| 摘要 |
PROBLEM TO BE SOLVED: To provide a power supply monitoring circuit normally outputting a reset signal despite an order of a fall and a fall time of a power-supply voltage.SOLUTION: A reference current generating circuit 2a and a reset signal output circuit 5a of a power supply monitoring circuit 1a are connected to a VCC via a diode D1, connected to a VREGD that is a power supply for a microcomputer formed by stepping down the VCC, via a diode D2, and are operated by a power-supply voltage having a higher voltage. When the VREGD voltage is higher than a detection voltage, a reset release circuit 3 outputs a reset release current and, when the reset release current is lower than the reference current of the reference current generating circuit 2a, the reset signal output circuit 5a outputs a reset signal of 0 V to reset the operation of the microcomputer. |
