| 摘要 |
PURPOSE: To provide a high-reliability protection circuit by minimizing time when a non-controlled current flows and simultaneously cutting off voltage build-up to apply damage to a power transistor especially in a low voltage driving circuit. CONSTITUTION: In this circuit to perform the cut-off controlled by metal-oxide field-effect transistor To, a transistor for power not shown in Figure is operated as the low voltage driving circuit in a power feeding circuit 10 for electric load ZL and this is inserted between a drain terminal D of transistor To and a positive voltage supply terminal VB to a ground potential M. A switchable discharging circuit 14 is provided between a gate terminal G and the ground terminal M and this is serially connected to an electric switch S. In this case, the circuit 14 is composed of a parallel circuit composed of an ohm resistor R and series-connected plural diodes D1-Dn. The switch S can input signals through a passing current detection circuit 12, and the short-circuitting current of circuit 10 including the transistor To is monitored by detecting the voltage drop of load ZL. |
