JP2008288824A - Microcomputer self-diagnosis device and power supply device using the same - Google Patents

Abstract

An object of the present invention is to provide a microcomputer self-diagnosis device that can take in two voltages with one analog input and judge abnormality, and a power supply device that can obtain high reliability by using the microcomputer.
One output terminal 19 (self-diagnosis output terminal 35) of a microcomputer 11 and one analog input terminal 13 (self-diagnosis analog input terminal 37) are connected by a self-diagnosis wiring 39. By outputting a low voltage and a high voltage from the self-diagnosis output terminal 35 with a simple circuit configuration, two voltages are taken in by one analog input, and if one of them exceeds the allowable range of the known voltage, it is judged as abnormal. Therefore, a highly reliable microcomputer 11 can be obtained, and a highly reliable power supply device can be realized by using this self-diagnosis device.
[Selection] Figure 1

Description

  The present invention relates to a self-diagnosis device for detecting an abnormality of a microcomputer and a power supply device using the same to supplementarily supply power to a load when a main power supply is abnormal.

  Conventionally, an analog-to-digital converter having a plurality of analog input terminals is disclosed in Patent Document 1, for example. A block circuit diagram of this analog-digital converter is shown in FIG. In FIG. 5, the analog-to-digital converter 101 generally has the following configuration. First, an input selection switch unit 103 for selecting four analog inputs is provided. The output of the input selection switch unit 103 is connected to a comparator 107 that performs comparison with the comparison voltage output from the comparison voltage selection unit 105. The output of the comparator 107 is connected to the conversion register unit 109. The output of the conversion register unit 109 is connected to the register storage unit 113 via a parity operation unit 111 that adds parity bits as necessary. In addition, an analog / digital conversion control unit 115 is connected to these components. Further, the analog-digital converter 101 is connected to a control unit 117 that exchanges various signals.

  Next, the operation of the analog-digital converter 101 will be briefly described. In FIG. 5, it is assumed that digital conversion of two analog voltages (first analog voltage 119 and second analog voltage 121 respectively) is performed. The first analog voltage 119 and the second analog voltage 121 are input to the first analog input terminal 123 and the second analog input terminal 125, respectively. The first analog input terminal 123 and the second analog input terminal 125 are connected to the input selection switch unit 103. Therefore, the analog / digital conversion control unit 115 selects, for example, the first analog input terminal 123 with respect to the input selection switch unit 103. As a result, the first analog voltage 119 is input to the comparator 107. By comparing this voltage with the comparison voltage output from the comparison voltage selection unit 105, a digital value corresponding to the first analog voltage 119 is input to the conversion register unit 109. The comparison voltage selection unit 105 generates a comparison voltage based on the reference voltage Vref. The obtained digital value is added with a parity bit by the parity calculation unit 111 and held in the register storage unit 113 in order to improve reliability at the time of data transmission to the control unit 117.

  By performing such an operation also on the second analog voltage 121, a digital value corresponding to the second analog voltage 121 is held in the register storage unit 113. These held digital values are transmitted to the control unit 117.

  Basically, the analog voltage is converted into a digital signal by the above operation, but the analog-digital converter 101 generally has the following problems. In other words, it is originally converted into a digital signal linearly with respect to an analog voltage, but actually, it is nonlinear (non-linear) from a true value due to the influence of peripheral circuits such as characteristics of the analog-digital converter 101 itself and noise. May result in abnormal output.

  Therefore, in the configuration of FIG. 5, an analog-digital conversion abnormality is determined as follows.

  First, as a configuration, the reference voltage Vref is connected to one of the four inputs of the input selection switch unit 103, and nothing is connected to the other input. In the circuit configuration of FIG. 5, the input voltage of the switch to which nothing is connected is the ground voltage.

  Next, as operation, when the first analog voltage 119 and the second analog voltage 121 are converted into digital signals, the reference voltage Vref and the ground voltage are also converted into digital signals. As a result, the register storage unit 113 holds four digital values.

  When these four digital values are transmitted to the control unit 117, the control unit 117 has digital values corresponding to the reference voltage Vref and the ground voltage corresponding to the known reference voltage Vref (for example, 5 V) and the ground voltage (0 V). It is determined whether or not. As a result, when any of these digital values is within the abnormality determination range, the control unit 117 can know that the analog-digital converter 101 is abnormal.

