BACKGROUND

Technical Field

The present disclosure relates to an integrated circuit and a power supply circuit.

Description of the Related Art

An AC-DC converter generates an output voltage at a target level from an alternating current (AC) voltage, and generally, when the input AC voltage is interrupted, the output voltage drops. In such a case, a load of the AC-DC converter may not operate normally, and thus, a detection circuit that detects that the AC voltage has been interrupted may be provided to the AC-DC converter (for example, Japanese Patent Application Publication No. 2006-223070).

Incidentally, the detection circuit for detecting that the AC voltage has been interrupted is generally configured with a large number of discrete components, which increases the cost of the AC-DC converter.

The present disclosure has been achieved in light of such an issue described above, and an object thereof is to provide an integrated circuit capable of detecting that an AC voltage has been interrupted, at low cost.

SUMMARY

A primary aspect of the present disclosure for solving an issue described above is an integrated circuit for a power supply circuit that generates an output voltage at a target level from an alternating current (AC) voltage input thereto, the power supply circuit including a rectifier circuit that rectifies the AC voltage, an inductor that receives a rectified voltage from the rectifier circuit, and a transistor that controls an inductor current flowing through the inductor, the integrated circuit being configured to drive the transistor based on the inductor current and the output voltage, the integrated circuit comprising: a signal output circuit that includes a first comparator circuit that compares a value of the inductor current and a predetermined current value, a timer circuit that measures a time elapsed since the first comparator circuit starts to output a result of the comparison indicating that the value of the inductor current is smaller than the predetermined current value, and a second comparator circuit that compares a level of the output voltage and a first level lower than the target level, the signal output circuit outputting a first signal indicating that the AC voltage is not input to the rectifier circuit, when the elapsed time reaches a predetermined time period and the second comparator circuit outputs a result of the comparison thereof indicating that the level of the output voltage is lower than the first level.

According to the present disclosure, it is possible to provide an integrated circuit capable of detecting that an AC voltage has been interrupted, at low cost.

