LTW-420DS4 White LED Datasheet - 5mm T-1 Through-Hole Package - 3.2V Forward Voltage - 120mW Power Consumption - Technical Documentation

1. Product Overview

LTW-420DS4 is a white light-emitting diode (LED) designed for through-hole mounting on printed circuit boards (PCBs). It employs the popular T-1 (5mm) diameter package with a transparent lens, making it suitable for a wide range of indicator and illumination applications. The device utilizes InGaN (Indium Gallium Nitride) technology to produce white light.

1.1 Core Advantages

The primary advantages of this LED include its compliance with the RoHS (Restriction of Hazardous Substances) directive, indicating it is a lead-free product. It features high luminous efficiency and relatively low power consumption, making it highly energy-efficient. Due to its low current requirement, the device is designed to be compatible with integrated circuits. Its through-hole design allows for flexible mounting on PCBs or panels, providing mechanical stability.

1.2 Target Market and Applications

This LED targets various electronics industries. Primary application areas include computer peripherals, communication equipment, consumer electronics, household appliances, and industrial control systems for status indication. Its main function is to serve as a status indicator or low-brightness illumination source within these devices.

2. In-depth Analysis of Technical Parameters

This section provides a detailed and objective analysis of the LED's key electrical, optical, and thermal characteristics based on the datasheet.

2.1 Absolute Maximum Ratings

These ratings define the extreme conditions that may cause permanent damage to the device and are not intended for normal operation.

• Power Dissipation (Pd):Maximum 120 mW. This is the total power that the LED package can dissipate as heat.
• DC Forward Current (IF):Continuous 30 mA. Exceeding this current increases the risk of thermal runaway and shortens service life.
• Peak Forward Current:100 mA, but only under pulse conditions (duty cycle ≤ 1/10, pulse width ≤ 10ms). This applies to brief, high-intensity flashes.
• Operating Temperature Range (TA):-30°C to +85°C. Ensures the LED operates normally within this ambient temperature range.
• Storage Temperature Range (Tstg):-40°C to +100°C.
• Lead Soldering Temperature:Maximum 260°C, up to 5 seconds, measurement point is 2.0mm from the LED body. This is crucial for assembly process control.

2.2 Electrical and Optical Characteristics (TA=25°C)

These are typical performance parameters under standard test conditions.

• Luminous Intensity (Iv):At a forward current (IF) of 20 mA, the range is from a minimum of 1150 mcd to a typical 2200 mcd, with a maximum of 5500 mcd. Actual intensity is binned (sorted), applying a ±15% tolerance to the guaranteed value. The Iv bin code is marked on the packaging bag.
• Viewing Angle (2θ1/2):45 degrees. This is the full angle at which the luminous intensity drops to half of its on-axis (0 degrees) value. The 45-degree angle provides a relatively wide beam, suitable for general indication purposes.
• Forward Voltage (VF):At IF=20mA, ranging from 2.8V (min) to 3.2V (typ) to 3.8V (max). Forward voltage is also binned, with a measurement tolerance of ±0.1V.
• Reverse Current (IR):At a Reverse Voltage (VR) of 5V, maximum 10 μA. It must be explicitly stated that this device不is not designed for reverse operation; this parameter is for test purposes only.
• Chromaticity Coordinates (x, y):At IF=20mA, typical values are x=0.29, y=0.28, derived from the CIE 1931 chromaticity diagram. Specific hues are also binned into defined regions on this diagram.

2.3 Thermal Characteristics

The derating factor for DC forward current is specified as linear derating starting from 30°C at a rate of 0.45 mA/°C. This means for every 1°C increase in ambient temperature above 30°C, the maximum allowable continuous forward current must be reduced by 0.45 mA to prevent exceeding the maximum junction temperature and power dissipation limits. For example, at an ambient temperature of 70°C, the maximum DC current will be derated to approximately 30 mA - (0.45 mA/°C * (70-30)°C) = 12 mA.

3. Binning System Description

Key LED parameters are binned to ensure consistency within a production lot and to allow designers to select components meeting specific requirements.

3.1 Luminous Intensity (Iv) Binning

LEDs are sorted into three intensity bins: QR (1150-1900 mcd), ST (1900-3200 mcd), and UV (3200-5500 mcd). A tolerance of ±15% is applied to the binning limits.

3.2 Forward Voltage (VF) Binning

Voltage is binned in 0.2V steps from 2.8V to 3.8V, with codes from 2E to 6E. This aids in designing consistent current drive circuits, especially when multiple LEDs are connected in parallel.

3.3 Chromaticity (Hue) Binning

The white light chromaticity point is binned according to CIE 1931 chromaticity coordinates. The datasheet defines eight main hue grades (A1, A2, B1, B2, C1, C2, D1, D2), each representing a specific quadrilateral area on the chromaticity diagram. A tolerance of ±0.01 is applied to each coordinate limit of these bins. This ensures color consistency among LEDs from the same hue bin.

