| 摘要 |
PROBLEM TO BE SOLVED: To improve efficiency by adaptively responding to decrease in switching frequency caused by switching from an operation in a continuous current mode (CCM) under a light load to an operation in a discontinuous current mode (DCM), and further decreasing switching frequency.SOLUTION: A semiconductor integrated circuit comprises: a drive control unit 2 for driving a high-side switch element Q1 and low-side switch element Q2 in response to a one-shot pulse PLS; a load detection circuit 6 for detecting off-states at a predetermined time of both the elements Q1, Q2 to generate a load detection signal LLSG of a first state indicating a light load state, and detecting off-states for a short time of both the elements Q1, Q2 to generate the load detection signal LLSG of a second state indicating a heavy load state; and a constant on-time pulse generation circuit 4 for generating a one-shot pulse PLS having a wide second pulse width Win response to the load detection signal LLSG of the first state, and generating a pulse PLS having a narrow first pulse width Win response to the load detection signal LLSG of the second state. |
