LTPA-2720ZCETU LED Datasheet - 2.7x2.0mm Package - 3.2V Typ - 1.26W Max - Cyan Color - English Technical Document

1. Product Overview

The LTPA-2720ZCETU is a high-power light-emitting diode (LED) belonging to the 2720 series. This product is specifically engineered for the demanding requirements of automotive electronic systems. The device utilizes an InGaN (Indium Gallium Nitride) semiconductor material to produce a cyan light output, filtered through a green lens. Its defining characteristic is its miniaturized footprint, making it suitable for space-constrained applications on printed circuit boards (PCBs) where automated assembly processes are employed.

1.1 Core Advantages and Target Market

The primary advantage of this LED is its combination of high luminous output within an extremely small form factor. It is designed to be compatible with standard automated pick-and-place equipment, facilitating high-volume manufacturing. The product is pre-conditioned to meet JEDEC Moisture Sensitivity Level 2 requirements, ensuring reliability during the solder reflow process. Its qualification is aligned with the AEC-Q102 standard, which is the key reliability standard for discrete optoelectronic semiconductors in automotive applications. The target market is primarily automotive accessory applications, where robust, reliable, and compact lighting solutions are required.

2. Technical Parameters: In-Depth Objective Interpretation

This section provides a detailed analysis of the LED's operational limits and performance characteristics under defined conditions.

2.1 Absolute Maximum Ratings

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

• Power Dissipation (P_D): 1.26 Watts maximum. This is the total electrical power the package can dissipate as heat without exceeding the maximum junction temperature.
• Forward Current (I_F): 5 mA minimum, 400 mA maximum DC. The device requires a minimum current to turn on effectively. The maximum continuous DC current should not exceed 400 mA.
• Peak Pulse Current (I_P): 750 mA under specific conditions (1/100 duty cycle, 0.1ms pulse width). This allows for short bursts of higher current, useful for pulsed-brightness applications.
• ESD Sensitivity (V_HBM): 8 kV (Human Body Model) per AEC-Q102-001. This indicates a robust level of electrostatic discharge protection suitable for automotive handling environments.
• Temperature Ranges: Junction temperature (T_j) must not exceed 150°C. The device is rated for operation from -40°C to +125°C ambient temperature (T_opr), with an identical storage temperature range (T_stg).

2.2 Electro-Optical Characteristics at T_a=25°C, I_F=200mA

These are the typical performance parameters measured under standard test conditions.

• Luminous Flux (Φ_V): 45 lm (minimum) to 63 lm (maximum). This is the total visible light output. The typical value is not specified, indicating performance is managed through the binning system.
• Viewing Angle (2θ_1/2): 120 degrees typical. This is the full angle at which the luminous intensity is half the value at the central axis, indicating a wide beam pattern.
• Chromaticity Coordinates (Cx, Cy): Typical values are x=0.165, y=0.362 on the CIE 1931 chromaticity diagram, defining the cyan color point. A tolerance of ±0.01 is applied to these coordinates.
• Forward Voltage (V_F): 2.8V (minimum) to 3.6V (maximum) at 200mA. The tolerance for any given unit is ±0.1V from its binned value. This parameter is crucial for driver design and thermal management.
• Reverse Current (I_R): 10 μA maximum at the specified test voltage. The datasheet explicitly states the device is not designed for reverse-bias operation.

2.3 Thermal Characteristics

Effective thermal management is critical for LED performance and longevity.

• Thermal Resistance, Junction-to-Solder Point (R_th,J-S):
  • Real (R_{th,J-S real}): 13 °C/W typical. This represents the actual thermal path from the semiconductor junction to the solder point on the PCB.
  • Electrical (R_{th,J-S el}): 9.1 °C/W typical. This is a calculated value derived from the forward voltage temperature coefficient and is used for in-situ temperature estimation.

A lower thermal resistance value is better, as it means heat can escape from the junction more easily, leading to lower operating temperatures and higher light output for a given drive current.

3. Binning System Explanation

To ensure consistency in mass production, LEDs are sorted into performance bins. The LTPA-2720ZCETU uses a three-dimensional binning system: Forward Voltage (V_F), Luminous Flux (Φ_V), and Color (Chromaticity). A complete part is specified by a combination like D7/5J/C4.

