Current sampling circuit applied to a multi-mode circuit and associated control method

A current sampling circuit applied to a multi-mode circuit, wherein the multi-mode circuit comprises a first switch, a second switch, a third switch and a fourth switch, the multi-mode circuit is configured to work in buck mode, boost mode or buck-boost mode, the current sampling circuit comprising:

• a first sampling circuit, configured to provide a first sampling current representing the current flowing through the first switch;
• a second sampling circuit, configured to provide a second sampling current representing the current flowing through the fourth switch;
• and
• a current processing circuit, configured to generate a third sampling current based on the first sampling current and the second sampling current, wherein the third sampling current equals to the second sampling current during an entire period when the multi-mode circuit works in buck mode, the third sampling current equals to the first sampling current during a period when the fourth switch is on and equals to zero otherwise when the multi-mode circuit works in boost mode, the third sampling current equals to zero during a first period, equals to the first sampling current during a second period, and equals to the second sampling current during a third period and a fourth period when the multi-mode circuit works in buck-boost mode;
• wherein
• one cycle of the buck-boost mode comprises four periods:
• the first period, the second period, the third period and the fourth period.

A control method for a current sampling circuit applied to a multi-mode circuit, wherein the multi-mode circuit comprises a first switch, a second switch, a third switch and a fourth switch, the multi-mode circuit is configured to work in buck mode, boost mode or buck-boost mode, the control method comprising:

• generating a first sampling current representing a current flowing through the first switch;
• generating a second sampling current representing a current flowing through the fourth switch;
• and
• generating a third sampling current based on the first sampling current and the second sampling current;
• wherein
• the third sampling current equals to the second sampling current during an entire period when the multi-mode circuit works in buck mode, the third sampling current equals to the first sampling current during a period when the fourth switch is on and equals to zero otherwise when the multi-mode circuit works in boost mode, the third sampling current equals to zero during a first period, equals to the first sampling current during a second period, and equals to the second sampling current during a third period and a fourth period when the multi-mode circuit works in buck-boost mode, wherein one cycle of the buck-boost mode comprises four periods:
• the first period, the second period, the third period and the fourth period.