Switching power-supply device having control circuit controlling switching element to turn on-and-off

摘要

A switching power-supply device, includes a first terminal; a first winding connected to the first terminal; a second winding, which is connected in series to the first winding and is magnetically coupled to the first winding; a first capacitor connected in series to the second winding; a transformer including a primary winding connected in series to the first capacitor and a secondary winding magnetically coupled to the primary winding; a rectifying-and-smoothing circuit connected to the secondary winding; a second terminal, which is connected to an opposite end of the primary winding opposite to a connection end connecting to the first capacitor; a first switching element, which is connected between a connection point of the first winding and the second winding and the second terminal; and a control circuit, which controls first switching element to turn on-and-off.

主权项

1. A switching power-supply device, comprising:
a first terminal configured to connect to one end of a DC power source; a first winding connected to the first terminal; a second winding, which is connected in series to the first winding and is magnetically coupled to the first winding; a first capacitor connected in series to the second winding; a transformer including a primary winding connected in series to the first capacitor and a secondary winding magnetically coupled to the primary winding; a rectifying-and-smoothing circuit connected to the secondary winding for rectifying-and-smoothing a voltage generated in the secondary winding and outputting the voltage to an output terminal; a second terminal, which is configured to connect to another end of the DC power source and is connected to an opposite end of the primary winding opposite to a connection end connected to the first capacitor; a first switching element, which is connected between a connection point of the first winding and the second winding and the second terminal; and a control circuit, which receives the voltage from the output terminal and controls the first switching element to turn on-and-off, wherein while the first switching element is being turned off, the first capacitor is charged by a voltage of the DC power source, and while the first switching element is being turned on, a voltage of the first capacitor and a voltage caused in the second winding are applied to the primary winding.