| 摘要 |
PROBLEM TO BE SOLVED: To control a range of a burst frequency of a DC/DC converter.SOLUTION: A burst control circuit 50 generates a burst control signal Sthat is asserted in a switching period and is negated in a stop period. The burst control circuit 50 asserts a comparison signal S1 when a feedback voltage Vbecomes higher than a threshold voltage V, and negates the comparison signal S1 when the feedback voltage Vbecomes lower than the threshold voltage V. A maximum frequency setting circuit 54 is triggered by the assertion of the comparison signal S1 to start time measurement, negates a mask signal S2 until a predetermined time period has passed since the start, and asserts the mask signal S2 after the predetermined time period has passed. A logic part 56 (i) negates the burst control signal Swhen the comparison signal S1 is negated and (ii) asserts the burst control signal Swhen the mask signal S2 is asserted and the comparison signal S1 is asserted. |
