Charging circuit

Patent metadata

Field	Value
Publication number	US-2022311259-A1
Application number	US-202217702204-A
Country	US
Kind code	A1
Filing date	Mar 23, 2022
Priority date	Mar 26, 2021
Publication date	Sep 29, 2022
Grant date	—

Abstract

The present disclosure provides a charging circuit capable of operating stably under a charging current of a wide range. A first transistor is connected between an input terminal and an output terminal. A current setting terminal is connected to an external current setting resistor. A second transistor is connected between the input terminal and the current setting terminal, and has a gate connected to a gate of the first transistor. A constant current feedback circuit feedback-controls a gate voltage of the first transistor in a manner that a voltage of the current setting terminal approaches a reference voltage. The constant current feedback circuit is configured in a manner that a phase compensation parameter is variable according to a current flowing through the first transistor.

First claim

1 . A charging circuit, comprising:
an input terminal; an output terminal; a first transistor, connected between the input terminal and the output terminal; a current setting terminal, to which an external current setting resistor is connectable; a second transistor, connected between the input terminal and the current setting terminal, and having a gate connected to a gate of the first transistor; and a constant current feedback circuit, feedback-controlling a gate voltage of the first transistor in a manner that a voltage of the current setting terminal approaches a reference voltage, wherein the constant current feedback circuit is configured in a manner that a phase compensation parameter is variable according to a current flowing through the first transistor.

2 . The charging circuit of claim 1 , wherein the constant current feedback circuit includes:
a third transistor, having a first end connected to the input terminal and a second end connected to the gate of the first transistor; a constant current load, connected between the second end of the third transistor and a ground; and a differential amplifier, receiving the voltage of the current setting terminal and the reference voltage, and having an output node connected to a control terminal of the third transistor.

3 . The charging circuit of claim 2 , wherein the constant current feedback circuit further includes a first resistor and a first capacitor connected in series and between the control terminal of the third transistor and the second end, wherein at least one of a resistance of the first resistor and a capacitance of the first capacitor is the phase compensation parameter, which is variable.

4 . The charging circuit of claim 3 , wherein the first resistor includes:
a first resistor element; and a series transistor and a second resistor element, connected in series and between both ends of the first resistor element, wherein a state of the series transistor changes according to the current flowing through the first transistor.

5 . The charging circuit of claim 1 , wherein the constant current feedback circuit includes:
a third transistor, having a first end connected to the input terminal and a second end connected to the gate of the first transistor; a constant current load, connected between the second end of the third transistor and a ground; a differential amplifier, receiving the voltage of the current setting terminal and the reference voltage, and having an output node connected to a control terminal of the third transistor; a first resistor element and a first capacitor, connected in series and between the control terminal of the third transistor and the second end; a first P-type transistor and a second resistor element, connected in series and between both ends of the first resistor element. a fourth transistor, having a gate connected to the gate of the first transistor and a source connected to a source of the first transistor; a current minor circuit, having an input node connected to the fourth transistor and an output node connected to the first P-type transistor; and an impedance circuit, connected between the input terminal and the output node of the current mirror circuit.

6 . The charging circuit of claim 5 , wherein the impedance circuit includes a second P-type transistor in which a gate/drain is connected.

7 . The charging circuit of claim 2 , wherein the constant current feedback circuit supplies a current proportional to the current flowing through the first transistor to the control terminal of the third transistor.

8 . The charging circuit of claim 2 , wherein a gain of the differential amplifier is the phase compensation parameter, which is variable.

9 . The charging circuit of claim 2 , wherein the differential amplifier includes:
a differential input stage; and an emitter-grounded type or source-grounded type amplification stage that amplifies an output of the differential input stage, wherein the constant current feedback circuit is configured in a manner that an output impedance of the amplification stage is variable according to a current proportional to the current flowing through the first transistor.

10 . The charging circuit of claim 9 , wherein a collector load or a drain load of the amplification stage is variably configured.

11 . The charging circuit of claim 9 , wherein an impedance of a grounded emitter transistor or a grounded source transistor of the amplification stage is variably configured.

12 . The charging circuit of claim 1 , wherein the constant current feedback circuit includes a fourth transistor, having a gate connected to the gate of the first transistor and a source connected to a source of the first transistor, wherein the phase compensation parameter of the constant current feedback circuit changes according to a current of the fourth transistor.

13 . The charging circuit of claim 1 , wherein the constant current feedback circuit includes a sense resistor connected in series with the first transistor, wherein the phase compensation parameter of the constant current feedback circuit changes according to a voltage drop of the sense resistor.

14 . The charging circuit of claim 1 , further comprising a voltage balance circuit connected between the second transistor and the current setting terminal to bring a voltage at one end of the second transistor closer to a voltage of the output terminal.

15 . The charging circuit of claim 2 , further comprising a voltage balance circuit connected between the second transistor and the current setting terminal to bring a voltage at one end of the second transistor closer to a voltage of the output terminal.

16 . The charging circuit of claim 5 , further comprising a voltage balance circuit connected between the second transistor and the current setting terminal to bring a voltage at one end of the second transistor closer to a voltage of the output terminal.

17 . The charging circuit of claim 12 , further comprising a voltage balance circuit connected between the second transistor and the current setting terminal to bring a voltage at one end of the second transistor closer to a voltage of the output terminal.

18 . The charging circuit of claim 1 , further comprising a constant voltage feedback circuit that feedback-controls the gate voltage of the first transistor such that a voltage of the output terminal approaches a second reference voltage.

19 . The charging circuit of claim 2 , further comprising a constant voltage feedback circuit that feedback-controls the gate voltage of the first transistor such that a voltage of the output terminal approaches a second reference voltage.

20 . The charging circuit of claim 5 , further comprising a constant voltage feedback circuit that feedback-controls the gate voltage of the first transistor such that a voltage of the output terminal approaches a second reference voltage.

Assignees

• Rohm Co Ltd

Inventors

• Kudo Masaya

Classifications

• H02M1/08

  Circuits specially adapted for the generation of control voltages for semiconductor devices incorporated in static converters · CPC title

• H02M3/156

  with automatic control of output voltage or current, e.g. switching regulators · CPC title

• H02M1/36

  Means for starting or stopping converters · CPC title

• H02J7/96

  in response to battery voltage · CPC title

• H02J7/56

  Active balancing, e.g. using capacitor-based, inductor-based or DC-DC converters · CPC title