Semiconductor switch control circuit and switching power source device

A semiconductor switch control circuit configured to perform an ON/OFF control of a semiconductor switch having a source electrode, a drain electrode and a gate electrode by supplying a drive current to the gate electrode, the semiconductor switch control circuit comprising:

• a pulse signal generating part configured to generate a pulse signal which becomes a time reference for performing the ON/OFF control of the semiconductor switch;
• a drive current generating part configured to generate the drive current based on the pulse signal which the pulse signal generating part generates and to supply the drive current to the gate electrode of the semiconductor switch;
• a current detecting part configured to detect a drain current or a source current of the semiconductor switch, or a current which flows through a predetermined current path of a peripheral circuit of the semiconductor switch;
• and
• a drive current control part configured to have a function of controlling the drive current which the drive current generating part generates based on the pulse signal which the pulse signal generating part generates and the current which the current detecting part detects,
• wherein the drive current generating part includes:
• a source part configured to charge a current to the gate electrode of the semiconductor switch;
• and
• a sink part configured to discharge a current from the gate electrode of the semiconductor switch,
• wherein the drive current control part is configured to control the drive current by controlling a charge current to be charged to the gate electrode of the semiconductor switch, or a discharge current to be discharged from the gate electrode of the semiconductor switch, and
• wherein the drive current control part is configured, when a current which the current detecting part detects exceeds a predetermined second set current, to control the drive current such that a rising speed of the gate voltage during a turn-on period of the semiconductor switch becomes lower than the rising speed of the gate voltage before detection of the current by the current detecting part which exceeds the predetermined second set current.

A semiconductor switch control circuit configured to perform an ON/OFF control of a semiconductor switch having a source electrode, a drain electrode and a gate electrode by supplying a drive current to the gate electrode, the semiconductor switch control circuit comprising:

• a pulse signal generating part configured to generate a pulse signal which becomes a time reference for performing the ON/OFF control of the semiconductor switch;
• a drive current generating part configured to generate the drive current based on the pulse signal which the pulse signal generating part generates and to supply the drive current to the gate electrode of the semiconductor switch;
• a current detecting part configured to detect a drain current or a source current of the semiconductor switch, or a current which flows through a predetermined current path of a peripheral circuit of the semiconductor switch;
• a drive current control part configured to have a function of controlling the drive current which the drive current generating part generates based on the pulse signal which the pulse signal generating part generates and the current which the current detecting part detects;
• and
• a gate voltage detecting part configured to detect a gate voltage of the semiconductor switch, wherein
• the drive current control part is configured to have a function of controlling the drive current which the drive current generating part generates based on the pulse signal which the pulse signal generating part generates and the gate voltage which the gate voltage detecting part detects.