FAN53741 2.5MHz Synchronous Buck Regulators onsemi FAN53741 2.5MHz Synchronous Buck Regulators provide a fixed output from an input voltage supply of 2.3V to 5.5V. The FAN53741 uses a proprietary architecture with synchronous rectification, that is capable of delivering a peak efficiency of 97% and can support a maximum load of 1300mA.