JPS648527B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to improvements in input circuits for electronic control devices employed in vehicles such as automobiles, industrial vehicles, and mobile agricultural machinery.

Conventionally, as shown in FIG. 1, this type of input circuit includes, for example, a resistor 31 that connects a microcomputer 20 to a detection switch 10 in a vehicle electronic control device, and a complementary metal oxide semiconductor integrated circuit 32 (hereinafter referred to as CMOS circuit 32),
Microcomputer 20 and CMOS circuit 32
and a resistor 34 that connects the detection switch 10 to the stabilized power supply circuit 33.
There is a structure composed of

Therefore, in such a configuration, the microcomputer 20 and the CMOS circuit 32 receive a constant voltage (+5V) from the stabilized power supply circuit 33 that is supplied with power from the battery B when the operation switch SW is closed. When in operation, both resistors 3
The ignition noise of the vehicle's engine, the alternator, which tends to occur on the conductor connecting the CMOS circuit 32 to the stabilizing power supply circuit 33 through the resistor 31 and/or the conductor connecting the CMOS circuit 32 to the detection switch 10 through the resistor 31. By reducing pulsed high voltage noise such as the noise of The CMOS circuit 32 is designed to prevent the CMOS circuit 32 from causing a latch-up phenomenon and being destroyed even if the voltage is increased.

However, in such a configuration, if the number of detection switches 10 increases along with both resistors 31 and 34, the current consumption of the stabilized power supply circuit 33 increases even if the current consumption of each detection switch 10 is small. As a result, the power capacity of the stabilized power supply circuit 33 must be increased, resulting in an increase in size and cost. Furthermore, as each detection switch 10 opens and closes, the constant voltage from the stabilized power supply circuit 33 varies in accordance with the variation in current consumption, which prevents the microcomputer 20 and CMOS circuit 32 from operating properly.

In order to prevent this, for example, as shown in FIG. 2, the CMOS circuit 32 is connected to each detection switch 10 via each pair of transistor circuits 35 and 36, and the battery B is The CMOS circuit 3 is connected to each detection switch 10 via each transistor circuit 36.
While preventing the occurrence of the latch-up phenomenon described in 2, power is supplied to each detection switch 10 by relying on the battery B without depending on the stabilizing power supply circuit 33, thereby preventing voltage fluctuations in the stabilizing power supply circuit 33. There is something. However, in such a configuration, as the number of detection switches 10 increases, the number of logarithms of the transistor circuits 35 and 36 also increases, resulting in an increase in cost due to an increase in the number of components.

Furthermore, as shown in FIG. 3, it is also conceivable to directly connect the battery B to each resistor 34 via the operation switch SW in the input circuit shown in FIG. Since the power supply is performed by relying on the battery B without depending on the stabilized power supply circuit 33 in the same way as the input circuit in FIG. 2, voltage fluctuations in the stabilized power supply circuit 33 can be prevented. each pair of resistors 31,
The high-energy, high-voltage noise on the conductor connecting the CMOS circuit 32 to the battery B through the battery B becomes very high, causing the CMOS circuit 32 to latch up. Also, when each detection switch 10 is opened, the voltage applied from the battery B to the CMOS circuit 32 via each resistor 31 is this voltage.
Since it is higher than the constant voltage from the stabilized power supply circuit 33 that is applied to the CMOS circuit 32, the CMOS
This causes a latch-up phenomenon in the circuit 32 and performance deterioration of each component of the CMOS circuit 32.

The present invention has been made in response to the above-mentioned problems, and its purpose is to provide an input circuit that is applied to a microcomputer and a plurality of detectors of a vehicle electronic control device at low cost and with a small number of parts. The object of the present invention is to make it possible to always and reliably prevent the occurrence of latch-up phenomenon in a CMOS circuit without causing fluctuations in the constant voltage of the stabilized power supply circuit.

To achieve such an object, the present invention has a structural feature that provides a vehicle electronic control device including a microcomputer and at least first and second detectors, including a CMOS circuit connected to the microcomputer; , when a DC voltage is applied from a DC power source, the microcomputer and
Each allowable power supply voltage of the CMOS circuit is generated as the first constant voltage, and the corresponding microcomputer and CMOS
a first stabilized power supply circuit applied to each power supply terminal of the circuit; and a second stabilized power supply that generates a second constant voltage lower than the DC voltage and higher than the first constant voltage when DC voltage is applied from the DC power supply. a circuit, the second regulated power supply circuit, the first detector and the second stabilized power supply circuit;
The first connecting conductor is interposed in a first connecting conductor connected between the first signal input terminals of the CMOS circuit to allow current to be applied from the second stabilized power supply circuit to the first detector. The first constant voltage of the CMOS circuit is divided by dividing the second constant voltage to a voltage lower than the first constant voltage while reducing high voltage noise on the CMOS circuit.
a first resistance circuit provided to the input terminal, the second stabilized power supply circuit, the second detector, and the CMOS
Interposed in a second connecting conductor connected between second signal input terminals of the circuit to allow current to be applied from the second stabilized power supply circuit to the second detector, and to allow the second connecting conductor to and a second resistor circuit that divides the second constant voltage to a voltage lower than the first constant voltage and applies it to the second input terminal of the CMOS circuit while reducing high voltage noise.

