# US 2026/0086591 A1 · Low-dropout regulator circuit and control method thereof > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2026/0086591 A1 - Document ID: US20260086591A1 - Status: Published application - Kind: A1 - Application number: 19/409,675 - Filed: 2025-12-04 - Published: 2026-03-26 - Earliest claimed: 2022-05-25 - Assignees: Realtek Semiconductor Corp. - Applicants: Realtek Semiconductor Corporation - Inventors: Sheng-Wei LIN; Wei-Cheng TANG - Web page: https://patentgrep.com/patent/US20260086591A1 ## CPC - G05F 1/575: characterised by the feedback circuit - G05F 1/468: {characterised by reference voltage circuitry, e.g. soft start, remote shutdown} - G05F 3/30: Regulators using the difference between the base-emitter voltages of two bipolar transistors operating at different current densities (G05F3/26 takes precedence) - G05F: SYSTEMS FOR REGULATING ELECTRIC OR MAGNETIC VARIABLES ## Abstract A low-dropout regulator circuit includes a reference circuit, an amplifying circuit, a power switch circuit, a feedback circuit, and a control circuit. The reference circuit is configured to generate a reference voltage. The amplifying circuit is configured to generate an amplifying voltage according to the reference voltage and a feedback voltage. The power switch circuit is configured to receive the amplifying voltage and generate an output voltage at an output terminal according to an input voltage. The feedback circuit is configured to generate the feedback voltage according to the output voltage. The control circuit is configured to control the power switch circuit according to the input voltage and a signal from the reference circuit. ## Claims ### Claim 1 A low-dropout regulator circuit, comprising: a reference circuit configured to generate a reference voltage; an amplifying circuit configured to generate an amplifying voltage according to the reference voltage and a feedback voltage; a power switch circuit configured to receive the amplifying voltage and generate an output voltage at an output terminal according to an input voltage; a feedback circuit configured to generate the feedback voltage according to the output voltage; and a control circuit configured to control the power switch circuit according to the input voltage and a signal from the reference circuit, wherein the signal from the reference circuit is a reference current from a current mirror in the reference circuit. ### Claim 2 (depends on 1) The low-dropout regulator circuit of claim 1, wherein the power switch circuit comprises a power switch, and the control circuit further comprises: a transistor comprising a first terminal, a second terminal, and a control terminal, wherein the first terminal of the transistor is configured to receive the input voltage, and the second terminal of the transistor is coupled to a control terminal of the power switch, and the reference circuit and the control terminal of the transistor are coupled at a node; and a capacitor coupled between the node and a ground terminal, wherein the reference current is configured to charge at the node. ### Claim 3 (depends on 2) The low-dropout regulator circuit of claim 2, further comprising: an overcurrent protection circuit comprising a first terminal and a second terminal, wherein the first terminal of the overcurrent protection circuit is configured to receive the input voltage, and the second terminal of the overcurrent protection circuit is coupled to the control terminal of the power switch. ### Claim 4 (depends on 2) The low-dropout regulator circuit of claim 2, wherein the control terminal of the power switch is configured to receive the amplifying voltage. ### Claim 5 (depends on 2) The low-dropout regulator circuit of claim 2, wherein the transistor and the power switch are transistors with a same type. ### Claim 6 (depends on 2) The low-dropout regulator circuit of claim 2, wherein when a node voltage at the node has an initial logic value, the transistor is turned on and the power switch is turned off. ### Claim 7 (depends on 6) The low-dropout regulator circuit of claim 6, wherein when the reference current charges the node, a turned-on degree of the power switch increases and the input voltage charges the output terminal. ### Claim 8 A control method of a low-dropout regulator circuit, comprising: generating, by a reference circuit, a reference voltage; generating, by an amplifying circuit, an amplifying voltage according to the reference voltage and a feedback voltage; receiving, by a power switch circuit, the amplifying voltage and generating, by the power switch circuit, an output voltage at an output terminal according to an input voltage; generating, by a feedback circuit, the feedback voltage according to the output voltage; and controlling, by a control circuit, the power switch circuit according to the input voltage and a signal from the reference circuit, wherein the signal from the reference circuit is a reference current from a current mirror in the reference circuit. ### Claim 9 (depends on 8) The control method of claim 8, wherein the power switch circuit comprises a power switch, and the control circuit further comprises: a transistor comprising a first terminal, a second terminal, and a control terminal, wherein the first terminal of the transistor is configured to receive the input voltage, and the second terminal of the transistor is coupled to a control terminal of the power switch, and the reference circuit and the control terminal of the transistor are coupled at a node; and a capacitor coupled between the node and a ground terminal, wherein the reference current is configured to charge at the node. ### Claim 10 (depends on 9) The control method of claim 9, wherein the low-dropout regulator circuit further comprises: an overcurrent protection circuit comprising a first terminal and a second terminal, wherein the first terminal of the overcurrent protection circuit is configured to receive the input voltage, and the second terminal of the overcurrent protection circuit is coupled to the control terminal of the power switch. ### Claim 11 (depends on 9) The control method of claim 9, wherein the control terminal of the power switch is configured to receive the amplifying voltage. ### Claim 12 (depends on 9) The control method of claim 9, wherein the transistor and the power switch are transistors with a same type. ### Claim 13 (depends on 9) The control method of claim 9, wherein when a node voltage at the node has an initial logic value, the transistor is turned on and the power switch is turned off. ### Claim 14 (depends on 13) The control method of claim 13, wherein when the reference current charges the node, a turned-on degree of the power switch increases and the input voltage charges the output terminal.