| 摘要 |
PURPOSE: A low voltage reset circuit for microcontroller is provided to perform stable operation by preventing generation of an operational error occurred when starting a low voltage detection after receiving power supply voltage. CONSTITUTION: The low voltage reset circuit for microcontroller(100) comprises a reset signal output circuit(300), a low voltage detection circuit(200), a PMOS transistor(MP1) playing a role of current path formed between the microcontroller and the low voltage detection circuit(200) and having a gate controlled by a status signal(STOP) outputted from the microcontroller(100) and a timer starting counting operation when power on or return to operation status from reset status. The reset signal output circuit(300) comprises an inverter inverting the fourth bit of signal(BIT4) among signals outputted from a counter of the microcontroller(100), the other inverter inverting the status signal (STOP) representing active/inactive status of the microcontroller(100), a latch circuit and an AND gate. The latch circuit consisting of SR flip-flop has the first input terminal(SN) receiving the inverted count signal(BIT4), the second input terminal (RN) receiving the inverted status signal(STOP) and an output terminal(Q). The AND gate receives signal from the latch circuit and signal from the low voltage detection circuit(200) and outputs a reset signal(reset).
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