An over-current protection apparatus constituted of: a transistor disposed on a substrate; a first thermal sense device arranged to sense a temperature reflective of a junction temperature of the transistor; a second thermal sense device arranged to sense a temperature reflective of a temperature of a casing surrounding the substrate; and a control circuitry, arranged to alternately: responsive to the sensed temperature by the first thermal sense device and the sensed temperature of the second thermal sense device being indicative that the temperature difference between the transistor junction and the substrate casing is greater than a predetermined value, switch off the transistor; and responsive to the sensed temperature by the first thermal sense device and the sensed temperature by the second thermal sense device being indicative that the temperature difference between the transistor junction and the substrate casing is not greater than the predetermined value, switch on the transistor.

An auxiliary circuit for providing current to an external device includes a first switch disposed between a first node and a second node. The first switch is configured to electrically couple the first node to the second node when a first voltage exceeds a first threshold. A comparison circuit has an input coupled to the second node and is configured to compare a second voltage at the input to a second threshold. A second switch has a control terminal coupled to an output of the comparison circuit, a first terminal coupled to a source, and a second terminal for coupling to the external device. The comparison circuit is configured to provide a third voltage at control terminal when the second voltage exceeds the second threshold. The second switch is configured to provide the current from the source to the external device when the third voltage exceeds a threshold of the second switch.

An image forming apparatus may have the followings. A switching transformer has a first coil, a second coil, and a first core. The switching transformer generates a secondary side current in the second coil by a magnetic flux generated in the first core by a current that flows in the first coil. A common mode choke coil has a third coil, a fourth coil, and a second core. The common mode choke coil reduces a common mode noise. The switching transformer and the common mode choke coil are mounted on a substrate so that a direction of the magnetic flux generated in the first core and a direction of a magnetic flux generated in the second core are perpendicular.

There is provided a method for capturing a line after an elapse of a predetermined time, in a case where the line has been disconnected caused by an occurrence of a specific event in which a heavy load signal is input to an input side connecting the line. The control method for controlling a communication apparatus configured to perform a data communication via a line, includes detecting a signal on the line, disconnecting the line based on a level of the detected signal, and capturing the line based on an elapse of a predetermined time after the line has been disconnected.

A structure protects a SLIC telephone line interface against overvoltages lower than a negative threshold or higher than a positive threshold. The structure includes at least one thyristor connected between each conductor of the telephone line and a reference potential. For all of the included thyristors, a metallization corresponding to the main electrode on the gate side is in contact, by its entire surface, with a corresponding semiconductor region. Furthermore, the gate of each thyristor is directly connected to a voltage source defining one of the thresholds.