3.1 Forward Voltage (V_F) Binning

Bins are defined at I_F = 200mA. Each bin has a ±0.1V tolerance.

• D7: 2.8V to 3.0V
• D8: 3.0V to 3.2V
• D9: 3.2V to 3.4V
• D10: 3.4V to 3.6V

3.2 Luminous Flux (Φ_V) Binning

Bins are defined at I_F = 200mA. Each bin has a ±10% tolerance.

• 5J: 45 lm to 50 lm
• 6J: 50 lm to 56 lm
• 7J: 56 lm to 63 lm

3.3 Color (Chromaticity) Binning

Color is defined by coordinates on the CIE 1931 diagram at I_F = 200mA. A tolerance of ±0.01 is applied to the (x, y) coordinates. The datasheet provides two bins defined by quadrilateral regions:

• C3 Bin: Defined by points (x,y): (0.100, 0.335), (0.105, 0.375), (0.195, 0.358), (0.195, 0.335).
• C4 Bin: Defined by points (x,y): (0.105, 0.375), (0.110, 0.420), (0.195, 0.386), (0.195, 0.358).

The LTPA-2720ZCETU part number corresponds to the C4 color bin.

4. Performance Curve Analysis

The datasheet includes several graphs depicting the relationship between key parameters. These are essential for circuit design and understanding performance under non-standard conditions.

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

This curve shows the non-linear relationship between the voltage across the LED and the current flowing through it. The voltage increases with current but not linearly. This graph is vital for selecting current-limiting resistors or designing constant-current drivers.

4.2 Relative Luminous Flux vs. Forward Current

This curve demonstrates how light output increases with drive current. It typically shows a sub-linear relationship at higher currents due to efficiency droop and increased junction temperature. It helps determine the optimal drive current for a desired brightness level while considering efficiency.

4.3 Forward Current Derating Curve

This is one of the most critical graphs for reliability. It shows the maximum allowable continuous forward current as a function of the ambient temperature (T_a). As ambient temperature rises, the maximum safe current decreases to prevent the junction temperature from exceeding its 150°C limit. Designers must operate below this curve.

4.4 Relative Luminous Flux vs. Junction Temperature

This graph illustrates the thermal quenching effect. As the LED's junction temperature (T_j) increases, its luminous output decreases. The curve is normalized to the output at 25°C. This information is crucial for thermal design to maintain consistent brightness.

4.5 Chromaticity Coordinate Shift vs. Junction Temperature

This plot shows how the color coordinates (x and y) shift with changes in junction temperature. Some shift is expected, and understanding its magnitude is important for applications requiring stable color output.

4.6 Voltage Shift vs. Junction Temperature

The forward voltage of an LED has a negative temperature coefficient (it decreases as temperature increases). This curve quantifies that shift, which can be used in some circuits to estimate or monitor the junction temperature.

5. Mechanical and Package Information

5.1 Package Dimensions

The LED uses the industry-standard 2720 package footprint. Key dimensions include a body size of approximately 2.7mm x 2.0mm. The leads are gold-plated. All dimensional tolerances are ±0.2mm unless otherwise specified. The exact mechanical drawing should be referenced for PCB land pattern design.

5.2 Polarity Identification and Pad Layout

The datasheet includes a recommended solder pad layout for infrared or vapor phase reflow soldering. This layout is designed to ensure a reliable solder joint and proper alignment during assembly. The cathode (negative) terminal is typically indicated by a visual marker on the LED package, such as a notch or a green tint. The pad layout diagram clearly shows the anode and cathode pads.

6. Soldering and Assembly Guidelines

6.1 Reflow Soldering Profile

The device is compatible with infrared reflow soldering processes. The datasheet references a lead-free soldering profile according to the J-STD-020 standard. Key parameters of this profile include:

• Preheat: A gradual ramp to activate flux and minimize thermal shock.
• Soak (Thermal Stabilization): A period at a stable temperature to ensure even heating of the board and components.
• Reflow (Liquidus): A peak temperature zone where the solder melts. The peak temperature and time above liquidus (TAL) are critical and must not exceed the LED's maximum ratings to avoid damage.
• Cooling: A controlled cool-down period to form reliable solder joints.

