SWITCHING POWER SUPPLY UNIT AND CONTROL CIRCUIT FOR SAME

摘要

PROBLEM TO BE SOLVED: To provide a switching power supply device, including an overcurrent detector capable of automatically discriminating a current detection system detecting overcurrent by an on-resistance RON, without having to add an exclusive terminal, and a current detection system for detecting overcurrent by an externally attached current detecting resistance Rs, and capable of optimally protecting the overcurrent, while responding to applications even though control circuits have the same configuration. SOLUTION: The control circuit of the switching power supply device detects a current flowing through a high-side switch as a current-detecting signal VSNS; detects overcurrent by comparing the current detecting signal VSNSwith an overcurrent detecting threshold VTH; and protects the switching power supply device by turning off the high-side switch 2. The control circuit of the switching power supply device includes a first current-detecting terminal CS, connected to a power-supply side terminal for the high-side switch 2 or a load side terminal for the high-side switch 2. The control circuit for the switching power supply device includes a temperature-compensating means 7 for temperature-compensating the overcurrent-detecting threshold VTH, or the current detecting signal VSNS, in response to the input voltage to the first current-detecting terminal CS. COPYRIGHT: (C)2011,JPO&INPIT