Although FIG. 5 shows a configuration in which the analog-digital converter 101 and the control unit 117 are independent, this may be a microcomputer incorporating both.
JP 2005-184118 A

  According to the analog-digital converter 101 described above, the abnormality can be surely recognized and the reliability of the digital value is improved. For that purpose, two out of only four analog inputs are used for abnormality determination. I was using it.

  It is assumed that such an analog-digital converter 101 is used for an auxiliary power supply device for an idling stop vehicle, for example. Idling stop vehicles need to supply auxiliary power so that the operation of loads such as audio and navigation will not stop even if the battery voltage temporarily drops by operating the starter after the idling stop is completed. is there. Therefore, even if the main power supply (battery) drops below a predetermined voltage, a power supply device that supplementarily supplies the power of the power storage unit to the load is required to continue driving the load. Such a power supply device needs to detect the voltage of the main power source in order to know whether or not the main power source has become a predetermined voltage or less, and detects the voltage of the power storage unit in order to control charging of the power storage unit Further, it is necessary to detect the output voltage in order to monitor whether the voltage is normally applied to the load. Accordingly, since there are three voltages to be measured, there is a problem that the analog-digital converter 101 having the conventional configuration cannot be used for such a power supply apparatus.

  On the other hand, Patent Document 1 describes that a voltage having a known voltage value may be input to at least one analog input. In this case, however, an abnormality is determined based on only one voltage value. Become. However, as described above, the digital signal may deviate from the true value non-linearly. If an abnormality is determined based on the voltage value of only one point at this time, if the digital value is close to the true value by chance near the voltage value, The analog-to-digital converter 101 may be determined to be normal despite being in an abnormal state, and a voltage value deviating from the true value may be captured. Therefore, in particular, when the analog-digital converter 101 is used for a power supply device that supplementarily supplies power, high reliability is required. Therefore, an abnormality determination must be made with two voltages as in the configuration of FIG. Don't be.

  The present invention solves the above-described conventional problems. A microcomputer self-diagnosis device that can take in two voltages with one analog input and can judge an abnormality, and a power source that can obtain high reliability by using the same. An object is to provide an apparatus.

  In order to solve the above-described conventional problems, a microcomputer self-diagnosis device and a power supply device using the same according to the present invention are connected to a plurality of analog input terminals and the analog input terminals. A selection switch for selecting one, an analog-to-digital converter connected to the output of the selection switch, a plurality of output terminals for outputting either a low voltage or a high voltage, the selection switch, and the output terminal In a microcomputer that controls an output signal and incorporates a control unit that captures the output of the analog-to-digital conversion unit, any one of the output terminals is used as a self-diagnosis output terminal, and any one of the analog input terminals One is an analog input terminal for self-diagnosis, and the self-diagnosis output terminal and the self-diagnosis analog input terminal are connected. And the control unit switches the selection switch to select the self-diagnosis analog input terminal, and the analog-to-digital conversion unit controls the self-diagnosis output terminal to be the low voltage. The output of the analog-to-digital converter when the output exceeds the allowable range with respect to the known low voltage stored in advance or the self-diagnosis output terminal is controlled to be the high voltage is the known high voltage stored in advance. When the voltage exceeds the allowable range, it is determined that the voltage is abnormal.

  According to the microcomputer self-diagnosis apparatus and the power supply apparatus using the same according to the present invention, one of the microcomputer output terminals (self-diagnosis output terminal) and one of the analog input terminals (self-diagnosis analog input terminal) With a simple circuit configuration that connects only two, a low voltage and a high voltage are output from the self-diagnosis output terminal, so that two abnormal voltages can be taken in with one analog input, so a highly reliable microcomputer By using this, it is possible to obtain an effect that a highly reliable power supply device can be realized.

  The best mode for carrying out the present invention will be described below with reference to the drawings. In the first embodiment, a microcomputer self-diagnosis device will be described. In the second embodiment, a case where the microcomputer self-diagnosis device is used as an auxiliary power supply for an idling stop vehicle will be described as an example.