6.2 Storage and Handling Cautions

The LED is rated as Moisture Sensitivity Level (MSL) 2 per JEDEC J-STD-020.

• Sealed Package: When stored in its original moisture-proof bag with desiccant, it should be kept at ≤30°C and ≤70% Relative Humidity (RH) and used within one year.
• Opened Package: Once the bag is opened, components should be stored at ≤30°C and ≤60% RH. It is recommended to complete the solder reflow process within 365 days of opening the bag.
• Application Note: The datasheet contains a standard disclaimer noting that the device is intended for ordinary electronic equipment. For applications where failure could jeopardize life or health (aviation, medical, etc.), additional consultation and qualification are necessary.

7. Packaging and Ordering Information

7.1 Tape and Reel Specifications

The LEDs are supplied in industry-standard packaging for automated assembly.

• Carrier Tape: 8mm wide tape.
• Reel: 7-inch (178mm) diameter reel.
• Quantity: 2000 pieces per full reel.
• Minimum Order Quantity (MOQ): 500 pieces for remainder quantities.
• Standards: Packaging conforms to ANSI/EIA-481 specifications. Empty pockets are sealed with cover tape, and a maximum of two consecutive missing components is allowed.

8. Application Suggestions and Design Considerations

8.1 Typical Application Scenarios

Given its AEC-Q102 qualification, high power, and small size, this LED is ideal for various automotive lighting functions beyond primary headlamps. Examples include:

• Daytime Running Lights (DRL) modules
• Center High-Mount Stop Lights (CHMSL)
• Interior ambient lighting and dashboard backlighting
• Exterior puddle lights, door handle lights, or badge illumination
• Signal lighting in side mirrors

8.2 Critical Design Considerations

1. Thermal Management: This is paramount. With a power dissipation up to 1.26W, the PCB must provide an adequate thermal path. Use the thermal resistance values (R_th,J-S) to calculate the expected junction temperature (T_j) for your design: T_j = T_a + (R_th × P_D). Ensure T_j remains below 150°C, and preferably lower to maximize light output and lifespan. Utilize thermal vias, copper pours, and possibly a metal-core PCB if necessary.
2. Drive Circuitry: Always use a constant-current driver, not a constant-voltage source with a simple resistor. This ensures stable light output regardless of variations in forward voltage (due to binning or temperature). The driver must be rated for the full operating temperature range (-40°C to +125°C).
3. Optical Design: The 120-degree viewing angle provides a wide beam. For focused applications, secondary optics (lenses, reflectors) will be required. Consider the initial color bin (C4) and its potential shift with temperature when specifying color requirements.
4. PCB Layout: Follow the recommended solder pad layout precisely. Ensure sufficient clearance between pads to prevent solder bridging. The pad design influences both solder joint reliability and thermal performance.

9. Technical Comparison and Differentiation

While a direct competitor comparison is not in the datasheet, key differentiators of this product can be inferred:

• Form Factor vs. Power: It offers a high luminous flux (up to 63 lm) from a miniature 2720 (2.7x2.0mm) package, providing a high power density.
• Automotive Qualification: Compliance with AEC-Q102 and preconditioning to MSL2 are critical differentiators for automotive vs. commercial-grade LEDs.
• Cyan Color Source: Using an InGaN die with a green lens to produce cyan is a specific solution for applications requiring that particular wavelength, as opposed to using a phosphor-converted white LED.
• Comprehensive Binning: The three-dimensional binning (V_F, Flux, Color) allows for tight system-level performance matching, which is important in automotive applications for consistency across a vehicle.

