PROTECTIVE CIRCUIT FOR TRANSISTOR

• Main Author: YOKOYAMA TAKAYUKI
• Format: Patent
• Language: English
• Published: 21.05.1991
• Subjects: CONVERSION OR DISTRIBUTION OF ELECTRIC POWER; ELECTRICITY; EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS; GENERATION

PURPOSE:To protect a transistor and other devices from thermal breakdown by a method wherein, if an overcurrent state is judged to occur continuously for a first predetermined period, an output transistor is cut off and conduction control is delayed so as to have the output transistor in a conducting state after a second predetermined period passes. CONSTITUTION:If an overcurrent state is continuously judged by an overcurrent judging means 4 for a first predetermined period, a cut-off delaying means 5 delays cut-off control by a driving control means 2 so as to have an output transistor 1 in a cut-off state. A conduction delaying means 6 delays conduction control by the driving control means 2 so as to have the output transistor 1 in a conducting state after a second predetermined period passes after the cut-off control of the output transistor 1 is performed by the driving control means 2 with the action of the cut-off delaying means 5. With this constitution, heat generated by the protective operation of the transistor 1 can be suppressed and the transistor 1 and other adjacent devices can be protected from thermal breakdown.