JPH05143202A - Malfunction preventing device - Google Patents

Abstract

PURPOSE:To omit the consideration to be given to the sequence of power supplies of many systems and at the same time to prevent the malfunction in a system applying a microcomputer. CONSTITUTION:The 3-terminal regulators 2 and 3 convert the voltage V2 and V3 except the working voltage V1 of a microcomputer 4 into this voltage V1 among those different levels of voltage received from a system power supply 1. An OR circuit 5 secures an OR between the converted V1 and the V1 of the microcomputer 4 and supplies the OR voltage to the microcomputer 4. Then the same timing as the output voltage having the fastest rise of the power supply 1 is set for the rise of the V1 of the microcomputer 4. Meanwhile the same timing as the output voltage of the slowest rise is set for the V1 of the microcomputer 4. Thus, it is not required to take the rising/falling timing of the output voltage of the power supply 1 into consideration at every system. Furthermore the devices never work in the down state of the power supply 1.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is used in a microcomputer system, and when a device using a voltage different from the voltage used by the microcomputer is included, the malfunction of the system at the rise and fall of the used voltage can be prevented. The present invention relates to a malfunction prevention device.

[0002]

2. Description of the Related Art In recent years, microcomputers have been used in various systems, and devices in these systems require a voltage (for example, 15V, 30V) different from the operating voltage (normally 5V) of the microcomputer.

Therefore, the above-mentioned 5V (V
1), a power supply device for outputting a voltage of 15V (V2), 30V (V3), etc. is provided, but the rise and fall of the voltage (V1) of the microcomputer and other voltages (V2, V3) Since it is difficult to set the same timing to each other and the system malfunctions depending on the timing, it is necessary to form a power supply sequence so that the voltage of the microcomputer rises first as shown in the graph of FIG.

[0004]

However, since each device is different for each system, there is a problem that the power supply sequence must be set up in consideration of the rise timing of the power supply each time.

On the other hand, as shown in the graph of FIG. 3, for example, when the operating voltage (V1) of the microcomputer falls before the voltage (V2) of another device (circuit) drops, the port of the microcomputer is lowered. The output becomes unstable, and the system malfunctions such that other devices such as the motor continue to operate.

In this case, the monitoring function of the reset IC or the like must be used to detect a drop in the operating voltage (V1) of the microcomputer and reset the microcomputer to prevent the malfunction.

The present invention has been made in view of the above problems, and an object thereof is to provide a malfunction prevention device capable of preventing malfunction of the device without considering the power supply sequence.

[0008]

In order to achieve the above object, the malfunction prevention device of the present invention converts an output voltage from a power supply of a system other than a voltage used by a microcomputer into the same voltage used. And a logical sum circuit for logically adding the voltage converted by the three-terminal regulator and the operating voltage of the microcomputer and supplying the logical sum voltage to the microcomputer. The gist is that the rise of the working voltage is set to the same timing as the output voltage of the earliest rising of the power supply, and the fall of the working voltage is set to the same timing as the output voltage of the slowest falling.

[0009]

With the above configuration, the operating voltage of the microcomputer automatically rises at the earliest rising timing of the output voltage of the power supply when the power supply rises, and similarly when the power supply falls (power supply At the time of down), the operating voltage of the microcomputer falls at the latest falling timing of the output voltage of the power supply.

Therefore, the operating voltage of the microcomputer can be raised fastest without considering the power supply sequence according to the system.

Further, when the power supply is down, the voltage of other circuits (other devices) in the system is not down even though the operating voltage of the microcomputer is down. For example, if the port output of the same microcomputer becomes unstable,
The other circuits described above do not malfunction.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS. In FIG. 1, the malfunction prevention device of the present invention is a three-terminal regulator (voltage conversion means) that converts each of the output voltages (V1, V2, V3) of the power supply 1 into a voltage (V1). 2, 3 and the output voltage (V1) of the power source 1 and the three-terminal regulator 2,
The logical sum circuit 5 logically sums the voltage (V1) converted in 3 and supplies the logically summed voltage to the microcomputer 4.

The system provided with the malfunction prevention device includes a microcomputer 4 and other circuits (other devices) 6 and 7 controlled by the microcomputer 4, for example, a working voltage of the microcomputer 4. Is V
1 (5 V), the operating voltage of the other device 6 is V2 (for example, 1
5V), the operating voltage of the other device 7 is V3 (for example, 30V).
V).

In this case, the three-terminal regulator 2 converts the voltage V2 (15V) into a working voltage V1 (5V) of the microcomputer 4, and the three-terminal regulator 3 uses the voltage V3 (30V) of the microcomputer 4. The voltage will be converted to V1 (5V).

Here, when the power supply 1 of the system is turned on, the voltages V1, V2 and V3 are output. The voltages V2 and V3 are directly supplied to the other devices 6 and 7, and The voltage V1 is converted by the three-terminal regulators 2 and 3, and the converted voltage V1 and the output voltage V1 of the power supply 1 are respectively forward diodes 5 of the OR circuit 5.
It is supplied to the microcomputer 4 via a, 5b and 5c.

