SMD LED 17-21/T1D-CP2R1TY/3T Datasheet - Pure White - 2.6-3.0V - 40mW - English Technical Document

1. Product Overview

The 17-21 SMD LED is a compact, surface-mount device designed for high-density electronic assemblies. Its primary advantage lies in its significantly reduced footprint compared to traditional lead-frame components, enabling smaller printed circuit board (PCB) designs, increased component packing density, and ultimately contributing to the miniaturization of end equipment. The device is lightweight, making it particularly suitable for applications where space and weight are critical constraints.

This LED is a mono-color type, emitting a pure white light, and is constructed with a yellow diffused resin. It is compliant with key environmental and safety standards, including being Pb-free, RoHS compliant, EU REACH compliant, and Halogen Free (with Bromine <900 ppm, Chlorine <900 ppm, and Br+Cl < 1500 ppm). The product is supplied in industry-standard 8mm tape on 7-inch diameter reels, ensuring compatibility with automated pick-and-place assembly equipment and standard infrared or vapor phase reflow soldering processes.

2. Technical Parameter Deep-Dive

2.1 Absolute Maximum Ratings

These ratings define the limits beyond which permanent damage to the device may occur. Operation under or at these conditions is not guaranteed.

• Reverse Voltage (V_R): 5V. Critical Note: This parameter is defined for infrared (IR) test conditions only. The LED is not designed for operation under reverse bias.
• Forward Current (I_F): 10 mA (continuous).
• Peak Forward Current (I_FP): 100 mA, permissible only under pulsed conditions with a duty cycle of 1/10 at 1 kHz.
• Power Dissipation (P_d): 40 mW. This is the maximum allowable power the package can dissipate as heat.
• Electrostatic Discharge (ESD) Human Body Model (HBM): 150V. Precautions against static electricity are essential during handling.
• Operating Temperature (T_opr): -40°C to +85°C.
• Storage Temperature (T_stg): -40°C to +90°C.
• Soldering Temperature (T_sol): Reflow soldering: 260°C peak for 10 seconds. Hand soldering: 350°C for 3 seconds maximum.

2.2 Electro-Optical Characteristics

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

• Luminous Intensity (I_v): Ranges from a minimum of 57.0 mcd to a maximum of 140.0 mcd at a forward current (I_F) of 5 mA. The typical viewing angle (2θ_1/2) is 150 degrees.
• Forward Voltage (V_F): Ranges from 2.6V to 3.0V at I_F = 5 mA.
• Reverse Current (I_R): Maximum of 50 μA when a reverse voltage (V_R) of 5V is applied (test condition only).

Important Tolerances: Luminous intensity has a ±11% tolerance, and forward voltage has a ±0.05V tolerance from the bin center values.

3. Binning System Explanation

To ensure consistent performance in production, LEDs are sorted into bins based on key parameters.

3.1 Luminous Intensity Binning

LEDs are categorized into four bins (P2, Q1, Q2, R1) based on their measured luminous intensity at I_F = 5 mA.

• P2: 57.0 - 72.0 mcd
• Q1: 72.0 - 90.0 mcd
• Q2: 90.0 - 112.0 mcd
• R1: 112.0 - 140.0 mcd

3.2 Forward Voltage Binning

LEDs are also binned by forward voltage at I_F = 5 mA into four codes (28, 29, 30, 31).

• 28: 2.6 - 2.7V
• 29: 2.7 - 2.8V
• 30: 2.8 - 2.9V
• 31: 2.9 - 3.0V

3.3 Chromaticity Coordinate Binning

The color consistency is controlled by binning based on CIE 1931 chromaticity coordinates (x, y) with a tolerance of ±0.01. The datasheet defines four specific bins (1, 2, 3, 4), each specifying a quadrilateral area on the CIE diagram to ensure the emitted white light falls within a tightly controlled color space.

4. Performance Curve Analysis

The datasheet includes several characteristic curves that illustrate the device's behavior under varying conditions. These are crucial for circuit design and thermal management.

