The LM34930 constant On-Time Step Down Switching Regulator features all the functions needed to implement a low cost, efficient, buck bias regulator capable of supplying in excess of 1A load current. This high voltage regulator contains an N-Channel Buck Switch, and is available in a SMD bumped package. The constant on-time regulation principle requires no loop compensation, results in fast load transient response, and simplifies circuit implementation. The operating frequency remains constant with line and load. The valley current limit results in a smooth transition from constant voltage to constant current mode when current limit is detected without the use of current limit foldback. To reduce the possibility of saturating the inductor the valley current limit threshold reduces as the input voltage increases, and the on-time is reduced when current limit is detected. Additional features include: Over-voltage indicator, Input over-voltage shutdown, Vcc under-voltage lock-out, thermal shutdown, and maximum duty cycle limiting.