SMD LED 17-21 Brilliant Yellow Datasheet - Package 1.6x0.8x0.6mm - Voltage 1.75-2.35V - Power 60mW - English Technical Document

1. Product Overview

The 17-21 SMD LED is a surface-mount device designed for high-density PCB applications. It utilizes AlGaInP semiconductor technology to produce a brilliant yellow light output. The primary advantage of this component is its miniature footprint, measuring 1.6mm x 0.8mm x 0.6mm, which enables significant space savings on circuit boards compared to traditional leaded LEDs. This reduction in size directly contributes to smaller end-product designs, reduced storage requirements for components, and higher packing density on PCBs. The device is also lightweight, making it ideal for portable and miniature electronic applications where weight is a critical factor.

The LED is classified as a mono-color type and is constructed using lead-free (Pb-free) materials. It complies with major environmental and safety regulations, including the EU RoHS directive, EU REACH regulations, and is classified as halogen-free, with bromine (Br) and chlorine (Cl) content each below 900 ppm and their sum below 1500 ppm. The product is supplied on 8mm tape, wound onto 7-inch diameter reels, making it fully compatible with standard automated pick-and-place assembly equipment. It is also designed to withstand common soldering processes, including infrared and vapor phase reflow.

2. Technical Specifications and Deep Objective Interpretation

2.1 Absolute Maximum Ratings

The absolute maximum ratings define the stress limits beyond which permanent damage to the device may occur. These values are not intended for normal operation.

• Reverse Voltage (VR): 5V. Exceeding this voltage in reverse bias can cause junction breakdown.
• Forward Current (IF): 25mA DC. This is the maximum continuous current recommended for reliable operation.
• Peak Forward Current (IFP): 60mA. This rating applies under pulsed conditions with a duty cycle of 1/10 at 1kHz. It allows for brief periods of higher brightness but should not be used for continuous drive.
• Power Dissipation (Pd): 60mW. This is the maximum power the package can dissipate as heat at an ambient temperature (Ta) of 25°C. Derating may be necessary at higher temperatures.
• Electrostatic Discharge (ESD): 2000V (Human Body Model). This indicates a moderate level of ESD sensitivity. Proper ESD handling procedures are essential during assembly and handling.
• Operating Temperature (Topr): -40°C to +85°C. The device is rated for industrial temperature range applications.
• Storage Temperature (Tstg): -40°C to +90°C.
• Soldering Temperature: The device can withstand reflow soldering with a peak temperature of 260°C for up to 10 seconds. For hand soldering, the iron tip temperature should 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 Ta=25°C and IF=20mA, unless otherwise specified. They define the optical and electrical performance of the LED.

• Luminous Intensity (Iv): Ranges from a minimum of 28.50 mcd to a maximum of 72.00 mcd. The typical value falls within this range. A tolerance of ±11% applies to the luminous intensity.
• Viewing Angle (2θ1/2): Typically 140 degrees. This wide viewing angle makes the LED suitable for applications requiring broad illumination or visibility from multiple angles.
• Peak Wavelength (λp): Typically 591 nm. This is the wavelength at which the spectral power distribution is maximum.
• Dominant Wavelength (λd): Ranges from 585.50 nm to 591.50 nm. This is the single wavelength perceived by the human eye that matches the color of the LED light. A tight tolerance of ±1nm is specified.
• Spectral Bandwidth (Δλ): Typically 15 nm. This defines the width of the emitted spectrum at half the maximum intensity (FWHM).
• Forward Voltage (VF): Ranges from 1.75V to 2.35V at IF=20mA. A tolerance of ±0.1V is noted. This parameter is crucial for designing the current-limiting circuit.
• Reverse Current (IR): Maximum 10 μA at VR=5V. The datasheet explicitly states the device is not designed for reverse operation; this test is for characterization only.

3. Binning System Explanation

To ensure consistency in production, LEDs are sorted into bins based on key parameters. This allows designers to select parts that meet specific performance criteria for their application.

3.1 Luminous Intensity Binning

LEDs are categorized into four bins (N1, N2, P1, P2) based on their measured luminous intensity at 20mA.

