US 11,742,774 B2
Switch driving device and switching power supply using the same
Kenji Hamachi, Kyoto (JP); and Akeyuki Komatsu, Kyoto (JP)
Assigned to ROHM CO., LTD., Kyoto (JP)
Filed by ROHM CO., LTD, Kyoto (JP)
Filed on Jul. 13, 2022, as Appl. No. 17/812,205.
Application 17/812,205 is a continuation of application No. 16/915,372, filed on Jun. 29, 2020, granted, now 11,424,691.
Claims priority of application No. 2019-124342 (JP), filed on Jul. 3, 2019; and application No. 2020-048066 (JP), filed on Mar. 18, 2020.
Prior Publication US 2022/0345051 A1, Oct. 27, 2022
Int. Cl. H02M 7/217 (2006.01); H02M 3/335 (2006.01); H02M 3/00 (2006.01); H02M 1/08 (2006.01); H02M 1/34 (2007.01); H02M 1/36 (2007.01); H02M 1/00 (2006.01)
CPC H02M 7/217 (2013.01) [H02M 3/01 (2021.05); H02M 3/33569 (2013.01); H02M 1/0058 (2021.05); H02M 1/083 (2013.01); H02M 1/34 (2013.01); H02M 1/36 (2013.01)] 8 Claims
OG exemplary drawing
 
1. A switching power supply, comprising:
a primary winding to which an alternating-current input voltage is applied;
a secondary winding electromagnetically coupled to the primary winding;
a bidirectional switch connected in series with the primary winding;
a resonance capacitor connected in parallel with at least one of the bidirectional switch or the primary winding;
a full-wave rectifier circuit configured to perform full-wave rectification of an induced voltage occurring in the secondary winding;
a smoothing capacitor configured to smooth output of the full-wave rectifier circuit;
a voltage detecting circuit connected to the bidirectional switch; and
a switch driving device, wherein the switch driving device comprises:
circuitry configured to perform individual zero voltage switching control of a first switch element and a second switch element, wherein
the first switch element and the second switch element form a bidirectional switch,
the second switch element is a switch element that switches from a state in which both the first switch element and the second switch element are on to an off state,
the bidirectional switch switches from an on state to the off state when the second switch element is set to the off state from the on state while the first switch element remains on,
when the bidirectional switch is switched from the off state to the on state, the circuitry is further configured to perform first zero voltage switching control so as to turn on the second switch element in timing in which a voltage across the second switch element becomes 0 V, and the first switch element is switched from the on state to the off state, and
when the bidirectional switch is switched from the off state to the on state, the circuitry is further configured to perform second zero voltage switching control following the first zero voltage switching control so as to turn off the first switch element in timing in which the second switch element is turned on, and turn on the first switch element in timing in which a voltage across the first switch element becomes 0 V;
and the switch driving device is configured to:
drive the bidirectional switch; and
perform the individual zero voltage switching control based on a switch voltage appearing between the second switch element and the primary winding.