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US 2003/0151423 A1Published application
Rush current limiting circuit for a PFM control charge pump
AssigneeSeiko Instruments Inc.
InventorToshiki Ishii
Life of this patent
Estimating the term…
Abstract
An input voltage detecting circuit for detecting an input voltage is provided inside a PFM control charge pump circuit, and potential differences between potentials appearing at gate terminals and potentials appearing at source terminals are reduced by gate voltage controlling circuits for in response to a signal from the input voltage detecting circuit, suppressing gate voltages of switch transistors of a charge pump to suppress a rush current value to thereby reduce a current to prevent generation of a noise.
Claims4
A rush current limiting circuit for a PFM control charge pump, comprising:
- an input voltage detecting circuit for detecting an input voltage through a power supply terminal;
- a driver circuit for supplying the electric charges to a pump capacitor or an output capacitor;
- and
- a gate voltage controlling circuit for driving the drive circuit,
- wherein the driver circuit has a switch transistor for adjusting a quantity of electric charges supplied to the pump capacitor or the output capacitor, and
- the gate voltage controlling circuit, in response to a signal from the input voltage detecting circuit, outputs a signal used to make variable a gate voltage of the switch transistor of the driver circuit.
3 more elements
Dependencies are inferred from the claim text.