Voltage detection circuit, power-on/off reset circuit, and semiconductor device
View Patent ↗The present invention comprises a first MOS transistor whose gate and drain are connected with a first node, a second MOS transistor whose gate and drain are connected with the first node and a third node, respectively, a first resistive element which is connected between the first node and a second node, a second resistive element which is connected between the second node and a ground voltage terminal, a first NOT circuit whose input terminal is connected with the second node, whose output terminal is a fourth node, and which is connected between the third node and the ground voltage terminal, and a second NOT circuit whose input terminal is connected with the fourth node and whose output terminal is a fifth node. Consequently, the present invention can detect voltage in a stable condition with low power consumption.
1. A power on/off reset circuit comprising:
a first voltage detection circuit which detects a power supply reaching a first voltage and outputs a first signal,
a second voltage detection circuit which detects the power supply reaching a second voltage higher than the first voltage and outputs a second signal,
a third voltage detection circuit which receives the first and second signals and outputs a third signal, and
a first circuit which has a first function of executing a series of operational sequences in accordance with an input control signal and a second function of not accepting said input control signal,
wherein the third signal is transmitted as the second signal when the power-supply voltage rises, and transmitted as the first signal when the power-supply voltage drops, and
the first function of the first circuit continues an ongoing sequence according to the input control signal and the second function of said first circuit prevents a new operational sequence regardless of the input control signal when a power-supply voltage is equal to or lower than a voltage for the third signal transmitted.
2. The power on/off reset circuit according to claim 1 further comprising:
a fourth voltage detection circuit which detects the power supply reaching a third voltage lower than the first voltage and outputs a fourth signal,
a second circuit which executes a series of operational sequences in accordance with the input control signal,
wherein an operation, which is being executed by the fourth voltage detection circuit, is immediately suspended when the power-supply voltage is equal to or lower than the third voltage.
3. The power on/off reset circuit according to claim 2 ,
wherein a time for the power-supply voltage to drop from the first voltage to the third voltage is longer than a predetermined operational sequence completion time.
4. A semiconductor device comprising:
the power on/off reset circuit of claim 1 , 2 or 3 , and a non-volatile memory, wherein
the first circuit of the power on/off reset circuit controls said non-volatile memory.