Abstract
A ripple-free drive circuit for LED backlights of an LCD panel includes a PFC circuit, a DC/DC converter, three output load units, and a drive voltage resetter. The PFC circuit is connected with the mains power for outputting DC power. The DC/DC converter is connected with the PFC circuit. The three output load units are connected with the DC/DC converter for outputting red, green, and blue lights respectively, each having an electrically-controlled switch. The drive voltage resetter is connected with the DC/DC converter and the three output load units for preventing the three output load units from generation of surge current in a moment of electric conduction. In light of this, the ripple-free drive circuit is qualified as the drive power source of the LED backlights and can effectively isolate the surge current to prevent the surge current from entry into the output load units.