Constant-time buck-boost switching regulator and control circuit and control method thereof

Patent metadata

Field	Value
Publication number	US-10644600-B2
Application number	US-201816171422-A
Country	US
Kind code	B2
Filing date	Oct 26, 2018
Priority date	Mar 25, 2018
Publication date	May 5, 2020
Grant date	May 5, 2020

Abstract

When a ramp signal intersects a feedback related signal, a constant time switching regulator enters a first state and maintains in the first state for a constant time, and after the constant time ends, when the ramp signal exceeds the feedback related signal, the switching regulator enters a second state, while when the ramp signal does not exceed the feedback related signal, the switching regulator enters a third state. In the first state, the first end of an inductor is connected to input voltage and the second end of the inductor is connected to output voltage; in the second state, the first end is connected to ground and the second end is connected to output voltage; and in the third state, the first end is connected to input voltage and the second end is connected to ground.

First claim

What is claimed is:

1. A constant time buck-boost switching regulator, comprising:
a power switch circuit, including an input switch unit and an output switch unit; the input switch unit being configured to operably switch a first end of an inductor between an input voltage and a ground, and the output switch unit being configured to operably switch a second end of the inductor between an output voltage and the ground; and
a control circuit including a constant time generation circuit for generated a constant time, when a ramp signal intersects a feedback related signal, the control circuit being configured to operably control the power switch circuit to enter a first state and maintain in the first state for the constant time, and after the constant time ends, when the ramp signal exceeds the feedback related signal, the control circuit being configured to operably control the power switch circuit to enter a second state, while when the ramp signal does not exceed the feedback related signal, the control circuit being configured to control the power switch circuit to enter a third state, wherein the feedback related signal is related to the output voltage;
wherein, in the first state, the power switch circuit electrically connects the first end of the inductor to the input voltage and electrically connects the second end of the inductor to the output voltage; in the second state, the power switch circuit electrically connects the first end of the inductor to the ground and electrically connects the second end of the inductor to the output voltage; and in the third state, the power switch circuit electrically connects the first end of the inductor to the input voltage and electrically connects the second end of the inductor to the ground.

2. The constant time buck-boost switching regulator according to claim 1 , wherein the ramp signal is related to a current of the inductor (inductor current), or simulates the inductor current.

3. The constant time buck-boost switching regulator according to claim 2 , wherein the ramp signal is proportional to the inductor current.

4. The constant time buck-boost switching regulator according to claim 3 , wherein the feedback related signal corresponds to a stable state value.

5. The constant time buck-boost switching regulator according to claim 2 , wherein the ramp signal does not include a direct current component of the inductor current.

6. The constant time buck-boost switching regulator according to claim 1 , wherein the control circuit includes:
a comparison circuit, configured to operably compare the ramp signal with the feedback related signal to generate a comparison output signal;
the constant time generation circuit, configured to operably trigger the constant time according to the comparison output signal when the ramp signal intersects the feedback related signal; and
a logic driver circuit, coupled to the comparison circuit and the constant time generation circuit, and configured to operably control the power switch circuit to enter the first state and maintain in the first state for the constant time, and control the power switch circuit to enter the second or third state when the constant time ends according to a level of the comparison output signal.

7. The constant time buck-boost switching regulator according to claim 6 , wherein the control circuit further includes an error amplifier circuit, configured to operably generate the feedback related signal according to a difference between a signal related to the output voltage and a reference voltage.

8. The constant time buck-boost switching regulator according to claim 6 , wherein the control circuit further includes a ramp generation circuit, configured to operably generate the ramp signal by one or more of the following ways: (1) the ramp generation circuit senses a current of the inductor (inductor current), and generates the ramp signal according to the inductor current; or (2) the ramp generation circuit simulates the inductor current according to the input voltage and the output voltage to generate the ramp signal.

9. The constant time buck-boost switching regulator according to claim 1 , wherein between the first state and the second state, or between the first state and the third state, there is a fourth state which is a dead time, wherein in the fourth state, the control circuit controls the power switch circuit such that the first end or the second end of the inductor is floating.

10. The constant time buck-boost switching regulator according to claim 1 , wherein the input switch unit includes:
an input upper switch, coupled between the input voltage and the first end of the inductor; and
an input lower switch or an input lower diode, coupled between the ground and the first end of the inductor;
wherein the control circuit controls the input upper switch, or the input upper switch and the input lower switch, to switch the first end of the inductor between the input voltage and the ground.

11. The constant time buck-boost switching regulator according to claim 1 , wherein the output switch unit includes:
an output lower switch, coupled between the ground and the second end of the inductor; and
an output upper switch or an output upper diode, coupled between the output voltage and the second end of the inductor;
wherein the control circuit controls the output lower switch, or the output upper switch and the output lower switch, to switch the second end of the inductor between the output voltage and the ground.

12. A control circuit for controlling a constant time buck-boost switching regulator, the constant time buck-boost switching regulator including a power switch circuit which includes an input switch unit and an output switch unit; the input switch unit being configured to operably switch a first end of an inductor between an input voltage and a ground, and the output switch unit being configured to operably switch a second end of the inductor between an output voltage and the ground, wherein an inductor current flows through the inductor; when a ramp signal intersects a feedback related signal, the control circuit being configured to operably control the power switch circuit to enter a first state and maintain in the first state for a constant time, and after the constant time ends, when the ramp signal exceeds the feedback related signal, the control circuit being configured to operably control the power switch circuit to enter a second state, while when the ramp signal does not exceed the feedback related signal, the control circuit being configured to control the power switch circuit to enter a third state, wherein, in the first state, the power switch circuit electrically connects the first end of the inductor to the input voltage and electrically connects the second end of the inductor to the output voltage; in the second state, the power switch circuit electrically connects the first end of the inductor to the ground and electrically connects the second end of the inductor to the output voltage; and in the third state, the power switch circuit electrically connects the first end of the inductor to the input voltage and electrically connects the second end of the inductor to the ground, and wherein the feedback related signal is related to the output voltage; the control circuit comprising:
a comparison circuit, configured to operably compare the ramp signal with the feedback related signal to generate a comparison output signal;
a constant time generation circuit, configured to operably trigger the constant time according to the comparison output signal when the ramp signal intersects the feedback related signal; and
a logic driver circuit, coupled to th

Assignees

• Richtek Technology Corp

Inventors

• Wu Kuo-Chun
• Cheng Hung-Yu

Classifications

• H02M3/1582 Primary

  Buck-boost converters (H02M3/1584 takes precedence) · CPC title

• H02M3/1563

  without using an external clock (H02M3/158 takes precedence) · CPC title

• H02M2001/0054

  Electricity · mapped topic

• H02M2003/1566

  Electricity · mapped topic

• H02M1/0054

  Transistor switching losses (periodically suspending operation of switching converter in low power mode H02M1/0035) · CPC title