LTLR42FTBK4KHBPT Blue LED Lamp Datasheet - T-1 Package - 3.2V - 20mA - 400mcd - English Technical Document

1. Product Overview

The LTLR42FTBK4KHBPT is a blue light-emitting diode (LED) lamp designed for through-hole mounting on printed circuit boards (PCBs). It is part of a Circuit Board Indicator (CBI) system, which utilizes a black plastic right-angle holder (housing) that mates with the LED lamp. This product family is known for its versatility, offering configurations such as top-view (spacer) or right-angle orientation, and can be arranged in horizontal or vertical arrays. The design emphasizes ease of assembly and stackability.

1.1 Core Features

• Ease of Assembly: Designed specifically for straightforward and efficient circuit board assembly processes.
• Solid-State Light Source: Provides high reliability, long lifetime, and resistance to shock and vibration compared to traditional incandescent lamps.
• Energy Efficiency: Features low power consumption and high luminous efficiency.
• Environmental Compliance: This is a lead-free product and is compliant with the Restriction of Hazardous Substances (RoHS) directive.
• Light Source: Utilizes an InGaN (Indium Gallium Nitride) semiconductor chip with a nominal peak emission of 470nm (blue).
• Packaging: Supplied in tape and reel packaging suitable for automated assembly equipment.

1.2 Target Applications

This LED is suitable for a broad range of electronic equipment requiring status indication, backlighting, or general illumination. Key application markets include:

• Computer and IT equipment
• Communication devices
• Consumer electronics
• Industrial controls and instrumentation

2. Technical Parameter Deep-Dive

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): 76 mW maximum. This is the total electrical power the device can dissipate as heat.
• Peak Forward Current (I_FP): 100 mA maximum. This is permissible only under pulsed conditions (duty cycle ≤ 1/10, pulse width ≤ 10μs).
• Continuous Forward Current (I_F): 20 mA maximum under DC conditions.
• Current Derating: The maximum allowable DC forward current must be linearly reduced by 0.273 mA for every degree Celsius the ambient temperature (T_A) rises above 30°C.
• Operating Temperature Range (T_opr): -30°C to +80°C.
• Storage Temperature Range (T_stg): -40°C to +100°C.
• Lead Soldering Temperature: 260°C maximum for 5 seconds, measured at a point 2.0mm (0.079 inches) from the LED body.

2.2 Electrical & Optical Characteristics

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

• Luminous Intensity (I_V): 140 - 680 mcd (millicandela), with a typical value of 400 mcd, measured at I_F = 20mA. The actual bin code determines the specific range.
• Viewing Angle (2θ_1/2): 45 degrees. This is the full angle at which the luminous intensity drops to half of its peak axial value.
• Peak Emission Wavelength (λ_P): 468 nm (nanometers). This is the wavelength at which the spectral output is strongest.
• Dominant Wavelength (λ_d): 465 - 475 nm, with a typical value of 470 nm. This is the single wavelength perceived by the human eye that defines the color.
• Spectral Line Half-Width (Δλ): 25 nm. This indicates the spectral purity or bandwidth of the emitted light.
• Forward Voltage (V_F): 2.7 - 3.4 V, with a typical value of 3.2 V, measured at I_F = 20mA.
• Reverse Current (I_R): 10 μA (microamperes) maximum, measured at a reverse voltage (V_R) of 5V. Important: This device is not designed for operation under reverse bias; this test is for characterization only.

3. Binning System Specification

The LTLR42FTBK4KHBPT is sorted (binned) according to two key optical parameters to ensure color and brightness consistency within an application. The bin code is marked on the packing bag.

3.1 Luminous Intensity Binning

Binned at a test current of 20mA. The tolerance for each bin limit is ±15%.

• Bin H: 180 - 240 mcd
• Bin J: 240 - 310 mcd
• Bin K: 310 - 400 mcd
• Bin L: 400 - 520 mcd
• Bin M: 520 - 680 mcd

3.2 Dominant Wavelength Binning

Binned at a test current of 20mA. The tolerance for each bin limit is ±1 nm.

• Bin B08: 465.0 - 470.0 nm
• Bin B09: 470.0 - 475.0 nm

4. Performance Curve Analysis

The datasheet includes typical characteristic curves which are essential for circuit design and understanding device behavior under varying conditions. These curves graphically represent relationships such as:

• Forward Current vs. Forward Voltage (I-V Curve): Shows the non-linear relationship between the voltage across the LED and the current flowing through it. This is critical for selecting the appropriate current-limiting resistor or driver circuit.
• Luminous Intensity vs. Forward Current: Illustrates how light output increases with current. It demonstrates the sub-linear relationship, indicating that efficiency may drop at very high currents.
• Luminous Intensity vs. Ambient Temperature: Shows the dependency of light output on junction temperature. Typically, luminous intensity decreases as temperature increases.
• Spectral Distribution: A plot of relative radiant power versus wavelength, showing the peak at 468nm and the 25nm half-width, confirming the blue color characteristics.

5. Mechanical & Packaging Information

5.1 Outline Dimensions

The LED lamp conforms to the standard T-1 (3mm) package dimensions. The associated black plastic right-angle holder has specific mechanical drawings provided in the datasheet. Key notes include:

• All dimensions are in millimeters (with inch equivalents).
• Standard tolerance is ±0.25mm (±0.010\") unless otherwise specified.
• The holder material is black plastic.
• The LED lamp itself has a blue InGaN chip and a water-clear (transparent) lens.

5.2 Packaging Specification

The device is supplied in an industry-standard tape and reel format for automated placement.

