LTW-1GHCX4 White LED Datasheet - 5mm Diameter - 3.1V Typical - 90mW Power - English Technical Document

1. Product Overview

The LTW-1GHCX4 is a high-brightness, through-hole white LED designed for status indication and illumination in a wide range of electronic applications. It features a standard T-1 (5mm) diameter package with a water-clear lens, offering design flexibility for various mounting configurations on printed circuit boards or panels.

1.1 Core Advantages

• RoHS Compliant: This product is lead (Pb) free, adhering to environmental regulations.
• High Efficiency: Provides high luminous output with low power consumption.
• Design Flexibility: Available in a popular package size suitable for versatile mounting.
• Low Current Operation: Compatible with integrated circuits due to its low current requirements.

1.2 Target Applications

This LED is suitable for numerous sectors including:

• Computer and communication equipment
• Consumer electronics
• Home appliances
• Industrial control and instrumentation

2. Technical Parameter Analysis

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): 90 mW maximum.
• DC Forward Current (IF): 25 mA continuous.
• Peak Forward Current: 100 mA (pulsed, duty cycle ≤ 1/10, width ≤ 10ms).
• Operating Temperature Range: -40°C to +85°C.
• 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.
• Electrostatic Discharge (ESD): Withstands up to 1000V.

Thermal Derating: The DC forward current must be linearly derated by 0.36 mA for every degree Celsius above 30°C ambient temperature to ensure the power dissipation limit is not exceeded.

2.2 Electrical & Optical Characteristics

These parameters are specified at an ambient temperature (TA) of 25°C and define the typical performance of the device.

• Luminous Intensity (Iv): Ranges from 4000 mcd (min) to 11000 mcd (max), with a typical value of 7500 mcd at a forward current (IF) of 20 mA. Measurement includes a ±15% testing tolerance.
• Viewing Angle (2θ1/2): Approximately 44 degrees (typical). This is the full angle at which luminous intensity drops to half its axial value.
• Forward Voltage (VF): Ranges from 2.7V to 3.5V, with a typical value of 3.1V at IF=20mA.
• Reverse Current (IR): Maximum of 5 μA at a reverse voltage (VR) of 5V. Important: The device is not designed for operation under reverse bias; this test condition is for characterization only.
• Chromaticity Coordinates (x, y): Typical coordinates are x=0.28, y=0.26 on the CIE 1931 chromaticity diagram, defining the white point of the LED.

3. Binning System Specification

The LEDs are sorted into bins based on key performance parameters to ensure consistency within a production lot. The bin code is marked on each packing bag.

3.1 Luminous Intensity Binning

Note: Tolerance on each bin limit is ±15%.

3.2 Forward Voltage Binning

Note: Forward voltage measurement allowance is ±0.1V.

3.3 Hue (Color) Binning

Multiple hue ranks are defined (U91, U01, U20, U22, U31, U32, U41, U42, U51), each specifying a quadrilateral region on the CIE 1931 chromaticity diagram with specific (x, y) coordinate boundaries. This ensures tight control over the color consistency of the white light output. The color coordinates measurement allowance is ±0.01.

4. Performance Curve Analysis

Typical performance curves illustrate the relationship between key parameters. These are essential for circuit design and understanding device behavior under different conditions.

• Forward Current vs. Forward Voltage (I-V Curve): Shows the exponential relationship, critical for selecting current-limiting resistors.
• Luminous Intensity vs. Forward Current: Demonstrates how light output increases with current, up to the maximum rated limits.
• Luminous Intensity vs. Ambient Temperature: Illustrates the decrease in light output as junction temperature rises, highlighting the importance of thermal management.
• Viewing Angle Pattern: A polar plot showing the angular distribution of light intensity.

5. Mechanical & Packaging Information

5.1 Outline Dimensions

The LED conforms to the standard T-1 (5mm) radial leaded package.

• Body Diameter: 5mm (nominal).
• Lead Spacing: Measured where leads emerge from the package.
• Protruded Resin: Maximum of 1.0mm under the flange.
• Tolerances: ±0.25mm unless otherwise specified.

Polarity Identification: The longer lead denotes the anode (positive), and the shorter lead denotes the cathode (negative). The cathode side may also be indicated by a flat spot on the LED lens flange.

5.2 Packaging Specifications

LEDs are supplied in anti-static packing bags.

• Bag Quantities: 1000, 500, 200, or 100 pieces per bag.
• Inner Carton: Contains 10 packing bags (e.g., 10,000 pcs if bags contain 1000 pcs each).
• Outer Carton: Contains 8 inner cartons (e.g., 80,000 pcs total).
• In every shipping lot, only the final pack may be a non-full pack.

6. Soldering & Assembly Guidelines

6.1 Storage

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

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 forming before soldering at normal temperature.
• Use minimum clinch force during PCB assembly to avoid mechanical stress.

6.3 Soldering Process

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

Warning: Excessive temperature or time can deform the lens or cause catastrophic failure. IR reflow soldering is not suitable for this through-hole LED.

6.4 Cleaning

If necessary, clean only with alcohol-based solvents such as isopropyl alcohol.

7. Application & Design Considerations

7.1 Drive Circuit Design

LEDs are current-operated devices. To ensure uniform brightness when driving multiple LEDs in parallel, a current-limiting resistor must be placed in series with each individual LED (Circuit A). Driving LEDs in parallel without individual resistors (Circuit B) is not recommended, as slight variations in the forward voltage (Vf) characteristic between LEDs will cause significant differences in current sharing and, consequently, brightness.

Circuit A (Recommended): [Vcc] — [Resistor] — [LED] — [GND] (per LED branch).
Circuit B (Not Recommended): [Vcc] — [Single Resistor] — [Multiple LEDs in parallel] — [GND].

7.2 ESD (Electrostatic Discharge) Precautions

Although rated for 1000V ESD, proper handling procedures should be followed. Use grounded workstations and wrist straps when handling these devices to prevent damage from static electricity or power surges.

7.3 Thermal Management

Adhere to the power dissipation (90mW) and derating specifications. In high ambient temperature applications or when driving at high currents, ensure adequate ventilation or heat sinking via the leads to prevent overheating, which reduces light output and lifespan.

8. Frequently Asked Questions (FAQ)

8.1 What is the difference between the Iv values in the characteristics table and the binning table?

The Electrical/Optical Characteristics table (Section 2.2) lists the absolute minimum, typical, and maximum values for the entire product family. The Binning Table (Section 3) shows how manufactured parts are sorted into tighter, more consistent groups (bins) based on tested performance. You select a bin code to guarantee the LEDs you receive fall within a specific, narrower performance range.

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

No. The forward voltage of an LED has a negative temperature coefficient and is not a fixed value. Connecting it directly to a voltage source will cause uncontrolled current flow, likely exceeding the maximum rating and destroying the device. A series resistor is mandatory for constant-voltage drive.

8.3 Why is maintaining a 2mm gap during soldering so important?

The epoxy lens material has a much higher coefficient of thermal expansion than the metal leads. Applying intense heat too close to the lens can create severe mechanical stress at the lead-epoxy interface, potentially cracking the seal, damaging the internal die bond, or allowing moisture ingress, leading to premature failure.

8.4 How do I interpret the Hue Rank table (U91, U01, etc.)?

Each hue rank (e.g., U31) defines a quadrilateral area on the CIE 1931 color space diagram using four sets of (x, y) coordinates. LEDs are tested, and their measured color coordinates must fall within the boundaries of their assigned hue rank polygon. This ensures all LEDs labeled with the same hue rank emit light of a very similar white color tone.