EG12523 Dual-tube Flyback -24V400W Solution
The control part of this scheme adopts the dual tube forward and backward dedicated chip EG12523, which has VCC undervoltage protection (UVLO), VCC overvoltage protection (VOP) Periodic current limitation, overload protection, soft start, etc. The main circuit of this scheme adopts a dual tube flyback converter, which has the following main advantages compared to single ended flyback: 1. It reduces energy loss, eliminates buffer loss and heat generation issues, and the leakage inductance energy when the switch tube is turned off is fed back to the DC input power supply through the freewheeling diode; 2. The voltage stress borne by the switch tube is only the DC input voltage, which is more suitable for high voltage and wide input scenarios. When the switch tube of a single ended flyback converter is turned off, the voltage it bears is equal to the sum of the maximum DC input voltage, the secondary side refracted voltage, and the leakage inductance peak voltage, requiring higher voltage resistant devices; 3. Compared to other multi tube converter topologies, there is no risk of direct short circuit between the two switching tubes in the dual tube flyback converter. Due to the two switching tubes being on the diagonal of the bridge, during normal operation, both tubes conduct and turn off simultaneously. At this time, the primary winding of the transformer is subjected to voltage, so there is no risk of direct current.