7070 White LED Datasheet - Size 7.0x7.0x2.8mm - Voltage 37.3V - Power 7.46W - English Technical Document

1. Product Overview

This document details the specifications for the T7C series of high-power white LEDs in a 7070 package. This product is designed for applications requiring high luminous flux output and robust thermal performance. The compact 7.0mm x 7.0mm footprint houses a thermally enhanced package, making it suitable for demanding lighting solutions.

Core Advantages: The key strengths of this LED series include its high current capability (up to 240mA continuous), high luminous flux output (typical values ranging from 900lm to over 1300lm depending on bin), and a wide 120-degree viewing angle. The package is designed for efficient heat dissipation, supporting reliable operation. It is compliant with Pb-free reflow soldering processes and adheres to RoHS standards.

Target Markets: Primary applications include architectural and decorative lighting, retrofit lighting solutions, general illumination, and backlighting for indoor and outdoor signage. Its performance characteristics make it ideal for both professional and commercial lighting projects where brightness and longevity are critical.

2. In-Depth Technical Parameter Analysis

2.1 Electro-Optical Characteristics

All measurements are specified at a junction temperature (Tj) of 25°C and a forward current (IF) of 200mA. The luminous flux varies with Correlated Color Temperature (CCT). For a 2700K LED with a Color Rendering Index (CRI or Ra) of 80, the typical luminous flux is 900 lumens (lm) with a minimum of 800 lm. For CCTs of 3000K and above (4000K, 5000K, 5700K, 6500K), the typical luminous flux is 985 lm with a minimum of 900 lm, all at Ra80. Tolerances for luminous flux measurement are ±7%, and for CRI measurement are ±2.

2.2 Electrical and Thermal Parameters

Absolute Maximum Ratings: The device must not be operated beyond these limits. The maximum continuous forward current (IF) is 240 mA. The maximum pulse forward current (IFP) is 360 mA under specific conditions (pulse width ≤ 100µs, duty cycle ≤ 1/10). The maximum power dissipation (PD) is 9600 mW. The maximum reverse voltage (VR) is 5 V. The operating temperature range (Topr) is -40°C to +105°C. The maximum junction temperature (Tj) is 120°C.

Electrical/Optical Characteristics at Tj=25°C: The typical forward voltage (VF) at IF=200mA is 37.3V, with a range from 36V (min) to 40V (max), and a measurement tolerance of ±3%. The typical viewing angle (2θ1/2) is 120 degrees. The typical thermal resistance from the junction to the solder point (Rth j-sp) is 2.5 °C/W. The Electrostatic Discharge (ESD) withstand voltage is 1000V (Human Body Model).

3. Binning System Explanation

3.1 Part Numbering System

The part number follows the structure: T □□ □□ □ □ □ □ – □ □□ □□ □. Key codes include: X1 (Type code, '7C' for 7070 package), X2 (CCT code, e.g., '27' for 2700K), X3 (Color Rendering code, '8' for Ra80), X4 (Number of serial chips), X5 (Number of parallel chips), X6 (Component code), and X7 (Color Code, e.g., 'R' for 85°C ANSI).

3.2 Luminous Flux Binning

LEDs are sorted into bins based on their luminous flux output at IF=200mA and Tj=25°C. Each CCT has specific bin codes with defined minimum and maximum flux ranges. For example, a 4000K, Ra82 LED can be binned as GW (900-950 lm), GX (950-1000 lm), 3A (1000-1100 lm), 3B (1100-1200 lm), or 3C (1200-1300 lm). This allows designers to select LEDs with consistent brightness for their application.

3.3 Forward Voltage Binning

LEDs are also binned by forward voltage (VF) at IF=200mA. The two primary bins are 6L (36V to 38V) and 6M (38V to 40V), with a measurement tolerance of ±3%. Selecting LEDs from the same voltage bin can help ensure uniform current distribution in parallel circuits.

3.4 Chromaticity Binning

The color consistency is defined using a 5-step MacAdam ellipse system on the CIE chromaticity diagram. The datasheet provides center coordinates (x, y) at both 25°C and 85°C, along with ellipse parameters (a, b, Φ) for each CCT code (e.g., 27R5 for 2700K). This ensures the LEDs are visually matched. Energy Star binning standards are applied to all products from 2600K to 7000K. The tolerance for chromaticity coordinates is ±0.005.

4. Performance Curve Analysis

The datasheet includes several key graphs for design analysis. Figure 1 shows the Color Spectrum at Tj=25°C, illustrating the spectral power distribution. Figure 2 depicts the Viewing Angle Distribution, confirming the Lambertian-like emission pattern. Figure 3 plots Relative Intensity versus Forward Current, showing how light output increases with current. Figure 4 shows the relationship between Forward Current and Forward Voltage (IV Curve). Figure 5 is critical for thermal design, showing how Relative Luminous Flux decreases as Ambient Temperature rises at a fixed current of 200mA. Figure 6 shows how Relative Forward Voltage changes with Ambient Temperature.

