| 摘要 |
PROBLEM TO BE SOLVED: To provide an overcurrent protection circuit which performs stable overcurrent protection. SOLUTION: The circuit comprises a Pch transistor (hereinafter abbreviated to as PTr)P1 having a source connected to a power supply line and a drain connected to an output terminal Vout which outputs a load current; a PTrP2 having a source and a gate connected to the source and gate of the PTrP1, respectively; resistant elements R1 and R2 serially connected between the output terminal Vout and the ground; a resistant element R3 connected between the drain of the PTrP2 and the ground; and an amplifier Amp which controls the PtrP1 and P2 based on difference between the potential of a connecting point of the resistant elements R1 and R2 and a reference potential so that the output potential of the output terminal Vout is constant. A comparator Cmp1 has a differential amplification input stage composed of an Nch transistor, compares a potential difference between both ends of the element R3 with a potential difference between the connecting point of the elements R1 and R2 and the ground, and controls the PTrP1, when the former is larger, so as to limit the value of the load current. COPYRIGHT: (C)2009,JPO&INPIT
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