Therefore, by configuring the present invention in this way, the second stabilized power supply circuit is configured to reduce the amount of high energy that rides on the connecting conductor with the DC power supply when converting the DC voltage to the second constant voltage. reducing voltage noise, and the first and second resistor circuits
reduce low energy high voltage noise on said first and second connecting conductors, respectively, and reduce said
Since the voltage applied to the first and second input terminals of the CMOS circuit is lowered to below the first constant voltage applied to the power supply terminal of the CMOS circuit, the
Occurrence of latch-up phenomenon in CMOS circuits and
Performance deterioration of CMOS circuit elements can be reliably prevented. In such a case, since the CMOS circuit receives the first constant voltage from the first stabilized power supply circuit that is different from the second stabilized power supply circuit that is the power supply source to each of the detectors, Even if a fluctuation occurs in the outflow current from the second stabilized power supply due to the operation of the detector, the first constant voltage from the first stabilized power supply circuit does not fluctuate.
CMOS can always perform the level conversion function of its input signal under a stable constant voltage. Furthermore, in the present invention, the second stabilized power supply circuit and each resistance circuit can be constructed relatively easily, so this type of input circuit becomes inexpensive.

Hereinafter, one embodiment of the present invention will be described with reference to the drawings. FIG. 4 shows a microcomputer 4 in which an input circuit according to the present invention constitutes a vehicle electronic control device.
An example in which the present invention is applied to zero and a plurality of detection switches s ₁ , s ₂ , . . . , s _o is shown. The input circuit includes a main stabilized power supply circuit 50, an auxiliary stabilized power supply circuit 60, and
The main stabilized power supply circuit 50 is connected at its input terminal to the positive terminal of the battery B via the ignition switch IG of the vehicle, and when the ignition switch IG is closed, the main stabilized power supply circuit 50 is It receives a DC voltage (+12V) from the battery B, generates a highly stable predetermined constant voltage from its output terminal, and applies it to each power supply terminal of the microcomputer 40 and the CMOS circuit 70. This means that the microcomputer 40 and the CMOS circuit 70 receive a constant voltage from the main stabilized power supply circuit 50 at their respective power supply terminals and are put into operation. In this case, the constant voltage from the main stabilized power supply circuit 50 is set to +5V in consideration of each allowable power supply voltage of the microcomputer 40 and the CMOS circuit 70. Note that the CMOS circuit 70 is connected to the input terminal of the microcomputer 40 at its output terminal.

The auxiliary stabilizing power supply circuit 60 has a power transistor 61.
1 is the ignition switch on the collector.
It is connected to the positive side terminal of battery B via IG, and grounded via a Zener diode 62 at its base. The Zener diode 62 has a Zener voltage V _z (+5V to +12V), and its cathode connected to the base of the power transistor 61 is connected to the collector of the power transistor 61 via a resistor 63 . Therefore, the Zener diode 62 is connected to the ignition switch IG.
When the power transistor 61 is closed, a DC voltage is received from the battery B through the resistor 63 to generate a Zener voltage _Vz , making the power transistor 61 conductive. This means that the power transistor 61 generates the Zener voltage V _z as a constant voltage from its emitter (that is, the output terminal of the stabilized power supply circuit 60) due to its conduction. In such a case, the battery B and the stabilized power supply circuit 6
The high-voltage noise with high energy from the battery B on the connection conductor with the power transistor 61, the Zener diode 62, and the resistor 63 is reduced by the cooperative action of the power transistor 61, the Zener diode 62, and the resistor 63. Both capacitors 64,6
5, when the ignition switch IG is closed,
Together, they form a closed circuit with battery B, and absorb high frequency noise riding on the connecting conductor of this closed circuit.