(Embodiment 1)
FIG. 1 is a block circuit diagram of a self-diagnosis apparatus for a microcomputer according to Embodiment 1 of the present invention. FIG. 2 is a flowchart for performing self-diagnosis of the microcomputer self-diagnosis apparatus according to Embodiment 1 of the present invention. FIG. 3 is a block circuit diagram of another configuration of the microcomputer self-diagnosis apparatus according to the first embodiment of the present invention.

  In FIG. 1, a microcomputer 11 has the following circuit configuration. First, a plurality of (four in the first embodiment) analog input terminals 13 to which analog voltage signals are input are provided. Each analog input terminal 13 is connected to a selection switch 15 for selecting one of the analog input terminals 13. The voltage output selected by the selection switch 15 is connected so as to be input to the analog-digital converter 17 as the voltage signal Vi. The detailed configuration of the analog-digital conversion unit 17 includes a comparison voltage selection unit 105, a comparator 107, a conversion register unit 109, a parity calculation unit 111, a register storage unit 113, and an analog-digital conversion control unit 115 shown in FIG. Since the connection is also the same as that in FIG. 5, the detailed configuration is omitted in FIG. The analog-to-digital conversion unit 17 used in the first embodiment has a specification for converting the input analog voltage into a 10-bit digital value.

  The microcomputer 11 is provided with a plurality of output terminals 19 for outputting either a low voltage or a high voltage. Here, in the first embodiment, the low voltage is the ground voltage, and the high voltage is the drive voltage Vcc of the microcomputer 11. As will be described later, these low voltage and high voltage are the minimum input voltage and the maximum input voltage of the analog-digital conversion unit 17, respectively. An output voltage changeover switch 21 composed of two FETs is connected to the output terminal 19 in order to output either a low voltage or a high voltage. Note that the output switching of the output voltage changeover switch 21 is performed by a high / low signal H / L output from the control unit 23 having a 16-bit internal arithmetic processing mainly performing the calculation in the microcomputer 11. Specifically, when the high / low signal H / L is input to the base terminal of the FET constituting the output voltage changeover switch 21, a low voltage (ground voltage) or a high voltage (drive voltage Vcc) is output from the output terminal 19. Is done.

  The control unit 23 is connected to the selection switch 15 for selecting and controlling the analog input terminal 13 in addition to the output voltage changeover switch 21 for controlling the output signal of the output terminal. The analog input terminal 13 is selected by transmitting a selection signal SL from the control unit 23 to the selection switch 15. The control unit 23 is connected to perform operations such as taking in the output of the analog-digital conversion unit 17. In addition, since a plurality of wirings are necessary for the connection between them in the same manner as the wiring connecting the analog-digital converter 101 and the control unit 117 in FIG. 5, these are collectively indicated by double arrows in FIG. Further, the digital output signal data after the voltage signal Vi is digitally converted in the analog-digital conversion unit 17 is transmitted to the control unit 23 through the wiring.

  Next, power supply related terminals to the microcomputer 11 will be described. The microcomputer 11 is provided with two terminals for supplying power. One is a power supply terminal 25, which is connected to the control unit 23 and the output voltage changeover switch 21. The other is provided with a reference voltage input terminal 27 for inputting an accurate voltage. The reference voltage input terminal 27 is connected to the analog-digital conversion unit 17 in order to perform accurate analog-digital conversion. As a result, the reference voltage Vref is supplied to the analog-digital converter 17. The grounds of the analog / digital conversion unit 17, the output voltage changeover switch 21, and the control unit 23 are collectively connected to the ground terminal 29 inside the microcomputer 11. The ground terminal 29 is connected to the ground outside the microcomputer 11. Therefore, the minimum input voltage of the analog-digital converter 17 is the ground voltage (0 V).

  Although a circuit such as a memory is connected to the microcomputer 11 in addition to the above, it is omitted in FIG. 1 because it is not particularly necessary for the description of the configuration and operation here.

  Next, external connection of the microcomputer 11 will be described. As described above, an external ground is connected to the ground terminal 29, but an external drive power supply 31 is connected to the power supply terminal 25 in addition thereto. Here, a driving power supply 31 of 5 V, which is a general driving voltage of the microcomputer 11, is used. This voltage is stabilized and supplied by a regulator (not shown). Therefore, the reference voltage input terminal 27 that requires an accurate voltage is also connected so that the voltage of the drive power supply 31 is input. Therefore, the reference voltage Vref is 5V. As a result, the maximum input voltage of the analog / digital converter 17 is 5V.

