SMD LED 17-21/GHC-YR1S2/3T Datasheet - 1.6x0.8x0.6mm - 3.5V - 25mA - Brilliant Green - English Technical Documentation

1. Product Overview

The 17-21/GHC-YR1S2/3T is a surface-mount device (SMD) LED designed for modern, compact electronic applications. This component represents a significant advancement over traditional lead-frame LEDs, offering substantial benefits in terms of board space utilization and assembly efficiency.

1.1 Product Positioning and Core Advantages

This LED is a mono-color type, emitting a brilliant green light. Its primary advantage lies in its miniature footprint. The significantly smaller size compared to leaded components enables designers to achieve higher packing density on printed circuit boards (PCBs). This directly translates to reduced board size, minimized storage requirements for components, and ultimately, the creation of smaller and lighter end-user equipment. The lightweight nature of the package further makes it an ideal choice for applications where weight is a critical factor.

1.2 Target Market and Applications

The device is targeted at a broad range of consumer and industrial electronics. Its typical applications include backlighting for instrument panels, switches, and symbols. It is also suitable for use in telecommunication equipment as status indicators or backlights for devices like telephones and fax machines. Furthermore, it serves as a general-purpose indicator light in various electronic products.

2. Technical Parameter Deep Dive

This section provides a detailed, objective analysis of the LED's key technical parameters as defined in the datasheet.

2.1 Absolute Maximum Ratings

The absolute maximum ratings define the limits beyond which permanent damage to the device may occur. These are not operating conditions.

• Reverse Voltage (VR): 5V. It is crucial to note that this rating is specified for infrared (IR) test conditions only. The datasheet explicitly states the device is not designed for reverse operation in an actual circuit. Exceeding this voltage in reverse bias can cause immediate failure.
• Forward Current (IF): 25 mA. This is the maximum continuous DC current that can be applied to the LED.
• Peak Forward Current (IFP): 100 mA. This is the maximum pulsed current, permissible only under a duty cycle of 1/10 at 1 kHz. This parameter is relevant for multiplexing or PWM dimming applications but must be used with caution to avoid overheating.
• Power Dissipation (Pd): 95 mW. This is the maximum power the package can dissipate, calculated from the forward voltage and current limits, and is critical for thermal management.
• Operating & Storage Temperature: The device can operate from -40°C to +85°C and be stored from -40°C to +90°C. This wide range makes it suitable for harsh environments.
• Soldering Temperature: For reflow soldering, a peak temperature of 260°C for a maximum of 10 seconds is specified. For hand soldering, the iron tip temperature must not exceed 350°C, and contact time should be limited to 3 seconds per terminal.

2.2 Electro-Optical Characteristics

These parameters are measured at a standard test condition of a forward current (IF) of 20 mA and an ambient temperature (Ta) of 25°C.

• Luminous Intensity (Iv): Ranges from a minimum of 112.0 mcd to a maximum of 285.0 mcd. The typical value is not specified, indicating performance is managed through a binning system (detailed later). The tolerance is ±11%.
• Viewing Angle (2θ1/2): A typical value of 140 degrees. This wide viewing angle makes the LED suitable for applications requiring broad illumination or visibility from multiple angles.
• Peak Wavelength (λp): Typically 518 nm, placing it in the brilliant green region of the visible spectrum.
• Dominant Wavelength (λd): Ranges from 520.0 nm to 535.0 nm, with a tight tolerance of ±1 nm. This parameter is more closely related to the perceived color of the light.
• Spectral Bandwidth (Δλ): Typically 35 nm, describing the spread of the emitted light's wavelengths around the peak.
• Forward Voltage (VF): Typically 3.5V, with a maximum of 4.0V at 20 mA. This is a critical parameter for circuit design, as it determines the voltage drop across the LED and the necessary current-limiting resistor value.
• Reverse Current (IR): Maximum of 50 μA at a reverse voltage of 5V (test condition).

3. Binning System Explanation

To ensure consistent performance, the LEDs are sorted into bins based on key optical parameters. This allows designers to select parts that meet specific brightness and color requirements.

3.1 Luminous Intensity Binning

LEDs are categorized into four bins (R1, R2, S1, S2) based on their measured luminous intensity at 20 mA.

• Bin R1: 112.0 – 140.0 mcd
• Bin R2: 140.0 – 180.0 mcd
• Bin S1: 180.0 – 225.0 mcd
• Bin S2: 225.0 – 285.0 mcd

The selection of a higher bin (e.g., S2) guarantees higher minimum brightness, which is essential for applications requiring high visibility or where multiple LEDs need to be matched for uniform appearance.