• N1: 28.50 - 36.00 mcd
• N2: 36.00 - 45.00 mcd
• P1: 45.00 - 57.00 mcd
• P2: 57.00 - 72.00 mcd

3.2 Dominant Wavelength Binning

The color (hue) is controlled by binning the dominant wavelength into two groups.

• D3: 585.50 - 588.50 nm
• D4: 588.50 - 591.50 nm

3.3 Forward Voltage Binning

Forward voltage is binned to aid in power supply design and to group LEDs with similar electrical characteristics.

• Bin 0: 1.75 - 1.95 V
• Bin 1: 1.95 - 2.15 V
• Bin 2: 2.15 - 2.35 V

The combination of these bin codes (e.g., CAT for intensity, HUE for wavelength, REF for voltage) is typically indicated on the product packaging label, allowing for precise component selection.

4. Performance Curve Analysis

The datasheet references typical electro-optical characteristic curves. While the specific graphs are not provided in the text, standard curves for such LEDs would typically include:

• Relative Luminous Intensity vs. Forward Current: This curve shows how light output increases with current, usually in a sub-linear fashion at higher currents due to heating effects.
• Forward Voltage vs. Forward Current: This is the diode's I-V characteristic, showing the exponential relationship.
• Relative Luminous Intensity vs. Ambient Temperature: This curve demonstrates the thermal quenching effect, where light output decreases as junction temperature rises.
• Spectral Power Distribution: A plot showing the intensity of emitted light across wavelengths, centered around the peak wavelength of 591 nm with a typical bandwidth of 15 nm.

These curves are essential for understanding the device's behavior under non-standard conditions (different currents or temperatures) and for optimizing the drive circuitry for efficiency and longevity.

5. Mechanical and Package Information

5.1 Package Dimensions

The 17-21 SMD LED has a compact rectangular package. Key dimensions (in mm) include a body length of 1.6, width of 0.8, and height of 0.6. The terminal pads are designed for reliable soldering. A cathode identification mark is present on the package, which is critical for correct orientation during assembly. All unspecified tolerances are ±0.1mm.

5.2 Polarity Identification

Correct polarity is vital for LED operation. The package features a distinct mark to identify the cathode (-) terminal. Designers must ensure the PCB footprint includes a corresponding marker and that assembly processes correctly align the component.

6. Soldering and Assembly Guidelines

Proper handling is crucial to maintain device reliability and performance.

6.1 Current Limiting

An external current-limiting resistor is mandatory. The LED's exponential I-V characteristic means a small increase in voltage can cause a large, potentially destructive, increase in current. The resistor value should be calculated based on the supply voltage, the LED's forward voltage (using the maximum value from the bin or datasheet for safety), and the desired forward current (not exceeding 25mA continuous).

6.2 Storage and Moisture Sensitivity

The product is packaged in a moisture-resistant bag with desiccant. To prevent moisture-induced damage during reflow ("popcorning"), the following precautions must be taken:

• Do not open the moisture-proof bag until ready for use.
• After opening, use the components within 168 hours (7 days) if stored at conditions ≤30°C and ≤60% RH.
• If the exposure time is exceeded or the desiccant indicates saturation, a bake-out at 60±5°C for 24 hours is required before reflow.

6.3 Reflow Soldering Profile

A lead-free (Pb-free) reflow profile is specified:

• Pre-heating: 150-200°C for 60-120 seconds.
• Time Above Liquidus (217°C): 60-150 seconds.
• Peak Temperature: Maximum 260°C, held for a maximum of 10 seconds.
• Heating Rate: Maximum 6°C/second up to 255°C.
• Cooling Rate: Maximum 3°C/second.

Reflow should not be performed more than two times. Avoid mechanical stress on the package during heating and do not warp the PCB after soldering.

6.4 Hand Soldering and Rework

If hand soldering is necessary, use a soldering iron with a tip temperature ≤350°C and power ≤25W. Contact time per terminal must be ≤3 seconds. Allow a cooling interval of at least 2 seconds between soldering each terminal. Rework is strongly discouraged. If unavoidable, a specialized double-head soldering iron must be used to simultaneously heat both terminals, preventing thermal stress on the silicon die. The impact of rework on LED characteristics must be verified beforehand.

