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Device Increases System Efficiency 1.5 Percent and Reduces Rectifier Device Temperature by 25 Degrees Celsius

21st April 2009

International Rectifier

ES Admin

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International Rectifier, IR has expanded its family of SmartRectifier ICs with the introduction of the IR1168 for AC-DC power converters for high-end applications such as LCD TVs. The 200V dual smart secondary-side rectifier driver IC is designed to drive two N-Channel power MOSFETs used as synchronous rectifiers (SR) in resonant half-bridge topologies. In contrast to traditional current transformer SR methods, the IR1168 accurately determines turn-on and turn-off based on MOSFET drain sensing voltage in close proximity to zero current transition, eliminating the need for additional components to simplify design.

While synchronous rectification provides significant energy savings compared to diode-based designs, traditional SR methods are complex and require a high component count. Using only two gate resistors and a supply capacitor, the IR1168 delivers a lower system temperature and increased power density for even greater efficiency and reliability than existing SR methods while simplifying design and drastically reducing component count to shrink PCB size.

Co-designed with IR’s DirectFET MOSFETs, which feature IR’s latest Trench silicon and packaging technology, the IR1168-based solution delivers an efficiency improvement of 1.5% for a standard 240W LCD TV SMPS and a reduction of rectifier device temperature of 25°C while shrinking board size by two thirds.

The IR1168, featuring IR’s proprietary high-voltage IC technology, supports burst mode operation to deliver efficiency benefits even at light loads. Ruggedness and noise immunity are accomplished using an advanced blanking scheme and double-pulse suppression that allows reliable operation in fixed and variable frequency applications. Other key features include maximum 500kHz switching frequency, anti-bounce logic and UVLO protection, 4A peak turn-off gate drive current, micropower start-up and ultra low quiescent current, 10.7V gate drive clamp, 70ns turn-off propagation delay and a wide Vcc operating range from 8.6V to 18V.