3.2 Dominant Wavelength Binning

LEDs are also binned by their dominant wavelength into three groups (X, Y, Z) to control color consistency.

• Bin X: 520.0 – 525.0 nm
• Bin Y: 525.0 – 530.0 nm
• Bin Z: 530.0 – 535.0 nm

For applications where color matching between multiple LEDs is critical (e.g., status bars, backlight arrays), specifying a single, narrow bin is necessary to avoid visible color differences.

4. Mechanical and Package Information

4.1 Package Dimensions

The 17-21 SMD LED has a compact rectangular package. Key dimensions include a length of 1.6 mm, a width of 0.8 mm, and a height of 0.6 mm (tolerance ±0.1 mm unless otherwise noted). The datasheet provides a detailed dimensional drawing including pad layout, which is essential for creating the PCB footprint. Correct pad design ensures proper soldering, alignment, and thermal performance.

4.2 Polarity Identification

The cathode is typically identified by a marking on the package or a specific pad geometry (e.g., a chamfered corner). Correct polarity orientation during placement is vital for the circuit to function.

5. Soldering and Assembly Guide

Proper handling and soldering are critical to the reliability and performance of SMD LEDs.

5.1 Reflow Soldering Profile

The datasheet specifies a lead-free reflow soldering profile. Key phases include:

• Pre-heating: Ramp from ambient to 150-200°C over 60-120 seconds.
• Soak/Reflow: Time above liquidus (217°C) should be 60-150 seconds. The peak temperature must not exceed 260°C, and the time at or above 255°C must be limited to a maximum of 30 seconds.
• Cooling: The maximum cooling rate should not exceed 6°C per second.

Critical Note: Reflow soldering should not be performed more than two times on the same LED assembly to prevent thermal damage to the package and die.

5.2 Storage and Moisture Sensitivity

This component is moisture-sensitive. Precautions include:

• Do not open the moisture-proof barrier bag until the components are ready for use.
• After opening, unused LEDs must be stored at ≤30°C and ≤60% relative humidity.
• The "floor life" after bag opening is 168 hours (7 days). If not used within this time, the LEDs must be rebaked at 60 ±5°C for 24 hours before use.
• If the desiccant indicator has changed color, baking is required regardless of time.

5.3 Hand Soldering and Rework

If hand soldering is unavoidable, extreme care must be taken:

• Soldering iron tip temperature must be ≤350°C.
• Contact time per terminal must be ≤3 seconds, with an interval of at least 2 seconds between soldering each terminal to allow cooling.
• Repair after soldering is strongly discouraged. If absolutely necessary, a dual-head soldering iron should be used to simultaneously heat both terminals, minimizing thermal stress. The impact on LED characteristics must be verified beforehand.

6. Packaging and Ordering Information

6.1 Standard Packaging

The LEDs are supplied in moisture-resistant packaging, which includes:

• Components placed in an 8mm wide carrier tape.
• The tape is wound on a 7-inch diameter reel.
• A standard reel contains 3000 pieces.
• The reel is placed inside an aluminum moisture-proof bag with a desiccant packet and a humidity indicator card.

6.2 Label Explanation

The reel label contains codes that specify the exact characteristics of the LEDs on that reel:

• P/N: Product Number (e.g., 17-21/GHC-YR1S2/3T).
• CAT: Luminous Intensity Rank (corresponds to the bin code: R1, R2, S1, S2).
• HUE: Chromaticity Coordinates & Dominant Wavelength Rank (corresponds to the bin code: X, Y, Z).
• REF: Forward Voltage Rank.
• LOT No: Traceable manufacturing lot number.

7. Application Suggestions and Design Considerations

7.1 Current Limiting is Mandatory

An external current-limiting resistor is absolutely required. LEDs are current-driven devices. A small increase in forward voltage can cause a large, potentially destructive increase in forward current. The resistor value (R) can be calculated using Ohm's Law: R = (V_supply - VF_LED) / I_desired. Always design for the *typical* VF to ensure current is within limits if the actual VF is at the minimum specified value.

7.2 Thermal Management

While small, the LED generates heat. The 95 mW power dissipation limit must be respected. Ensure the PCB pad design provides adequate thermal relief, especially if operating at or near the maximum continuous current (25 mA). Avoid placing the LED near other heat-generating components.

7.3 ESD Precautions

The device has an ESD rating of 1000V (Human Body Model). Standard ESD handling procedures should be followed during assembly and handling to prevent latent damage that may not cause immediate failure but can degrade long-term reliability.