  Next, a circuit configuration that is a feature of the first embodiment will be described. First, any one of the plurality of output terminals 19 is set as a self-diagnosis output terminal 35. In FIG. 1, the lowermost output terminal 19 is a self-diagnosis output terminal 35. At the same time, any one of the four analog input terminals 13 is set as an analog input terminal 37 for self-diagnosis. Also in this case, the analog input terminal 13 at the bottom of FIG. The self-diagnosis output terminal 35 and the self-diagnosis analog input terminal 37 are connected by an external self-diagnosis wiring 39. In FIG. 1, the self-diagnosis wiring 39 is indicated by a bold line. By connecting in this way, the self-diagnosis signal Vdg (low voltage ground voltage = 0 V or high voltage drive voltage Vcc = 5 V) output from the self-diagnosis output terminal 35 is the self-diagnosis analog input terminal. 37 and the selection switch 15 to be input to the analog-digital conversion unit 17. A configuration in which the self-diagnosis output terminal 35 and the self-diagnosis analog input terminal 37 of the microcomputer 11 are connected by an external self-diagnosis wiring 39 is referred to as a self-diagnosis device of the microcomputer 11.

  Next, the self-diagnosis operation in the self-diagnosis device of the microcomputer 11 will be described with reference to the flowchart of FIG. In addition, since the self-diagnosis operation of the microcomputer 11 is performed at predetermined time intervals (for example, every minute), it is possible to make an abnormality determination timely. Therefore, the self-diagnosis operation shown in FIG. 2 is in the form of a subroutine.

  When the predetermined time has elapsed, the control unit 23 executes the flowchart of FIG. 2 as follows. First, a selection signal SL is transmitted to the selection switch 15 so as to select the self-diagnosis analog input terminal 37 (S11). In response to this, the selection switch 15 switches to select the self-diagnosis analog input terminal 37.

  Next, the high / low signal H / L is transmitted and controlled so that the self-diagnosis output terminal 35 becomes a low voltage (0 V) (S13). As a result, the self-diagnosis signal Vdg at the self-diagnosis output terminal 35 becomes 0V. Thereafter, it is determined whether or not the digital output signal data of the analog-to-digital converter 17 exceeds an allowable range with respect to a known low voltage (digital value corresponding to 0 V) stored in advance in a memory (not shown) (S15). . Here, the allowable range may be determined from the accuracy required for the apparatus using the microcomputer 11. In the first embodiment, for example, it is within 5 LSB for a digital value of 0V. Note that LSB is the least significant bit, and within 5 LSB means a range within 5 times the least significant bit. Therefore, if 0V, which is the lowest input voltage, is converted into a digital value by the 10-bit analog-digital conversion unit 17, if the analog-digital conversion unit 17 is normal, it becomes 0H (H indicates a hexadecimal number), but within 5LSB The range is from 0H to 5H. Therefore, if a digital value in the range of 0H to 5H is output when 0V is input, it is within the allowable range.

  As a result of such determination, if the obtained digital value is not within the allowable range (No in S15), the microcomputer 11 is abnormal, and the process jumps to S21 described later. On the other hand, if it is within the allowable range (Yes in S15), the high / low signal H / L is transmitted and controlled so that the self-diagnosis output terminal 35 becomes a high voltage (5V) (S17). As a result, the self-diagnosis signal Vdg at the self-diagnosis output terminal 35 becomes 5V. Thereafter, it is determined whether or not the digital output signal data of the analog-to-digital converter 17 exceeds an allowable range with respect to the known high voltage (digital value corresponding to 5 V) stored in the memory in advance (S19). In the first embodiment, if the analog-to-digital converter 17 is normal, a digital value of 3FFH can be obtained for the maximum input voltage of 5V. However, since the allowable range is within 5LSB, the digital value in the range of 3FAH to 3FFH is obtained. Is within the allowable range.

  If the obtained digital value is within the allowable range as a result of the determination (Yes in S19), both the low voltage and the high voltage are within the allowable range. 11 can be determined to be normal. In this case, nothing is done and the flowchart of FIG. 2 is terminated. On the other hand, if the allowable range is exceeded (No in S19), since the microcomputer 11 is abnormal, an abnormal signal is output (S21). Specifically, for example, when the control unit 23 outputs a high voltage (5 V) from one of the output terminals 19, the abnormality of the microcomputer 11 itself is output to the outside. Thereafter, the flowchart ends.

