JPH11161380A - Reset circuit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a simple reset circuit which does not initiate resetting in normal operation owing to an external noise, etc. SOLUTION: This circuit consists of a main power source part 11 for normal operation, an auxiliary power source part 12 for standby operation, a reset part 13 which receives power from both the main power source part 11 and auxiliary power source part 12, and an auxiliary reset part 14 which receives power only from the main power source part 11. The auxiliary reset part 14 which is connected to the main power source part 11 to receive power increases current when resetting is initiated in normal operation, so the reset circuit is stable against external noise.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a reset circuit using a microcomputer having a standby mode.

[0002]

2. Description of the Related Art Conventionally, a configuration of a reset circuit of a microcomputer having a standby mode is as shown in FIG. In FIG. 2, the main power supply 21 for normal operation
And an auxiliary power supply unit 22 for standby operation are connected to the reset unit 23 in parallel. As another conventional example, as shown in FIG. 3, a main power supply 43 and a backup power supply 44 separated from the main power supply 43 by a diode 37 and obtained by charging a capacitor 34 are provided. The backup power supply 44 maintains the operation of the microcomputer 40 even when the power supply to the power supply is stopped, and when the voltage of the backup power supply 44 decreases, the power supply voltage detection IC 42, the resistor 32 that pulls up the output of the IC 42, and the inverter In a reset circuit configured to reset the microcomputer 40 by the control circuit 39, a transistor 36 is connected to a differentiating circuit 35 configured by a resistor 31 and a capacitor 33 operated by a main power supply 43, and
The collector 38 of the transistor 36 is connected to an inverter 39
When the microcomputer 40 runs out of control due to some abnormality, the main power supply 43 is turned off.
A reset circuit has been disclosed in which the microcomputer 40 can be reset by an operation of N-OFF (Japanese Utility Model Laid-Open No. 6-11020).

[0003]

However, in the conventional example shown in FIG. 2, since a battery or the like is used for the auxiliary power supply 221 of the auxiliary power supply section 22, the resistor 231 is used to suppress the current consumption of the reset section 23. Is several hundred k to several MΩ.
Therefore, the current at the time of resetting is in the unit of μA regardless of the normal operation or the standby operation. Therefore, there is a problem that the reset is applied due to external noise or the like during the normal operation. Also, in the conventional example shown in FIG.
2 has a high resistance and is susceptible to external noise. SUMMARY OF THE INVENTION It is an object of the present invention to provide a simple reset circuit that is not reset due to external noise or the like during a normal operation.

[0004]

In order to solve the above-mentioned problems, a reset circuit according to the present invention comprises a main power supply for normal operation, an auxiliary power supply for standby operation, the main power supply and the auxiliary power supply. It comprises a reset unit supplied with power from both power supply units and an auxiliary reset unit supplied with power only from the main power supply unit. By this means, the auxiliary reset unit connected to the main power supply unit for normal operation and supplied with power increases the amount of current flowing when a reset occurs during normal operation, so that it is stable against external noise. It becomes a reset circuit.

[0005]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be specifically described below based on an embodiment shown in FIG. In FIG. 1, reference numeral 11 denotes a main power supply unit, 12 denotes an auxiliary power supply unit, 13 denotes a reset unit, and 14 denotes an auxiliary reset unit. The main power supply 111 of the main power supply unit 11 is connected in parallel to the resistor 131 of the reset unit 13 and the resistor 141 of the auxiliary reset unit 14 via diodes 112 and 113. The auxiliary power supply 121 of the auxiliary power supply unit 12 is connected to the reset unit 1 via the diode 122.
3 is connected to the resistor 131. In the figure, 132 is a capacitor.

In this embodiment, the resistance 131 of the reset unit 13 is several hundred kΩ to several MΩ, and the resistance 141 of the auxiliary reset unit 14 is several KΩ. In the embodiment shown in FIG. 1, a main power supply 11 for normal operation and an auxiliary power supply 12 for standby operation are connected to a reset unit 13 in parallel,
When the main power supply 111 is off,
A current of several μA flows from the auxiliary power supply 121 to the resistor 131. On the other hand, during normal operation, the auxiliary reset unit 14 connected to the main power supply unit 11 and supplied with power is connected to the reset unit 13, and the resistance 141 of the auxiliary reset unit 14 is several kΩ. Flows. As described above, when the reset occurs during the normal operation, the current flows from the main power supply 111 to the auxiliary reset unit 14 and the amount of the flowing current increases, so that the reset circuit is stable against external noise.

[0007]

As described above, according to the present invention, it is possible to increase the current due to the occurrence of reset during normal operation, and there is an effect that malfunction does not occur with a small current generated by external noise or the like.

[Brief description of the drawings]

FIG. 1 is a circuit diagram showing an embodiment of the present invention.

FIG. 2 is a circuit diagram showing a conventional example.

FIG. 3 is a circuit diagram showing another example of the related art.

[Explanation of symbols]

11 main power supply, 111 main power, 112, 113 diode, 12 auxiliary power, 121 auxiliary power, 122
Diode, 13 reset unit, 131 resistor, 13
2 capacitor, 14 auxiliary reset part, 141 resistor

Claims (1)

[Claims] 1. A main power supply unit for normal operation, an auxiliary power supply unit for standby operation, a reset unit supplied with power from both the main power supply unit and the auxiliary power supply unit, and only the main power supply unit Reset circuit consisting of an auxiliary reset unit supplied with power from the unit.