| 摘要 |
<p>A pwm controller 10 which includes a Vcc node (pin 6); a start-up current source 180 connected to the Vcc node; and a driver circuit 150, 190 also connected to the Vcc node, wherein the pwm controller 10 is arranged to operate in a first phase in which the start-up current source supplies 180 current to the Vcc node but the driver circuit is turned off; a second phase in which the driver circuit 150,190 is enabled and draws current from the Vcc node; and a third phase in which both the start-up current source 180 and the driver circuit 150,190 are turned off whereby very little current may be drawn from the Vcc node (pin 6) during the third phase. <IMAGE></p> |