  Thus, when the low voltage exceeds the allowable range with respect to the known low voltage, or the high voltage exceeds the allowable range with respect to the known high voltage, it can be determined that the microcomputer 11 is abnormal.

  By connecting the self-diagnosis output terminal 35 and the self-diagnosis analog input terminal 37 by the above configuration and operation, two voltages (low voltage and high voltage) can be obtained by using only one analog input terminal 13. Since it is possible to determine abnormalities in capture, a microcomputer self-diagnosis device that can obtain high reliability with a simple configuration has been realized.

  The self-diagnosis operation shown in FIG. 2 is performed at predetermined time intervals. This is because the abnormality of the microcomputer 11 itself is output to the outside when the controller 23 determines that the analog-digital converter 17 is abnormal. Therefore, after that, the output of the analog-digital converter 17 may not be used, and the self-diagnosis operation of FIG. 2 may not be performed.

  Further, in the first embodiment, one of the four analog input terminals 13 is occupied as the self-diagnosis analog input terminal 37. However, as shown in FIG. Alternatively, a common terminal of the three-terminal input changeover switch 41 may be connected, and one selection terminal of the input changeover switch 41 may be connected to the self-diagnosis output terminal 35. In FIG. 3, the internal configuration of the microcomputer 11 is the same as that in FIG.

  With such a configuration, another input voltage V4 can be connected to the other selection terminal of the input selector switch 41. Therefore, the control unit 37 can input the four voltages V1 to V4 at the normal time by switching the input changeover switch 41 to the input voltage V4 side except when the analog / digital conversion unit 17 determines abnormality. Note that the switching operation of the input switch 41 includes, for example, the input switch 41 composed of a plurality of FETs, and controls the on / off of the FET using an output signal obtained from one of the output terminals 19 as an input switch signal Vsel. You can do that.

(Embodiment 2)
FIG. 4 is a block circuit diagram of a power supply device using the microcomputer self-diagnosis device according to the second embodiment of the present invention. In FIG. 4, thick lines indicate power system wirings, and thin lines indicate control system wirings. Also, in the configuration of FIG. 4, the same components as those in FIG.

  In FIG. 4, the power supply device includes a power storage device 51 and a main power supply 55. The power storage device 51 is connected between the main power supply 55 and the load 57. The main power supply 55 is a battery, and a starter (not shown) that consumes a large current intermittently is also connected. The load 57 is an auxiliary device such as audio and navigation, and is usually supplied with power from the main power supply 55.

  The power storage device 51 has the following configuration. First, a charging circuit 59 and a main power supply voltage detection circuit 61 for detecting the voltage Vb of the main power supply 55 are connected to the output of the main power supply 55. A power storage unit 63 is connected to the charging circuit 59. The charging circuit 59 incorporates a power storage unit voltage detection circuit (not shown) that detects the voltage Vc of the power storage unit 63. Therefore, the power storage unit 63 is charged by the charging circuit 59 while detecting the voltage Vc of the power storage unit 63. The charging circuit 59 also has a function of outputting the voltage Vc of the power storage unit 63 to the microcomputer 11. The power storage unit 63 uses an electric double layer capacitor as a power storage element for storing the power of the main power supply 55, and a plurality of these are connected in series to cover the necessary power. Further, a changeover switch 67 for supplying power from the power storage unit 63 to the load 57 is connected between the power storage unit 63 and the load 57 as shown in FIG.

  Although the charging circuit 59 is provided and the power storage unit voltage detection circuit is built in the second embodiment, the charging circuit 59 may not be provided particularly in the case of a power supply device that does not require charging control. However, in this case, it is necessary to connect the power storage unit voltage detection circuit to the power storage unit 63 alone.

  The main power supply voltage detection circuit 61 has a function of detecting the voltage Vb of the main power supply 55, and the input side and the output side of the power system wiring (thick line) are connected to have the same voltage. A first diode 68 is connected between the main power supply voltage detection circuit 61 and the load 57. The first diode 68 has an anode connected to the main power supply voltage detection circuit 61 and a cathode connected to the load 57. A second diode 71 is connected between the connection point 69 of the first diode 68 and the load 57 and one end of the changeover switch 67. The second diode 71 has an anode connected to the changeover switch 67 and a cathode connected to the connection point 69. The first diode 68 and the second diode 71 are provided so that the electric power of the power storage unit 63 and the main power supply 55 do not flow backward.

