JP3223647B2 - Semiconductor integrated circuit device - Google Patents

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. Related to the device.

[0002]

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

That is, an engine control IC 1 for performing an operation for controlling the engine according to various external signals.
Has an input circuit section 4 in which a CPU 2 and an A / D conversion circuit 3 are formed, and an external signal to the CPU 2 is received. The power input terminals Va and Vb are supplied with a voltage of, for example, 5 V from an 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 the terminal b. The DC power supply circuit 5 converts, for example, a voltage supplied from a 12V vehicle-mounted battery 7 to 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 on the IC 1 into a digital signal based on a power supply voltage, and
PU2. CPU2 is A / D
According to an input signal provided from the conversion circuit 3, an operation of engine control is executed and a control signal is output to an output terminal 9.

[0005] The input circuit section 4 includes a plurality of input circuits 1.
0, each of which is connected to a corresponding switch input terminal 11. Switch input terminal 1
1 is connected to a power supply terminal VD to which the positive terminal of the vehicle-mounted battery 7 is connected via a switch circuit 14 including a current limiting resistor 12 and a switch 13.
3 is supplied with an external signal when turned on.

In each input circuit 10, protective diodes 15, 16 having the polarity shown in the figure are connected between the switch input terminal 11 and the power supply lines 6a, 6b, and when an overvoltage is applied to the switch input terminal 11, Power line 6
A current is caused to flow to the a and 6b sides so that an overvoltage is not applied to the input circuit 10. The input circuit 10 determines the level of an input external signal and supplies the digital signal to the CPU 2 as a digital signal of a predetermined voltage. And CP
U2 is configured to execute an engine control operation in response to a given external signal and output a control signal to an output terminal 9.

According to the above configuration, when the switch 13 of the switch circuit 14 is turned on, an external signal input through the current limiting resistor 12 is transmitted 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 supply line 6a
A current is supplied to the input circuit 10 so that an overvoltage is not applied to the input circuit 10 and an input is made as an external signal having a voltage level within a predetermined range.

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

[0009]

By the way, recently,
In the case of performing engine control, there is a tendency that a large number of external information is input as an external signal by a switch input or the like and arithmetic processing is performed according to the external information. With the conventional configuration, the following problems occur.

That is, in the above-described device, the output voltage of the power supply circuit 5 is 5 V, whereas the switch signal input terminal 11 is connected to the voltage 12 V of the vehicle-mounted battery 7 via the switch circuit 14. As described above, current flows into the power supply line 6a via the protection diode 15. The current flowing into the power supply line 6a is
Although there is no problem when the number is small, a large number of switch circuits 14
Is turned on and simultaneously flows into the power supply line 6a via 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,
A malfunction may occur due to a malfunction of U2 or a change in reference voltage of the A / D conversion circuit 3 to digital data.

In order to solve the above-mentioned problem, a configuration as shown in FIG. 3 can be considered. That is, the engine control IC 17 is replaced with the power supply line 6a instead of the power line 6a.
The power supply lines 6c and 6d are provided, and are connected so that power is supplied from the DC power supply circuit 5 as power supply terminals Vc and Vd, respectively. The power supply line 6c supplies power to the input circuit unit 4, and the power supply line 6d supplies power to the CPU 2 and the A / D conversion circuit 3.
This prevents an adverse effect of a voltage drop when a current flows from the protection diode 15 from affecting the CPU 2 and the A / D conversion circuit 3.

However, in order to provide the two power supply lines 6c and 6d in the IC 1, the width dimension for the wiring is required to be twice or more. A problem that the chip size becomes large occurs. Also, in order to take such wiring space, the design of the actual chip as a whole may need to be significantly changed.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and has as its object the purpose of receiving a large number of external input signals without increasing the size of a chip. An object of the present invention is to provide a semiconductor integrated circuit device capable of performing accurate signal processing by reducing fluctuations in a power supply voltage.

[0015]

According to the present invention, a plurality of external signals are input via corresponding input circuit sections, and arithmetic processing according to the external signals is executed by the arithmetic processing circuit section. A semiconductor integrated circuit device, comprising a first and a second power supply line provided with a power supply voltage of a certain level and provided to supply power to the arithmetic processing circuit unit; And a first and second auxiliary power supply line extending from the power supply line and provided to supply power to the input circuit unit. A plurality of external signal input terminals provided so as to be provided to the input circuit section, and a 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 supply line and the auxiliary power supply line.

