Switching converter having linear conversion function and conversion control circuit and method thereof

Patent metadata

Field	Value
Publication number	US-12401282-B2
Application number	US-202318486978-A
Country	US
Kind code	B2
Filing date	Oct 13, 2023
Priority date	Mar 3, 2023
Publication date	Aug 26, 2025
Grant date	Aug 26, 2025

Abstract

A switching converter for converting an input voltage to an output voltage includes: a power stage circuit which includes a high-side switch, a low-side switch and an auxiliary transistor; and a conversion control circuit for controlling the high-side switch, the low-side switch and the auxiliary transistor. In a switching conversion mode, the conversion control circuit controls the auxiliary transistor to be ON, and controls the high-side switch and the low-side switch to switch an inductor to convert the input voltage to the output voltage. In a pre-charging mode, the conversion control circuit controls the low-side switch to be OFF, and controls the auxiliary transistor to pre-charge the output voltage. In a linear conversion mode, the conversion control circuit controls the low-side switch to be OFF, and controls the auxiliary transistor to linearly convert the input voltage to the output voltage according to a feedback signal related to the output voltage.

First claim

What is claimed is:

1. A switching converter capable of performing linear conversion, wherein the switching converter is configured to operably convert an input voltage to an output voltage; the switching converter comprising:
a power stage circuit which includes: a high-side switch, a low-side switch and an auxiliary transistor, wherein one end of the high-side switch, one end of the low-side switch and one end of an inductor are coupled to a switching node, wherein another end of the high-side switch and one end of the auxiliary transistor are coupled to an intermediate node, wherein another end of the auxiliary transistor is coupled to the output voltage; and
a conversion control circuit, which is configured to operably control the high-side switch, the low-side switch and the auxiliary transistor;
wherein in a switching conversion mode, the conversion control circuit is configured to operably control the auxiliary transistor to be ON and control the high-side switch and the low-side switch to switch the inductor, so as to convert the input voltage to the output voltage;
wherein in a pre-charging conversion mode, the conversion control circuit is configured to operably control the low-side switch to be OFF and control the auxiliary transistor to pre-charge the output voltage;
wherein in a linear conversion mode, the conversion control circuit is configured to operably control the low-side switch to be OFF and control the auxiliary transistor to linearly convert the input voltage to the output voltage according to a first feedback signal related to the output voltage.

2. The switching converter of claim 1 , wherein in the pre-charging conversion mode, the conversion control circuit is configured to operably control the high-side switch to be OFF; and/or
wherein in the linear conversion mode, the conversion control circuit is configured to operably control the high-side switch to be ON.

3. The switching converter of claim 1 , wherein in the switching conversion mode, the conversion control circuit is configured to operably control switching of the high-side switch and the low-side switch, so as to regulate the output voltage to a target voltage level, wherein when a difference between the target voltage level and the input voltage is smaller than a first predetermined level, the switching converter enters the linear conversion mode.

4. The switching converter of claim 3 , wherein in the linear conversion mode, the conversion control circuit is configured to operably control the auxiliary transistor, so as to regulate the output voltage to the target voltage level, wherein when the difference between the target voltage level and the input voltage is greater than a second predetermined level, the switching converter enters the switching conversion mode.

5. The switching converter of claim 1 , wherein in the pre-charging conversion mode, when the output voltage is being pre-charged close to the input voltage, the switching converter enters the switching conversion mode.

6. The switching converter of claim 1 , wherein an anode and a cathode of a body diode of the high-side switch are coupled to the switching node and the intermediate node respectively, and an anode and a cathode of a body diode of the auxiliary switch are coupled to the output voltage and the intermediate node, respectively.

7. The switching converter of claim 1 , wherein the conversion control circuit includes:
a first feedback circuit, which is configured to operably generate the first feedback signal according to the output voltage; and
an error amplifier, which is configured to operably amplify a difference between the first feedback signal and a first reference signal to generate an error amplification signal;
wherein in the linear conversion mode, the auxiliary transistor is configured to operably convert the input voltage to the output voltage linearly according to the error amplification signal.

8. The switching converter of claim 7 , wherein the conversion control circuit further includes: a current mirror circuit, wherein the current mirror circuit includes the auxiliary transistor;
wherein in the pre-charging conversion mode, the current mirror circuit is configured to operably mirror a bias current source, so as to control the auxiliary transistor to generate a pre-charging current for pre-charging the output voltage;
wherein the pre-charging current is positively proportional to the bias current source.

9. The switching converter of claim 8 , wherein the conversion control circuit further includes: a transconductance transistor;
wherein in the linear conversion mode, the transconductance transistor is configured to operably generate a linear control current according to the error amplification signal, wherein the current mirror circuit is further configured to operably mirror the linear control current, so as to control the auxiliary transistor to linearly convert the input voltage to the output voltage.

10. The switching converter of claim 7 , wherein the conversion control circuit further includes: a transconductance transistor and a current mirror circuit, wherein the current mirror circuit includes the auxiliary transistor;
wherein in the linear conversion mode, the transconductance transistor is configured to operably generate a linear control current according to the error amplification signal, wherein the current mirror circuit is configured to operably mirror the linear control current, so as to control the auxiliary transistor to linearly convert the input voltage to the output voltage.

11. The switching converter of claim 1 , wherein when the output voltage is higher than an overly-high voltage threshold and lower than an overly-low voltage threshold and/or when an output current related to the output voltage is higher than an overly-high current threshold, the conversion control circuit is configured to operably control the auxiliary transistor to be OFF.

12. A conversion control circuit, which is configured to operably control a switching converter, wherein the switching converter is configured to operably convert an input voltage to an output voltage, wherein the switching converter includes: a high-side switch, a low-side switch and an auxiliary transistor, wherein one end of the high-side switch, one end of the low-side switch and one end of an inductor are coupled to a switching node, wherein another end of the high-side switch and one end of the auxiliary transistor are coupled to an intermediate node, wherein another end of the auxiliary transistor is coupled to the output voltage; the conversion control circuit comprising:
a switching control circuit, which is configured to operably control the high-side switch and the low-side switch to switch the inductor, so as to convert the input voltage to the output voltage in a switching conversion mode, wherein in the switching conversion mode, the auxiliary transistor is ON;
a pre-charging control circuit, which is configured to operably control the auxiliary transistor to pre-charge the output voltage in a pre-charging conversion mode, wherein in the pre-charging conversion mode, the low-side switch is OFF;
a linear control circuit, which is configured to operably control the auxiliary transistor to linearly convert the input voltage to the output voltage according to a first feedback signal related to the output voltage in a linear conversion mode, wherein in the linear conversion mode, the low-side switch is OFF.

13. The conversion control circuit of claim 12 , wherein in the pre-charging conversion mode, the conversion control circuit is configured to operably control the high-side switch to be OFF; and/or

Assignees

• Richtek Technology Corp

Inventors

• Liu San-Hsien
• Wu Che-Wei
• Fan Po-Chin

Classifications

• H02M1/32

  Means for protecting converters other than automatic disconnection · CPC title

• H02M3/003

  Constructional details, e.g. physical layout, assembly, wiring or busbar connections · CPC title

• H02M1/0025

  Arrangements for modifying reference values, feedback values or error values in the control loop of a converter · CPC title

• H02M1/36

  Means for starting or stopping converters · CPC title

• H02M1/0045

  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 title