Back to results
US 2007/0176671 A1Published application
Charge pump circuit and electric appliance therewith
AssigneeRohm Co., Ltd.
InventorTakuya Ishida
Life of this patent
Estimating the term…
Abstract
In a charge pump circuit, the through rate at which a clock signal is fed to charge transfer transistors is changed according to the output voltage. This configuration helps alleviate rush currents at start-up without unduly lowering efficiency.
Claims10
A charge pump circuit comprising:
- a plurality of charge transfer transistors that are turned on and off periodically according to a clock signal;
- a charge accumulation capacitor that is charged and discharged as the charge transfer transistors are turned on and off so as to produce a desired output voltage from an input voltage;
- a slew rate changer portion that changes a slew rate at which the clock signal is fed to the charge transfer transistors;
- and
- a controller portion that controls the slew rate changer portion to change the slew rate according to a level of the output voltage,
- wherein the controller portion gives instructions to the slew rate changer portion to increase the slew rate as the output voltage approaches a target voltage level.
3 more elements
A charge pump circuit comprising:
- a plurality of charge transfer transistors that are turned on and off periodically according to a clock signal;
- a charge accumulation capacitor that is charged and discharged as the charge transfer transistors are turned on and off so as to produce a desired output voltage from an input voltage;
- a current mirror circuit including a pair of transistors, the current mirror circuit mirroring a constant current flowing through one transistor to make the other transistor output a mirrored current;
- and
- a controller portion that controls whether or not to permit driving of the current mirror circuit according to a level of the output voltage,
- wherein a first of the charge transfer transistors that is connected between one terminal of the charge accumulation capacitor and an input voltage application terminal and that is turned on when the charge accumulation capacitor is charged is used as a mirrored current output side transistor of the current mirror circuit, and
- wherein the controller portion permits driving of the current mirror circuit until the output voltage reaches a predetermined threshold voltage so as to turn the current mirror circuit on and off periodically according to the clock signal, and the controller portion prohibits driving of the current mirror circuit after the output voltage has reached the predetermined threshold voltage so as to turn the first transistor on and off directly according to the clock signal.
4 more elements
An electric appliance including a charge pump circuit, the charge pump circuit comprising:
- a plurality of charge transfer transistors that are turned on and off periodically according to a clock signal;
- a charge accumulation capacitor that is charged and discharged as the charge transfer transistors are turned on and off so as to produce a desired output voltage from an input voltage;
- a slew rate changer portion that changes a slew rate at which the clock signal is fed to the charge transfer transistors;
- and
- a controller portion that controls the slew rate changer portion to change the slew rate according to a level of the output voltage,
- wherein the controller portion gives instructions to the slew rate changer portion to increase the slew rate as the output voltage approaches a target voltage level.
3 more elements
An electric appliance including a charge pump circuit, the charge pump circuit comprising:
- a plurality of charge transfer transistors that are turned on and off periodically according to a clock signal;
- a charge accumulation capacitor that is charged and discharged as the charge transfer transistors are turned on and off so as to produce a desired output voltage from an input voltage;
- a current mirror circuit including a pair of transistors, the current mirror circuit mirroring a constant current flowing through one transistor to make the other transistor output a mirrored current;
- and
- a controller portion that controls whether or not to permit driving of the current mirror circuit according to a level of the output voltage,
- wherein a first of the charge transfer transistors that is connected between one terminal of the charge accumulation capacitor and an input voltage application terminal and that is turned on when the charge accumulation capacitor is charged is used as a mirrored current output side transistor of the current mirror circuit, and
- wherein the controller portion permit driving of the current mirror circuit until the output voltage reaches a predetermined threshold voltage so as to turn the current mirror circuit on and off periodically according to the clock signal, and the controller portion prohibits driving of the current mirror circuit after the output voltage has reached the predetermined threshold voltage so as to turn the first transistor on and off directly according to the clock signal.
4 more elements
Dependencies are inferred from the claim text.