10. Frequently Asked Questions (Based on Technical Parameters)

1. Q: Can I drive this LED with a 3.3V supply and a resistor?
   A: It is possible but not recommended for a professional design. The forward voltage ranges from 2.8V to 3.6V. At 3.3V, an LED from the D10 bin (3.4V-3.6V) may not turn on, while one from the D7 bin (2.8V-3.0V) would have a highly variable current depending on the exact V_F, leading to inconsistent brightness and potential over-current. A constant-current driver is essential.
2. Q: Why does the luminous output decrease when the LED gets hot?
   A: This is due to "thermal quenching" or "efficiency droop," a fundamental characteristic of semiconductor LEDs. Increased temperature increases non-radiative recombination processes within the semiconductor, reducing the internal quantum efficiency (the ratio of photons generated to electrons injected).
3. Q: What is the difference between R_{th,J-S real} and R_{th,J-S el}?
   A: R_{th,J-S real} is measured directly using a thermal test method. R_{th,J-S el} is calculated using the temperature-sensitive parameter (TSP) method, which relies on the change in forward voltage with temperature. The electrical method is often used for in-situ temperature monitoring in an actual application.
4. Q: The ESD rating is 8kV. Do I still need ESD protection on my board?
   A: The 8kV HBM rating indicates good robustness for handling during assembly. However, for automotive applications, the system-level ESD requirements (e.g., ISO 10605) may be more stringent. It is often prudent to include transient voltage suppression (TVS) diodes or other protection on the LED driver lines, especially if they are routed to connectors exposed to the vehicle's electrical environment.

11. Practical Design and Usage Case

Scenario: Designing a Daytime Running Light (DRL) Module
A designer is creating a compact DRL module for a car. Space is limited, but high brightness is required for daytime visibility. They select the LTPA-2720ZCETU for its high flux in a small package.

1. Electrical Design: They design a buck-mode constant-current driver that can deliver 350mA (below the 400mA max) from the vehicle's 12V battery, operating from -40°C to +105°C ambient.
2. Thermal Design: The module housing is aluminum. The PCB is a 2-layer board with a large, exposed copper pad on the bottom layer connected to the LED's thermal pad via multiple thermal vias. Thermal simulations are run using R_{th,J-S real} = 13°C/W and the expected ambient temperature to ensure T_j < 120°C for long life.
3. Optical Design: A secondary TIR (Total Internal Reflection) lens is placed over each LED to collimate the wide 120-degree beam into a controlled horizontal fan pattern suitable for a DRL.
4. Manufacturing: The BOM specifies the bin code 7J/D8/C4 to ensure high brightness (7J: 56-63 lm), mid-range voltage (D8: 3.0-3.2V) for driver efficiency, and consistent cyan color (C4). The assembler uses the provided tape-and-reel packaging in automated pick-and-place machines, following the J-STD-020 reflow profile.

12. Principle Introduction

The LTPA-2720ZCETU is a semiconductor light source. Its core is a chip made of InGaN (Indium Gallium Nitride) materials. When a forward voltage is applied, electrons and holes are injected into the active region of the semiconductor. When an electron recombines with a hole, energy is released in the form of a photon (light particle). The specific composition of the InGaN alloy determines the wavelength (color) of the emitted light; in this case, it produces light in the cyan/blue-green spectrum. This primary light passes through an internal green-tinted lens (package lens), which may absorb some wavelengths and transmit others, resulting in the final perceived cyan color. The efficiency of this electroluminescent process is affected by drive current and temperature, as shown in the performance curves.

13. Development Trends

The evolution of LEDs like the LTPA-2720ZCETU follows several clear industry trends:

• Increased Power Density: Continuous improvement in semiconductor epitaxy and package thermal design allows for higher luminous flux from ever-smaller packages, enabling more compact and brighter automotive lighting systems.
• Enhanced Reliability Standards: Automotive requirements are driving more stringent qualification standards beyond AEC-Q102, including longer lifetime testing, higher temperature cycling ranges, and more robust resistance to sulfur and other corrosive agents.
• Tighter Binning and Color Consistency: As LEDs are used in clusters for styling (e.g., light bars), the demand for extremely tight color and flux binning ("super-binning") is increasing to avoid visible variations between adjacent LEDs.
• Integration with Drivers and Control: There is a trend towards more integrated solutions, such as LEDs with built-in current regulators or smart LED drivers that can communicate over automotive buses (LIN, CAN), though the device described here remains a discrete component.
• Focus on Spectral Characteristics: Beyond color coordinates, there is growing interest in the full spectral power distribution (SPD), especially for applications where light interacts with cameras (Advanced Driver-Assistance Systems - ADAS) or specific materials.