In an electronic circuit, a first circuit region is electrically connected to an input circuit region of an isolated switching power source, and a second circuit region is electrically connected to an output circuit region thereof. A driver of an IC is located in the second circuit region and drives a target device based on output power supplied to the second circuit region via the output circuit region from the isolated switching power source. A transferring module of the IC transfers a value of a parameter indicative of the output power from the second circuit region to the first circuit region while maintaining electrical isolation between the first and second circuit regions. An operating module of the IC performs on-off operations of a switching element to perform feedback control of the value of the parameter indicative of the output power to a target value.