The Fujitsu MB3769A is a pulse-width-modulation controller which is applied to fixed frequency pulse modulation technique. The MB3769A contains wide band width Op-Amp and high speed comparator to construct very high speed switching regulator system up to 700 kHz. Output is suitable for power MOS FET drive owing to adoption of totem pole output. The MB3769A provides stand-by mode at low voltage power supply when it is applied in primary control system.