SMD LED 17-21/R6C-AN2Q1B/3T Datasheet - Brilliant Red - 20mA - 2.35V Max - English Technical Document

1. Product Overview

This document details the specifications for a surface-mount device (SMD) LED emitting Brilliant Red light. The component utilizes an AlGaInP chip encapsulated in a water-clear resin. Its compact SMD package offers significant advantages for modern electronic design, enabling higher board density and contributing to the miniaturization of end equipment.

1.1 Key Features and Advantages

The primary benefits of this LED stem from its packaging and compliance standards:

• Automation-Friendly Packaging: Supplied on 8mm tape mounted on a 7-inch diameter reel, making it fully compatible with high-speed automatic pick-and-place assembly equipment.
• Robust Manufacturing Compatibility: Designed to withstand standard infrared (IR) and vapor phase reflow soldering processes, ensuring reliable attachment to printed circuit boards (PCBs).
• Environmental Compliance: The product is lead-free (Pb-free) and conforms to the RoHS (Restriction of Hazardous Substances) directive.
• Space and Weight Efficiency: The SMD format is significantly smaller and lighter than traditional leaded LEDs. This reduction in size allows for smaller PCB designs, higher component packing density, reduced storage requirements, and ultimately, more compact final products.

1.2 Target Applications

This LED is suitable for a variety of applications requiring a compact, reliable red indicator or backlight source. Typical use cases include:

• Telecommunication Equipment: Status indicators and keypad backlighting in telephones and fax machines.
• Consumer Electronics: Flat backlighting for liquid crystal displays (LCDs), backlighting for switches and symbols on control panels.
• General Purpose Indication: Any application requiring a bright, efficient red light source in a minimal footprint.

2. Technical Parameter Deep-Dive

This section provides a detailed, objective analysis of the LED's electrical, optical, and thermal specifications. All data is specified at an ambient temperature (Ta) of 25°C unless otherwise noted.

2.1 Absolute Maximum Ratings

These ratings define the limits beyond which permanent damage to the device may occur. Operation under or at these limits is not guaranteed and should be avoided in circuit design.

• Reverse Voltage (V_R): 5V. Exceeding this voltage in the reverse direction can cause junction breakdown.
• Continuous Forward Current (I_F): 25mA. The maximum DC current that can be continuously applied.
• Peak Forward Current (I_FP): 60mA. This is permissible only under pulsed conditions with a duty cycle of 1/10 at 1kHz. It allows for brief periods of higher brightness.
• Power Dissipation (P_d): 60mW. The maximum power the package can dissipate as heat, calculated as Forward Voltage (V_F) × Forward Current (I_F).
• Operating & Storage Temperature: -40°C to +85°C (operating), -40°C to +90°C (storage).
• Electrostatic Discharge (ESD): 2000V (Human Body Model). Proper ESD handling procedures are essential during assembly.
• Soldering Temperature: The device can withstand reflow soldering with a peak temperature of 260°C for up to 10 seconds, or hand soldering at 350°C for up to 3 seconds per terminal.

2.2 Electro-Optical Characteristics

These are the typical performance parameters measured under standard test conditions (I_F = 20mA).

• Luminous Intensity (I_v): Ranges from 36.0 mcd (millicandela) minimum to 90.0 mcd maximum, with a typical tolerance of ±11%. This defines the perceived brightness of the LED.
• Viewing Angle (2θ_1/2): A typical wide angle of 140 degrees. This is the angle at which the luminous intensity is half of the intensity at 0 degrees (on-axis).
• Peak Wavelength (λ_p): Typically 632 nm. This is the wavelength at which the spectral power distribution is maximum.
• Dominant Wavelength (λ_d): Specified between 617.5 nm and 633.5 nm. This wavelength corresponds to the perceived color of the light and is more relevant for color definition than peak wavelength.
• Spectral Bandwidth (Δλ): Typically 20 nm. This indicates the spectral purity; a smaller bandwidth means a more monochromatic color.
• Forward Voltage (V_F): Ranges from 1.75V to 2.35V at 20mA, with a tolerance of ±0.1V. This is the voltage drop across the LED when operating.
• Reverse Current (I_R): Maximum of 10 μA at a reverse bias of 5V.

3. Binning System Explanation

To ensure consistency in mass production, LEDs are sorted into performance bins. The part number 17-21/R6C-AN2Q1B/3T contains bin codes for key parameters.

3.1 Luminous Intensity Binning (Code: N2, P1, P2, Q1)

LEDs are grouped based on their measured luminous intensity at 20mA. The bin code in the part number (e.g., Q1) specifies the guaranteed intensity range for that specific unit.