7. Packaging and Ordering Information

7.1 Reel and Tape Specifications

The LEDs are supplied in embossed carrier tape with pockets suitable for the 17-21 package. The tape width is 8mm, wound on a standard 7-inch (178mm) diameter reel. Each reel contains 3000 pieces. Detailed reel and carrier tape dimensions are provided in the datasheet for compatibility with automated feeders.

7.2 Label Information

The packaging label contains several key codes:

• P/N: Product Number (e.g., 17-21/Y2C-CN1P2B/3T).
• QTY: Packing Quantity (3000 pcs/reel).
• CAT: Luminous Intensity Rank (e.g., N1, P2).
• HUE: Chromaticity/Dominant Wavelength Rank (e.g., D3, D4).
• REF: Forward Voltage Rank (e.g., 0, 1, 2).
• LOT No: Traceability lot number.

8. Application Suggestions

8.1 Typical Application Scenarios

• Backlighting: Ideal for backlighting indicators, symbols, and switches in automotive dashboards, consumer electronics, and industrial control panels.
• Status Indicators: Perfect for power, connectivity, and status indicators in telecommunications equipment (phones, faxes), networking hardware, and home appliances.
• LCD Flat Backlighting: Can be used in arrays to provide uniform backlighting for small monochrome or segmented LCD displays.
• General Purpose Indication: Suitable for any application requiring a bright, reliable, and compact visual indicator.

8.2 Design Considerations

• Drive Circuit: Always use a constant-current driver or a voltage source with a series resistor. Consider the forward voltage binning when calculating resistor values to ensure consistent brightness across different production batches.
• Thermal Management: While the power is low, ensure adequate PCB copper area or thermal vias if operating at high ambient temperatures or near the maximum current to manage junction temperature and maintain light output and lifespan.
• ESD Protection: Incorporate ESD protection diodes on sensitive lines if the LED is in an exposed location (e.g., a panel indicator).
• Optical Design: The wide 140-degree viewing angle may require light guides or diffusers if a more focused beam is needed. For optimal visibility, consider the contrast ratio against the background.

9. Technical Comparison and Differentiation

The 17-21 LED offers specific advantages in its category:

• vs. Larger SMD LEDs (e.g., 3528, 5050): The 17-21 provides a significantly smaller footprint, enabling ultra-miniaturized designs. The trade-off is generally lower maximum light output and power handling.
• vs. Leaded LEDs: It eliminates the need for through-hole mounting, enabling fully automated assembly, reducing board size, and improving mechanical robustness by eliminating bent leads.
• vs. Other Yellow LEDs: The use of AlGaInP technology typically offers higher luminous efficiency and better color saturation for yellow and amber colors compared to older technologies like GaAsP on GaP.
• Key Differentiators: Its combination of a very small 1.6x0.8mm footprint, a wide 140-degree viewing angle, compliance with halogen-free and other environmental standards, and detailed binning for color and intensity consistency.

10. Frequently Asked Questions (Based on Technical Parameters)

Q1: What resistor value should I use with a 5V supply?
A: Using the maximum VF of 2.35V (from Bin 2) and a target IF of 20mA for safety: R = (Vsupply - VF) / IF = (5V - 2.35V) / 0.020A = 132.5 Ohms. Use the nearest standard value (e.g., 130 or 150 Ohms). Always verify actual current in the circuit.

Q2: Can I drive this LED at 30mA for higher brightness?
A: No. The Absolute Maximum Rating for continuous forward current (IF) is 25mA. Operating at 30mA exceeds this rating, which will reduce reliability and lifespan, and may cause immediate failure due to overheating.

Q3: The viewing angle is 140 degrees. How do I get a more focused beam?
A: You would need to use an external optical component, such as a lens placed over the LED. The native package emits a wide, lambertian pattern.

Q4: My automated optical inspection (AOI) system is having trouble with the cathode mark. Is there a recommended way to identify polarity on the PCB?
A: Yes. The PCB footprint should include a silkscreen or copper feature that matches the package's cathode mark. Ensure the pick-and-place machine's vision system is programmed to recognize this asymmetry. Refer to the package dimension drawing for the exact location of the mark.

