The APW7057 is a 300kHz constant frequency voltage mode synchronous switching controller that drives external N-channel MOSFETs. When the input supply drops close to output, the upper MOSFET remains on, achieving 100% duty cycle. Internal loop compensation is optimized for fast transient response, eliminating external compensation network. The precision 0.8V reference makes this part suitable for a wide variety of low voltage applications. Soft start is internally set to 2ms, limiting the input in-rush current and preventing the output from overshoot during powering up. The APW7057 has over current and short circuit protections. Over current protection is achieved by monitoring the voltage drop across the high side MOSFET, eliminating the need for a current sensing resistor and short circuit condition is detected through the FB pin. If either fault conditions occur, the APW7057 would initiate the soft start cycle. After three cycles and if the fault condition persists, the controller will be shut down. To restart the controller, either recycle the VCC supply or momentarily pull the OSCSET pin below 1.25V.