LLC, on a single QR fly-back topology
Fairchild Semiconductor, providing a competitive alternative
Dual Switch Flyback Solution

m WSaver™ technology-based solution meeting 2013 ErP standards without additional parts

Power designers for All-In-One (AIO) applications face the challenge of finding a solution that offers space constraints, meets global energy regulations, and provides design ease. To address these issues, Fairchild Semiconductor, a leading global supplier of high-performance power and portable products, offers a dual-switch fly-back solution featuring mWSaver™ technology.

Traditional power topology solutions for AIO applications include LLCs and single-switch QR (Quasi-Resonant) flybacks. Each has its own advantages and disadvantages when seeking to balance ease of design, power loss at different loads, and efficiency. In the AIO power range, LLCs offer overall superior efficiency compared to dual-switch QR and single-switch QR flyback converters. LLC transformers are difficult to design and therefore result in the highest, lowest-load power loss among the three topologies. Single-switch QR flyback converters are the least efficient, but they are easy to design and provide low power loss at low loads.

Fairchild’s dual-switch QR fly-back topology and secondary-side synchronous rectification are ideal alternatives for AIO applications, offering design ease while enabling low power loss at low loads and providing good overall efficiency. Fairchild’s AIO solution is perfectly ideal for applications ranging from 75W to 230W and consists of the FAN6920MR, which features a critical mode PFC and a quasi-resonant current mode PWM controller; the FAN7382 gate driver; and the FAN6204, an auxiliary synchronous rectification controller for fly-back topology and unstable rectification. Combined, these products provide maximum power consumption even at no or low loads, enabling compliance with 2013 ErP standards without the additional circuitry required by LCC solutions.

These products integrating mWSaver technology also provide minimal standby power input for AIO applications. While improving thermal performance, pseudo-resonant control can reduce snubber and leakage inductance losses. Additionally, to provide efficiency, it reduces the Vds of SR MOSFETs, enabling a smaller footprint. The output of the built-in two-level PFC improves low-line efficiency. The addition of the FAN7382, an upper and lower gate driver IC, completes Fairchild's solution by providing the capability to drive Fairchild's high-voltage MOSFETs up to 600V. This product provides stable operation of the high-side driver even in noisy environments with significant voltage fluctuations per unit time.

The FAN6920MR combines a Power Factor Correction (PFC) controller with a pseudo-resonant PWM controller for a cost-effective design using minimal external components. For PFC, the product provides a rectified DC output voltage and utilizes controlled real-time technology for automatic power factor correction. Through innovative Total Harmonic Distortion (THD) optimization, the FAN6920MR can reduce input current distortion in the zero-crossing region to improve THD performance. For PWM control, the FAN6920MR provides several features that can improve power system performance, such as Valley Detect extended to the 12th Valley Cycle for reduced switching frequencies, improved low load efficiency, green mode operation, internal 10ms soft start, and overpower compensation on high/low lines.

Using proprietary linear predictive timing control technology not limited to the RDS(ON) of external Fairchild Power Trench SR MOSFETs, the FAN6204 is suitable for pseudo-resonant (QR) flyback converters operating in fixed frequency or discontinuous or continuous conduction mode control (DCM and CCM). This technology involves a simple control method without a current sensing circuit, providing better noise characteristics. Through PWM frequency tracking and secondary winding voltage sensing, this product can operate in both fixed and variable frequency systems applicable to flyback and unstable topologies. The FAN6204 also provides a very low green mode operating current of 1.1mA (average). This internal green mode offers lower no-load power consumption and high light-load efficiency.

The FAN7382 can drive Fairchild’s super-junction SupreMOS® and SuperFET® MOSFETs. Fairchild’s high-voltage (up to 600 V) process and common-mode noise rejection technology provide stable operation in noisy environments with high voltage fluctuations per unit time. An improved level shift circuit enables high-side gate driver operation down to VS = -9.8 V (average) for VBS = 15 V. Input logic levels are compatible with standard TTL-series logic gates. When VCC and VBS are lower than the specified threshold voltages, the two-channel UVLO circuit prevents malfunction.

Fairchild Semiconductor helps engineers drive innovation in design by providing miniaturization and performance enhancements through improved silicon technology and package options. This dual fly-back solution for AIO PC applications, equipped with mWSaver™ technology, enables designers to meet today's stringent requirements for power reduction and performance.

Fairchild Semiconductor: Solutions for Your Success™

Price: Based on quantity of 1,000

FAN6920MR US $1.20

FAN6204 US $0.57

FAN7382 US $0.83

Samples are currently available

Delivery: 8-10 weeks ARO