• Forward Current vs. Forward Voltage (I-V Curve): Shows the exponential relationship. A small increase in voltage beyond the knee point causes a large increase in current, highlighting the need for current-limiting circuitry.
• Relative Luminous Intensity vs. Forward Current: Demonstrates how light output increases with current, typically in a near-linear fashion within the operating range before potential saturation or efficiency drop.
• Relative Luminous Intensity vs. Ambient Temperature: Shows the negative temperature coefficient of light output. Luminous intensity decreases as the junction temperature rises, which is a critical consideration for high-reliability or high-temperature applications.
• Forward Current Derating Curve: Dictates the maximum allowable continuous forward current as a function of ambient temperature. As temperature increases, the maximum current must be reduced to stay within the power dissipation limits and prevent overheating.
• Radiation Pattern: A polar plot showing the angular distribution of light intensity, confirming the wide 150-degree viewing angle.
• Spectrum Distribution: A graph plotting relative intensity against wavelength, characterizing the spectral content of the emitted \"pure white\" light.

5. Mechanical & Packaging Information

5.1 Package Dimension

The LED has a compact SMD footprint. The drawing specifies key dimensions including body length, width, and height, as well as the solder pad layout and spacing. A cathode mark is clearly indicated on the package for correct polarity orientation during assembly. All unspecified tolerances are ±0.1 mm.

5.2 Reel, Tape, and Moisture-Sensitive Packaging

The device is supplied in a moisture-resistant packing format. Key elements include:

• Carrier Tape: Holds the components. Dimensions for pocket size, pitch, and tape width are provided. Each reel contains 3000 pieces.
• Reel Dimensions: Specifications for the 7-inch diameter reel, including hub diameter, flange diameter, and width.
• Moisture Barrier Bag (MBB): The reel is sealed inside an aluminum moisture-proof bag along with a desiccant and a humidity indicator card to protect the LEDs from ambient moisture, which they are sensitive to.
• Label Explanation: The packaging label includes codes for Part Number (P/N), quantity (QTY), and the specific bins for Luminous Intensity (CAT), Chromaticity (HUE), and Forward Voltage (REF).

6. Soldering & Assembly Guidelines

6.1 Critical Precautions

• Over-Current Protection: An external current-limiting resistor is mandatory. The LED's exponential I-V characteristic means a slight voltage increase can lead to a destructive current surge.
• Storage: The bag is moisture-sensitive (MSL). Do not open until ready for use. After opening, use within 168 hours (7 days) in an environment of ≤30°C and ≤60% RH. Unused parts must be resealed. If the exposure time is exceeded or the desiccant indicates moisture, a bake at 60 ±5°C for 24 hours is required before reflow.
• Soldering: Follow the Pb-free reflow profile (peak 260°C). 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.

7. Application Suggestions

7.1 Typical Application Scenarios

The 17-21 SMD LED is versatile and suitable for various low-power indicator and backlighting functions.

• Automotive Interior: Backlighting for dashboard instruments, switches, and control panels.
• Telecommunication Equipment: Status indicators and keypad backlighting in telephones and fax machines.
• Consumer Electronics: Flat backlighting for small LCD displays, switch illumination, and symbol lighting.
• General Purpose Indication: Any application requiring a compact, reliable, and bright white indicator.

7.2 Design Considerations

• Current Drive: Always use a series resistor or constant current driver set for ≤10 mA continuous current. Calculate the resistor value based on the supply voltage (V_cc), the LED's forward voltage bin (V_F), and the desired current (I_F): R = (V_cc - V_F) / I_F.
• Thermal Management: Although low power, ensure adequate PCB copper or thermal relief if operating near maximum ratings or in high ambient temperatures. Refer to the derating curve.
• Optical Design: The wide 150-degree viewing angle provides good off-axis visibility. For focused light, a secondary optic (lens) may be required.
• ESD Protection: Implement standard ESD handling procedures during assembly, as the device is sensitive to electrostatic discharge.

8. Technical Comparison & Differentiation

The 17-21 LED offers distinct advantages in its class:

• Size vs. Leaded Counterparts: Its primary advantage is the drastic reduction in board space compared to through-hole LEDs (e.g., 3mm or 5mm LEDs), enabling modern, miniaturized designs.
• Compatibility: Full compatibility with automated SMT assembly lines reduces manufacturing cost and improves reliability compared to manual insertion.
• Environmental Compliance: Being Pb-free, Halogen-Free, and RoHS/REACH compliant meets stringent global regulatory requirements, which may not be true for all older or generic LED components.
• Binning: The detailed binning for intensity, voltage, and chromaticity allows for tighter color and brightness matching in applications requiring consistency across multiple LEDs, a key differentiator from unbinned or loosely binned parts.