The resistor _a1 is connected at one end to the output terminal of the stabilized power supply circuit 60, and at the other end is grounded via the detection switch _{s1 .}
When the detection switch S1 is closed, the current flowing into this detection switch _S1 from the stabilized power supply circuit 60 is limited to a permissible value or less based on its constant voltage, and the resistor _A2 is connected to the output terminal of the stabilized power supply circuit 60 at one end. It is connected and grounded at the other end via the detection switch _s2 , and when the detection switch _s2 is closed, the current flowing into the detection switch _s2 from the stabilized power supply circuit 60 based on its constant voltage is set to a permissible value. Limit to..., and the resistance a _o is
One end thereof is connected to the output terminal of the stabilized power supply circuit 60, and the other end is connected to the detection switch _SO
When the detection switch _SO is closed, the current flowing into the detection switch _SO from the stabilized power supply circuit 60 based on its constant voltage is limited to a permissible value or less.

The resistor b ₁ has one end connected to the common connection terminal of the resistor a ₁ and the detection switch s ₁ and the other end connected to the first input terminal of the CMOS circuit 70 to connect the detection switch s ₁ . and the first of the CMOS circuit 70
The resistor b 2 reduces the current flowing into the CMOS circuit 70 due to pulsed high voltage noise such as engine ignition noise and alternator noise of both vehicles on the connecting conductor between the input terminal and the resistor b ₂ at one end. ,
It is connected to the common connection end of the resistor a ₂ and the detection switch s ₂ , and the other end is connected to the second input terminal of the CMOS circuit 70, so that the detection switch s ₂ and
The CMOS circuit 7 due to the high voltage noise riding on the connecting conductor between the second input terminal of the CMOS circuit 70
0, and the resistance b _o is
At one end, it is connected to the common connection end of the resistor a _o and the detection switch _so , and at the other end,
connected to the nth input terminal of the CMOS circuit 70;
Due to the high voltage noise riding on the connecting conductor between the detection switch _SO and the n-th input terminal of the CMOS circuit 70.
The current flowing into the CMOS circuit 70 is reduced.

The resistor c ₁ is grounded at one end and connected at the other end to the connection end of the resistor b ₁ to the first input terminal of the CMOS circuit 70 , and is connected to the stabilized power supply circuit 60 .
The constant voltage from _C2 is divided by cooperation with resistor b1 and this divided voltage is applied to the first input terminal of CMOS circuit 70, resistor _c2 is grounded at one end and connected to resistor b at the other end. The stabilized power supply circuit 6 is connected to the connection terminal with the _second input terminal of the CMOS circuit 70 of
A constant voltage from 0 is divided by the cooperation of resistor _b2 , and this divided voltage is applied to the second input terminal of the CMOS circuit 70, and the resistor _c0 is grounded at one end and grounded at the other end. CMOS circuit 70 with resistance b _o at
is connected to the connection end with the n-th input terminal of the CMOS circuit 70, divides the constant voltage from the stabilized power supply circuit 60 in cooperation with the resistor b _o , and applies this divided voltage to the n-th input terminal of the CMOS circuit 70.
Assigned to the input terminal. In such a case, the divided voltages applied to the first, second, ..., n-th input terminals of the CMOS circuit 70 are the same as those of the respective detection switches s ₁ , ...,
The input voltage (e.g., 4 V) or higher that allows the input of the CMOS circuit 70 to be determined to be at a high level is lower than the power supply voltage (5 V) of the CMOS circuit 70 when the _s
The resistance values of each resistor c ₁ , ..., c _o are set so that the CMOS circuit 70 has a value that does not cause a latch-up phenomenon and that allows the input to be determined as a _{high level} .
..., _ao and the resistance values of the respective resistors b ₁ , b ₂ , ..., b _o, respectively.

In this embodiment configured as above, when the vehicle is placed in a running state by closing the ignition switch IG, the ignition system and other various systems of the vehicle are activated, and the main stabilizing power supply circuit 5 is activated.
0 generates a constant voltage and applies it to each power supply terminal of the microcomputer 40 and the CMOS circuit 70 to put them in an operating state, and the auxiliary stabilizing power supply circuit 60 generates a constant voltage and applies it to each power terminal of the microcomputer 40 and the CMOS circuit 70, and the auxiliary stabilizing power supply circuit 60 generates a constant voltage and applies it to each power terminal of the microcomputer ₄₀ and the _{CMOS circuit 70} . ..., _ao respectively through each detection switch s ₁ , s ₂ , ..., s _o and each resistor
Assigned to b ₁ , b ₂ , …, bo _o . Then, the constant voltage from the auxiliary stabilizing power supply circuit 60 is applied to each pair of resistors b ₁ ,
CMOS voltage is divided by c _{1 ;} b ₂ , _{c 2} ;…;
It is applied to the first, second, . . . , nth input terminals of the circuit 70. In such a case, the first of the CMOS circuits 70,
Since the divided voltages applied to the second, ..., n-th input terminals are not higher than the constant voltage from the main stabilized power supply circuit 50 applied to the power supply terminal of the CMOS circuit 70, the CMOS circuit 70 No latch-up phenomenon occurs due to piezoelectric voltage.

