Patent ID: 7888920

Claim:
A power supply device with fast output voltage switching capability comprising: a DC-DC boost converter for boosting an input voltage to generate an output voltage and for switching a voltage level of the output voltage according to a level switching signal; and a charge recycling circuit, coupled to the DC-DC boost converter, for generating a current path according to the level switching signal to recycle redundant charges from the DC-DC boost converter when the output voltage is switched from high to low and to return stored charges back to the DC-DC boost converter when the output voltage is switched from low to high, so as to accelerate voltage switching of the output voltage and to reduce power consumption of the DC-DC boost converter, the charge recycling circuit comprising: an energy storage module; a multiplexer, coupled to a turn-on voltage and a turn-off voltage, for switching to output the turn-on voltage and the turn-off voltage according to a control signal; a power transistor, having a first end coupled to the energy storage module, a second end coupled to the DC-DC boost converter and a control end coupled to the multiplexer, the power transistor controlling electrical connection between the first end and the second end to form the current path according to an output voltage of the multiplexer; and a control module, coupled to the multiplexer, the power transistor and the DC-DC boost converter, for outputting a first logic level of the control signal according to the level switching signal to control the multiplexer to output the turn-on voltage and for outputting a second logic level of the control signal according to current magnitude on the current path when the power transistor is turned on to control the multiplexer to output the turn-off voltage.