JPH0731055A - Semiconductor integrated circuit device - Google Patents

Abstract

PURPOSE:To prevent erroneous function by stabilizing the supply voltage to a CPU or an A/D converting circuit without increasing the chip size even when a large number of external signals are accepted. CONSTITUTION:In an engine control IC 21, a CPU 22 and an A/D converting circuit 23 are fed with power from power supply lines 26a, 26b whereas an input circuit section 24 is fed with power from auxiliary power supply lines 27a, 27b extending from the power supply lines 26a, 26b. A resistor 38 is connected between the auxiliary power supply lines 27a, 27b. Each comparator circuit 31 at the input circuit section 24 passes an overvoltage external signal, applied by a protective diode 36, to the auxiliary power supply line 27a side in the form of current. Consequently, even if a large number of external signals are inputted simultaneously, the current can be bypassed to the resistor 38 and the voltage fluctuation can be suppressed between the power supply lines 26a, 26b.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor integrated circuit in which a plurality of external signals are input through corresponding input circuit sections and arithmetic processing according to the external signals is executed by the arithmetic processing circuit section. Regarding the device.

[0002]

2. Description of the Related Art In recent years, a control device for controlling an engine of an automobile has begun to be used in which a CPU, an A / D conversion circuit and the like are integrally formed on a one-chip IC. For example, FIG. There is something like the one shown.

That is, an engine control IC 1 for performing arithmetic operations for engine control according to various external signals.
Includes a CPU 2 and an A / D conversion circuit 3 therein, and an input circuit section 4 for receiving an external signal to the CPU 2. The power input terminals Va and Vb are supplied with a voltage of, for example, 5V from the external DC power supply circuit 5, and the power supply lines 6a and 6 wired in the IC1.
Power is supplied to the CPU 2, the A / D conversion circuit 3, and the input circuit unit 4 via b. The DC power supply circuit 5 converts a voltage supplied from the 12V in-vehicle battery 7 into 5V and outputs the converted voltage.

The A / D conversion circuit 3 converts an analog signal input from a plurality of analog signal input terminals 8 provided in the IC 1 into a digital signal with the power supply voltage as a reference, and C
It is designed to be given to PU2. CPU2 is A / D
The engine control calculation is executed according to the input signal supplied from the conversion circuit 3 and the control signal is output to the output terminal 9.

Further, the input circuit section 4 includes a plurality of input circuits 1.
0, each input terminal of which is connected to a corresponding switch input terminal 11. Switch input terminal 1
1 is connected to the power supply terminal VD to which the positive terminal of the vehicle-mounted battery 7 is connected via the switch circuit 14 including the current limiting resistor 12 and the switch 13.
An external signal is supplied when 3 is turned on.

In each input circuit 10, protective diodes 15 and 16 of the illustrated polarities are connected between the switch input terminal 11 and the power supply lines 6a and 6b, and when an overvoltage is applied to the switch input terminal 11. Power line 6
A current is passed to the sides a and 6b to prevent an overvoltage from being applied to the input circuit 10. The input circuit 10 determines the level of an input external signal and supplies it to the CPU 2 as a digital signal of a predetermined voltage. And CP
U2 is configured to execute an engine control operation in accordance with a given external signal and output a control signal to the output terminal 9.

According to the above configuration, when the switch 13 of the switch circuit 14 is turned on, an external signal input via the current limiting resistor 12 is transferred to the switch input terminal 11 of the IC 1.
When the voltage of the external signal is equal to or higher than a predetermined voltage, the power source line 6a is supplied through the protection diode 15.
A current is passed to the side to prevent an overvoltage from being applied to the input circuit 10, and the input signal is input as an external signal having a voltage level within a predetermined range.

The input circuit 10 compares a predetermined threshold value in accordance with an external signal and inputs it to the CPU 2 as a digital signal. On the other hand, for the analog signal input from the analog signal input terminal 8, the digital signal converted by the A / D conversion circuit 3 is input to the CPU 2.
The CPU 2 executes engine control calculation according to these signals in accordance with a prestored program, and outputs control signals for various loads connected to the output terminal 9.

[0009]

By the way, recently,
There is a tendency to input a large amount of external information as an external signal when performing engine control as a switch input or the like, and to perform arithmetic processing according to them, but if such an external signal increases to several tens or more, for example, as described above. With the conventional configuration, the following problems occur.

