POWER SUPPLY CIRCUIT, CONTROL CIRCUIT THEREOF, AND ELECTRONIC APPARATUS

• US 20150076906A1
• Filed: 09/11/2014
• Published: 03/19/2015
• Est. Priority Date: 09/13/2013
• Status: Active Grant

• Current Assignee: ROHM Co., Ltd.
• Original Assignee: ROHM Co., Ltd.
• Inventors: TAMEGAI, Yoichi, HORIMOTO, Masashi
• Granted Patent: US 10,186,959 B2
• Time in Patent Office: Days
• US Class Current: 307/31
• CPC Class Codes: H02J 2207/20 Charging or discharging characterised by the power electronics converter
• CPC Class Codes: H02M 1/0032 Control circuits allowing low power mode operation, e.g. in standby mode
• CPC Class Codes: H02M 1/0045 Converters combining the concepts of switch-mode regulation and linear regulation, e.g. linear pre-regulator to switching converter, linear and switching converter in parallel, same converter or same transistor operating either in linear or switching mode
• CPC Class Codes: H02M 1/0054 Transistor switching losses periodically suspending operation of switching converter in low power mode H02M1/0035
• CPC Class Codes: H02M 3/156 with automatic control of output voltage or current, e.g. switching regulators
• CPC Class Codes: Y02B 40/00 Technologies aiming at improving the efficiency of home appliances, e.g. induction cooking or efficient technologies for refrigerators, freezers or dish washers
• CPC Class Codes: Y02B 70/10 Technologies improving the efficiency by using switched-mode power supplies [SMPS], i.e. efficient power electronics conversion e.g. power factor correction or reduction of losses in power supplies or efficient standby modes

Abstract

A power supply circuit including a DC/DC converter having switching elements and configured to receive an input voltage in an input line and generate an output voltage in an output line; and a linear regulator configured to receive the output voltage and supply a stabilized voltage to a load. The DC/DC converter switches between a switching mode to switch the switching elements and a bypass mode to put a switching element existing on a path from the input line to the output line, of the switching elements, in a full-on state and stop switching of the other switching element.

Claims

1. A power supply circuit comprising:

a DC/DC converter comprising at least two switching elements and configured to receive an input voltage in an input line and generate an output voltage in an output line; and

a linear regulator configured to receive the output voltage of the output line of the DC/DC converter, stabilize the received output voltage to a target level, and supply the stabilized voltage to a corresponding load,

wherein the DC/DC converter is configured to switch between a switching mode to switch the switching elements such that the output voltage approaches the target level and a bypass mode to put a switching element existing on a path from the input line to the output line, of the switching elements, in a full-on state and stop switching of the other switching element.

2. The power supply circuit of claim 1, wherein the DC/DC converter is a step-down type DC/DC converter comprising a switching transistor and a synchronous rectification transistor as the switching elements and, in the bypass mode, fully turns on the switching transistor and turns off the synchronous rectification transistor.

3. The power supply circuit of claim 1, wherein the load connected to the linear regulator is a microcomputer, and

wherein the DC/DC converter selects one of the switching mode and the bypass mode based on an instruction from the microcomputer.

4. The power supply circuit of claim 1, wherein the DC/DC converter selects the bypass mode when an electronic apparatus equipped with the power supply circuit enters a standby state.

5. The power supply circuit of claim 1, wherein the DC/DC converter includes a current detector to detect an output current and selects one of the switching mode and the bypass mode based on an amount of the output current.

6. The power supply circuit of claim 1, wherein the DC/DC converter stops operations other than an operation of a circuit block required to fix a state of the switching elements in the bypass mode.

7. The power supply circuit of claim 1, wherein, when switching from the bypass mode to the switching mode, the DC/DC converter sets a target value of the output voltage to a value larger than a normal value and then decreases the target value to the normal value.

