A single-chip fast-transient-responding DC-DC converter employing new control methods is proposed. The proposed quasi-PWM control provides the advantages of both accurate PWM control and fast hysteresis control. In addition, automatic loop-bandwidth (ALB) control is used for the output voltage to return to its original value quickly when an abrupt transition occurs at line voltage or load current. The ALB controlled quasi-PWM boost converter chip is implemented using standard 0.35 mu m CMOS process, and the test results are shown.