SMD LED 19-21/Y2C-CP1Q2B/3T Datasheet - Size 2.0x1.25x0.8mm - Voltage 1.75-2.35V - Color Brilliant Yellow - English Technical Document

1. Product Overview

The 19-21/Y2C-CP1Q2B/3T is a surface-mount device (SMD) LED designed for modern electronic applications requiring compact size and reliable performance. This component utilizes an AlGaInP (Aluminum Gallium Indium Phosphide) semiconductor chip to produce a brilliant yellow light output. The LED is encapsulated in a water-clear resin package, which enhances light extraction and provides environmental protection. Its primary advantages include a significantly reduced footprint compared to traditional lead-frame LEDs, enabling higher packing density on printed circuit boards (PCBs), reduced storage requirements, and ultimately contributing to the miniaturization of end equipment. The lightweight construction further makes it ideal for portable and miniature applications.

1.1 Key Features and Compliance

• Packaged on 8mm tape wound on a 7-inch diameter reel for compatibility with automated pick-and-place assembly equipment.
• Designed for use with standard infrared (IR) and vapor phase reflow soldering processes.
• Mono-color type emitting brilliant yellow light.
• Constructed with Pb-free (lead-free) materials.
• The product complies with the RoHS (Restriction of Hazardous Substances) directive.
• Compliance with EU REACH (Registration, Evaluation, Authorisation and Restriction of Chemicals) regulations.
• Halogen-free construction, with limits for Bromine (Br) and Chlorine (Cl) set at <900 ppm individually and <1500 ppm for their combined total.

2. Technical Specifications Deep Dive

2.1 Absolute Maximum Ratings

These ratings define the limits beyond which permanent damage to the device may occur. Operation under these conditions is not guaranteed. All values are specified at an ambient temperature (Ta) of 25°C.

• Reverse Voltage (VR): 5 V. Exceeding this voltage in reverse bias can cause junction breakdown.
• Continuous Forward Current (IF): 25 mA. The maximum DC current that can be continuously applied.
• Peak Forward Current (IFP): 60 mA. This is the maximum pulsed forward current, permissible only under a duty cycle of 1/10 at a frequency of 1 kHz. It is crucial for applications involving brief, high-intensity flashes.
• Power Dissipation (Pd): 60 mW. The maximum power the device can dissipate as heat, calculated as Forward Voltage (VF) multiplied by Forward Current (IF).
• Electrostatic Discharge (ESD) Human Body Model (HBM): 2000 V. This rating indicates the LED's sensitivity to static electricity. Proper ESD handling procedures must be followed during assembly and handling.
• Operating Temperature Range (Topr): -40°C to +85°C. The ambient temperature range over which the device is designed to function.
• Storage Temperature Range (Tstg): -40°C to +90°C.
• Soldering Temperature (Tsol): For reflow soldering, a peak temperature of 260°C for a maximum of 10 seconds is specified. For hand soldering, the iron tip temperature should not exceed 350°C for a maximum of 3 seconds per terminal.

2.2 Electro-Optical Characteristics

These parameters define the LED's performance under normal operating conditions, typically measured at Ta=25°C and IF=20mA unless otherwise stated.

• Luminous Intensity (Iv): Ranges from a minimum of 45.0 mcd to a maximum of 112.0 mcd. The typical value falls within this range based on the binning code (see Section 3).
• Viewing Angle (2θ1/2): Approximately 100 degrees. This is the full angle at which the luminous intensity is half of the intensity at 0 degrees (on-axis).
• Peak Wavelength (λp): Typically around 591 nm. This is the wavelength at which the spectral power distribution reaches its maximum.
• Dominant Wavelength (λd): Ranges from 585.5 nm to 591.5 nm. This is the single wavelength perceived by the human eye that matches the color of the LED's light.
• Spectral Bandwidth (Δλ): Typically 15 nm. This is the width of the spectrum at half the maximum intensity (Full Width at Half Maximum - FWHM).
• Forward Voltage (VF): Ranges from 1.75 V to 2.35 V. The voltage drop across the LED when operating at the specified forward current.
• Reverse Current (IR): Maximum of 10 μA when a reverse voltage of 5V is applied. The device is not intended for operation in reverse bias.

Important Notes: Tolerances are specified as ±11% for Luminous Intensity, ±1nm for Dominant Wavelength, and ±0.1V for Forward Voltage. The Reverse Voltage rating applies only to the IR test condition.

3. Binning System Explanation

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

3.1 Luminous Intensity Binning

Bins define the minimum and maximum luminous intensity at IF=20mA.
P1: 45.0 - 57.0 mcd
P2: 57.0 - 72.0 mcd
Q1: 72.0 - 90.0 mcd
Q2: 90.0 - 112.0 mcd

3.2 Dominant Wavelength Binning

Bins define the color consistency.
D3: 585.5 - 588.5 nm
D4: 588.5 - 591.5 nm

3.3 Forward Voltage Binning

Bins aid in circuit design for current regulation.
0: 1.75 - 1.95 V
1: 1.95 - 2.15 V
2: 2.15 - 2.35 V

4. Performance Curve Analysis

The datasheet provides several characteristic curves essential for design.

