Switching power supply device

A switching power supply device comprising:

• an induction element connected between a first input node and a first node;
• a first switching element connected between the first node and a first output node;
• a second switching element connected between a second input node and the first output node;
• a first thyristor connected between the first node and a second output node;
• a second thyristor connected between the second input node and the second output node;
• a capacitive element connected between the first output node and the second output node;
• a detector that detects an input voltage received via the first input node and the second input node;
• and
• a control circuit that controls the first thyristor, the second thyristor, the first switching element, and the second switching element according to the input voltage, wherein
• the control circuit maintains the second thyristor and the first switching element in an on state while maintaining the first thyristor and the second switching element in an off state in a first period in which an absolute amplitude value is equal to or less than a first threshold value within a latter half of a first half-cycle in the input voltage at startup, and maintains the first thyristor and the second switching element in an on state while maintaining the second thyristor and the first switching element in an off state in a second period in which an absolute amplitude value is equal to or less than a second threshold value larger than the first threshold value within a latter half of a second half-cycle following the first half-cycle in the input voltage at startup.

A switching power supply device comprising:

• first and second input nodes;
• first and second output nodes;
• an induction element connected to the first input node;
• a first switching element connected between the induction element and the first output node;
• a second switching element connected between the induction element and the second output node, the first and second switching elements being connected to each other;
• a first thyristor connected between the second input node and the first output node;
• a second thyristor connected between the second input node and the second output node, the first and second thyristors being connected to each other;
• a capacitive element connected between the first output node and the second output node;
• a voltage detector configured to detect an input voltage on the first and second input nodes;
• and
• a control circuit configured to:
• switching element to an on state and the first thyristor and the second switching element to an off state, in a first period in which an absolute amplitude value of the input voltage is equal to or less than a first threshold value;
• and
• set the first thyristor and the second switching element to an on state and the second thyristor and the first switching element to off state in a second period in which an absolute amplitude value of the input voltage is equal to or less than a second threshold value.