• Carrier Tape: Made of black conductive polystyrene alloy. Thickness is 0.50 ±0.06 mm.
• Reel: Standard 13-inch diameter reel containing 400 pieces.
• Carton Packaging:
  • 1 reel is packed with a humidity indicator card and desiccant inside one Moisture Barrier Bag (MBB).
  • 2 MBBs are packed in one Inner Carton (total 800 pcs).
  • 10 Inner Cartons are packed in one Outer Carton (total 8,000 pcs).

6. Soldering & Assembly Guidelines

6.1 Storage Conditions

• Sealed Package: Store at ≤30°C and ≤70% Relative Humidity (RH). Use within one year of the bag seal date.
• Opened Package: Store at ≤30°C and ≤60% RH. Components should undergo IR reflow soldering within 168 hours (7 days) of exposure.
• Extended Storage (Opened): For storage beyond 168 hours, store in a sealed container with desiccant or in a nitrogen desiccator. Components stored out of the original bag for more than 168 hours must be baked at approximately 60°C for at least 48 hours before solder assembly to remove absorbed moisture and prevent \"popcorning\" damage during reflow.

6.2 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 lead forming at room temperature and before the soldering process.
• During PCB insertion, use the minimum clinch force necessary to avoid imposing excessive mechanical stress on the component.

6.3 Soldering Process

General Rule: Maintain a minimum clearance of 2mm from the base of the lens/holder to the soldering point. Avoid dipping the lens/holder into solder. Do not apply external stress to the leads while the LED is at high temperature.

• Hand Soldering (Iron):
  • Temperature: 350°C maximum.
  • Time: 3 seconds maximum per solder joint.
  • Position: No closer than 2mm from the base.
• Wave Soldering:
  • Pre-heat Temperature: 100°C maximum.
  • Pre-heat Time: 60 seconds maximum.
  • Solder Wave Temperature: 260°C maximum.
  • Soldering Time: As per standard wave soldering profile, ensuring the 2mm clearance is maintained.

6.4 Cleaning

If cleaning is required after soldering, use alcohol-based solvents such as isopropyl alcohol. Avoid using harsh or aggressive chemical cleaners.

7. Application Notes & Design Considerations

7.1 Typical Application Scenarios

This blue LED is well-suited for both indoor and outdoor signage applications, as well as general status indication in a wide variety of electronic equipment including computers, networking gear, consumer appliances, and industrial control panels. The right-angle holder provides a 90-degree light emission path ideal for panel-mounted indicators.

7.2 Circuit Design

• Current Limiting: An external current-limiting resistor is mandatory when driving the LED from a voltage source. The resistor value can be calculated using Ohm's Law: R = (V_supply - V_F) / I_F. Always use the maximum V_F from the datasheet (3.4V) for a conservative design to ensure the current does not exceed 20mA.
• Thermal Management: Observe the power dissipation and current derating specifications. For applications with high ambient temperatures or continuous operation, ensure adequate ventilation or heat sinking if necessary to keep the junction temperature within safe limits.
• Reverse Voltage Protection: As the device is not designed for reverse bias operation, consider adding a protection diode in series or parallel (depending on the circuit) if there is any possibility of reverse voltage being applied.

7.3 Optical Design

• The 45-degree viewing angle provides a reasonably wide beam, suitable for general indication.
• The water-clear lens produces a bright, focused point source. For diffused light, an external diffuser or a holder with a diffused lens would be required.
• When selecting bins for an application requiring multiple LEDs, specify the same luminous intensity and dominant wavelength bin codes to ensure visual uniformity across all indicators.

8. Technical Comparison & Differentiation

While specific competitor comparisons are not provided in the datasheet, the LTLR42FTBK4KHBPT can be evaluated based on its standard specifications:

• Package: The classic T-1 through-hole package offers robustness and ease of manual prototyping, though it is being supplanted by surface-mount devices (SMDs) in high-volume automated production.
• Efficiency: With a typical luminous intensity of 400 mcd at 20mA (approx. 64mW), it offers good efficiency for a standard blue LED. Newer high-brightness or low-current SMD LEDs may offer higher efficacy (lumens per watt).
• System Integration: The key differentiator is the integrated CBI (Circuit Board Indicator) system concept—the separate, stackable right-angle holder. This allows for flexible mechanical design and easy replacement of the LED element without changing the holder mounted on the PCB.

9. Frequently Asked Questions (FAQ)

Q1: What is the difference between Peak Wavelength (λ_P) and Dominant Wavelength (λ_d)?
A1: Peak Wavelength is the physical wavelength where the LED emits the most optical power. Dominant Wavelength is a calculated value based on human color perception (CIE chromaticity diagram) that represents the single wavelength of the perceived color. They are often close but not identical.

Q2: Can I drive this LED with a constant voltage source without a resistor?
A2: No. LEDs are current-driven devices. Their forward voltage has a tolerance range (2.7V-3.4V). Connecting directly to a voltage source even slightly above the minimum V_F can cause excessive current flow, overheating, and rapid failure. Always use a series current-limiting resistor or a constant-current driver.

Q3: Why is the 168-hour floor life after bag opening so important?
A3: Plastic LED packages can absorb moisture from the air. During the high-temperature reflow soldering process, this trapped moisture can vaporize rapidly, creating internal pressure that can delaminate the package or crack the die (\"popcorning\"). The 168-hour limit and baking procedure are critical moisture sensitivity level (MSL) precautions to prevent this failure mode.

Q4: How do I interpret the bin code on the bag?
A4: The bin code, e.g., \"K-B09\\