JPH0795734A - Power supply circuit - Google Patents

Abstract

PURPOSE:To provide a power supply circuit which supplies electric power to an arithmetic element having at least a program calculating section and can automatically initialize the arithmetic element without giving any damage to a system. CONSTITUTION:A power supply circuit is provided with a switching means 13 which can switch the power supply to an arithmetic element 10 form a continuous power supply 12 to a ON/OFF power supply 11, abnormality detecting means 14 which detects an abnormal state and generates a warning signal upon detecting the abnormal state, and control means 15 which switches the power supply to the element 10 to the power supply side in accordance with the warning signal and restores the power supply to the power supply side before the power supply 11 is turned on next after the power supply 12 is turned off.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power supply circuit for supplying power to a computing element having a program computing section or a data storage section used for computing at least in part.

[0002]

2. Description of the Related Art In an arithmetic processing unit equipped with an arithmetic element having a program arithmetic section or a data storage section used for arithmetic operation at least in part, normally, if the power supply to the arithmetic element is turned off and then turned on again, the arithmetic operation is The element start-up program is automatically executed, and the terminal voltage of the arithmetic element, the input / output terminal of the AD converter attached to the arithmetic element, the storage contents of the RAM, etc. are uniformly initialized.

However, in some types of arithmetic processing devices, the operator is free to turn on the power supply to the arithmetic elements.
-The power supply circuit is configured so that it cannot be turned off. In a complex system with a built-in arithmetic processing unit, if the operator arbitrarily turns on and off the power supply to the arithmetic element while the system is operating, the system may malfunction and cause a danger, or It may not be possible to boot.

An example of an arithmetic processing device equipped with an arithmetic element having a program arithmetic part at least in part is an E of an automobile.
It is a CU (Electric Control Unit). For example, an ECU relating to engine control of an automobile controls the fuel injection amount and the supply timing every moment based on the outputs of a water temperature sensor, an oxygen sensor, an intake pressure sensor, a throttle opening sensor, etc. arranged in each part of the engine.

In an ECU for controlling an engine of an automobile, when some abnormality occurs in a computing element during driving,
The power supply to the arithmetic element cannot be immediately shut off. At least the minimum driving conditions must be maintained until the vehicle can be safely stopped and the danger can be evacuated.

Therefore, the E for controlling the engine of the automobile is used.
When some abnormality occurs, the CU switches the normal program to the fail-safe program or the normal control circuit to the fail-safe circuit instead of initializing the ECU to ensure the necessary operation function. ing.

FIG. 4 is an explanatory diagram of a conventional ECU power supply circuit. Here, an ECU for controlling the engine of the automobile
Is shown, and the arithmetic element is directly supplied with power from the battery.

In FIG. 4, an arithmetic element 40 is an element in which a digital arithmetic circuit and an AD converter 40A are formed together on the same chip. The AD converter 40A has a plurality of input channels, selects an input channel according to a command from the digital arithmetic circuit side, and outputs an analog voltage from a sensor or the like connected to the input channel, for example, a water temperature sensor 49A as a digital value. Convert to.

The digital arithmetic circuit of the arithmetic element 40 performs the necessary arithmetic operation using this digital value. The output of the arithmetic element 40 is output to various devices related to engine control via the output interface 48.

The power supplied from the battery 42 is supplied to the arithmetic element 40 after being made constant by the 5V regulator 47. The electric power supplied from the battery 42 is also supplied to the 5V regulator 46 of the ECU via the ignition switch 41 that can be operated by the driver at any time to turn it on and off.

The 5V regulator 46 supplies electric power to an ON / OFF system for engine control through an input / output interface 48 of the ECU. The electric power supplied from the battery 42 through the ignition switch 41 is also supplied to other electric equipment inside the vehicle other than the ECU.

The watchdog timer 44 includes an arithmetic element 4
A pulse output periodically sent from the arithmetic element 40 is received by the step inserted in the program executed at 0, and an alarm signal is output when the pulse output is interrupted. The alarm signal output by the watchdog timer 44 is
Only the programmed state is reset without shutting off the power of the arithmetic element 40.

[0013]

In the ECU power supply circuit of FIG. 4, when the arithmetic element 40 is constituted by arranging a plurality of digital arithmetic circuits etc. together on one chip, an abnormal phenomenon of the element called latch-up. Can happen.

Latch-up is caused by abnormal current flowing in the circuit on the IC chip when a lightning strike occurs on the vehicle body or when static electricity charged on the human body is applied, and circuit connection other than that designed occurs. Is a phenomenon in which the IC malfunctions. In addition, even after the lightning strike or static electricity disappears, the circuit connection other than the designed one may continue to maintain the state.
The only way to cancel this state is to turn off the IC power.