  An output voltage detection circuit 73 that detects the output voltage Vd of the power storage device 51 is connected to the connection point 69 that is the output of the power storage device 51.

  The charging circuit 59, the main power supply voltage detection circuit 61, the changeover switch 67, and the output voltage detection circuit 73 are also connected to the microcomputer 11. Accordingly, the microcomputer 11 uses the charging circuit 59 to change the voltage Vc of the power storage unit 63 from the output of the main power supply voltage detection circuit 61 to the voltage Vb of the main power supply 55 and from the output of the output voltage detection circuit 73 to the power storage device 51. The output voltage Vd is read. These analog voltage values are connected to three of the analog input terminals 13 of the microcomputer 11. Further, the microcomputer 11 controls the charging circuit 59 by transmitting a control signal cont to the charging circuit 59 and performs on / off control of the switching switch 67 by transmitting an on / off signal VOF to the changeover switch 67. This on / off signal VOF is connected to one of the output terminals 19 of the microcomputer 11. Further, the output terminal 19 of the microcomputer 11 includes the microcomputer abnormality signal described in FIG. 2 so that a power storage device abnormality signal Tna indicating any abnormality of the power storage device 51 is output to the vehicle-side control circuit (not shown). Is connected to the vehicle-side control circuit.

  As a self-diagnosis device of the microcomputer 11, in the second embodiment, as in the first embodiment, the self-diagnosis output terminal 35 and the self-diagnosis analog input terminal 37 are connected by a self-diagnosis wiring 39. Yes.

  Next, a power supply system that supplies power to the microcomputer 11 will be described. As described in the first embodiment, the microcomputer 11 is provided with the power supply terminal 25 and the reference voltage input terminal 27. The input voltages to these terminals are all 5V, and the reference voltage input terminal 27 requires a highly accurate voltage of 5V. Therefore, the power to the microcomputer 11 is converted into a highly accurate 5 V voltage by the regulator 75 from the main power supply 55 in the normal state and from the power storage unit 63 when the voltage of the main power supply 55 is lowered. The output (5 V voltage) of the regulator 75 is connected to both the power supply terminal 25 and the reference voltage input terminal 27 as in the first embodiment. Note that the power of the main power supply 55 and the power of the power storage unit 63 are switched between the third diode 77 having the anode connected to the main power supply 55 and the cathode connected to the regulator 75, the anode connected to the output of the changeover switch 67, and the regulator 75. This is done by a fourth diode 79 connected to each cathode.

  Next, the operation of such a power supply device will be described.

  First, the basic operation as an idling stop automobile power supply device will be described. When the ignition switch (not shown) is turned on to start the vehicle, the engine is driven and the microcomputer 11 transmits a control signal cont to charge the power storage unit 63 to the charging circuit 59. In response to this, the charging circuit 59 performs charging until it reaches full charge while detecting the voltage Vc of the power storage unit 63. At this time, the microcomputer 11 transmits an on / off signal VOF so as to turn off the changeover switch 67 so that the charging current to the power storage unit 63 does not flow to the load 57 side.

  When the power storage unit 63 reaches full charge, charging is completed, and the charging circuit 59 performs constant voltage control to maintain the full charge voltage. Thereafter, the microcomputer 11 monitors the voltage Vb of the main power supply 55 by reading the output of the main power supply voltage detection circuit 61 through the analog input terminal 13.