Furthermore, even if high voltage noise with high energy from the battery B is placed on the connecting conductor between the battery B and the auxiliary stabilizing power supply circuit 60, this high voltage noise is transmitted to the power transistor 61 of the auxiliary stabilizing power supply circuit 60, Zener diode 62 and resistor 63
The thus reduced high voltage noise is reduced by the cooperative action of the auxiliary stabilizing power supply circuit 60.
Even if a constant voltage is applied to each resistor b ₁ , b ₂ , ..., b _o of the CMOS circuit 70, the first, second, ...,
The voltage applied to the n-th input terminal is applied to each resistor b ₁ , b ₂ ,
Due to the action of ..., b _o , the constant voltage applied to the power supply terminal of the CMOS circuit 70 will never be higher than the constant voltage, and as a result, the CMOS circuit 70 will not be affected by high voltage noise from battery B and will not cause a latch-up phenomenon. . In addition, each detection switch s ₁ , s ₂ ,..., s _o
Even if the above-mentioned high-voltage noises having low energy are applied to the connecting conductors that connect to the first, _second , . b ₂ ,…, b _o
Therefore, the CMOS circuit 70 does not cause a latch-up phenomenon. Such things include high voltage noise with low energy, suppressed high voltage noise with high energy, and each resistance
The same holds true even if the divided voltages of c ₁ , c ₂ , . . . , or c _o are superimposed together. In addition, each detection switch s ₁ , s ₂ ,
..., even if large fluctuations occur in the outflow current from the _stabilized power supply circuit 60 due to the opening and closing operations of the microcomputer 40 and the CMOS circuit 70,
Since power is supplied from the main stabilized power supply circuit 50 that is separate from the auxiliary stabilized power supply circuit 60, the constant voltage from the main stabilized power supply circuit 50 will not fluctuate due to insufficient capacity, and the microcomputer 40 and
A proper input signal level conversion operating state of the CMOS circuit 70 can be maintained at all times. Note that even if high-frequency noise is applied to the connecting conductor between battery B and the auxiliary stabilizing power supply circuit 60, the capacitors 64 and 65 absorb the high-frequency noise, so that the CMOS circuit 70
This will not cause the latch-up phenomenon.

Further, in implementing the present invention, for example, each resistor c ₁ , c ₂ , ..., c _o is grounded at one end thereof, and each pair of resistors a ₁ , b ₁ is connected at each other end. ;a ₂ ,
Even if it is connected to the common connection end of b ₂ ;...; a _o and b _o , the same effect as in the embodiment described above can be achieved.

[Brief explanation of drawings]

1 to 3 are block diagrams of a conventional input circuit employed in a vehicle electronic control device, and FIG. 4 is a block diagram showing an input circuit according to the present invention. Explanation of symbols, 40...Microcomputer,
50...Main stabilized power supply circuit, 60...Auxiliary stabilized power supply circuit, 70...CMOS circuit, B...Battery, _a1 ~ _ao , _b1 ~ _bo , _c1 ~ _co ...resistance, s ₁ ~ _{s o} …
...detection switch.

Claims (1)

[Claims] 1. A vehicle electronic control device comprising a microcomputer and at least first and second detectors, which is connected to the microcomputer.
CMOS circuit, and when DC voltage is applied from a DC power supply, the microcomputer and CMOS
A first stabilized power supply circuit that generates each allowable power supply voltage of the circuit as a first constant voltage and applies it to each power supply terminal of the microcomputer and CMOS circuit; A second stabilized power supply circuit that generates a second constant voltage that is lower and higher than the first constant voltage, and a second stabilized power supply circuit that is connected between the second stabilized power supply circuit, the first detector, and a first signal input terminal of the CMOS circuit. The second stabilizing power supply circuit is interposed in the first connecting conductor to allow current to be applied from the second stabilized power supply circuit to the first detector, and reduces high voltage noise on the first connecting conductor. a first resistor circuit that divides a voltage into a voltage lower than the first constant voltage and applies it to a first input terminal of the CMOS circuit, the second stabilized power supply circuit, the second detector, and the first resistor circuit of the CMOS circuit; 2
The second connecting conductor is interposed in a second connecting conductor connected between the signal input terminals to allow current to be applied from the second stabilized power supply circuit to the second detector.
and a second resistor circuit that divides the second constant voltage to a voltage lower than the first constant voltage and applies it to the second input terminal of the CMOS circuit while reducing high voltage noise on the connecting conductor. An input circuit for a featured vehicle electronic control device.