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

This curve shows the exponential relationship between current and voltage. A small increase in voltage beyond the turn-on threshold causes a large increase in current. This underscores the critical need for a current-limiting resistor or constant-current driver in the application circuit to prevent thermal runaway and device failure.

4.2 Relative Luminous Intensity vs. Ambient Temperature

The light output of an LED decreases as the junction temperature increases. The curve typically shows a gradual decline in intensity from low temperatures up to around 25°C, followed by a more pronounced decrease at higher ambient temperatures. This must be factored into designs where the LED operates in elevated temperature environments to ensure sufficient brightness.

4.3 Relative Luminous Intensity vs. Forward Current

This curve demonstrates that light output increases with forward current, but not linearly. Efficiency (lumens per watt) often peaks at a current lower than the absolute maximum rating. Operating above this optimal point reduces efficiency and generates more heat.

4.4 Spectrum Distribution

The graph plots relative intensity against wavelength, showing a single peak in the yellow region (~591 nm) with a typical bandwidth of 15 nm, confirming its monochromatic nature.

4.5 Radiation Pattern

A polar diagram illustrates the spatial distribution of light. The 19-21 package typically exhibits a lambertian or near-lambertian pattern, providing a wide, even viewing angle suitable for indicator and backlight applications.

4.6 Forward Current Derating Curve

This curve dictates the maximum allowable continuous forward current as a function of ambient temperature. As ambient temperature rises, the maximum safe current must be reduced to keep the junction temperature within limits and prevent accelerated degradation.

5. Mechanical and Package Information

5.1 Package Dimensions

The 19-21 SMD LED has a compact rectangular footprint. Key dimensions (in mm, tolerance ±0.1mm unless noted) include a body length of approximately 2.0 mm, a width of 1.25 mm, and a height of 0.8 mm. The package features two anode and cathode terminals on the bottom for soldering. A cathode identification mark is clearly indicated on the package, which is crucial for correct PCB orientation.

6. Soldering and Assembly Guidelines

6.1 Current Protection

An external current-limiting mechanism (resistor or driver IC) is mandatory. The LED's exponential I-V characteristic means minor supply voltage fluctuations can cause large current surges, leading to instantaneous failure.

6.2 Storage and Moisture Sensitivity

The LEDs are packaged in a moisture-resistant barrier bag with desiccant.
- Do not open the bag until ready for use.
- After opening, unused LEDs should be stored at ≤30°C and ≤60% Relative Humidity.
- The "floor life" after bag opening is 168 hours (7 days).
- If the floor life is exceeded or the desiccant indicates moisture ingress, a bake-out at 60±5°C for 24 hours is required before reflow soldering to prevent "popcorn" damage.

6.3 Reflow Soldering Profile

A lead-free (Pb-free) reflow profile is specified:
- Preheat: 150-200°C for 60-120 seconds.
- Time above liquidus (217°C): 60-150 seconds.
- Peak Temperature: 260°C maximum, for no more than 10 seconds.
- Heating Rate: Maximum 6°C/sec up to 255°C.
- Cooling Rate: Maximum 3°C/sec.
- Reflow should not be performed more than two times.

6.4 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 with a power rating ≤25W. Allow a cooling interval of at least 2 seconds between terminals. Rework is strongly discouraged. If unavoidable, a dual-head soldering iron should be used to simultaneously heat both terminals during removal to avoid mechanical stress on the package. Always verify device functionality after any rework.

7. Packaging and Ordering Information

7.1 Tape and Reel Specifications

The components are supplied in embossed carrier tape with a width of 8 mm, wound onto a standard 7-inch (178 mm) diameter reel. Each reel contains 3000 pieces. Detailed dimensions for the carrier tape pockets and the reel are provided to ensure compatibility with automated feeders.

7.2 Label Explanation

The reel label contains critical information for traceability and correct application:
- CPN: Customer's Part Number (if assigned).
- P/N: Manufacturer's Part Number (e.g., 19-21/Y2C-CP1Q2B/3T).
- QTY: Quantity of pieces on the reel.
- CAT: Luminous Intensity bin code (e.g., P1, Q2).
- HUE: Chromaticity/Dominant Wavelength bin code (e.g., D3, D4).
- REF: Forward Voltage bin code (e.g., 0, 1, 2).
- LOT No: Manufacturing lot number for quality tracking.

8. Application Suggestions

8.1 Typical Application Scenarios

• Backlighting: Ideal for backlighting symbols, switches, and small areas on dashboards, control panels, and consumer electronics.
• Status Indicators: Perfect for power, connectivity, or function status indicators in telecommunications equipment (phones, faxes), networking hardware, and industrial controls.
• General Purpose Indication: Suitable for any application requiring a compact, bright, yellow visual signal.

