Charge pumped driver for switched mode power supply
A driver circuit provides a driving signal to the power stage of a switched mode power supply in correspondence with a pulse width modulated duty cycle. A voltage doubler circuit including a bucket capacitor and plural switches is arranged to successively couple the bucket capacitor to the input power source and to the driver circuit. The voltage doubler circuit thereby provides the driving signal to the driver circuit having a voltage approximately double the corresponding voltage of the input power source. The voltage doubler circuit discharges the bucket capacitor into the driver circuit to provide the driving signal in correspondence with a first portion of the pulse width modulated duty cycle, and the voltage doubler circuit recharges the bucket capacitor in correspondence with a second portion of the pulse width modulated duty cycle. The power switch comprises an internal capacitance, wherein charge stored in the bucket capacitor is transferred to the internal capacitance of the at least one power switch during the first portion of the pulse width modulated duty cycle. Remaining charge in the internal capacitance of the power switch is recycled back to the bucket capacitor during the second portion of the pulse width modulated duty cycle.
1 . A switched mode power supply comprising:
a power stage having at least one power switch adapted to apply a voltage from an input power source to a load;
a driver circuit providing a driving signal to the power stage in correspondence with a pulse width modulated duty cycle; and
a voltage doubler circuit including a bucket capacitor and plural switches arranged to successively couple the bucket capacitor to the input power source and to the driver circuit, the voltage doubler circuit thereby providing the driving signal to the driver circuit having a voltage approximately double the corresponding voltage of the input power source;
wherein, the voltage doubler circuit at least partially discharges the bucket capacitor into the driver circuit to provide the driving signal in correspondence with a first portion of the pulse width modulated duty cycle and the voltage doubler circuit recharges the bucket capacitor in correspondence with a second portion of the pulse width modulated duty cycle.
2 . The switched mode power supply of claim 1 , wherein said at least one power switch comprises an internal capacitance, and wherein charge stored in the bucket capacitor is transferred to the internal capacitance of the at least one power switch during the first portion of the pulse width modulated duty cycle.
3 . The switched mode power supply of claim 2 , wherein remaining charge in the internal capacitance of the at least one power switch is at least partially recycled back to the bucket capacitor during the second portion of the pulse width modulated duty cycle.
4 . The switched mode power supply of claim 1 , further comprising a linear regulator operatively coupled to the input power source and the voltage doubler circuit, the linear regulator adapted to regulate the input power source prior to delivery to the voltage doubler circuit.
5 . The switched mode power supply of claim 1 , wherein the first portion of the pulse width modulated duty cycle comprises a turn-on period of the at least one power switch.
6 . The switched mode power supply of claim 5 , wherein the second portion of the pulse width modulated duty cycle comprises a turn-off period of the at least one power switch.
7 . The switched mode power supply of claim 1 , wherein at least one of the plural switches of the voltage doubler circuit is activated by the pulse width modulated duty cycle.
8 . The switched mode power supply of claim 1 , wherein the at least one power switch further comprises a low side switch of the power stage, the driving signal provided by the driver circuit being referenced to ground.
9 . The switched mode power supply of claim 1 , wherein the at least one power switch further comprises a high side switch of the power stage, the driving signal provided by the driver circuit being floating with respect to ground.
10 . The switched mode power supply of claim 1 , further comprising means for selectively disabling the voltage doubler circuit to permit the driver circuit to drive the at least one power switch at a level corresponding to the input voltage.
11 . In a switched mode power supply comprising a power stage having at least one power switch adapted to apply a voltage from an input power source to a load, a charge pumped driver comprises:
a driver circuit providing a driving signal to the power stage in correspondence with a pulse width modulated duty cycle; and
a voltage doubler circuit including a bucket capacitor and plural switches arranged to successively couple the bucket capacitor to the input power source and to the driver circuit, the voltage doubler circuit thereby providing the driving signal to the driver circuit having a voltage approximately double the corresponding voltage of the input power source;
wherein, the voltage doubler circuit at least partially discharges the bucket capacitor into the driver circuit to provide the driving signal in correspondence with a first portion of the pulse width modulated duty cycle and the voltage doubler circuit recharges the bucket capacitor in correspondence with a second portion of the pulse width modulated duty cycle.
12 . The charge pumped driver of claim 11 , wherein said at least one power switch comprises an internal capacitance, and wherein charge stored in the bucket capacitor is transferred to the internal capacitance of the at least one power switch during the first portion of the pulse width modulated duty cycle.
13 . The charge pumped driver of claim 12 , wherein remaining charge in the internal capacitance of the at least one power switch is at least partially recycled back to the bucket capacitor during the second portion of the pulse width modulated duty cycle.
14 . The charge pumped driver of claim 11 , further comprising a linear regulator operatively coupled to the input power source and the voltage doubler circuit, the linear regulator adapted to regulate the input power source prior to delivery to the voltage doubler circuit.
15 . The charge pumped driver of claim 11 , wherein the first portion of the pulse width modulated duty cycle comprises a turn-on period of the at least one power switch.
16 . The charge pumped driver of claim 15 , wherein the second portion of the pulse width modulated duty cycle comprises a turn-off period of the at least one power switch.
17 . The charge pumped driver of claim 11 , wherein at least one of the plural switches of the voltage doubler circuit is activated by the pulse width modulated duty cycle.
18 . The charge pumped driver of claim 11 , wherein the at least one power switch further comprises a low side switch of the power stage, the driving signal provided by the driver circuit being referenced to ground.
19 . The charged pumped driver of claim 11 , wherein the at least one power switch further comprises a high side switch of the power stage, the driving signal provided by the driver circuit being floating with respect to ground.
20 . The charge pumped driver of claim 11 , further comprising means for selectively disabling the voltage doubler circuit to permit the driver circuit to drive the at least one power switch at a level corresponding to the input voltage.
21 . A method of controlling a switched mode power supply comprising a power stage having at least one power switch coupled to an input power source, said method comprising:
discharging a bucket capacitor to provide a driving signal to the at least one power switch in correspondence with a first portion of a pulse width modulated duty cycle, the driving signal having a voltage approximately double the corresponding voltage of the input power source; and
recharging the bucket capacitor in correspondence with a second portion of the pulse width modulated duty cycle.
22 . The method of claim 21 , wherein said discharging step further comprises coupling the bucket capacitor in series with the input power source to the at least one power switch.
23 . The method of claim 21 , wherein said recharging step further comprises recycling remaining charge from an internal capacitance of the at least one power switch back to the bucket capacitor.
24 . The method of claim 21 , wherein said recharging step further comprises coupling the bucket capacitor in parallel with the input power source.
25 . The method of claim 21 , further comprising regulating the input power source to a voltage less than the input power source.
26 . The method of claim 21 , wherein the first portion of the pulse width modulated duty cycle comprises a turn-on period of the at least one power switch.
27 . The method of claim 26 , wherein the second portion of the pulse width modulated duty cycle comprises a turn-off period of the at least one power switch.