Protection circuit
View Patent ↗In a protection circuit of an input/output terminal I/O, three types of PNP bipolar transistors are included. In a first PNP type bipolar transistor 10 A, the emitter thereof is connected to the input/output terminal I/O, the base thereof is connected to a high-potential power supply terminal VDD, and the collector thereof is connected to a low-potential power supply terminal VSS. In a second PNP type bipolar transistor 10 B, the emitter thereof is connected to the input/output terminal I/O, and the base and the collector thereof are connected to the high-potential power supply terminal VDD. In a third PNP type bipolar transistor 10 C, the emitter thereof is connected to the low-potential power supply terminal VSS, and the base and the collector thereof are connected to the high-potential power supply terminal VDD.
1. A protection circuit comprising, wherein
a first PNP type bipolar transistor including an emitter thereof connected to an input/output terminal, a collector thereof connected to a first power supply terminal, and a base thereof connected to a second power supply terminal,
a second PNP type bipolar transistor including an emitter thereof connected to the input/output terminal, and a base and collector thereof connected to the second power supply terminal, and
a third PNP type bipolar transistor including an emitter thereof connected to the first power supply terminal, and a base and collector thereof connected to the second power supply terminal.
2. The protection circuit according to claim 1 , wherein said first power supply terminal comprises a low potential power supply terminal and said second power supply terminal comprises a high potential power supply terminal.