For example, the latch-up is the AD converter 4
When it occurs at 0A, the water temperature sensor 49A operates normally,
Even when the voltage corresponding to the normal temperature is output, abnormal AD conversion data is output from the AD converter 40A to the digital arithmetic circuit every time the channel of the water temperature sensor 49A is selected by the AD converter 40A. there is a possibility.

At this time, although the engine cooling water temperature is normal, a warning message indicating that the water temperature is abnormal is displayed, and the arithmetic element of the ECU arbitrarily shifts to the fail-safe program. For example, the driving speed of an automobile is suddenly suppressed to 30 km / hour or less.

In such a case, the driver cannot judge whether the water temperature sensor 49A is normal / abnormal by himself, and thus makes a mistaken judgment that the water temperature is actually abnormal or that the water temperature sensor 49A is functionally abnormal. It will be. As a result, the vehicle is brought to a service center or a repair shop to replace the normal water temperature sensor 49A.

When the battery is removed when the water temperature sensor 49A is replaced, the output state inside the arithmetic element 40 is initialized and abnormal AD conversion data is output from the AD converter 40A to the digital arithmetic circuit. Since it disappears, the problem is apparently solved by replacing the water temperature sensor 49A.

However, if such a latch-up state is not released and is left as it is, the arithmetic element 4
Overcurrent may continue to flow through some internal elements of 0 to cause element destruction, and even if the battery 42 is disconnected, the original normal state may not be restored, or serious system malfunction or danger may occur. Become.

It is an object of the present invention to provide a power supply circuit capable of automatically initializing an arithmetic element at proper timing without damaging the system.

[0021]

FIG. 1 is an explanatory view of the basic constitution of the present invention. In FIG. 1, the power supply circuit according to claim 1 is an ON-OFF power supply 11 capable of executing an ON-OFF operation by an operator at any time, and a constant power supply 12 capable of continuing power supply regardless of the ON-OFF operation. Has,
In a power supply circuit for supplying electric power to an arithmetic element 10 having at least a part of a program arithmetic section or a data storage section used for arithmetic, power is supplied to the arithmetic element 10 from the constant power supply 12 to the ON state.
-OFF switching means 13 capable of switching to only the power supply 11
An abnormality detecting means 14 for detecting an abnormal situation in the arithmetic element 10 to generate a warning signal, and the switching means 13 in response to the warning signal, and turning on the power supply in response to the warning signal. It is switched to the -OFF power supply 11 side, and at least the ON-OFF power supply 11 is turned on.
The control means 15 for returning the power supply to the constant power source 12 side between the FF operation and the next ON operation.
And, are provided.

A power supply circuit according to a second aspect is the power supply circuit according to the first aspect, wherein the control means restores the power supply to the constant power supply side when the ON-OFF power supply is turned ON next time. Means.

[0023]

In FIG. 1, in the power supply circuit according to claim 1, when an abnormality occurs in the arithmetic element 10 or a peripheral arithmetic circuit, at least as long as the system does not cause a dangerous or a serious malfunction, the program of the arithmetic element 10 is for the time being. Is operated from the beginning to carry out initialization of calculation.

Then, the operator turns ON-OF next time.
Utilizing the opportunity to turn off the F power supply 11, the computing element 1
The power of 0 is cut off, and the abnormality of the arithmetic element 10 and the peripheral arithmetic circuits is released.

Then, for example, after a lapse of a certain time after being turned off, the power supply state of the arithmetic element 10 is restored to the original state, and the arithmetic element 10 and the peripheral arithmetic circuits are automatically initialized to at least The root cause of the abnormality in the arithmetic element 10 up to that point is eliminated.

According to another aspect of the power supply circuit of the present invention, after the operator turns off the on-off power supply 11, the next time the operator turns on the on-off power supply 11, the power supply state of the arithmetic element is restored. Return to.

[0027]

FIG. 2 is an explanatory diagram of an ECU power supply circuit of the embodiment. In the figure, (a) shows the circuit configuration and (b) shows the details of the processing circuit. Here, the power supply to the arithmetic element is switched to the ignition switch side at the time when the abnormality is notified to the processing circuit, and the program processing in the arithmetic element is continued. Then, when the operator thereafter turns on the ignition switch again, initialization of the arithmetic element and the like is executed.

