| 摘要 |
PROBLEM TO BE SOLVED: To provide a low-input-voltage malfunction prevention circuit with an overvoltage protection function, enabling reduction of the number of semiconductor integrated circuit and a chip area. SOLUTION: A first current source CF, having dependency to an input voltage 1, is connected to one end of a current mirror circuit CM having second and third transistors 4, 5 of reverse polarity. The other end of the current mirror circuit CM is connected to one end of a resistor 6. The other end of the resistor 6 is connected to the source of a fourth transistor 7 of reverse polarity, of which drain is connected to the input voltage 1. A second constant current source 8 is connected between the gate of the fourth transistor 7 of reverse polarity and the input voltage 1, while a zener diode 9 is connected between the gate of the fourth transistor 7 and the ground. A drain voltage VA of the third transistor 5 of reverse polarity, and a voltage VB corresponding to a low input voltage detection threshold and an overvoltage detection threshold are supplied to the comparator 11, as input voltages thereto. A signal VCOUT detecting low input voltage and overvoltage is obtained, as an output of the comparator 11. COPYRIGHT: (C)2005,JPO&NCIPI
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