That is, in the above-mentioned one, the output voltage of the power supply circuit 5 is 5V, whereas the switch signal input terminal 11 is connected to the voltage 12V of the vehicle battery 7 via the switch circuit 14. As described above, current flows into the power supply line 6a via the protective diode 15. The current flowing into this power supply line 6a is
If the number is small, there is no problem, but a large number of switch circuits 14
Is turned on and flows into the power supply line 6a at the same time through each protection diode 15, the voltage drop due to the wiring resistance component of the power supply line 6a becomes a level that cannot be ignored.

Then, due to the voltage drop, the CPU 2 and the A / D conversion circuit 3 connected in the middle of the power supply line 6a.
The power supply voltage to the power supply will also fluctuate, and eventually CP
There may occur a case where the U2 malfunctions or the A / D conversion circuit 3 fluctuates the reference voltage to cause an erroneous conversion into digital data.

Therefore, in order to solve the above-mentioned inconvenience, a device as shown in FIG. 3 can be considered. That is, the IC 17 for controlling the engine is replaced by the IC 2 instead of the power supply line 6a.
The power supply lines 6c and 6d are provided, and the power supply terminals Vc and Vd are connected so that power is supplied from the DC power supply circuit 5. Then, the power supply line 6c is configured to supply power to the input circuit unit 4, and the power supply line 6d is configured to supply power to the CPU 2 and the A / D conversion circuit 3.
This prevents the CPU 2 and the A / D conversion circuit 3 from being adversely affected by the voltage drop when the current flows from the protection diode 15.

However, in order to provide the two power supply lines 6c and 6d in the IC 1 as described above, the width dimension for wiring the wires is required to be twice or more. The problem that the chip size becomes large occurs. In addition, in order to save the wiring space in this way, the actual design of the entire chip may have to be significantly changed.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a large number of external input signals without increasing the size of the chip even if the external input signals are used. It is another object of the present invention to provide a semiconductor integrated circuit device capable of performing accurate signal processing while preventing fluctuations in power supply voltage.

[0015]

According to the present invention, a plurality of external signals are input through the corresponding input circuit units, and the arithmetic processing circuit units execute arithmetic processing according to the external signals. The present invention is intended for a semiconductor integrated circuit device, and is provided with first and second power supply lines provided so as to supply a power supply voltage of a constant level and supply power to the arithmetic processing circuit section, and the first and second power supply lines. The first and second auxiliary power supply lines extending from the power supply line for supplying electric power to the input circuit section, and external signals of a level different from the power supply voltage are applied to the first and second auxiliary power supply lines, respectively. A plurality of external signal input terminals provided so as to be applied to the input circuit section, and protection connected between each of the plurality of external signal input terminals and the first and second auxiliary power supply lines A diode, the first and second
And a resistor connected between the auxiliary power source line and the auxiliary power source line.

[0016]

According to the semiconductor integrated circuit device of the present invention, when a plurality of external signals are input, the level of the external signals is different from the power supply voltage, and the input circuit section is protected by the protective diode. When a current flows into the first auxiliary power supply line as a current, the current component at that time flows to the second auxiliary power supply line side via the resistor connected in parallel to this input circuit unit. There is almost no component that flows into the first power supply line side via the auxiliary power supply line. As a result, the voltage drop caused by the increase in the current flowing through the auxiliary power supply line is reduced, and it is possible to suppress the adverse effect of the voltage fluctuation on the power supply line side as much as possible. Therefore, even when the configuration is such that a large number of external signals can be input, the voltage fluctuation of the first power supply line that supplies power to the arithmetic processing circuit unit is suppressed, so that malfunction can be prevented. Like
Further, since it is not necessary to make the first and second power supply lines wider than necessary to set the resistance low, it is possible to prevent the circuit from becoming large in size.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention applied to a semiconductor integrated circuit device for controlling an engine of an automobile will be described below with reference to FIG. In FIG. 1 showing the entire circuit configuration, an IC 21 for engine control as a semiconductor integrated circuit device has a CPU as an arithmetic processing circuit unit inside.
22 and an A / D conversion circuit 23 are formed, and an input circuit section 24 for receiving an external signal and inputting it to the CPU 22 is formed.

The power input terminals VA and VB are adapted to be supplied with a voltage of, for example, 5 V from an external DC power supply circuit 25. The first and second power supply lines 26a and 26b formed in the IC 21 have power supply input terminals VA and V.
Power is supplied from B to the CPU 22 and the A / D conversion circuit 23. Further, the first and second auxiliary power supply lines 27 a and 27 b formed by connecting to the tip end portions of the first and second power supply lines 26 a and 26 b are provided so as to supply power to the input circuit unit 24. The DC power supply circuit 25 converts the voltage supplied from the 12V in-vehicle battery 28 into 5V and outputs the voltage.