8.2 Design Considerations

• Current Drive: Always use a series resistor or constant-current driver. Calculate the resistor value using R = (Vsupply - VF) / IF, where VF should be chosen from the maximum value in the bin or datasheet to ensure current does not exceed limits under worst-case conditions.
• Thermal Management: While the package is small, ensure adequate PCB copper area or thermal vias under the thermal pad (if applicable) to dissipate heat, especially when operating near maximum ratings or in high ambient temperatures.
• ESD Protection: Implement ESD protection on input lines if the LED is in a user-accessible location. During handling and assembly, use grounded workstations and wrist straps.
• Optical Design: The wide viewing angle makes it suitable for applications requiring broad visibility. For focused light, external lenses or light guides may be necessary.

9. Technical Comparison and Differentiation

The 19-21/Y2C-CP1Q2B/3T offers several advantages in its category:
Size Advantage: Its 2.0x1.25mm footprint is significantly smaller than traditional 3mm or 5mm through-hole LEDs, enabling denser PCB layouts.
Material Technology: The use of AlGaInP semiconductor material provides high efficiency and excellent color purity in the yellow/orange/red spectrum compared to older technologies.
Reliability: The SMD construction and robust packaging contribute to good mechanical stability and resistance to vibration.
Compliance: Full compliance with RoHS, REACH, and halogen-free standards makes it suitable for global markets with strict environmental regulations.

10. Frequently Asked Questions (FAQ)

Q1: What is the purpose of the binning codes?
A1: Binning ensures color and brightness consistency within a production batch. For applications requiring uniform appearance (e.g., multi-LED arrays), specifying tight bins or ordering from the same lot is recommended.

Q2: Can I drive this LED directly from a 3.3V or 5V logic supply?
A2: No. You must always use a current-limiting resistor. For example, with a 3.3V supply and a typical VF of 2.0V at 20mA, the resistor value would be (3.3V - 2.0V) / 0.020A = 65 Ohms. A standard 68 Ohm resistor would be suitable.

Q3: Why is there a strict 7-day floor life after opening the moisture barrier bag?
A3: SMD packages can absorb moisture from the atmosphere. During the high-temperature reflow soldering process, this trapped moisture can vaporize rapidly, causing internal delamination or cracking ("popcorn effect"), which destroys the device.

Q4: How do I identify the cathode?
A4: The package has a distinct cathode mark. On the 19-21 package, this is typically a green stripe, a notch, or a chamfered corner on the side of the cathode terminal. Always refer to the package dimension drawing for the specific marking.

11. Practical Design Case Study

Scenario: Designing a compact status indicator panel with 10 yellow LEDs for a portable medical device.
Design Steps:
1. Circuit Design: Use a common 3.3V rail. Calculate the worst-case series resistor: R = (3.3V - 2.35V_{max VF}) / 0.020A = 47.5 Ohms. Select a standard 47 Ohm, 1/10W resistor. This ensures the current never exceeds 20.2 mA even if the LED has the minimum VF.
2. PCB Layout: Place the LEDs with a center-to-center spacing of at least 5mm for individual visibility. Include a small copper pour connected to the cathode pads to aid in heat dissipation. Add silkscreen outlines and polarity marks (+ for anode, - or cathode symbol for cathode) for assembly clarity.
3. Assembly: Order all LEDs from the same luminous intensity (e.g., Q1 bin) and dominant wavelength (e.g., D4 bin) to ensure uniform brightness and color. Schedule PCB assembly so that the LEDs are used immediately after opening the moisture barrier bag.
4. Testing: Verify forward voltage and light output of a sample from the panel under the designed operating conditions.

12. Operating Principle

Light emission in this LED is based on electroluminescence in a semiconductor p-n junction made of AlGaInP. When a forward voltage exceeding the junction's built-in potential is applied, electrons from the n-type region and holes from the p-type region are injected into the active region. There, they recombine, releasing energy in the form of photons. The specific bandgap energy of the AlGaInP alloy determines the wavelength of the emitted light, which in this case is in the yellow spectrum (~591 nm). The water-clear epoxy resin encapsulant protects the chip, provides mechanical support, and shapes the light output pattern.

13. Technology Trends

The trend in SMD LEDs like the 19-21 series continues towards:
Increased Efficiency: Ongoing improvements in epitaxial growth and chip design yield higher lumens per watt (lm/W), reducing power consumption for the same light output.
Miniaturization: Even smaller package sizes (e.g., 1.0x0.5mm) are being developed for ultra-compact devices.
Enhanced Reliability: Improved packaging materials and processes lead to longer operational lifetimes and better performance under high temperature and humidity.
Smart Integration: The broader market is seeing growth in LEDs with integrated drivers or control circuits, though standard discrete components like the 19-21 remain essential for cost-effective, high-volume indicator and backlight applications.