9. Frequently Asked Questions (Based on Technical Parameters)

Q: Can I drive this LED directly from a 3.3V or 5V logic supply?

A: No. You must use a series current-limiting resistor. Without it, the forward voltage is only ~2.8V, so connecting 3.3V directly would cause excessive current, potentially destroying the LED instantly.

Q: Why is the reverse voltage rating only 5V, and what does \"for IR test only\" mean?

A: This LED, like most, is a diode with a small reverse breakdown voltage. The 5V rating is the maximum it can withstand during a quality control test without damage. It is not designed to be operated in reverse bias in a circuit. Always ensure correct polarity.

Q: How do I interpret the luminous intensity bins (P2, Q1, etc.)?

A> These codes allow you to select LEDs with a guaranteed minimum brightness for your design. For example, specifying bin R1 ensures every LED will be between 112 and 140 mcd at 5mA, providing predictable performance.

Q: The storage instructions seem strict. What happens if I exceed the 7-day floor life?

A> SMD LEDs can absorb moisture from the air. During reflow soldering, this trapped moisture can rapidly vaporize, causing internal delamination or \"popcorning,\" which cracks the package and destroys the device. Baking drives out this moisture, restoring a safe condition for reflow.

10. Practical Design Case

Scenario: Designing a status indicator panel with 10 white LEDs powered from a 5V rail. Uniform brightness is important.

Design Steps:

1. Select Bin: Choose LEDs from the same luminous intensity bin (e.g., Q2: 90-112 mcd) and chromaticity bin to ensure visual consistency.
2. Calculate Current-Limiting Resistor: Use the worst-case V_F from the bin. For bin 30 (2.8-2.9V), use V_F(max) = 2.9V for a conservative design. Target I_F = 8 mA (below the 10 mA max for margin).
   
   R = (5V - 2.9V) / 0.008A = 262.5 Ω. Select the nearest standard value, 270 Ω.
   
   Recalculate actual current: I_F = (5V - 2.8V) / 270 Ω ≈ 8.15 mA (using V_F(min)). This is safe and within the bin's test condition of 5mA.
3. Layout: Place the LEDs on the PCB with correct polarity (cathode mark). Ensure the PCB pads match the recommended land pattern from the dimension drawing to avoid tombstoning or poor solder joints.
4. Assembly: Follow the moisture handling procedures. Program the reflow oven to the recommended Pb-free profile with a peak of 260°C.
5. Result: A reliable, uniformly bright indicator panel with controlled current and proper thermal/mechanical assembly.

11. Operating Principle

The 17-21 LED is a solid-state light source based on a semiconductor chip. The core material is Indium Gallium Nitride (InGaN), which is capable of emitting light in the blue/ultraviolet spectrum. To produce white light, the chip is coated with a yellow phosphor layer (contained within the yellow diffused resin package). When the chip emits blue light, a portion of it is absorbed by the phosphor and re-emitted as yellow light. The combination of the remaining blue light and the converted yellow light is perceived by the human eye as white. This technology is known as phosphor-converted white LED.

12. Technology Trends

The 17-21 form factor represents a mature stage in SMD LED development. Current industry trends relevant to such components include:

• Increased Efficiency: Ongoing improvements in InGaN chip technology and phosphor formulations lead to higher luminous efficacy (more light output per electrical watt), allowing for lower current drive or brighter output from the same package.
• Color Quality: Advancements focus on improving the Color Rendering Index (CRI) and achieving more precise and consistent color points (smaller chromaticity bins) for high-quality display and lighting applications.
• Miniaturization: While the 17-21 is already small, the drive for ever-smaller consumer electronics continues to push for even more compact LED packages (e.g., 0402, 0201 metric sizes) with maintained or improved performance.
• Integration: A trend towards integrating multiple LED chips, current-limiting resistors, or even control ICs into a single package module to simplify circuit design and save board space.