  In this state, it is assumed that idling stop is performed and then the engine is restarted. As a result, the voltage Vb of the main power supply 55 is drastically lowered due to a large current flowing through the starter (not shown). The change in the voltage Vb is detected by the main power supply voltage detection circuit 61 and transmitted to the microcomputer 11. The microcomputer 11 switches to supply a stable voltage to the load 57 when the voltage Vb becomes equal to or lower than a threshold value (10.5 V which is the lower limit voltage capable of driving the load 57 in the second embodiment). An on / off signal VOF is transmitted to turn on the switch 67. As a result, electric power is supplied from power storage unit 63 to load 57 in the direction of the arrow written as the discharge path in FIG. At this time, since the voltage Vb of the main power supply 55 is lowered by the starter drive, the voltage at the connection point 69 (output voltage Vd) becomes lower than the voltage Vc of the power storage unit 63. Accordingly, the second diode 71 is turned on, and the power of the power storage unit 63 is preferentially supplied to the load 57. Similarly, the fourth diode 79 is turned on, and the power of the power storage unit 63 is also supplied to the power supply terminal 25 and the reference voltage input terminal 27 of the microcomputer 11 via the regulator 75. Thereby, the microcomputer 11 continues to operate.

  When power is supplied from the power storage unit 63 to the load 57, the microcomputer 11 detects a discharge abnormality of the power storage unit 63. Specifically, the microcomputer 11 detects the amount of change in the output voltage Vd at a predetermined time by the output voltage detection circuit 73. If the amount of change is larger than the predetermined voltage change obtained in advance from the maximum consumption current of the load 57, the microcomputer 11 discharges the current. The amount of change in voltage is large, that is, overcurrent flows. In this case, in order to protect the power supply device from overcurrent, the microcomputer 11 immediately turns off the changeover switch 67 to stop the power supply from the power storage unit 63 to the load 57 and the discharge of the power storage device 51 is abnormal. In order to notify the vehicle side control circuit of this, the power storage device abnormality signal Tna is set to a high voltage (5 V). In response to this, the vehicle-side control circuit prohibits a subsequent idling stop operation and warns the driver of an abnormality of the power storage device 51 and prompts repair.

  On the other hand, when power storage device 51 is normally discharged, it operates as follows. Since the current consumed by the starter decreases when the engine restart is nearing completion, the voltage Vb of the main power supply 55 increases. When this change is detected by the main power supply voltage detection circuit 61 and exceeds a predetermined value (10.5 V which is the same as the above-described threshold value), the microcomputer 11 turns off the changeover switch 67. Thereby, the power of the main power supply 55 is thereafter supplied to the load 57, and the discharge from the power storage unit 63 stops. Further, the microcomputer 11 instructs the charging circuit 59 to recharge the power supplied from the power storage unit 63 to the load 57.

  By repeating the operations described so far, even if the idling stop operation is performed many times during use of the vehicle, the voltage fluctuation during the starter driving can be compensated by the electric power of the power storage unit 63. It can continue to operate stably.

  Next, a self-diagnosis operation in the self-diagnosis device of the microcomputer 11 will be described. As described in the first embodiment, this is performed at predetermined time intervals (for example, every minute). Since the self-diagnosis operation itself is exactly the same as the flowchart shown in FIG. 2, detailed description is omitted, but the basic operation of the power supply apparatus described above is performed only when the microcomputer 11 is normal as a result of self-diagnosis. continue.

  On the other hand, when it is determined that the microcomputer 11 is abnormal, the output terminal 19 connected to the vehicle-side control circuit is switched to a high voltage, thereby transmitting the power storage device abnormality signal Tna as the microcomputer abnormality signal (FIG. 2 corresponds to S21). Since the power storage device abnormality signal Tna is transmitted even when the discharge abnormality is detected as described above, in the second embodiment, the discharge abnormality and the abnormality of the microcomputer 11 cannot be distinguished from each other by the power storage device abnormality signal Tna. . However, since the power storage device 51 cannot be used if any abnormality occurs, it is transmitted to the vehicle-side control circuit without distinction here. In addition, what is necessary is just to set it as the structure which performs serial communication between the said vehicle side control circuits, when it is desired to distinguish the kind of abnormality. Thereby, even one output terminal 19 can distinguish and transmit discharge abnormality and microcomputer 11 abnormality.

  In the operation of FIG. 2, the self-diagnosis output terminal 35 is switched between a low voltage and a high voltage, and the voltage taken from the self-diagnosis analog input terminal 37 in each case is within the allowable range of the known voltage. Since only the comparison is made, the time until the operation of FIG. 2 is completed is extremely short. Therefore, the operation shown in FIG. 2 may be performed by interrupting every predetermined time (every minute) during any basic operation of the power supply apparatus. However, if there is an operation that cannot be executed by interrupting the operation of FIG. 2 in the basic operation, control may be performed so as to prohibit interruption during that time.