4. Performance Curve Analysis

Although the provided datasheet excerpt mentions typical curves, a standard analysis should cover the following relationships, which are crucial for design.

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

An LED is a diode with an exponential I-V characteristic. This curve shows the relationship between the current flowing through the LED and the voltage across it. The "knee" voltage is around the typical VF (3.2V). Operating significantly above the knee voltage causes a sharp increase in current, which must be controlled by an external current-limiting resistor or constant current driver.

4.2 Luminous Intensity vs. Forward Current

Wannan curve yawanci yana nuna ƙarfin haske yana ƙaruwa yayin da kwararar wutar lantarki ta gaba ke ƙaruwa, amma ba lallai ba ne cikakkiyar alaƙar layi, musamman a cikin mafi girman kwararar wutar lantarki, saboda zafi, inganci na iya raguwa. Ƙimar Iv na takamaiman takarda an ƙayyade shi a 20mA, wannan shine wurin aiki na yau da kullun.

4.3 Luminous Intensity vs. Ambient Temperature

Fitowar haske na LED yawanci tana raguwa yayin da zafin jiki ya tashi. Fahimtar wannan ragewa yana da mahimmanci ga aikace-aikacen da ke aiki a cikin yanayin zafi don tabbatar da kiyaye isasshen haske.

5. Mechanical and Packaging Information

5.1 Outline Dimensions

The LED is packaged in a T-1 (5mm) radial leaded form. The body diameter is approximately 5mm. The leads are designed for through-hole mounting. The leadframe/spacer material is specified as black nylon plastic, with the LED lens itself being white. A key mechanical consideration is that all dimensions have a tolerance of ±0.25mm unless otherwise noted.

5.2 Polarity Identification

For through-hole LEDs, polarity is typically indicated by the lead length (the longer lead is the anode, positive) and/or a flat spot on the edge of the plastic lens (usually near the cathode, negative). Consult this model's datasheet for specific markings.

6. Soldering and Assembly Guide

Proper handling is crucial to prevent damage.

6.1 Lead Forming

The pin must be bent at a minimum distance of 3mm from the LED lens base. The lead frame base must not be used as a fulcrum. Bending must be performed at room temperature and在completed before the soldering process.

6.2 Soldering Process

Hand Soldering (Soldering Iron):Maximum temperature 350°C, maximum 3 seconds per pin. The solder point must be at least 2mm from the epoxy resin lens/bulb base. Do not apply stress to the pins while the LED is at high temperature.
Wave Soldering:Recommended conditions include preheating up to 100°C, maximum 60 seconds; solder wave temperature up to 260°C, maximum 5 seconds. The immersion position must be no less than 2mm from the epoxy bulb base. Immersion of the lens into the solder must be avoided.
Important Note:Clearly indicate infrared (IR) reflow soldering不is applicable for this type of through-hole LED product. Excessive temperature or duration may cause lens deformation or lead to catastrophic failure.

6.3 Storage and Cleaning

During storage, the ambient temperature should not exceed 30°C or relative humidity 70%. LEDs removed from their original packaging should be used within three months. For storage outside the original packaging for longer periods, it is recommended to use a sealed container with desiccant or a nitrogen environment. If cleaning is required, alcohol-based solvents such as isopropyl alcohol should be used.

7. Packaging and Ordering Information

7.1 Packaging Specifications

LEDs are packaged in bags. Standard bag quantities are 1000, 500, 200, or 100 pieces. Every 10 bags are packed into an inner box, totaling 10,000 pieces. Every 8 inner boxes are packed into an outer shipping carton, with each outer carton totaling 80,000 pieces. The datasheet specifies that within each shipping lot, only the final package may not be a full package.

7.2 Labels and Markings

The luminous intensity (Iv) binning code is marked on each packaging bag, facilitating users to identify the performance grade of the internal products.

8. Application Suggestions

8.1 Typical Application Circuit

LEDs are current-driven devices. To ensure uniform brightness when multiple LEDs are connected in parallel,It is strongly recommendedConnect an independent current-limiting resistor in series with each LED (Circuit A in the datasheet). It is not recommended to directly connect LEDs in parallel without using independent resistors (Circuit B), as slight differences in the forward voltage (VF) between LEDs can lead to significant variations in current distribution and brightness. The resistor value can be calculated using Ohm's law: R = (Power Supply Voltage - VF) / IF, where VF is the typical or maximum forward voltage from the datasheet, and IF is the desired operating current (e.g., 20mA).

