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US 7,466,111 B2Granted
Power supply unit and portable apparatus utilizing the same
AssigneeRohm Co., Ltd.
InventorTakanobu Komaki
Life of this patent
Estimating the term…
Abstract
An input source voltage is supplied from a battery for example to a switching power supply circuit such as a switching DC-DC converter via a series regulator for stepping down the input source voltage by a constant voltage. The series regulator serves as a buffer having a variable resistance to reduce the switching noise generated by the switching power supply circuit, thereby reducing the switching noise in the input source voltage and in turn reducing adverse influence of the noise on other circuit blocks that operate at the input source voltage.
Claims13
A power supply unit, comprising:
- a series regulator receiving an input source voltage and adapted to output a first output voltage that is lower than said input source voltage;
- and
- a switching power supply circuit supplied with said first output voltage and adapted to output a second output voltage, wherein
- said series regulator and said switching power supply circuit are simultaneously operated or stopped by a control signal provided from the outside,
- said input source voltage and second output voltage are made available to other circuit blocks,
- wherein said series regulator includes:
- a control transistor receiving at one end thereof said input source voltage and outputting at the other end thereof said first output voltage;
- a reference voltage formation circuit for forming a reference voltage lower than said input source voltage by a predetermined voltage;
- and
- a control circuit receiving said reference voltage and a feedback voltage representing said first output voltage and adapted to control said control transistor based on said reference voltage and said feedback voltage.
7 more elements
A power supply unit, comprising:
- a series regulator receiving an input source voltage and adapted to output a first output voltage that is lower than said input source voltage;
- and
- a switching power supply circuit supplied with said first output voltage and adapted to output a second output voltage, wherein
- said series regulator and said switching power supply circuit are simultaneously operated or stopped by a control signal provided from the outside,
- said input source voltage and second output voltage are made available to other circuit blocks, and, said other circuit blocks receiving said input source voltage include circuits that are susceptible to the influence of noise,
- wherein said series regulator includes:
- a control transistor receiving at one end thereof said input source voltage and outputting at the other end thereof said first output voltage;
- a reference voltage formation circuit for forming a reference voltage Vref1 lower than said input source voltage by a predetermined voltage;
- and
- a control circuit receiving said reference voltage and a feedback voltage representing said first output voltage and adapted to control said control transistor based on said reference voltage and said feedback voltage.
7 more elements
A power supply unit, comprising:
- a series regulator receiving an input source voltage and adapted to output a first output voltage that is lower than said input source voltage;
- and
- a switching power supply circuit supplied with said first output voltage and adapted to output a second output voltage, wherein
- said series regulator and said switching power supply circuit are simultaneously operated or stopped by a control signal provided from the outside,
- said input source voltage and second output voltage are made available to other circuit blocks, and, said series regulator is controlled so as to maintain said first output voltage lower than said input source voltage by a constant voltage,
- wherein said series regulator includes:
- a control transistor receiving at one end thereof said input source voltage and outputting at the other end thereof said first output voltage;
- a reference voltage formation circuit for forming a reference voltage Vref1 lower than said input source voltage by a predetermined voltage;
- and
- a control circuit receiving said reference voltage and a feedback voltage representing said first output voltage and adapted to control said control transistor based on said reference voltage and said feedback voltage.
7 more elements
Dependencies are inferred from the claim text.