Therefore, when the output voltage V2 of the power source 1 rises earliest and earliest, the voltage V1 obtained by converting the output voltage V2 is supplied to the microcomputer 4 through the diode 5a.

Further, as shown in FIG.
At the time of FF (when the power supply 1 is down), the output voltage V1 (5V) of the normal power supply 1 is changed to another output voltage V2 (15V).
V) fall earlier than At this time, if the other circuit 6 is being driven by the control of the microcomputer 4, for example, the output of the microcomputer 4 becomes unstable, and in the conventional case, the output voltage V2 is reduced until the output voltage V2 decreases. The load continues to drive or malfunctions.

However, in the present invention, as already described, the voltage V converted by the three-terminal regulator 2 is used.
1 is supplied to the microcomputer 4 via the OR circuit 5, and the voltage V1 is supplied to the microcomputer 4 until the input voltage V2 of the three-terminal regulator 2 becomes equal to or lower than the minimum voltage a.

Therefore, even if the output voltage V1 of the power source 1 is quickly lowered, the microcomputer 4
Does not stop operating, that is, the power source V2 of the other circuit 5
The port output of the microcomputer 4 does not become unstable until is down.

As a result, the microcomputer 4 is
Also, since the voltage of the other circuit 6 is reduced at almost the same time, the other circuit 6 does not malfunction even when the power source is down.

When the voltage V3 of the output voltage of the power supply 1 is the slowest, the output voltage V3 is converted by the three-terminal regulator 3 to obtain the voltage V1 via the OR circuit 5. It is supplied to the microcomputer 4.

Therefore, similarly to the above, since the voltages of the microcomputer 4 and the other circuit 6 are lowered almost at the same time, the load of the other circuit 6 does not malfunction.

Further, since the malfunction prevention device is composed of the three-terminal regulators 2 and 3 and the OR circuit 5 of the diodes, it is inexpensive and can be simply constructed. In this case, as the diode, it is preferable to use a diode having excellent rising characteristics as much as possible.

Further, even if there are many types of output voltage of the power source 1, that is, even if the power source is a multi-system power source, the same operation,
The effect can be obtained.

As described above, among the multi-system power supplies (voltages) of the system, the voltage which rises first is converted into the working voltage of the microcomputer 4, the converted voltage V1 is supplied to the microcomputer 4, and the latest rises. Similarly, the reduced voltage is converted to the same use voltage and the converted voltage V1 is supplied to the microcomputer 4, so that it is not necessary to consider the power supply sequence for each system, and the output of the microcomputer is reduced when the power is down. Even if the circuit becomes unstable, the other circuits do not malfunction.

[0026]

As described above, according to the malfunction prevention apparatus of the present invention, in a system requiring a multi-system power supply (voltage), among the power supplies (voltages) other than the operating voltage V1 of the microcomputer. Voltage of each of the three is converted into a voltage V1 by a three-terminal regulator, and these converted voltages V
1 and the output voltage V1 from the power source are supplied to the microcomputer through the OR circuit, so that the voltage V1 supplied to the microcomputer is almost the same timing as the voltage that rises earliest among other voltages. It can be started up and can be started up at almost the same timing as the slowest falling voltage. For example, it is not necessary to assemble the power supply sequence considering the rising and falling of each voltage for each system, and for example, the system concerned. When the power supply of the device goes down, the port output of the microcomputer does not become unstable before the other voltage drops, and the malfunction of the system can be prevented, and the logical sum circuit of the three-terminal regulator and the diode is provided. It is cheap and easy.

[Brief description of drawings]

FIG. 1 is a schematic block diagram of a malfunction prevention device showing an embodiment of the present invention.

FIG. 2 is a schematic time chart diagram for explaining the operation of the malfunction prevention device shown in FIG.

FIG. 3 is a schematic time chart diagram for explaining rise and fall of a power supply of a conventional system.

[Explanation of reference numerals] 1 power supply 2,3 3 terminal regulator 4 microcomputer 5 OR circuit 5a, 5b, 5c diode 6,7 other circuit (other device)

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Internal reference number FI technical display location H02H 7/20 A 7335-5G

Claims (2)

[Claims] 1. The output voltage from the system power supply,
A voltage converting means for converting an output voltage other than the operating voltage of the microcomputer to the operating voltage, a logical sum of the voltage converted by the voltage converting means and the operating voltage of the microcomputer, and the logical sum of the logical sums. A logical sum means for supplying to the computer, the rise of the operating voltage of the microcomputer is set to the same timing as the output voltage of the earliest rising of the power supply, and the falling of the operating voltage is the same as the output voltage of the latest falling. Malfunction preventing device characterized by timing. 2. The voltage converting means is a three-terminal regulator, and the logical sum means is a diode. The voltage converted by the three-terminal regulator is logically summed with the voltage used by the microcomputer, and the logical sum is obtained. The malfunction prevention device according to claim 1, wherein the malfunction prevention device is supplied to the microcomputer.