Patent ID: 7688053

Claim:
A variable voltage regulating device, comprising: a DC-DC converter being a direct current voltage converter and containing an input voltage terminal, an output voltage terminal and a reference voltage terminal, the input voltage terminal being used for inputting power, the output voltage terminal being used for outputting power, and the reference voltage terminal being used for providing a steady fixed voltage; and an output voltage controller, comprising: a pulse signal input terminal for the input of pulse width modulation (PWM) signal; a filter for regulating the PWM signal with specific duty cycle fed from the pulse signal input terminal into a signal output with specific voltage; a voltage follower containing an operational amplifier, the high-potential end of the operational amplifier being electrically connected to the filter, the low-potential end being electrically connected to the output end of operational amplifier to achieve a state of negative feedback; and a voltage-dividing circuit consisting of a first resistor divider, a second resistor divider, and a third resistor divider, one end of the first resistor divider being electrically connected to the output end of the operational amplifier of voltage follower, the other end of the first resistor divider, together with one end of the second resistor divider and one end of the third resistor divider being electrically connected to the reference voltage terminal, the other end of the third resistor divider being electrically connected to a ground terminal, the other end of the second resistor divider being electrically connected to the output voltage terminal.