Power circuit having multiple stages of charge pumps
The present invention discloses a power circuit having multiple stages of charge pumps. The power circuit comprises a first charge pump, a second charge pump, a voltage stabilizing capacitor, and an output capacitor. The first charge pump adjusts an input voltage and produces a first output voltage. The second charge pump adjusts the first output voltage, produces a second output voltage, and outputs the second output voltage for driving a loading. The voltage stabilizing capacitor is coupled between the first and second charge pumps and connected externally to the output of the first charge pump. The output capacitor is coupled to the second charge pump for providing the second output voltage. According to the present invention, the effect of supplying large transient currents to the loading can be achieved by connecting externally the voltage stabilizing capacitor to the output of the first charge pump.
1. A power circuit having multiple stages of charge pumps, comprising:
a first charge pump, producing a first output voltage according to an input voltage;
a second charge pump, producing a second output voltage according to said first output voltage, and outputting said second output voltage for driving a loading;
a voltage stabilizing capacitor, coupled between said first charge pump and said second charge pump, and connected externally to an output of said first charge pump; and
an output capacitor, coupled to said second charge pump for outputting said second output voltage;
where when said loading becomes heavy, the charges output by said voltage stabilizing capacitor increase.
2. The power circuit of claim 1 , wherein said loading is a plurality of pixels of a displaying device, and when said loading becomes heavy, the charges output by said voltage stabilizing capacitor increase so that said second charge pump can output said second output voltage to a driver of said displaying device for driving said plurality of pixels.
3. The power circuit of claim 1 , wherein when said loading becomes heavy, the charges output by said output capacitor increase so that said second charge pump can output said second output voltage for driving said loading.
4. The power circuit of claim 1 , and further comprising:
a timing controller, outputting a timing control signal; and
a control circuit, outputting a clock signal or a multiple adjusting signal to said first charge pump according to said timing control signal, said clock signal determining the switching frequency of said first charge pump, said multiple adjusting signal determining the multiple of said first charge pump, and the multiple of said first charge pump being the multiple between said input voltage and said first output voltage.
5. The power circuit of claim 4 , wherein said control circuit comprise:
a frequency adjusting unit, generating said clock signal according to said timing control signal; and
a multiple selecting unit, generating said multiple adjusting signal according to said timing control signal.
6. The power circuit of claim 4 , and further comprising a level detecting unit, detecting said first output voltage, outputting a detecting signal to said control circuit according to said first output voltage, and said control circuit further outputting said clock signal or said multiple adjusting signal according said detecting signal for controlling the switching frequency or multiple of said first charge pump.
7. The power circuit of claim 6 , wherein said level detecting unit has a threshold value, and when said level detecting unit judges that said first output voltage is higher than said threshold value, said level detecting unit outputs said detecting signal to make said control circuit output said clock signal for reducing the switching frequency of said first charge pump or output said multiple adjusting signal for reducing the multiple of said first charge pump.
8. The power circuit of claim 6 , wherein said level detecting unit has a threshold value, and when said level detecting unit judges that said first output voltage is lower than said threshold value, said level detecting unit outputs said detecting signal to make said control circuit output said clock signal for increasing the switching frequency of said first charge pump or output said multiple adjusting signal for increasing the multiple of said first charge pump.
9. The power circuit of claim 1 , and further comprising:
a timing controller, outputting a timing control signal; and
a control circuit, outputting a clock signal or a multiple adjusting signal to said second charge pump according to said timing control signal, said clock signal determining the switching frequency of said second charge pump, said multiple adjusting signal determining the multiple of said second charge pump, and the multiple of said second charge pump being the multiple between said first output voltage and said second output voltage.
10. The power circuit of claim 9 , wherein said control circuit comprise:
a frequency adjusting unit, generating said clock signal according to said timing control signal; and
a multiple selecting unit, generating said multiple adjusting signal according to said timing control signal.
11. The power circuit of claim 9 , and further comprising a level detecting unit, detecting said second output voltage, outputting a detecting signal to said control circuit according to second first output voltage, and said control circuit further outputting said clock signal or said multiple adjusting signal according said detecting signal for controlling the switching frequency or multiple of said second charge pump.