Voltage regulator
AssigneeSeiko Instruments Inc.
InventorsAkihito Yahagi, Takashi Imura
Life of this patent
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Abstract
Provided is a voltage regulator including a soft-start circuit having a small area and capable of suppressing an inrush current by causing a reference voltage circuit to rise gently with time. In the soft-start circuit, a capacitor is connected to an output of a reference voltage circuit driven by a constant current of a constant current circuit, and hence the soft-start circuit can raise a reference voltage gently to prevent an inrush current with a small area. After the end of a soft-start period, the constant current circuit is disconnected, and the reference voltage circuit is driven by a power source. Thus, the operation becomes stable.
Claims2
A voltage regulator comprising a soft-start circuit, the soft-start circuit comprising:
- a constant current circuit;
- a reference voltage circuit driven by a current of the constant current circuit;
- a capacitor at an output of the reference voltage circuit;
- a soft-start signal output circuit for detecting a reference voltage of the reference voltage circuit to output a soft-start signal through first and second series connected inverters;
- a first switch circuit connecting the constant current circuit to the reference voltage circuit, the first switch circuit being turned ON in response to the soft-start signal from an output of the second inverter during a soft-start period;
- and
- a second switch circuit connecting a power source to the reference voltage circuit in parallel with the first switch circuit, the second switch circuit being turned OFF in response to the soft-start signal from an output of the first inverter during the soft-start period.
Dependencies are inferred from the claim text.