In FIG. 2A, in the power supply device of the embodiment, the arithmetic element 20 is an element in which a digital arithmetic circuit and an AD converter 20A are formed together on the same chip.
The AD converter 20A has an input channel, for example, a water temperature sensor 29A, in response to a command from the digital arithmetic circuit side.
Select to convert the analog voltage to a digital value.

The digital arithmetic circuit of the arithmetic element 20 performs the necessary arithmetic operation using this digital value. The output of the arithmetic element 20 is output to various devices related to engine control via the output interface 28.

The power supplied to the battery 22 is usually 5V.
It is supplied to the arithmetic element 20 after being made a constant voltage by the regulator 27. The power supplied from the battery 22 is also supplied to the 5V regulator 26 via the ignition switch 21.
Is supplied to. The 5V regulator 26 is turned on through the input / output interface 28 for engine control.
Supply power to the system that can be turned off.

The diode 23A is provided to eliminate the supply from the battery 22 to the 5V regulator 26 and to enable the supply from the IG switch 21 to the 5V regulator 27.

The watchdog timer 24A outputs an alarm signal when the pulse output periodically sent from the arithmetic element 20 is interrupted. The alarm signal output by the watchdog timer 24A resets the progress of the program of the arithmetic element 20.

The processing circuit 25 uses the watchdog timer 2
4A or another abnormality detection circuit, for example, when an abnormality is reported from a detector of overcurrent or abnormality output of each part of the ECU, a detector of overvoltage of the battery 22, or the like, the contact of the relay 23R is opened to open the 5V regulator. The power supply to 27 is switched from the battery 22 side to only the ignition switch 21 side.

At this time, the output of the battery 22 is 5 from the ignition switch 21 through the diode 23A.
The power supply is switched without reaching the V regulator 27 and causing a power failure in the arithmetic element 20.

The processing circuit 25 also first opens the ignition switch 21 after the contact of the relay 23R is opened.
When is turned on, the contact of the relay 23R is closed. As a result, the power supply to the arithmetic element 20 via the 5V regulator 27 starts to be directly supplied from the battery 22 again.

In FIG. 2 (b), the relay 23R has its contact closed at all times and opens the contact when a current is applied to the coil.
Then, the contact of the relay 23R opens when the transistor 23C is turned on. The flip-flop 23D inverts the output Q at the rising edge of the pulse supplied to the terminal CLK and controls the transistor 23C. The reset circuit 23E includes a capacitor that forms a differentiating circuit, a resistor, and a diode that absorbs a reverse surge.

The power source of the flip-flop 23D is taken out from the battery 22 side from the contact of the relay 23R,
Even if the contact of the relay 23R is opened and then the ignition switch 21 is turned off, the flip-flop 23
D continues to operate.

The OR circuit 24D outputs a reset signal composed of a short L level pulse when a warning signal is issued from the watchdog timer 24A or another abnormality detection circuit. The reset signal becomes an H level pulse through the relay circuit 24E and is input to the clock input CLK of the flip-flop 23D.

The flip-flop 23D outputs the value of the input D from the output Q at the rising edge of the clock input CLK,
The transistor 23C is turned on to open the contact of the relay 23R. After that, the driver turns on the ignition switch 21.
When the switch is turned off, the ignition switch 21 is turned off
However, the contact of relay 23R is left open, so 5V
The power supply to the regulator 27 is cut off. for that reason,
For example, even if the arithmetic element 20 is latched up, it is resolved at this point.

Next time, the ignition switch 2
When 1 is turned on, the flip-flop 23D is reset through the differentiation circuit of the reset circuit 23E, the output Q is output at the L level, the transistor 23C is turned off, and the contact of the relay 23R is returned to the original closed state.

In FIG. 3, the ignition switch 21 of FIG. 2 (a) is turned on to start the operation of the automobile. Since the warning signal was not generated during the previous operation, the relay 23R was kept closed and the power source of the arithmetic element 20 was constantly supplied from the battery 22.

However, an abnormality occurs in the arithmetic element 20 during operation, and a warning signal is input, a reset signal is input, and a pulse is input to the CLK terminal of the flip-flop 23D shown in FIG. 2B. Although the output Q is inverted at the rising timing of the flip-flop 23D, there is no apparent change in the power supply state of the arithmetic element 20, and the arithmetic element 20 receives the program reset by the watchdog timer 24A, but continues the program control.

After that, after the driver moves the vehicle to a safe place, the ignition switch 21 is turned off.
Then, the power supply to the arithmetic element 20 is cut off. While the power supply to the arithmetic element 20 is interrupted, for example, the latch-up state of the arithmetic element 20 is released.

