Multi-level switching converter circuit and multi-level switching conversion method

A multi-level switching conversion method for converting a first voltage to a second voltage or convert the second voltage to the first voltage, the multi-level switching conversion method comprising:

• switching a flying capacitor and an inductor by a plurality of power switches of a power stage circuit coupled between the first voltage and the second voltage;
• generating a first control signal for periodically operating a first portion of the plurality of power switches of the power stage circuit and a second control signal for periodically operating a second portion of the plurality of power switches of the power stage circuit;
• generating a first ramp signal to determine a first duty ratio of the first control signal, and generating a second ramp signal to determine a second duty ratio of the second control signal through a valley current mode control, thereby a switching node connected to one end of the inductor is switched between two of k levels of voltages, such that the first voltage or the second voltage is regulated to a predetermined target level, and a flying capacitor voltage across the flying capacitor is regulated and balanced at one (k-1)th of the first voltage;
• wherein k is an integer equal to or greater than 3, and the k levels of voltages include the first voltage, a ground potential and at least one divided voltage of the first voltage.

A multi-level switching converter circuit configured to convert a first voltage to a second voltage or convert the second voltage to the first voltage, the multi-level switching converter comprising:

• a first power stage circuit, which is coupled between the first voltage and the second voltage, and includes a plurality of first power switches for switching a first flying capacitor and a first inductor;
• a second power stage circuit, which is coupled between the first voltage and the second voltage, and includes a plurality of second power switches for switching a second flying capacitor and a second inductor;
• and
• a conversion control circuit, which is configured to generate a first control signal, a second control signal, a third control signal and a fourth control signal, wherein the first control signal is for periodically operating a first portion of the plurality of first power switches, the second control signal is for periodically operating a second portion of the plurality of first power switches, the third control signal is for periodically operating a first portion of the plurality of second power switches, and the fourth control signal is for periodically operating a second portion of the plurality of second power switches;
• wherein through a first valley current mode control, the conversion control circuit generates a first ramp signal to determine a first duty ratio of the first control signal, and generates a second ramp signal to determine a second duty ratio of the second control signal, thereby a first switching node connected to one end of the first inductor is switched between two of k levels of voltages, such that the first voltage or the second voltage is regulated to a predetermined target level, and a first flying capacitor voltage across the first flying capacitor is regulated and balanced at one (k-1)th of the first voltage;
• wherein through a second valley current mode control, the conversion control circuit generates a third ramp signal to determine a third duty ratio of the third control signal, and generates a fourth ramp signal to determine a fourth duty ratio of the fourth control signal, thereby a second switching node connected to one end of the second inductor is switched between two of p levels of voltages, such that the first voltage or the second voltage is regulated to the predetermined target level, and a second flying capacitor voltage across the second flying capacitor is regulated and balanced at one (p-1)th of the first voltage;
• wherein k and p are both integers equal to or greater than 3, and the k levels of voltages include the first voltage, a ground potential and at least one divided voltage of the first voltage, and the p levels of voltages include the first voltage, a ground potential and at least one divided voltage of the first voltage.