FSBH0F70WA: 700V Integrated Power Switch for 8Watt offline flyback converters, 100kHz, Brown In/Out Protection

The highly integrated FSBH-series consists of an integrated current-mode Pulse Width Modulator (PWM) and an avalanche-rugged 700V SenseFET. It is specifically designed for high-performance offline Switched-Mode Power Supplies (SMPS) with minimal external components.

The integrated PWM controller features include a proprietary green-mode function that provides off-time modulation to linearly decrease the switching frequency at light-load conditions to minimize standby power consumption. To avoid acoustic-noise problems, the minimum PWM frequency is set above 18kHz. This green-mode function enables the power supply to meet international power conservation requirements. The PWM controller is manufactured using the BiCMOS process to further reduce power consumption. The FSBH-series turns off some internal circuits to improve power saving when VFB is lower than 1.6V, which allows an operating current of only 2.5mA.

The FSBH-series has built-in synchronized slope compensation to achieve stable peak-current-mode control. The proprietary external line compensation ensures constant output power limit over a wide AC input voltage range, from 90VAC to 264VAC.

The FSBH-series provides many protection functions. In addition to cycle-by-cycle current limiting, the internal open-loop protection circuit ensures safety when an open-loop or output short occurs. PWM output is disabled until VDD drops below the VTH-OLP, then the controller starts up again. As long as VDD exceeds 28V, the internal OVP circuit is triggered.

Compared with a discrete MOSFET and controller or RCC switching converter solution, the FSBH-series reduces component count, design size, and weight; while increasing efficiency, productivity, and system reliability. These devices provide a basic platform that is well suited for the design of cost-effective flyback converters, such as in PC auxiliary power supplies.

Application Notes