DC/DC CONVERTER, CONTROL CIRCUIT OF THE SAME, CONTROL METHOD, POWER SUPPLY DEVICE USING THE SAME, POWER SUPPLY ADAPTER, AND ELECTRONIC DEVICE

摘要

PROBLEM TO BE SOLVED: To stably control a DC/DC converter on the basis of voltage in auxiliary winding.SOLUTION: A bottom detection comparator 402 generates a bottom detection signal S3 to be asserted when voltage Vzt of one end of the auxiliary winding becomes lower than threshold voltage Vth_zt. A logic section (401) asserts an ON-signal Swhen: (i) the bottom detection signal S3 is asserted after a switching transistor turns off and then a set mask time elapses; (ii) predetermined first timeout time elapses after the switching transistor turns off; or (iii) the state where the bottom detection signal S3 is not asserted continues for a second timeout time shorter than the first timeout time, after the bottom detection signal S3 is asserted.