After that, the ignition switch 2
When 1 is turned on, the power supply to the arithmetic element 20 is restored to the original state, and the arithmetic element 20 executes the initialization program to restore the states of the arithmetic element 20 and the peripheral circuits to the normal state.

The differential pulse R of the reset circuit 23E is formed every time the ignition switch 21 is turned on. However, unless the output Q is reversed at the previous operation, the output Q is kept at the L level and the ignition switch 21 is turned on. Regardless of whether it is ON or OFF, power is continuously supplied from the battery 22 to the arithmetic element 20 through the contact of the relay 23R.

In this embodiment, when a warning signal is generated during operation, the power supply to the arithmetic element 20 is cut off at the time when the ignition switch 21 is turned off, and thereafter,
A procedure for initializing the arithmetic element 20 and the like when the ignition switch 21 is turned on is adopted. However, it is not necessary to wait until the ignition switch 21 is turned on as long as the timing for initializing the arithmetic element 20 and the like exceeds the time when the abnormality of the arithmetic element 20 can be canceled.

For example, set the ignition switch 21 to O
The power supply to the arithmetic element 20 via the relay 23R may be restarted 10 minutes after the FF.

[0048]

According to the power supply circuit of the first aspect, the arithmetic element can be properly initialized and damages such as latch-up can be effectively removed without damaging the system. Further, the operator can freely select the timing for returning the operation of the arithmetic element to his or her own convenience. further,
Abnormalities such as arithmetic elements are removed automatically by power-off and initialization by reconnection is performed automatically, so the abnormalities of arithmetic elements are reliably removed and reliability at system restart is secured. .

Therefore, for example, even if some abnormality occurs in a vehicle, after ensuring safe driving for the time being by a fail-safe program or the like, moving the vehicle to a safe position or consuming an emergency driving schedule, again,
The abnormality can be solved by initializing the arithmetic element. Further, it is not necessary to erroneously determine the abnormality of the arithmetic element as the abnormality of the sensor or the like and replace the sensor or the like unnecessarily.

When an abnormality such as a latch-up occurs in the arithmetic element, the arithmetic element and the system are not left to be left for a long time without being initialized and the arithmetic element and the system are not fatally damaged.

In particular, it is effective for canceling the latch-up phenomenon that is likely to occur in the arithmetic element in which the AD converter and the input / output circuit are arranged together on the CPU chip. While the power supply to the arithmetic element is cut off, the abnormal voltage of the specific circuit element on the chip is released, the voltage charged up in the floating capacitance is also released, and each circuit element restores its original function. it can.

Therefore, adverse effects on the system due to garbled data due to latch-up, operation error, program halt, intermediate device output state, etc. can be eliminated early.
It is possible to avoid serious system malfunction and danger due to element destruction caused by leaving it alone.

According to the power supply circuit of the second aspect, the operator arbitrarily sets the time during which the power supply is continuously cut off in accordance with the time until the abnormality such as latch-up is canceled after the power supply to the arithmetic element is cut off. Can be set to.

[Brief description of drawings]

FIG. 1 is an explanatory diagram of a basic configuration of the present invention.

FIG. 2 is an explanatory diagram of an ECU power supply circuit according to the embodiment.

FIG. 3 is an explanatory diagram of a flowchart of an embodiment.

FIG. 4 is an explanatory diagram of a conventional ECU power supply circuit.

[Explanation of symbols]

 10 arithmetic element 11 ON-OFF power supply 12 constant power supply 13 switching means 14 abnormality detection means 15 control means

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Office reference number FI technical display location H02J 9/00 R 9/06 502 E

Claims (2)

[Claims] 1. An ON-OFF power supply (11) capable of executing an ON-OFF operation by an operator at any time, and a constant power supply (12) capable of continuing power supply irrespective of the ON-OFF operation. In a power supply circuit that supplies power to a computing element (10) that has a program computing section or a data storage section used for computing, at least in part, at least the constant power supply to the computing element (10) is required. ON-OFF from the power supply (12)
Switching means (13) capable of switching only to the power supply (11)
An abnormality detecting means (14) for detecting an abnormal situation in the arithmetic element (10) and generating a warning signal; and a control means for controlling the switching means (13) according to the warning signal, and according to the warning signal. The power supply is switched to the ON-O
The FF power supply (11) is switched to the side, and at least the ON-OFF power supply (11) is turned OFF, and the next O
A power supply circuit comprising: a control means (15) for returning the power supply to the constant power supply (12) side until N operations are performed. 2. The power supply circuit according to claim 1, wherein the control means is means for returning the power supply to the constant power supply side when the ON-OFF power supply is turned ON next time. Characteristic power supply circuit.