[0016]

According to the semiconductor integrated circuit device of the present invention, when a plurality of external signals are input, the levels of the external signals are different from the power supply voltage, so that the input circuit is connected via the protection diode in the input circuit section. When the 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 a resistor connected in parallel to the input circuit section. Almost no component flows into the first power supply line through the auxiliary power supply line. As a result, a voltage drop due to an increase in the current flowing through the auxiliary power supply line is reduced, and it is possible to suppress as much as possible the voltage fluctuation from adversely affecting the power supply line side. Therefore, even in a configuration in which a large number of external signals can be input, voltage fluctuations in the first power supply line that supplies power to the arithmetic processing circuit portion are suppressed, so that malfunction can be prevented. Become like
Further, since it is not necessary to make the first and second power supply lines wider than necessary and to set the resistance low, it is not necessary to increase the size of the circuit.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment in which the present invention is 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 engine control IC 21 as a semiconductor integrated circuit device has a CPU as an arithmetic processing circuit unit therein.
22 and an A / D conversion circuit 23, and an input circuit section 24 for receiving an external signal and inputting it to the CPU 22.

The power supply input terminals VA and VB are 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 are connected to power supply input terminals VA, V
B supplies power to the CPU 22 and the A / D conversion circuit 23. The first and second auxiliary power supply lines 27a and 27b formed to be connected to the tips of the first and second power supply lines 26a and 26b are provided to supply power to the input circuit unit 24. The DC power supply circuit 25 converts, for example, a voltage supplied from a 12 V vehicle-mounted battery 28 to 5 V and outputs the converted voltage.

The A / D conversion circuit 23 converts an analog signal input from a plurality of analog signal input terminals 29 provided on the IC 21 into a digital signal with reference to a power supply voltage, and supplies the digital signal to the CPU 22. It has become. The CPU 22 outputs a control signal to an output terminal 30 by executing an engine control operation in accordance with an input signal supplied from the A / D conversion circuit 23.

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

In each comparison circuit path 31, between the switch input terminal 31 and the first and second auxiliary power supply lines 27a and 27b, protection diodes 36 and 37 having the illustrated polarities are connected, respectively. When an overvoltage is applied to the input terminal 32, a current flows to the first and second power supply lines 27a and 27b so that the overvoltage is not applied to the comparison circuit 31. The comparison circuit 31 compares the level of an external signal input to one input terminal with a reference voltage applied to the other input terminal, and compares the comparison result as a digital signal of a predetermined voltage with the CPU.
22. And the CPU 22
Performs an engine control operation according to a given external signal and outputs a control signal to an output terminal 30.

The first and second power supply lines 27a
A resistor 38 set at a predetermined resistance value is provided between and 27b. The resistor 38 is set to a resistance value such that a current of about several tens of milliamps flows, for example. The current supplied to the CPU 22 and the A / D conversion circuit 23 is about several tens of milliamps. Also, the first input from the switch input terminal 31 via the protection diode 36.
Of the current flowing into the side of the auxiliary power supply line 27a is on 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 through the current limiting resistor 33 is input from the switch input terminal 32 of the IC 21, and the voltage of the external signal becomes a predetermined voltage. At this time, the first auxiliary power supply line 2 is connected via the protection diode 36.
A current is caused to flow to the side 7a so that an overvoltage is not applied to the comparison circuit 31 and 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 a result of comparison with a reference voltage to the CPU 22 as a digital signal of a predetermined level according to an external signal. On the other hand, for an analog signal input from the analog signal input terminal 29, a digital signal converted by the A / D conversion circuit 23 is input to the CPU 22. The CPU 22
In accordance with these signals, an engine control operation is executed in accordance with a program stored in advance, and an output terminal 3
Control signals for various loads connected to 0 are output.

When, for example, 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 terminal 32 to the first auxiliary power supply line 27a via the protection diode 36. However, most of the current flows at this time in such a manner as to be absorbed by the resistor 38, so that components flowing into the first and second power supply lines 26a and 26b are 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.

[0026] Thus, Ki de is possible to prevent the current from flowing from the input circuit unit 24 side to the first power supply line 26a, is possible as much as possible to prevent the occurrence of malfunction due to the current flowing from the switch input terminal 32 become able to.

