Fairchild Delivers Best-in-Class Performance with New Active Bridge Solution
Lowering temperature and increasing efficiency while reducing the size of the solution

Effective heat management is always an important issue for designers, especially for the new generation of IoT devices that require more than 25.5W of power.

In response, Fairchild Semiconductor set out to solve the overheating problem using the advanced MOSFET technology of its latest GreenBridge™ series. The company recently launched the FDMQ8205, strengthening its industry-leading GreenBridge quad MOSFET active bridge technology.

Enhanced state-of-the-art GreenBridge quad MOSFET active bridge technology

This product is the first in the next-generation GreenBridge series and utilizes POE technology for applications such as security cameras, wireless access points, LED lighting, and other POE-based power devices (PDs). Designers can now leverage GreenBridge’s industry-leading Rdson performance, ultra-small form factor, and superior thermal characteristics to lower temperatures and increase efficiency while simultaneously reducing the size of their solutions.

The next-generation GreenBridge series complies with the IEEE 802.3at standard and has up to 90% lower power consumption than Schottky diodes. Thanks to these excellent thermal characteristics, designers can simplify product design, reduce BOM costs, and decrease PCB size by reducing or eliminating the heatsink.

Another significant advantage of the new GreenBridge series is its very low conduction loss. This is because power and voltage must be maximized due to the input power limitations of POE systems. The GreenBridge series boasts the industry's best Rdson performance, which is 47% lower than competing products thanks to the power conversion efficiency of optimized PowerTrench MOSFET technology.

Due to its small size, the GreenBridge series is ideal for next-generation POE-based architectures that are smaller than existing POE generations. Four full-bridge MOSFETs are integrated into an MLP package measuring only 4.5mm x 5mm. Therefore, despite its small size, GreenBridge products do not require external drivers, saving PCB space.

We conducted an interview with Mike Speed, General Manager of Fairchild Semiconductor, regarding the features of the first product in the GreenBridge series and the future direction of POE-based products.

Q. Why was the new technology named GreenBridge, and what is the significance of this name?
A. GreenBridge signifies that the power consumption of a MOSFET bridge is significantly lower than that of a Schottky diode, thereby enabling energy savings.

Q. What is the reason that GreenBridge's power consumption is 90% lower than that of a Schottky diode?
A. The patented medium-voltage MOSFET technology boasts excellent RDS-on performance and has very low power consumption compared to diodes.

Q. How does recent MOSFET technology solve the heat generation problem? Is there a particular breakthrough?
A. Medium-voltage gate blocking technology reduces RDS-on for both N-channel and P-channel MOS and also resolves overheating situations caused by diodes.

Q. What enabled GreenBridge products to integrate everything internally without external drivers?
A. These MOSFETs do not require an external driver. This is because GreenBridge has integrated a patented gate driver circuit inside every MOSFET.

Q. Could you please introduce PowerTrench MOSFET technology in detail?
A. Gate Channel Blocking MOSFET technology is suitable for the standby state power usage of GreenBridge by adding an oxygen layer to the gate and connecting it to the bridge, thereby preventing capacitance leakage from the gate and reducing RDS-on in charge balance technology.

Q. How do you foresee the trends for POE-based products?
A. The output of IoT products is steadily increasing. Since they are moving toward higher power consumption, there is no need to worry about power issues. The new products will be utilized in Micro Stations, tilt and UHD CCTVs, LED lighting, and more. Since the new 802.3 standard has increased the output processing capability of PSE ports from 25W to 90W, more efficient new solutions will be required. For example, products like GreenBridge.