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

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 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.

A control method 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;
• the control method comprising:
• when a ramp signal intersects a feedback related signal, controlling the power switch circuit to enter a first state and maintain in the first state for a constant time, wherein the feedback related signal is related to the output voltage;
• when the constant time ends, judging whether the ramp signal exceeds the feedback related signal;
• and
• when the ramp signal exceeds the feedback related signal, controlling the power switch circuit to enter a second state, or when the ramp signal does not exceed the feedback related signal, controlling 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.