| 摘要 |
PROBLEM TO BE SOLVED: To provide a step-down switching regulator and its control circuit, capable of securely detecting reversing of a direction of an inductor current at a light load. SOLUTION: A pulse signal generation circuit 10 generates a pulse signal SIG 10 a duty ratio of which is controlled so that an output voltage Vout may approximate a predetermined reference voltage. A driver circuit 20 generates first and second gate voltages Vg1, Vg2 applied to gates of a switching transistor M1 and a transistor M2 for synchronous rectification on the basis of the pulse signal SIG 10. A threshold generating portion 40 is the voltage synchronized with the second gate voltage Vg2, which is brought to a high level in a period where the transistor M2 for the synchronous rectification should be turned off, and generates a threshold voltage Vth which is brought to a low level in a period where the transistor M2 for the synchronous rectification should be turned on. A light load detection comparator 42 compares a switching voltage Vsw with the threshold voltage Vth to output the light load detection signal SIG 12. COPYRIGHT: (C)2007,JPO&INPIT
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