LLC circuit topology and switching power supply

The invention provides an LLC circuit topology and a switching power supply. The LLC circuit topology comprises a three-phase staggered LLC unit, a first switch unit and a first rectification unit, the input end of the three-phase staggered LLC unit is used for receiving three-phase input voltage; the three-phase staggered LLC unit comprises a three-phase LLC branch; each phase of LLC branch comprises a phase of transformer; a first switch unit is arranged between the first ends of the secondary coils of the transformers of all phases in the three-phase staggered LLC unit, so that secondary coil coupling or secondary coil decoupling is achieved between the LLC branches of all phases. The first end of the secondary coil of each phase transformer in the three-phase interleaving LLC unit is respectively connected with the first input end, the second input end and the third input end of the first rectification unit; the output end of the three-phase interleaving LLC unit is correspondingly connected to the output