The A / D conversion circuit 23 converts an analog signal input from a plurality of analog signal input terminals 29 provided in the IC 21 into a digital signal with the power supply voltage as a reference, and supplies the digital signal to the CPU 22. It has become. The CPU 22 is configured to execute an engine control calculation according to an input signal given from the A / D conversion circuit 23 and output a control signal to the output terminal 30.

The input circuit section 24 is composed of a plurality of comparator circuits 31 driven by a constant current, each input terminal of which is connected to a corresponding switch input terminal 32.
The switch input terminal 32 as an external signal input terminal,
It is connected to the power supply terminal VD connected to the positive terminal of the vehicle-mounted battery 27 via the switch circuit 35 including the current limiting resistor 33 and the switch 34. When the switch 34 is turned on, the voltage signal at that time is used as an external signal. To be given.

In each comparison circuit 31, protection diodes 36 and 37 of the polarities shown are connected between the switch input terminal 31 and the first and second auxiliary power supply lines 27a and 27b, respectively. When an overvoltage is applied to the input terminal 32, a current is passed through the first and second power supply lines 27a and 27b to prevent the overvoltage from being applied to the comparison circuit 31. The comparator circuit 31 compares the level of the external signal input to one input terminal with the reference voltage applied to the other input terminal and outputs the comparison result as a digital signal of a predetermined voltage to the CPU.
Twenty-two. And the CPU 22
Outputs an control signal to the output terminal 30 by executing an engine control calculation according to a given external signal.

Further, the first and second power supply lines 27a
A resistor 38 whose resistance value is set to a predetermined value is provided between the first and the second terminals 27b and 27b. The resistor 38 is set to have a resistance value such that a current of about several tens of milliamperes flows. The current supplied to the CPU 22 and the A / D conversion circuit 23 is about several tens of milliamperes. In addition, the first input from the switch input terminal 31 via the protection diode 36.
The level of the current flowing into the auxiliary power supply line 27a side is of the order of milliamperes.

Next, the operation of this embodiment will be described.
According to the above configuration, when the switch 33 of the switch circuit 34 is turned on, an external signal input via the current limiting resistor 33 is input from the switch input terminal 32 of the IC 21, and the voltage of the external signal is a predetermined voltage. When the above is the case, the first auxiliary power supply line 2 is passed through the protection diode 36.
A current is supplied to the 7a side so that the overvoltage is not applied to the comparison circuit 31, and the comparison circuit 31 is input as an external signal having a voltage level within a predetermined range.

Each comparison circuit 31 of the input circuit section 24 inputs the comparison result with the reference voltage to the CPU 22 as a digital signal of a predetermined level according to an external signal. On the other hand, for the analog signal input from the analog signal input terminal 29, the digital signal converted by the A / D conversion circuit 23 is input to the CPU 22. CPU22,
According to these signals, engine control calculation is executed according to a pre-stored program, and the output terminal 3
It will output control signals for various loads connected to zero.

Then, for example, when the switches 34 of a large number of switch circuits 35 are turned on at the same time, a current flows from the corresponding switch input terminals 32 to the first auxiliary power supply line 27a via the protection diode 36. However, since the current at this time flows so that most of it is absorbed by the resistor 38, the component flowing into the first and second power supply lines 26a and 26b is greatly reduced, and the first The adverse effect of the voltage drop due to the resistance component of the auxiliary power supply line 27a does not reach the first power supply line 26a side.

As a result, it is possible to prevent a current from flowing into the first power supply line 26a from the input circuit section 24 side, and thus the CPU 22 or the A / D conversion circuit 23.
It becomes possible to suppress the voltage fluctuation of the path leading to the CPU 22 and the A / D conversion circuit 23 and the CPU 22 which is supplied with power by the first power supply line 26a. It is possible to prevent the occurrence of malfunction due to the current inflow from 32 as much as possible.

In this case, for example, the switch input terminal 32
Even if there is no external signal input from the resistor 3
By providing 8, the level of current consumption as a whole increases. Therefore, the effect of the heat generated by the consumed current in the resistor 38 on the whole will be estimated.

That is, assuming that the current consumption of the resistor 38 is 40 milliamperes, a power supply voltage of 5V is applied, and the consumed power P (watt) is P (W) = 40 (mA) × 5. (V) = 200 (mW). On the other hand, the total thermal resistance of IC21 is usually several tens of degrees Celsius.
/ W, so if it is 40 ° C / W,
The temperature increase ΔT (° C.) due to the power consumption of the resistor 38 is ΔT (° C.) = 40 (° C./W)×200(mW)=8(° C.).