8. The power supply circuit of claim 1, wherein the DC/DC converter is configured to switch between a PWM (pulse width modulation) mode and a PFM (pulse frequency modulation) mode in the switching mode, and

wherein, when switching from the bypass mode to the switching mode, regardless of an amount of an output current of the DC/DC converter, the DC/DC converter selects the PWM mode temporarily and then selects one of the PWM mode and the PFM mode based on the amount of the output current.

9. An electronic apparatus comprising:

a battery;

one or more loads; and

a power supply circuit of claim 1, wherein the power supply circuit receives a voltage of the battery and supplies power to the one or more loads.

10. An electronic apparatus comprising:

a battery;

an application processor;

a baseband processor; and

a power supply circuit configured to supply power to the application processor and the baseband processor,

wherein the power supply circuit comprises;

a DC/DC converter comprising at least two switching elements and configured to receive an input voltage of the battery in an input line and generate an output voltage in an output line;

a first linear regulator configured to receive the output voltage of the output line of the DC/DC converter, stabilize the received output voltage to a first target level, and supply the stabilized voltage to the application processor; and

a second linear regulator configured to receive the output voltage of the output line of the DC/DC converter, stabilize the received output line voltage to a second target level, and supply the stabilized voltage to the baseband processor,

wherein the DC/DC converter is configured to switch between a switching mode to switch the switching elements such that the output voltage approaches the first and second target levels and a bypass mode to put a switching element existing on a path from the input line to the output line, of the switching elements, in a full-on state and stop switching of the other switching element.

11. The electronic apparatus of claim 10, wherein the DC/DC converter selects one of the switching mode and the bypass mode based on an instruction from the application processor.

12. A control circuit of a power supply circuit configured to supply power to one or more loads, wherein the power supply circuit comprises:

a DC/DC converter comprising at least two switching elements and configured to receive an input voltage in an input line and generate an output voltage in an output line; and

a linear regulator configured to receive the output voltage of the output line of the DC/DC converter, stabilize the received output voltage to a target level, and supply the stabilized voltage to a corresponding load, comprising;

a controller configured to control an on/off state of the switching elements and switch between a switching mode to switch the switching elements such that the output voltage approaches the target level and a bypass mode to put a switching element existing on a path from the input line to the output line, of the switching elements, in a full-on state and stop switching of the other switching element.

13. The control circuit of claim 12, wherein the DC/DC converter is a step-down type DC/DC converter comprising a switching transistor and a synchronous rectification transistor as the switching elements and, in the bypass mode, fully turns on the switching transistor and turns off the synchronous rectification transistor.

14. The control circuit of claim 12, wherein the load connected to the linear regulator is a microcomputer, and

wherein the controller selects one of the switching mode and the bypass mode based on an instruction from the microcomputer.

15. The control circuit of claim 12, wherein the controller selects the bypass mode when an electronic apparatus equipped with the power supply circuit enters a standby state.

16. The control circuit of claim 12, further comprising a current detector to detect an output current of the DC/DC converter,

wherein the controller selects one of the switching mode and the bypass mode based on an amount of the output current.

17. The control circuit of claim 12, wherein the controller stops operations other than an operation of a circuit block required to fix a state of the switching elements in the bypass mode.

18. The control circuit of claim 12, wherein the controller further comprises a voltage source to generate a reference voltage indicating a target value of the DC/DC converter, and

wherein, when switching from the bypass mode to the switching mode, the voltage source sets the reference voltage to a value larger than a normal value and then decreases the reference voltage to the normal value.

19. The control circuit of claim 12, wherein the controller is configured to switch between a PWM mode and a PFM mode in the switching mode, and

wherein, when switching from the bypass mode to the switching mode, regardless of an amount of an output current of the DC/DC converter, the controller selects the PWM mode temporarily and then selects one of the PWM mode and the PFM mode based on the amount of the output current.

20. The control circuit of claim 12, wherein the control circuit is integrated on a single semiconductor substrate.