| 摘要 |
PROBLEM TO BE SOLVED: To perform ripple injection more appropriately than ever before.SOLUTION: A power supply IC has a ripple injection circuit 11 which adds a ripple voltage Vrpl that represents a coil current to a divided voltage Vdiv of an output voltage Vout to generate a feedback voltage Vfb. The ripple injection circuit 11 includes: a current source 111 for generating a current I1 according to an input voltage Vin; a current source 112 for generating a current I2 according to an output voltage Vout; a capacitor 114 which is charged by a differential current (I1-I2) during an ON period of an output transistor and discharged by a current I2 during an OFF period of the output transistor; a terminal voltage application part 115 for adding a voltage between both ends of the capacitor 114 to the divided voltage Vdiv as a ripple voltage Vrpl; a discharge switch 116 connected to the capacitor 114 in parallel with each other; and a discharge control part 117 for turning ON the discharge switch 116 before every start of discharge of the capacitor 114.SELECTED DRAWING: Figure 7 |
