Current sampling circuit applied to boost-buck circuit and control method thereof

The invention discloses a current sampling circuit applied to a boost-buck circuit and a control method thereof. The boost-buck circuit comprises a reference field, a first MOS (Metal-Oxide-Semiconductor) transistor, a second MOS transistor, a third MOS transistor, a fourth MOS transistor and an inductor; the current sampling circuit comprises a first current sampling circuit, a second current sampling circuit and a current processing circuit; the first sampling circuit is used for sampling current flowing through the first MOS transistor to obtain first sampling current; the second sampling circuit is used for sampling current flowing through the fourth MOS transistor to obtain second sampling current; the current processing circuit is used for generating third sampling current accordingto the first sampling current and the second sampling current; and the average value of the third sampling current in one circuit working period represents the output current of the boost-buck circuit. Compared with the prior