• Bin N2: 36.0 – 45.0 mcd
• Bin P1: 45.0 – 57.0 mcd
• Bin P2: 57.0 – 72.0 mcd
• Bin Q1: 72.0 – 90.0 mcd

3.2 Dominant Wavelength Binning (Code: E4, E5, E6, E7)

LEDs are sorted into groups (A) and bins based on their dominant wavelength, which defines the precise shade of red.

• Bin E4: 617.5 – 621.5 nm
• Bin E5: 621.5 – 625.5 nm
• Bin E6: 625.5 – 629.5 nm
• Bin E7: 629.5 – 633.5 nm

3.3 Forward Voltage Binning (Code: 0, 1, 2)

LEDs are grouped (B) and binned by their forward voltage drop at 20mA. This is critical for designing current-limiting circuits, especially when multiple LEDs are connected in parallel.

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

4. Performance Curve Analysis

The datasheet includes several characteristic curves that illustrate the device's behavior under varying conditions. Understanding these is key to optimal circuit design.

4.1 Luminous Intensity vs. Forward Current & Temperature

The light output is directly proportional to the forward current. However, the relationship is not perfectly linear, and efficiency can drop at very high currents. Furthermore, luminous intensity decreases as the ambient temperature rises. The derating curve shows that the maximum permissible forward current must be reduced when operating above 25°C to avoid exceeding the power dissipation limit and to ensure long-term reliability.

4.2 Forward Voltage vs. Forward Current

This IV curve shows the exponential relationship typical of a diode. The forward voltage increases with current. The curve's shape is important for understanding the dynamic resistance of the LED and for thermal management calculations.

4.3 Spectral Distribution and Radiation Pattern

The spectral distribution plot confirms the red emission with a peak around 632 nm and a defined bandwidth. The radiation diagram (polar plot) visually represents the 140-degree viewing angle, showing how light intensity is distributed spatially.

5. Mechanical and Package Information

The LED is housed in a compact, industry-standard SMD package. The detailed dimensioned drawing is essential for creating the correct PCB footprint (land pattern) in CAD software. Key mechanical notes include:

• All unspecified tolerances are ±0.1mm.
• The drawing defines the body size, lead (terminal) dimensions, and recommended pad layout to ensure proper soldering and mechanical stability.
• Polarity is indicated by the package outline or marking; correct orientation is crucial for circuit operation.

6. Soldering and Assembly Guidelines

Proper handling and soldering are critical to yield and reliability.

6.1 Storage and Moisture Sensitivity

The LEDs are packaged in a moisture-resistant barrier bag with desiccant. To prevent popcorning (package cracking due to rapid vapor expansion during reflow), users must adhere to the following:

• Do not open the bag until ready for use.
• Store unopened bags at ≤30°C and ≤90% RH.
• After opening, the "floor life" is 1 year at ≤30°C and ≤60% RH. Unused parts should be resealed.
• If the desiccant indicator changes color or the storage time is exceeded, a bake-out at 60±5°C for 24 hours is required before reflow.

6.2 Reflow Soldering Profile

A lead-free reflow profile is specified:

• Pre-heat: 150–200°C for 60–120 seconds.
• Time Above Liquidus (TAL): 60–150 seconds above 217°C.
• Peak Temperature: Maximum of 260°C, held for no more than 10 seconds. The time above 255°C must not exceed 30 seconds.
• Heating/Cooling Rates: Maximum 3°C/sec heating to peak, maximum 6°C/sec cooling from peak.
• Important: Reflow should not be performed more than two times. Avoid mechanical stress on the LED during heating and do not warp the PCB after soldering.

6.3 Hand Soldering and Rework

If hand soldering is necessary, use a soldering iron with a tip temperature ≤350°C, apply heat to each terminal for ≤3 seconds, and use an iron rated ≤25W. Allow at least a 2-second interval between soldering each terminal. Rework is strongly discouraged. If absolutely unavoidable, a specialized double-head soldering iron must be used to simultaneously heat both terminals and prevent thermal-mechanical damage to the solder joints or the LED die.

7. Packaging and Ordering Information

7.1 Tape and Reel Specifications

The LEDs are supplied in embossed carrier tape with dimensions provided. Each reel contains 3000 pieces. Reel dimensions (7-inch diameter) are also specified for compatibility with automated equipment feeders.

7.2 Label Explanation

The reel label contains several key fields: Customer Part Number (CPN), Manufacturer Part Number (P/N), Packing Quantity (QTY), and the specific bin codes for Luminous Intensity (CAT), Dominant Wavelength/Hue (HUE), and Forward Voltage (REF), along with the manufacturing Lot Number.

