US 11,735,994 B2
Integrated circuit and power supply circuit
Shinji Matsumoto, Matsumoto (JP); and Hiroki Yamane, Matsumoto (JP)
Assigned to FUJI ELECTRIC CO., LTD., Kawasaki (JP)
Filed by FUJI ELECTRIC CO., LTD., Kawasaki (JP)
Filed on Sep. 24, 2021, as Appl. No. 17/484,508.
Claims priority of application No. 2020-196267 (JP), filed on Nov. 26, 2020; and application No. 2021-048768 (JP), filed on Mar. 23, 2021.
Prior Publication US 2022/0166303 A1, May 26, 2022
Int. Cl. H02M 3/335 (2006.01); H02M 1/00 (2006.01)
CPC H02M 1/0003 (2021.05) [H02M 3/33523 (2013.01)] 12 Claims
OG exemplary drawing
 
1. An integrated circuit for a power supply circuit that generates an output voltage at a target level from an input voltage inputted thereto, the power supply circuit including
a transformer including a primary coil, a secondary coil, and an auxiliary coil, and
a transistor configured to control a current flowing through the primary coil,
the integrated circuit being configured to drive the transistor, the integrated circuit comprising:
a first terminal configured to receive a voltage corresponding to a coil voltage across the auxiliary coil when the transistor is off;
a second terminal configured to receive a feedback voltage corresponding to the output voltage;
a third terminal configured to receive a voltage, which
corresponds to a current flowing through the transistor when the transistor is on, and
corresponds to the coil voltage when the transistor is off;
a first detection circuit configured to detect whether the voltage at the third terminal when the transistor is off is lower than a first reference voltage; and
a control circuit configured to control switching of the transistor based on the feedback voltage, the voltage at the third terminal when the transistor is on, and a result of detection of the first detection circuit.