In this case, for example, the switch input terminal 32
Even when there is no external signal input from the
The provision of 8 increases the level of current consumption as a whole. 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 milliamps, a power supply voltage of 5 V is applied. Therefore, the consumed power P (watt) is P (W) = 40 (mA) × 5. (V) = 200 (mW). On the other hand, the overall thermal resistance of the IC 21 is usually several tens of degrees Celsius.
/ W, so if it is 40 ° C / W,
The temperature rise ΔT (° C.) due to the power consumption of the resistor 38 is ΔT (° C.) = 40 (° C./W)×200 (mW) = 8 (° C.).

In a normal IC, the temperature rises by about 10 ° C., and in the engine control IC 21 in this embodiment, the temperature rise is further increased by about 8 ° C. by the resistor 38, so that the overall temperature is 18 ° C., ie, about 20 ° C. The temperature rises by about ℃.

By the way, in the operating environment of the engine control IC 21 provided in such an automobile, the maximum ambient temperature may be about 80 to 100 ° C., and the temperature rise to this maximum temperature of 100 ° C. Add 20 ° C to get 120
About ℃. Generally, the maximum allowable temperature of IC is 1
Since the temperature is set to about 50 ° C., there is still a margin of about 30 ° C. in operation, so that there is substantially no problem.

According to this embodiment, 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 caused by an external signal flowing into the first auxiliary power supply line 27a from the switch input terminal 32 via the protection diode 36 of the input circuit unit 24. The first and second power supply lines 26 absorb the components by the resistor 38.
Since the voltage fluctuation between the power supply terminals a and 26b is suppressed, a large number of circuits can be provided without using a configuration in which two power supply lines are provided from the power supply input terminals Va and Vb, that is, without increasing the chip size. Even when an external input is received, malfunction of the CPU 22 and the A / D conversion circuit 23 can be prevented, and reliability can be improved.

In the above-described embodiment, the case where the present invention is applied to the IC 21 for engine control has been described. However, the present invention is not limited to this, but is applied to a general semiconductor integrated circuit device which receives a plurality of external inputs. Is what you can do.

[0033]

As described above, according to the semiconductor integrated circuit device of the present invention, the input circuit unit is connected to the second power supply line extending from the first power supply line for supplying power to the arithmetic processing circuit unit. Since the resistors are provided in parallel, when a plurality of external signals are input, the level of the external signals is different from the power supply voltage and the second level is supplied via the protection diode.
When the current flows into the power supply line, the current at that time can flow through the resistor, so that the component flowing in the first power supply line can be reduced as much as possible, and the voltage fluctuation can be suppressed. Therefore, even in a configuration in which a large number of external signals can be input, voltage fluctuations in the first power supply line that supplies power to the arithmetic processing circuit portion are suppressed, so that malfunction can be prevented. In this case as well, the first power supply line is wider than necessary and the resistance does not need to be set low. Therefore, an excellent effect that the circuit configuration does not increase in size does not occur. To play.

[Brief description of the drawings]

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

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

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

[Description of References] 21 is an IC (semiconductor integrated circuit device) for engine control,
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 first and second power supply lines, 27a and 27b
Denotes first and second auxiliary power lines, 28 denotes a vehicle-mounted battery, 29 denotes an analog signal input terminal, 30 denotes an output terminal,
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 1-1-1, Showa-cho, Kariya-shi, Aichi Japan Inside Denso Co., Ltd. (56) References JP-A-4-261332 (JP, A) Japanese Utility Model Application 63-24627 , U) (58) Fields investigated (Int. Cl. ⁷ , DB name) H02J 1/00 F02D 45/00

Claims (1)

(57) [Claims] 1. A semiconductor integrated circuit device according to claim 1, wherein a plurality of external signals are input via corresponding input circuit sections, and arithmetic processing according to the external signals is executed by the arithmetic processing circuit section. And a first and second power supply line provided to supply power to the arithmetic processing circuit unit, and extend from the first and second power supply lines to supply power to the input circuit unit. And a plurality of external signals provided so as to supply external signals of a level different from the power supply voltage to the corresponding input circuit sections when the external signals are supplied. 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; The semiconductor integrated circuit device being characterized in that comprising a resistor connected body between the auxiliary power supply line.