8. Application and Design Considerations

8.1 Circuit Design Imperative: Current Limiting

This is the most critical design rule. An LED is a current-driven device. Its forward voltage has a negative temperature coefficient and varies from unit to unit (as shown in the binning). Therefore, it must be driven by a constant current source or, more commonly, with a series current-limiting resistor. Connecting the LED directly to a voltage source, even one matching its nominal V_F, will result in an uncontrolled current surge leading to immediate failure. The resistor value is calculated using Ohm's Law: R = (V_supply - V_F) / I_F.

8.2 Thermal Management

While the power dissipation is low, effective thermal design extends lifespan and maintains brightness. Ensure the PCB pads provide adequate thermal relief and avoid placing the LED near other heat-generating components. Adhere to the forward current derating curve for high-temperature environments.

8.3 Optical Design

The wide 140-degree viewing angle makes this LED suitable for applications requiring broad illumination or visibility from multiple angles. For focused beams, secondary optics (lenses) would be required. The water-clear resin is optimal for achieving the highest possible light output.

9. Technical Comparison and Differentiation

The primary differentiators of this component are its specific combination of material, package, and performance:

• AlGaInP Chip Technology: This material system is renowned for producing high-efficiency red, orange, and amber LEDs with excellent brightness and color stability compared to older technologies.
• SMD Package Advantage: Compared to through-hole LEDs, it offers the aforementioned size, weight, and assembly speed benefits, which are standard for modern SMD components.
• Detailed Binning: The three-parameter binning (intensity, wavelength, voltage) allows designers to select parts for applications requiring tight consistency in brightness, color, or electrical behavior, reducing the need for circuit adjustments on the production line.

10. Frequently Asked Questions (FAQ)

Q: Can I drive this LED at 30mA for higher brightness?
A: No. The Absolute Maximum Rating for continuous forward current is 25mA. Exceeding this rating compromises reliability and may cause permanent damage. For higher brightness, select an LED bin with higher luminous intensity (e.g., Q1) or use pulsed operation within the I_FP rating.

Q: The datasheet shows a V_F of 2.0V typical. Why does my circuit need a 3.3V supply?
A: The extra voltage is required to overcome the voltage drop across the current-limiting resistor. For example, to drive the LED at 20mA from a 3.3V supply with a V_F of 2.0V, you need a resistor: R = (3.3V - 2.0V) / 0.020A = 65 Ohms. The resistor dissipates the excess power.

Q: How do I interpret the part number 17-21/R6C-AN2Q1B/3T?
A> While the full naming convention may be proprietary, key segments can be deduced: "17-21" likely references the package style/size. "R6C" may indicate the color (Red) and chip type. "AN2Q1B" contains the bin codes: A (Wavelength Group), N2 (Intensity Bin), Q1 (Intensity Bin), B (Voltage Group). "3T" could relate to tape packing or a revision.

11. Practical Design Case Study

Scenario: Designing a status indicator panel with 10 identical red LEDs, all powered from a stable 5V rail. Uniform brightness is important.

Design Steps:

1. Select Bin: Choose LEDs from the same luminous intensity bin (e.g., all Q1: 72-90 mcd) and the same dominant wavelength bin (e.g., all E6: 625.5-629.5 nm) to ensure visual consistency.
2. Calculate Series Resistor: Use the maximum V_F from the bin (e.g., Bin 2: 2.35V) for a worst-case design to guarantee the current never exceeds 20mA. R = (5V - 2.35V) / 0.020A = 132.5 Ohms. Use the nearest standard value (130 or 150 Ohms). A 150 Ohm resistor provides a safety margin: I_F = (5V - 2.35V) / 150 = ~17.7mA.
3. PCB Layout: Place the LEDs using the package dimensions. Connect each LED with its own series resistor to the 5V rail. Avoid connecting multiple LEDs in parallel with a single resistor, as slight V_F variations will cause significant current imbalance and uneven brightness.
4. Assembly: Follow the moisture handling and reflow profile guidelines precisely to ensure solder joint integrity and prevent damage.

12. Operating Principle

Light is produced through a process called electroluminescence within the AlGaInP semiconductor chip. When a forward voltage exceeding the junction's built-in potential is applied, electrons and holes are injected into the active region from the n-type and p-type materials, respectively. These charge carriers recombine, releasing energy in the form of photons (light). The specific composition of the aluminum, gallium, indium, and phosphide in the chip's layers determines the bandgap energy, which directly defines the wavelength (color) of the emitted light—in this case, brilliant red.

13. Technology Trends

The general trend in LED technology continues toward higher efficiency (more lumens per watt), improved color rendering, and increased power density. For indicator-type SMD LEDs like this one, trends include further miniaturization (e.g., chip-scale packages), broader adoption of higher-performance materials like InGaN for blue/green and AlGaInP for red/orange, and enhanced reliability under harsh environmental conditions. Integration with drive electronics (e.g., built-in current regulation or PWM controllers) within the package is also an ongoing development to simplify end-user circuit design.