Patent ID: 7545658
Filing Date: 2009-06-09
Classification: H02M

Abstract:
1. A DC-DC boost converter, comprising: a charge pump selectively operating in a voltage doubler mode or in a voltage tripler mode; a switching arrangement connecting the charge pump to an input voltage terminal in a charge phase and to an output voltage terminal in a discharge phase; a controllable current source connected in series with the charge pump in the discharge phase; and an error amplifier having a first input connected to a reference voltage, a second input connected to the output voltage terminal, and an output connected to a control input of the controllable current source; and further comprising a mode changeover circuit including: a first comparator having a first input connected to the output of the error amplifier and a second input connected to a first threshold voltage source; a second comparator having a first input connected to the output of the error amplifier and a second input connected to a second threshold voltage source; and a flip-flop having a RESET input connected to the output of the first comparator, a SET input connected to the output of the second comparator, and an output connected to the switching arrangement to switch the charge pump from the voltage doubler mode to the voltage tripler mode when the voltage at the output of the error amplifier exceeds the second threshold voltage, and back to the voltage doubler mode when the output voltage at the error amplifier drops below the first threshold voltage.