| 摘要 |
PROBLEM TO BE SOLVED: To provide a gate-drive circuit having a superior overcurrent protective function such that it can control a power element, without raising the switching period of the element after detecting an overcurrent. SOLUTION: An electric circuit having a power source 8 and a power element 5 which controls the current flowing to a load 7 is provided with a current- detecting circuit 1, which detects the current flowing to the power element 5 and converts the current into a voltage, a reference voltage generating circuit 3 which outputs a reference voltage 10 corresponding to an overcurrent value, an overcurrent-detecting circuit 2 which compares the output of the current- detecting circuit 1 with the reference voltage 10. When the output becomes an overcurrent, it outputs an overcurrent signal 11, a drive circuit 4 which drives the power element 5, a PWM signal generating circuit 6 which outputs a PWM(pulse width modulation) signal 12 that controls the drive circuit 4, and a cut-off holding circuit 9 which inputs the overcurrent signal 11 from the overcurrent detecting circuit 2 and outputs a cut-off signal 13 to the drive circuit 4 for turning off the power element 5 for one or longer periods of the PWM signal 12. |
