| 摘要 |
PURPOSE:To reduce switch drive current and power loss and enable to integrate circuits by a method wherein a detection resistance for detecting the short circuit of loads is unnecessitated, and then protection circuits are composed of MOS transistor sources which are grounded. CONSTITUTION:When a switching signal VIN is inputted, the gate voltage VG1 of an MOS transistor TR 12 increases at the time constant decided by the gate capacitances of a resistor 14 and the TR 12. When the voltage VG1 reaches the threshold voltage of the TR 12, the TR 12 conducts, and then the drain voltage VDS begins to decrease. When the voltage VG1 increases and reaches the reference voltage VE of a comparator 15, the output signal V1 of the comparator 15 turns at H level. But, the output V2 of an AND circuit 16 is at L level, and the output of a latch circuit 17 also turns at L level, accordingly a MOST TR 13 becomes non-conducted, and the TR 12 becomes conducted. On the other hand, TR 12 maintains non-conduction at the time of the short circuit of the load 11. This constitution unnecessitates a detection resistor for load short circuit. In this constitution, the TR 13 and the circuits 15-17 are composed of MOST TR's sources being grounded. |
