Semiconductor integrated circuit for regulator, and fan motor system

Patent metadata

Field	Value
Publication number	US-11474549-B2
Application number	US-202017117705-A
Country	US
Kind code	B2
Filing date	Dec 10, 2020
Priority date	Dec 18, 2019
Publication date	Oct 18, 2022
Grant date	Oct 18, 2022

Abstract

Disclosed is a semiconductor integrated circuit for a regulator, including: a voltage control transistor connected between a voltage input terminal to which a DC voltage is input and an output terminal; a control circuit that controls the voltage control transistor according to a feedback voltage of an output; a first transistor which is provided in parallel with the voltage control transistor and to which an electric current in a proportional reduction from an electric current flowing to the voltage control transistor flows; a first comparison circuit that determines which of the electric current flowing to the first transistor and a predetermined current value is larger; and a first output terminal for outputting the determination result. An output of the first comparison circuit is inverted in response to the flowing to the first transistor of the electric current smaller than a preset rotation lock detection current value.

First claim

What is claimed is:

1. A fan motor system, comprising:
a motor that rotates a fan;
a drive circuit that drives the motor to rotate; and
a semiconductor integrated circuit for a regulator, the semiconductor integrated circuit supplying an operation voltage of the drive circuit, and the semiconductor integrated circuit comprising:
a voltage control transistor that is connected between a voltage input terminal to which a DC voltage is input and an output terminal;
a control circuit that controls the voltage control transistor according to a feedback voltage of an output;
a first transistor which is provided in parallel with the voltage control transistor and to which an electric current in a proportional reduction from an electric current flowing to the voltage control transistor flows;
a first comparison circuit that determines which of the electric current flowing to the first transistor and a predetermined current value is larger;
a first output terminal for outputting outside a determination result by the first comparison circuit;
a second transistor which is provided in parallel with the voltage control transistor and the first transistor and to which an electric current in a proportional reduction from the electric current flowing to the voltage control transistor flows;
a second current-voltage converting element that converts the electric current flowing to the second transistor into a voltage;
a second comparison circuit that compares the voltage obtained by converting of the electric current by the second current-voltage converting element with a second comparison voltage corresponding to a voltage obtained by current-voltage conversion of an abnormality detection current value of the semiconductor integrated circuit which is set in advance, and determines which of the voltage obtained by the second current-voltage converting element and the second comparison voltage is larger; and
an inverter circuit that inverts an output of the first comparison circuit in response to the electric current flowing to the first transistor, the electric current being smaller than a rotation lock detection current value of the drive circuit, the rotation lock detection current value being set in advance, and the inverter circuit being provided in a stage before an output transistor and generating a signal to be input to a gate terminal of the output transistor,

wherein:
an output of the second comparison circuit is inverted in response to the electric current flowing to the second transistor, the electric current being larger than the abnormality detection current value, and
an abnormality detection signal is output from the first output terminal in response to inversion of the output of one of the first comparison circuit and the second comparison circuit.

2. The fan motor system according to claim 1 , further comprising a first external terminal for connecting a first current-voltage converting element that converts the electric current flowing to the first transistor into a voltage,
wherein the first comparison circuit compares a voltage corresponding to the predetermined current value with the voltage obtained by converting of the electric current by the first current-voltage converting element connected to the first external terminal.

3. The fan motor system according to claim 2 , wherein a first capacity element is connected to the first external terminal in parallel with the first current-voltage converting element.

4. The fan motor system according to claim 1 , further comprising a delay circuit that delays an output of the second comparison circuit,
wherein the abnormality detection signal is a signal obtained by having a logical sum of an output signal of the first comparison circuit and a signal delayed by the delay circuit.

5. The fan motor system according to claim 4 , further comprising a second external terminal for connecting a second capacity element to form the delay circuit.

6. A fan motor system, comprising:
a motor that rotates a fan;
a drive circuit that drives the motor to rotate; and
a semiconductor integrated circuit for a regulator, the semiconductor integrated circuit supplying an operation voltage of the drive circuit, and the semiconductor integrated circuit comprising:
a voltage control transistor that is connected between a voltage input terminal to which a DC voltage is input and an output terminal to which an external load is connected;
a control circuit that controls the voltage control transistor according to a feedback voltage of an output;
a rotation lock detection circuit which detects that an electric current flowing to the voltage control transistor becomes smaller than a rotation lock detection current value;
an external terminal to output a detection result of the rotation lock detection circuit; and
an abnormal current detection circuit which detects that an electric current flowing to the voltage control transistor becomes larger than an abnormal current detection value,

wherein:
an abnormality signal is output to the drive circuit from the external terminal in response to detection of a rotation lock state by the rotation lock detection circuit, and in response to detection of an abnormal current by the abnormal current detection circuit, the semiconductor integrated circuit performs one of (i) an overcurrent protection operation, and (ii) outputting of the abnormality signal from the external terminal.

Assignees

• Takano Yoichi
• Maki Shinichiro
• Mitsumi Electric Co Ltd

Inventors

• Takano Yoichi
• Maki Shinichiro

Classifications

• G05F1/561 Primary

  Voltage to current converters (amplifiers H03F) · CPC title

• G05F1/445

  being transistors in series with the load · CPC title

• G05F1/575 Primary

  characterised by the feedback circuit · CPC title

• G05F1/573 Primary

  with overcurrent detector · CPC title

• H02P6/08

  Arrangements for controlling the speed or torque of a single motor (H02P6/10, H02P6/28 take precedence) · CPC title