Starting circuit of LLC resonant converter, chip and method

Abstract

The invention provides a starting circuit of an LLC resonant converter, a chip and a method, the starting circuit of the LLC resonant converter comprises a switch tube, and the starting circuit comprises: a detection module used for being connected with the LLC resonant converter, wherein the detection module is configured to obtain electrical parameters of the LLC resonant converter and output effective detection signals when the electrical parameters meet preset conditions; a driving module configured to output a driving signal for controlling the switch tube to work; and a control module respectively connected with the detection module and the driving module, wherein the control module is used for being connected with the switching tube, and the control module is configured to obtain the shielded driving signal according to the effective detection signal and transmit the shielded driving signal to the switching tube so as to prevent the parasitic diode of the switching tube from reversely recovering to damage the switching tube. The starting circuit can avoid the reverse recovery phenomenon of a parasitic diode of the switching tube in the starting process of the LLC resonant converter, prevents the switching tube from being damaged, and improves the reliability of the switching tube.

Description

technical field [0001] The invention belongs to the technical field of switching power supplies, and in particular relates to a starting circuit, chip and method of an LLC resonant converter. Background technique [0002] A switched resonant converter is a direct-current (DC-DC) converter. In normal working condition, the switched resonant converter has soft switching characteristics. However, during start-up, since the average value of the DC voltage on the resonant capacitor in the switched resonant converter changes from 0 to VIN / 2, hard switching may seriously damage the switching tube 11 in the first few switching cycles. Due to the poor reverse recovery capability of the body diode of the high-side / low-side switching tube in the switching resonant converter, hard switching may cause serious damage to the switching tube and cause a large instantaneous current. For special cases where repeated start-up of a resonant converter is required, hard switching is more harmful...

AI Technical Summary

Problems solved by technology

However, during start-up, since the average value of the DC voltage on the resonant capacitor in the switched resonant converter will change from 0 to VIN / 2, hard switching may occur in the first few switching cycles and seriously damage the switching tube 11.

Due to the poor reverse recovery ability of the body diode of the high-side / low-side switching tube in the switching resonant converter, hard switching may cause serious damage to the switching tube and cause a large instantaneous current

For special cases where resonant converters need to be started repeatedly, hard switching is more harmful

Images