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US 2007/0182397 A1Published application
Switching regulator
AssigneeSeiko Instruments Inc.
InventorMichiyasu Deguchi
Life of this patent
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Abstract
In a switching regulator circuit having a function of bypassing a power supply and an output terminal, there is provided a switching regulator that obtains a stable output voltage even if the operation of the bypass function is changed over. A reference voltage that is inputted to an error amplifier is set to a higher voltage value in a bypass state, and is gradually decreased to a desired value when the bypass state is canceled.
Claims4
A switching regulator, comprising:
- a voltage-dividing resistor for dividing a voltage outputted to an output terminal;
- an error amplifier for comparing a voltage outputted by the voltage-dividing resistor with a reference voltage;
- a chopping wave generator circuit for generating a chopping wave;
- a control circuit for inputting an output of the error amplifier and the chopping wave;
- a p-type MOS transistor and an n-type MOS transistor controlled according to an output of the control circuit and connected in series between a power supply and a ground;
- and
- a bypass transistor connected between the power supply and the output terminal, wherein a circuit for generating the reference voltage comprises:
- a first reference voltage circuit;
- a first switching means for connecting the first reference voltage circuit to the error amplifier in inversion synchronism with the bypass transistor;
- a time constant circuit disposed between the first switch means and the error amplifier;
- a second reference voltage circuit;
- and
- a second switch means for connecting the second reference voltage circuit to the error amplifier in synchronism with the bypass transistor.
10 more elements
Dependencies are inferred from the claim text.