Low-dropout regulator circuit and electronic device

A low-dropout regulator circuit comprising:

• a supply terminal for receiving a supply voltage;
• an output terminal for providing an output voltage;
• a pass element coupled between the supply terminal and the output terminal;
• and
• a control block configured to control the pass element based on a difference between a feedback voltage which is derived from the output voltage, and a reference voltage, which determines a target output voltage;
• wherein:
• the control block is configured to be selectively operated in a normal mode of operation and in a low-supply mode of operation depending on a selection signal;
• in the normal mode of operation the control block is configured to be operated with a first operating range for the supply voltage, the first operating range excluding the target output voltage;
• and
• in the low-supply mode of operation the control block is configured to be operated with a second operating range for the supply voltage, the second operating range including the target output voltage and only partially overlapping with the first operating range,
• wherein the control block comprises:
• a first differential amplifier having a first input for receiving the reference voltage, having a second input for receiving the feedback voltage and having an output for providing a first intermediate voltage depending on a difference between the reference voltage and the feedback voltage;
• a second differential amplifier having a first input for receiving the reference voltage, having a second input for receiving the feedback voltage and having an output for providing a second intermediate voltage depending on a difference between the reference voltage and the feedback voltage;
• wherein:
• the first differential amplifier is designed for the normal mode of operation;
• the second differential amplifier is designed for the low-supply mode of operation;
• wherein the low-dropout regulator is operable such that:
• during the normal mode of operation the first intermediate voltage is provided to a control input of the pass element;
• and
• during the low-supply mode of operation the second intermediate voltage is provided to the control input of the pass element.

A low-dropout regulator circuit comprising:

• a supply terminal for receiving a supply voltage;
• an output terminal for providing an output voltage;
• a pass element coupled between the supply terminal and the output terminal;
• and
• a control block configured to control the pass element based on a difference between a feedback voltage which is derived from the output voltage, and a reference voltage, which determines a target output voltage;
• wherein:
• the control block is configured to be selectively operated in a normal mode of operation and in a low-supply mode of operation depending on a selection signal;
• in the normal mode of operation the control block is configured to be operated with a first operating range for the supply voltage, the first operating range excluding the target output voltage;
• and
• in the low-supply mode of operation the control block is configured to be operated with a second operating range for the supply voltage, the second operating range including the target output voltage and only partially overlapping with the first operating range,
• wherein the control block comprises:
• a differential amplifier having a first input for receiving the reference voltage, having a second input for receiving the feedback voltage (vfb) and having an output for providing an intermediate voltage depending on a difference between the reference voltage and the feedback voltage;
• a first series connection of a first mirror transistor and a first steering transistor coupled between the supply terminal and a reference potential terminal;
• a second series connection of a second mirror transistor and a second steering transistor coupled between the supply terminal and the reference potential terminal;
• wherein:
• a connection between the first mirror transistor and the first steering transistor and a connection between the second mirror transistor and the second steering transistor bare commonly connected to a control input of the pass element;
• the first mirror transistor is stronger than the second mirror transistor;
• the second steering transistor is stronger than the first steering transistor;
• wherein the low-dropout regulator is operable such that:
• during the normal mode of operation a gate terminal of the first mirror transistor is connected to the output of the differential amplifier, a gate terminal of the first steering transistor is connected to a bias connection of the differential amplifier, and a gate terminal of the second steering transistor is connected to the reference potential terminal;
• and
• during the low-supply mode of operation a gate terminal of the second mirror transistor is connected to the output of the differential amplifier, the gate terminal of the first steering transistor is connected to the reference potential terminal, and the gate terminal of the second steering transistor is connected to the bias connection of the differential amplifier.