Q5: Do I need to bake the components if the bag has been open for 10 days?
A: Yes. The specification states a "floor life" of 168 hours (7 days) after opening the moisture barrier bag. Since 10 days (240 hours) exceeds this, you must perform the baking treatment (60±5°C for 24 hours) before subjecting the LEDs to reflow soldering to prevent moisture-related damage.

11. Practical Application Case Study

Scenario: Designing a compact multi-status indicator panel for a portable medical device.

Requirements: The device needs 6 independent status indicators (Power, Battery Low, Bluetooth, Error, Mode A, Mode B) in a very limited space on the front panel. The indicators must be clearly visible in various lighting conditions, consume minimal power, and withstand cleaning with disinfectants.

Design Implementation:

1. Component Selection: The 17-21 brilliant yellow LED is chosen for all indicators due to its small size (allowing 6 LEDs to fit in a row with spacing), good brightness, and wide viewing angle ensuring visibility from different angles.
2. Circuit Design: A common 3.3V rail is used. Using the typical VF of 2.0V and IF=15mA (for a balance of brightness and power saving), the current-limiting resistor is calculated: R = (3.3V - 2.0V) / 0.015A ≈ 87 Ohms. A 91 Ohm, 1% tolerance resistor is selected for each LED to ensure uniform brightness.
3. PCB Layout: The LEDs are placed on 3mm centers. The PCB footprint is designed according to the datasheet's recommended pad layout, with a clear silkscreen dot next to the cathode pad. A small ground pour around the LEDs is omitted to simplify soldering and cleaning.
4. Panel Design: The front panel has 1.2mm diameter apertures aligned with each LED. A thin, milky-white diffuser film is placed behind the panel to soften the LED's hotspot and create a uniform illuminated dot.
5. Software Control: The microcontroller drives each LED via a GPIO pin configured as an open-drain output with an internal pull-up disabled, sinking current through the LED/resistor pair to ground.
6. Result: A clean, professional-looking indicator panel that meets all size, visibility, and reliability requirements. The consistent binning (specifying CAT=P1 or higher, HUE=D4) in the bill of materials ensures all units have uniform color and brightness.

12. Technical Principle Introduction

The 17-21 LED is based on Aluminum Gallium Indium Phosphide (AlGaInP) semiconductor material grown on a substrate. When a forward voltage exceeding the diode's turn-on voltage (approximately 1.8V) is applied, electrons and holes are injected into the active region from the n-type and p-type layers, respectively. These charge carriers recombine radiatively, releasing energy in the form of photons. The specific composition of the AlGaInP alloy determines the bandgap energy, which directly defines the wavelength (color) of the emitted light. For brilliant yellow, the peak wavelength is engineered to be around 591 nm. The water-clear epoxy resin encapsulant protects the semiconductor chip, acts as a lens to shape the light output (contributing to the 140-degree viewing angle), and may contain phosphors or dyes, though for this mono-color type, it is likely unmodified to preserve color purity.

13. Industry Trends and Developments

The market for miniature SMD LEDs like the 17-21 continues to evolve. Key trends influencing this product segment include:

• Increased Efficiency: Ongoing material science and chip design improvements aim to deliver higher luminous efficacy (more light output per unit of electrical power) from the same or smaller package sizes.
• Enhanced Reliability: Demands from automotive and industrial applications are driving improvements in high-temperature performance, moisture resistance, and longevity.
• Tighter Color Binning: Applications requiring precise color matching, such as multi-LED indicators or backlighting arrays, are pushing manufacturers towards narrower binning tolerances for dominant wavelength and luminous intensity.
• Integration: A trend towards integrating multiple LED chips, current-limiting resistors, or even control ICs into a single package module to simplify end-user circuit design and save board space.
• Environmental Compliance: Regulations like RoHS and REACH are becoming stricter and more global, making full material declaration and halogen-free compliance standard expectations, not differentiators.

Devices like the 17-21 represent a mature and optimized solution for basic indication needs, with future iterations likely focusing on the trends above rather than radical changes in form factor for this ultra-miniature class.