| 摘要 |
<p><P>PROBLEM TO BE SOLVED: To provide a method and device for a lossless integrated bleeder for triac dimming of an LED driver for illumination. <P>SOLUTION: A controller 138 for a switched mode power supply 100 includes a zero-crossing detector, drive logic, and an on-time extension block. The zero-crossing detector is coupled so that a first signal is generated before zero-crossing of an input voltage of the power supply 100. The drive logic responds to a feedback signal to generate a drive logic output signal, and the drive logic output signal indicates initial on time. The on-time extension block is coupled to the zero-crossing detector and the drive logic so that the drive signal is generated in response to the drive logic output signal. The drive signal controls switching of a switch so that charge is removed from a filter capacitor of the power supply 100. The drive signal indicates entire on time of a switch, which is equal to the sum of the initial on time and the extended on time and the extended on time responds to the first signal. <P>COPYRIGHT: (C)2011,JPO&INPIT</p> |