8.2 Design Considerations

• Current Drive:Always use a current-limiting mechanism (resistor or driver).
• Thermal Management:Adhere to power dissipation and current derating rules, especially in high ambient temperatures or enclosed spaces.
• Optical Design:A 45-degree viewing angle is suitable for wide-angle viewing. For more focused light, an external lens or reflector may be required.
• PCB Layout:Ensure the hole pitch matches the LED's pin pitch. Leave sufficient clearance around the LED body to meet the requirements of a 3mm pin bend radius and 2mm soldering clearance.

9. Technical Comparison and Differentiation

Compared to older technologies like incandescent bulbs, this LED offers significantly higher power efficiency, longer lifespan, and faster switching speed. Within the LED market, its key differentiating features are its specific package combination (5mm T-1 through-hole), white light, defined intensity and voltage binning, and 45-degree viewing angle. It is positioned as a general-purpose indicator LED, not a high-power lighting source.

10. Frequently Asked Questions (Based on Technical Parameters)

Q: Can I drive this LED directly with a 5V power supply?
A: No. A series resistor must be used. For example, with a typical VF of 3.2V and a required IF of 20mA, the resistor value should be (5V - 3.2V) / 0.02A = 90 ohms. A standard 91 or 100 ohm resistor is suitable.

Q: What does "±15% tolerance" on luminous intensity mean?
A: This means the actual measured intensity of an LED from a given bin (e.g., ST bin: 1900-3200 mcd) can be up to 15% higher or lower than the bin's nominal limits. This is the allowable range for production variation.

Q: Why is it so important to require pin bending at least 3mm from the body?
A: Bending the pin too close to the body places excessive mechanical stress on the internal bond wires and epoxy package, which can lead to immediate breakage or potential failure over time.

Q: Can I use this LED for outdoor applications?
A: The datasheet states it is suitable for indoor and outdoor signage. However, for harsh outdoor environments, additional design considerations are needed, such as waterproofing, UV resistance of external materials, and a wider temperature cycling range.

11. Practical Use Case Examples

Scenario: Designing a status indicator panel for a network router.Panel ɗin yana buƙatar LED 10 masu haske mai haske don nuna wutar lantarki, ayyukan cibiyar sadarwa, da yanayin tashar. Masu zane sun zaɓi LTW-420DS4 daga rukunin ƙarfin UV don samun babban ganuwa. Akwai layin wutar lantarki na 5V akan PCB. Yi amfani da VF mafi girma (3.8V) don ƙididdigar resistor a jere, don tabbatar da cewa ko da a cikin mafi munin yanayin ɓangaren, ƙarfin baya wuce 20mA: R = (5V - 3.8V) / 0.02A = 60 ohms. Zaɓi resistor 62 ohms, 1/4W don kowane LED. Tsarin PCB yana sanya LED a matsayin tazarar ƙusa 2.54mm (0.1 inci), kuma wurin rami yana ba da damar lanƙwasa ƙusa na 5mm bayan shigarwa. A lokacin haɗawa, yi amfani da tsarin gudanar da walda mai ƙayyadaddun yanayin zafi da lokaci, tabbatar da cewa walda ba ta taɓa jikin LED ba.

12. Introduction to Working Principles

LED wata diodi ce ta semiconductor p-n junction. Lokacin da ake amfani da ƙarfin lantarki mai kyau, electrons daga kayan n-type suna haɗuwa da ramuka daga kayan p-type a cikin yanki mai aiki. Wannan tsarin haɗuwa yana sakin makamashi a cikin nau'in photon (haske). Launin hasken da aka fitar (tsawon zango) yana ƙayyade ta hanyar tazarar band na kayan semiconductor. Ana yin LED na fari gabaɗaya ta hanyar amfani da guntun InGaN LED shuɗi mai lulluɓe da Layer na phosphor. Haske shuɗi daga guntun yana motsa phosphor, sannan phosphor yana fitar da hasken rawaya. Haɗin hasken shuɗi da rawaya yana fahimtar idon mutum a matsayin farin haske.

13. Technology Trends

Gabaɗayan yanayin fasahar LED yana zuwa ga mafi inganci (lumen kowace watt), mafi girman ƙarfin wutar lantarki, da mafi kyawun launi. Ga LED irin na nuna alama kamar LTW-420DS4, trends sun haɗa da ƙananan ƙira (ƙananan fakitin, kamar na'urorin haɗawa na saman 0402 ko 0201), haɗakar resistor mai iyakancewa a cikin fakitin, da haɓaka LED tare da mafi faɗin kallo ko takamaiman tsarin hasken. Kimiyyar kayan tushe tana ci gaba da ci gaba, yana haifar da madaidaicin launi da tsayin rayuwa. Bin RoHS da sauran ƙa'idodin muhalli ya zama buƙatu na asali na kayan lantarki.