.3 Temperature Dependence

Luminous intensity typically decreases as the junction temperature increases. The derating factor of 0.4 mA/°C above 30°C is specified to manage thermal effects and maintain reliability by reducing the maximum allowable current at higher ambient temperatures.

5. Mechanical & Package Information

5.1 Outline Dimensions

The LED conforms to the standard T-1 (5mm) radial through-hole package. Key dimensional notes include:

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

5.2 Polarity Identification

The longer lead typically denotes the anode (positive terminal), while the shorter lead denotes the cathode (negative terminal). Additionally, a flat spot on the lens flange is often aligned with the cathode.

6. Soldering & Assembly Guidelines

Proper handling is critical to prevent damage and ensure long-term reliability.

6.1 Lead Forming

• Bending must be performed 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.
• Form leads before soldering, at room temperature.
• Use minimum clinch force during PCB assembly to avoid mechanical stress.

6.2 Soldering Conditions

A minimum clearance of 3mm must be maintained between the solder point and the lens base. Dipping the lens into solder must be avoided.

• Soldering Iron: Temperature: 350°C Max. Time: 3 seconds Max. (one time only). Position: No closer than 1.6mm from the epoxy bulb base.
• Wave Soldering: Pre-heat: 100°C Max for 60 seconds Max. Solder Wave: 260°C Max. Time: 5 seconds Max. Dipping Position: No lower than 2mm from the epoxy bulb base.
• Important: IR reflow soldering is not suitable for this through-hole LED product. Excessive temperature or time can cause lens deformation or catastrophic failure.

6.3 Storage & Cleaning

• Storage: Recommended ambient: ≤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.
• Cleaning: Use alcohol-based solvents like isopropyl alcohol if necessary.

7. Packaging & Ordering Information

7.1 Packaging Specification

• 1,000 pieces per anti-static packing bag.
• 10 packing bags per inner carton (total 10,000 pcs).
• 8 inner cartons per master outer carton (total 80,000 pcs).
• In every shipping lot, only the final pack may be a non-full quantity.

8. Application Design Recommendations

8.1 Drive Circuit Design

LEDs are current-operated devices. To ensure uniform brightness when driving multiple LEDs, a current-limiting resistor should be placed in series with each LED (Circuit A). Connecting LEDs directly in parallel (Circuit B) is not recommended due to variances in individual forward voltage (V_F), which can cause significant differences in current sharing and brightness.

8.2 Electrostatic Discharge (ESD) Protection

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

• Using grounded wrist straps or anti-static gloves.
• Ensuring all equipment, worktables, and storage racks are properly grounded.
• Using ionizers to neutralize static charge on the plastic lens.
• Maintaining ESD training and certification for personnel.

8.3 Thermal Management

While the power dissipation is low, adhering to the current derating specification above 30°C ambient is essential for maintaining luminous output and device lifetime, especially in enclosed or high-temperature environments.

9. Technical Comparison & Considerations

The LTL17KCBP5D offers a balance of brightness, viewing angle, and reliability in a ubiquitous package. Compared to clear lens variants, the diffused lens provides a wider and more uniform viewing cone, ideal for status indicators where the viewing angle is not fixed. Its typical forward voltage of 3.2V makes it compatible with common 3.3V and 5V logic supplies when used with an appropriate series resistor.

10. Frequently Asked Questions (FAQs)

10.1 Can I drive this LED without a current-limiting resistor?

No. Connecting an LED directly to a voltage source is highly discouraged as it allows uncontrolled current flow, which will quickly exceed the maximum rating and destroy the device. A series resistor is mandatory for safe operation from a constant voltage source.

10.2 What is the difference between Peak Wavelength and Dominant Wavelength?

Peak Wavelength (λ_p): The wavelength at which the spectral power distribution is maximum. Dominant Wavelength (λ_d): The single wavelength that, when combined with a reference white light, matches the perceived color of the LED. λ_d is more relevant for color specification in human vision.

10.3 How do I interpret the binning codes?

The bin code (e.g., MN-B08) printed on the packing bag specifies the luminous intensity range (MN: 520-880 mcd) and the dominant wavelength range (B08: 465-470 nm) of the LEDs inside. Selecting a specific bin ensures color and brightness consistency in your application.

11. Design Use Case Example

Scenario: Designing a front-panel status indicator for a network router powered by a 5V rail. The indicator needs to be clearly visible from various angles.

• Component Selection: The LTL17KCBP5D with its 50° viewing angle and diffused lens is an excellent choice.
• Circuit Design: Target I_F = 20 mA for typical brightness. Using the typical V_F of 3.2V, calculate the series resistor: R = (V_supply - V_F) / I_F = (5V - 3.2V) / 0.02A = 90Ω. A standard 91Ω or 100Ω resistor can be used. The resistor power rating: P = I²R = (0.02)² * 90 = 0.036W, so a standard 1/8W or 1/4W resistor is sufficient.
• Layout: Ensure the LED is placed at least 3mm from any solder point on the PCB. Follow the lead bending guidelines if the PCB hole spacing differs from the LED's lead spacing.

12. Operating Principle

The LED operates on the principle of electroluminescence in a semiconductor p-n junction. When a forward voltage exceeding the diode's turn-on threshold is applied, electrons from the n-type region and holes from the p-type region are injected into the active region (the junction). When these charge carriers recombine, energy is released in the form of photons (light). The specific material used in the active region (InGaN for this blue LED) determines the wavelength (color) of the emitted light. The diffused epoxy lens encapsulates the semiconductor chip, provides mechanical protection, and shapes the light output pattern.

13. Technology Trends

Through-hole LEDs like the T-1 package remain widely used in applications where manual assembly, repair, or prototyping is common, and where high reliability in harsh environments is valued. The industry trend continues to focus on improving luminous efficacy (more light output per watt of electrical input), achieving tighter color consistency through advanced binning, and enhancing long-term reliability under various thermal and environmental stresses. While surface-mount device (SMD) LEDs dominate high-volume automated production, through-hole variants maintain a strong position in specific market segments requiring their unique mechanical and assembly characteristics.