| 摘要 |
PROBLEM TO BE SOLVED: To prevent overshoot which occurs at switching action if it shares the feedback point of a series regulator and a switching regulator. SOLUTION: A power supply apparatus 10 controls the battery voltage Vbat from a power source 11 into fixed output voltage V0 by switching and operating an LDO regulator 20 and a DC/DC converter 30 connected in parallel. The detected voltage Vs at the common output end of the LDO regulator 20 and the DC/DC converter 30 is entered into a feedback input terminal FBIN, and is fed back to the LDO regulator 20 and the DC/DC converter 30. To suppress the undershoot at switching from the LDO regulator 20 to the DC/DC converter 30, a timing signal generator 50 gives a predriver circuit 38 a capability switching timing signal CNTSW, thereby switching the controllability of the DC/DC converter 30 from a low-capability mode at start to a high-capability mode. COPYRIGHT: (C)2005,JPO&NCIPI
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