Abstract: The disclosure provides a cover assembly and a packaging box, wherein the cover assembly comprises: a shield provided with an opening; a sliding cover slidably arranged on the shield; a lid located between the shield and the sliding cover and rotatably connected to the shield, so that the opening can be opened or closed under the drive of the sliding cover. The cover assembly provided by the disclosure can directly drive the lid to move by means of the sliding cover during the sliding process, so that the lid can open or close the opening, with the whole structure being small and delicate, easy to operate for the user, and at the same time reducing the cost of the cover assembly to ensure the storage of stuff inside the box body of the packaging box.

Abstract: A forward-flyback DC-DC converter topology includes a transformer, a main switch, a clamp circuit, first and second rectifying switches, an LC resonant circuit and an output capacitor; a primary winding of the transformer and the main switch are connected in series between a first input terminal and a second input terminal, the clamp circuit constituted by a clamp capacitor and a clamp switch connected in series is connected in parallel with the primary winding or with the main switch, a secondary winding of the transformer includes a forward winding and a flyback winding, a terminal of the primary winding through which current flows into is a dotted terminal of the primary winding, and a connecting mode of a secondary side of the transformer is: the dotted terminal of the forward winding being connected with a first output terminal via the first rectifying switch, a dotted terminal of the flyback winding being connected with a second output terminal via the second rectifying switch, the LC resonant circuit b

Abstract: A forward-flyback DC-DC converter topology includes a transformer, a main switch, a clamp circuit, first and second rectifying switches, an LC resonant circuit and an output capacitor; a primary winding of the transformer and the main switch are connected in series between a first input terminal and a second input terminal, the clamp circuit constituted by a clamp capacitor and a clamp switch connected in series is connected in parallel with the primary winding or with the main switch, a secondary winding of the transformer includes a forward winding and a flyback winding, a terminal of the primary winding through which current flows into is a dotted terminal of the primary winding, and a connecting mode of a secondary side of the transformer is: the dotted terminal of the forward winding being connected with a first output terminal via the first rectifying switch, a dotted terminal of the flyback winding being connected with a second output terminal via the second rectifying switch, the LC resonant circuit b