8. Technical Comparison and Differentiation

The primary differentiation of the 17-21 LED lies in its form factor and performance balance.

• vs. Larger SMD LEDs (e.g., 3528, 5050): It offers a significantly smaller footprint, enabling higher-density designs, but typically at a lower total light output per device.
• vs. Chip-Scale Packages (CSP): It is larger than cutting-edge CSP LEDs but is easier to handle with standard SMT equipment and offers a more robust package for many applications.
• vs. Leaded LEDs: It eliminates the need for through-holes, enables automated pick-and-place assembly, reduces parasitic inductance, and allows for much smaller and lighter end products.

9. Frequently Asked Questions (Based on Technical Parameters)

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

No. This is explicitly warned against in the "Precautions For Use" section. The forward voltage has a range (typ. 3.5V, max. 4.0V). Connecting it directly to a voltage source even slightly above its VF will cause excessive current, leading to rapid overheating and failure. A series resistor is mandatory for safe operation.

9.2 Why is the reverse voltage rating only 5V, and what does the note mean?

The 5V rating is for test purposes only to measure reverse leakage current (IR). The datasheet clearly states "The device is not designed for reverse operation." In a circuit, you must ensure the LED is never subjected to a reverse bias, as it is not a Zener diode and will likely be damaged at voltages well below 5V if reverse-biased. Use protection diodes in circuits where reverse voltage is possible (e.g., AC coupling, inductive loads).

9.3 How do I choose the right bin code?

Select the bin based on your application's needs: - For maximum brightness, specify Bin S2. - For tight color consistency across multiple LEDs in an array, specify a single, narrow Dominant Wavelength bin (e.g., only Bin Y). - For cost-sensitive applications where brightness variation is acceptable, a broader mix or a lower bin (R1, R2) may be suitable.

10. Design and Usage Case Study

10.1 Designing a Compact Status Indicator Panel

Scenario: Designing a dense panel of 20 status indicators for a networking device. Uniform brightness and color are important for user experience. Design Steps: 1. Current Setting: Choose a drive current of 15 mA (below the 25 mA max) for good brightness and longevity. Calculate resistor value for a 5V supply: R = (5V - 3.5V) / 0.015A = 100 Ohms. Use a 1% tolerance resistor. 2. Binning Selection: To ensure uniformity, specify all LEDs from the same luminous intensity bin (e.g., S1) and the same dominant wavelength bin (e.g., Y). This information must be provided when ordering. 3. PCB Layout: Use the exact pad dimensions from the datasheet. Provide a small thermal relief connection for each pad to aid soldering and prevent tombstoning, but ensure the copper area is sufficient for heat dissipation. 4. Assembly: Follow the specified reflow profile. Keep the panels in sealed bags until the moment they are loaded into the pick-and-place machine to respect the 7-day floor life.

11. Operating Principle Introduction

The 17-21/GHC-YR1S2/3T LED is based on a semiconductor chip made of Indium Gallium Nitride (InGaN), as indicated in the Device Selection Guide. When a forward voltage exceeding the diode's built-in potential is applied, electrons and holes are injected into the active region of the semiconductor. Their recombination releases energy in the form of photons (light). The specific composition of the InGaN material determines the bandgap energy, which directly correlates to the wavelength (color) of the emitted light—in this case, brilliant green (~518 nm peak). The water-clear resin encapsulant protects the chip and acts as a lens, shaping the 140-degree viewing angle of the emitted light.

12. Technology Trends and Context

The 17-21 package represents a mature and widely adopted form factor in the SMD LED market. The general trend in LED technology continues towards several key areas relevant to such components:

• Increased Efficiency: Ongoing material science improvements aim to produce more lumens per watt (higher efficacy), meaning brighter light or lower power consumption for the same size package.
• Miniaturization: While the 17-21 (1.6x0.8mm) is small, the industry pushes towards even smaller chip-scale packages (CSP) that are nearly the size of the bare semiconductor die, enabling ultra-high-density lighting arrays.
• Improved Color Consistency: Advances in epitaxial growth and binning processes allow for tighter control over dominant wavelength and luminous intensity, reducing the need for stringent bin selection in some applications.
• Enhanced Reliability: Improvements in packaging materials, such as more robust silicones and phosphors (for white LEDs), and better thermal management designs extend operational lifetime and allow for use in higher-temperature environments.

This datasheet reflects a reliable, well-characterized component that balances performance, size, and manufacturability for a broad range of mainstream electronic applications.