| 摘要 |
PROBLEM TO BE SOLVED: To add other functions easily even when an overheat detection/protective function is incorporated, in a power supply control circuit structured with an integrated circuit that controls the operation of a switching power supply. SOLUTION: This power supply control circuit includes a first constant current source IS1, which supplies a current to an OTP terminal to which a capacitor Co is attached externally, a second constant current source IS2, which discharges a current, and first, second, and third comparators CP1-CP3, which compare the voltage level of the OTP terminal with a first thresh level for overheat detection and second and third thresh levels higher in order than the first level. The circuit is configured to have an oscillator function in which a voltage is changed between the second and third thresh levels by the currents of the first constant current source IS1 and by the second constant current source IS2 and the changeover between MOS transistors PM1, NM1 by a flip-flop FF2. The switching of the switching power supply is controlled based on the change of the voltage level of the OTP terminal. COPYRIGHT: (C)2008,JPO&INPIT
|