In the normal IC, there is a temperature rise of about 10 ° C. In the engine control IC 21 of this embodiment, the resistor 38 further raises the temperature by about 8 ° C., so that the temperature is 18 ° C. or about 20 as a whole. The temperature rises by about ℃.

By the way, in the environment in which the IC 21 for engine control installed in such an automobile is used, it is sufficient to consider a maximum ambient temperature of about 80 to 100.degree. 120 when adding 20 ℃
It becomes about ℃. Generally, the maximum allowable temperature of IC is 1
Since it is set to about 50 ° C., there is still a margin of about 30 ° C. in operation, so that there is practically no problem.

According to the present embodiment as described above, the first and second power supply lines 26a and 26b are extended from the first and second power supply lines 26a and 26b.
A resistor 38 is provided between the second auxiliary power supply line 27a and the second auxiliary power supply line 27b, and a current due to an external signal flows from the switch input terminal 32 into the first auxiliary power supply line 27a through the protection diode 36 of the input circuit section 24. The component is absorbed by the resistor 38, and the first and second power supply lines 26
Since the voltage fluctuation between a and 26b is suppressed, a configuration in which two power supply lines from the power supply input terminals Va and Vb are not used, that is, a configuration in which the size of the chip is not increased, is used. Even when receiving an external input, it is possible to prevent the CPU 22 and the A / D conversion circuit 23 from malfunctioning, and it is possible to improve reliability.

In the above embodiment, the case where the present invention is applied to the IC 21 for engine control has been described, but the present invention is not limited to this, and is applied to all semiconductor integrated circuit devices that accept a plurality of external inputs. Is something that can be done.

[0033]

As described above, according to the semiconductor integrated circuit device of the present invention, the input circuit section is connected to the second power supply line extending from the first power supply line feeding the arithmetic processing circuit section. Since the resistors are provided in parallel, when a plurality of external signals are input, the levels of the external signals are different from the power supply voltage and the second diode is provided via the protection diode.
When the current flows into the power source line as a current, the current at that time can flow through the resistor, so that the component flowing in the first power source line can be reduced as much as possible and the voltage fluctuation can be suppressed. Therefore, even when the configuration is such that a large number of external signals can be input, the voltage fluctuation of the first power supply line that supplies power to the arithmetic processing circuit unit is suppressed, so that malfunction can be prevented. Even in this case, since it is not necessary to make the first power supply line wider than necessary and to set the resistance low, it is possible to prevent the circuit from becoming large in size. Play.

[Brief description of drawings]

FIG. 1 is an electrical configuration diagram showing an embodiment of the present invention.

FIG. 2 is a view corresponding to FIG. 1 showing a conventional example.

FIG. 3 is a view corresponding to FIG. 1 showing a different conventional example.

[Explanation of symbols]

Reference numeral 21 denotes an engine control IC (semiconductor integrated circuit device),
22 is a CPU (arithmetic processing circuit unit), 23 is an A / D conversion circuit, 24 is an input circuit unit, 25 is a DC power supply circuit, 26a,
26b is the first and second power supply lines, 27a and 27b
Is the first and second auxiliary power supply lines, 28 is a vehicle battery, 29 is an analog signal input terminal, 30 is an output terminal, 3
1 is a comparison circuit, 32 is a switch input terminal (external signal input terminal), 33 is a current limiting resistor, 34 is a switch, 35 is a switch circuit, 36 and 37 are protection diodes, and 38 is a resistor.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Tadashi Shibata 1-1, Showa-cho, Kariya city, Aichi Nihon Denso Co., Ltd.

Claims (1)

[Claims] 1. A semiconductor integrated circuit device in which a plurality of external signals are input via respective corresponding input circuit units and arithmetic processing corresponding to the external signals is executed by the arithmetic processing circuit unit First and second power supply lines provided so as to supply power to the arithmetic processing circuit section, and power is supplied to the input circuit section extending from the first and second power supply lines. And the plurality of external signals provided so that when an external signal having a level different from that of the power supply voltage is applied, the auxiliary power supply line is provided to the corresponding input circuit section. An input terminal; a protection diode connected between each of the plurality of external signal input terminals and the first and second auxiliary power supply lines; and the first and second protection diodes. The semiconductor integrated circuit device being characterized in that comprising a resistor connected body between the auxiliary power supply line.