| 摘要 |
PROBLEM TO BE SOLVED: To provide a control circuit for DC-DC converter which can realize quick drop in the output voltage, with low power consumption at the stoppage of power supply, in a synchronous rectifying system of DC-DC converter. SOLUTION: While a power supply stop signal STP is on a low level, a control unit 40 controls an NMOS transistor FET2, according to the output signal of a comparator COMP2 and a flip-flop circuit FF; whereas while the power supply stop signal STP is on a high level, the control unit 40 masks the output signal of a counterflow detection signal BUD and a flip-flop circuit FF, and controls the NMOS transistor FET2, according to the detection signal DET of the comparator COMP3. When the output voltage VOUT drops to the output reference voltage OE2, corresponding to the reference voltage E2 by a choke coil current flowing in reverse, the NMOS transistor FET2 is switched off, and the power is regenerated to an input terminal (VI). COPYRIGHT: (C)2006,JPO&NCIPI
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