# US 2015/0177752 A1 · Voltage regulator

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- Number: US 2015/0177752 A1
- Document ID: US20150177752A1
- Status: Published application
- Kind: A1
- Application number: 14/639,681
- Filed: 2015-03-05
- Published: 2015-06-25
- Earliest claimed: 2012-09-07
- Assignees: Seiko Instruments Inc.
- Applicants: Seiko Instruments Inc.
- Inventors: Takao NAKASHIMO; Tadashi KUROZO
- Web page: https://patentgrep.com/patent/US20150177752A1

## CPC

- G05F 1/10: Regulating voltage or current (G05F1/02 takes precedence)
- G05F 1/56: using semiconductor devices in series with the load as final control devices (G05F1/461 takes precedence)
- G05F 1/575: characterised by the feedback circuit
- H02M 1/32: Means for protecting converters other than automatic disconnection
- G05F: SYSTEMS FOR REGULATING ELECTRIC OR MAGNETIC VARIABLES
- H02M: APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF (transformers H01F; dynamo-electric converters H02K47/00; controlling transformers, reactors or choke coils, control or regulation of electric motors, generators or dynamo-electric converters H02P)

## Abstract

Provided is a voltage regulator that is low in current consumption and is capable of suppressing the occurrence of an excessive overshoot at an output terminal when a power supply voltage becomes high in a non-regulated state. The voltage regulator includes: an overshoot limiting circuit for detecting an occurrence of an overshoot in an output voltage and limiting a current of the output transistor; and a non-regulated state detection circuit for detecting a non-regulated state of the voltage regulator based on a voltage of an output terminal and a current flowing through the output transistor. The overshoot limiting circuit has an operating current controlled by a detection signal of the non-regulated state detection circuit.

## Claims

### Claim 1

A voltage regulator, comprising:
an error amplifier circuit for amplifying a difference between a divided voltage obtained by dividing an output voltage output from an output transistor and a reference voltage, and outputting the amplified difference to control a gate of the output transistor;
an overshoot limiting circuit for detecting an occurrence of an overshoot in the output voltage and limiting a current of the output transistor; and
a non-regulated state detection circuit for detecting that the voltage regulator is in a non-regulated state based on the output voltage and the current flowing through the output transistor,
the overshoot limiting circuit having an operating current controlled by a detection signal of the non-regulated state detection circuit.

### Claim 2 (depends on 1)

A voltage regulator according to claim 1,
wherein the non-regulated state detection circuit comprises:
a first detection circuit and a second detection circuit; and
an output circuit for outputting a detection signal by inputting an output of the first detection circuit and an output of the second detection circuit,
wherein: in a normal state, the first detection circuit allows a larger current to flow than a current of the second detection circuit; and in a non-regulated state, the second detection circuit allows a larger current to flow than a current of the first detection circuit, and
wherein the output circuit outputs the detection signal in accordance with the current of the first detection circuit and the current of the second detection circuit.

### Claim 3 (depends on 2)

A voltage regulator according to claim 2,
wherein the first detection circuit and the second detection circuit each comprise a circuit for converting a current into a voltage, and
wherein the output circuit outputs the detection signal in accordance with a voltage obtained by converting the current of the first detection circuit and a voltage obtained by converting the current of the second detection circuit.