Patent ID: 7777473
Filing Date: 2010-08-17
Classification: H02M,H03K

Abstract:
1. A DC-DC converter comprising: a first transistor receiving an input voltage; a second transistor coupled to the first transistor; a control circuit generating a first signal which controls the first transistor to turn on and off; a comparator for detecting current flowing through the second transistor to generate a second signal which controls the second transistor, and for turning on the second transistor after a first period from the first transistor is turned off; a variable voltage supply which applies an offset voltage to the comparator, the variable voltage supply setting the offset voltage to a first level when the DC-DC converter is powered down and setting the offset voltage to a second level after a given delay time elapses from when the DC-DC converter recovers to a normal operation from a power down operation; and a pulse generation circuit for controlling the first signal and the second signal for turning off the second transistor during a second period from before the first transistor is turned on.