5. Mechanical and Package Information

The LED comes in a 7070 surface-mount device (SMD) package. The package dimensions are 7.00mm in length and width, with a height of 2.80mm. The detailed dimension drawing shows the solder pad layout, with anode and cathode terminals clearly marked for polarity. A recommended land pattern (footprint) for PCB design is provided, with dimensions including a 7.50mm x 7.50mm pad area and specific spacing. The drawing also indicates the location of the series and parallel chip connections within the package. All unspecified tolerances are ±0.1mm.

6. Soldering and Assembly Guidelines

6.1 Reflow Soldering Profile

The LED is suitable for lead-free reflow soldering. A detailed temperature profile is provided: Preheat from 150°C to 200°C over 60-120 seconds. The maximum ramp-up rate to peak temperature is 3°C/second. The time above liquidus (TL=217°C) should be 60-150 seconds. The peak package body temperature (Tp) must not exceed 260°C. The time within 5°C of this peak temperature should be a maximum of 30 seconds. The maximum ramp-down rate is 6°C/second. The total time from 25°C to peak temperature should not exceed 8 minutes. Adherence to this profile is crucial to prevent thermal damage to the LED.

7. Application Notes and Design Considerations

7.1 Thermal Management

Effective heat sinking is paramount for performance and longevity. The low thermal resistance (2.5 °C/W) indicates good heat transfer from the junction, but this only works if the PCB and heatsink can effectively dissipate the heat. The total power dissipation can be up to 7.46W (200mA * 37.3V). Designers must ensure the operating junction temperature remains well below the maximum of 120°C, ideally below 85°C for optimal lifetime, as shown by the flux vs. temperature curve.

7.2 Electrical Drive

These LEDs require a constant current driver, not a constant voltage source, due to the exponential IV relationship. The high forward voltage (~37V) means standard low-voltage LED drivers are not suitable; drivers capable of delivering stable current at higher voltages (e.g., >40V) are required. When connecting multiple LEDs, series connections are preferred to ensure identical current, but the driver must supply the summed voltage. If parallel connection is unavoidable, meticulous binning for forward voltage is essential to prevent current hogging.

7.3 Optical Integration

The wide 120-degree viewing angle makes this LED suitable for applications requiring broad, even illumination without secondary optics. For focused beams, appropriate lenses or reflectors must be selected. The small, bright source may require diffusers to eliminate glare or hotspots in certain applications.

8. Frequently Asked Questions (Based on Technical Parameters)

Q: What driver current should I use?
A: The device is characterized at 200mA, which is the recommended operating point for the specified flux and lifetime. It can be driven up to the absolute maximum of 240mA, but this will increase junction temperature and may reduce lifespan. Always refer to the derating curves.

Q: How do I interpret the luminous flux bins?
A: The bin code (e.g., GW, 3A) defines a guaranteed range of light output. For consistent brightness in an array, specify LEDs from the same flux bin and, if possible, the same voltage bin.

Q: Is a heatsink necessary?
A> Yes, absolutely. With a typical power of over 7W, a properly designed metal-core PCB (MCPCB) or other heatsinking method is required to maintain a safe junction temperature. The thermal resistance value is measured on an MCPCB, indicating this is the intended mounting method.

Q: Can I use wave soldering?
A: The datasheet only specifies reflow soldering parameters. Wave soldering is generally not recommended for such packages due to the extreme and uneven thermal stress it can impose.

9. Practical Design Case Study

Consider designing a high-bay light fixture requiring 10,000 lumens. Using 4000K LEDs from the 3C bin (1200-1300 lm typical), you would need approximately 8-9 LEDs. A series configuration would require a driver capable of ~300mA (slightly above 200mA for headroom) and an output voltage greater than 9 * 40V = 360V. A more practical approach might be to use two parallel strings of 4-5 LEDs in series each, requiring careful voltage bin matching and a driver with two independent channels or a current-balancing circuit. The thermal design must dissipate nearly 70W of total heat, necessitating a substantial aluminum heatsink with the LEDs mounted on an MCPCB that is thermally bonded to it.

10. Technical Principles and Trends

10.1 Operating Principle

White LEDs in this class typically use a blue-emitting indium gallium nitride (InGaN) semiconductor chip. Part of the blue light is converted to longer wavelengths (yellow, red) by a phosphor coating inside the package. The mixture of blue and phosphor-converted light results in white light. The CCT and CRI are determined by the precise composition and thickness of the phosphor layer. The high voltage indicates multiple semiconductor junctions are connected in series within the single package.

10.2 Industry Trends

The market for high-power LEDs continues to focus on increasing luminous efficacy (lumens per watt), improving color quality and consistency (tighter binning), and enhancing reliability at higher operating temperatures. There is also a trend towards standardized packages (like 7070) that simplify optical and thermal design for fixture manufacturers. Furthermore, driver integration and smart controllability are becoming increasingly important features in professional lighting systems.