| 摘要 |
PROBLEM TO BE SOLVED: To reduce noise in a stand-by mode. SOLUTION: A pulse width modulaton controller which includes a Vcc node (pin 6), a start-up current source 180 connected to the Vcc node and a drive circuit 150 connected to the Vcc node is made to operate with a 1st phase, wherein the start-up current source 180 supplies a current to the Vcc node and moreover the drive circuit 150 is turned off, a 2nd phase where the drive circuit 150 is enabled, and a current is taken out of the Vcc node and a 3rd phase, where both the start-up current source 180 and the drive circuit 150 are turned off. In the 3rd phase, only very little current is drawn out of the Vcc.
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