  In this way, by performing a self-diagnosis operation using the self-diagnosis device of the microcomputer 11 at predetermined time intervals, the main power supply 55 for determining whether or not the power of the power storage unit 63 is supplied to the load 57 in particular. In the detection of the voltage Vb and the detection of the output voltage Vd for determining the discharge abnormality of the power storage unit 63, extremely high reliability can be obtained.

  By applying the self-diagnosis device of the microcomputer 11 described in the first embodiment to the power supply device of the vehicle by the above configuration and operation, the abnormality of the microcomputer 11 can be determined in a timely manner. A simple power supply.

  In the second embodiment, the electric double layer capacitor is used as the electric storage element in the electric storage unit 63, but this may be another electric storage element such as an electrochemical capacitor. Furthermore, although the electrical storage part 63 was set as the structure which connected the several electrical storage element in series, according to the electric power specification which the load 57 requires, it is good also as parallel or a series-parallel connection, A single power storage element may be used.

  In the second embodiment, the case where the power supply device is applied to an idling stop vehicle has been described. However, the present invention is not limited thereto, and each of the hybrid vehicle, the electric power steering, the electric supercharger, the vehicle braking by the electric hydraulic control, etc. The present invention can also be applied to an auxiliary power supply for vehicles in a system, a general emergency power supply device, and the like.

  Since the microcomputer self-diagnosis device according to the present invention can judge an abnormality in the conversion portion from the analog input voltage to the digital signal by using only one analog input terminal, it can be applied to a microcomputer that requires high reliability. In addition to being useful, a power supply device using the same improves the reliability of the microcomputer, so that it is particularly useful as an auxiliary power supply that supplies power from the power storage unit when the voltage of the main power supply decreases.

1 is a block circuit diagram of a microcomputer self-diagnosis device according to Embodiment 1 of the present invention. Flowchart for performing self-diagnosis of the microcomputer self-diagnosis device in Embodiment 1 of the present invention The block circuit diagram of the other structure of the self-diagnosis apparatus of the microcomputer in Embodiment 1 of this invention Block circuit diagram of a power supply device using a microcomputer self-diagnosis device in Embodiment 2 of the present invention Block diagram of a conventional analog-digital converter

Explanation of symbols

DESCRIPTION OF SYMBOLS 11 Microcomputer 13 Analog input terminal 15 Selection switch 17 Analog-digital conversion part 19 Output terminal 23 Control part 35 Self-diagnosis output terminal 37 Self-diagnosis analog input terminal 51 Power storage device 55 Main power supply 57 Load 61 Main power supply voltage detection circuit 63 Power storage Part 67 selector switch 73 output voltage detection circuit

Claims (7)

Multiple analog inputs and
A selection switch connected to the analog input terminal and selecting one of the analog input terminals;
An analog-to-digital converter connected to the output of the selection switch;
A plurality of output terminals for outputting either low voltage or high voltage;
In the microcomputer having a built-in control unit that controls the selection switch and the output signal of the output terminal and takes in the output of the analog-digital conversion unit,
Any one of the output terminals is a self-diagnosis output terminal, and any one of the analog input terminals is a self-diagnosis analog input terminal, and the self-diagnosis output terminal and the self-diagnosis analog input terminal are Connected,
The control unit switches the selection switch to select the analog input terminal for self-diagnosis,
The output of the analog-to-digital converter when the self-diagnosis output terminal is controlled to become the low voltage exceeds an allowable range with respect to a known low voltage stored in advance, or the self-diagnosis output terminal A microcomputer self-diagnosis device which judges that an output is abnormal when an output of the analog-digital converter when controlled to be a high voltage exceeds an allowable range with respect to a known high voltage stored in advance. 2. The microcomputer self-diagnosis device according to claim 1, wherein, when it is determined that the analog-digital conversion unit is abnormal, the control unit does not use the output of the analog-digital conversion unit thereafter. 2. The microcomputer self-diagnosis device according to claim 1, wherein the low voltage is a minimum input voltage of the analog-to-digital conversion unit, and the high voltage is a maximum input voltage of the analog-to-digital conversion unit. 4. The microcomputer self-diagnosis apparatus according to claim 3, wherein the minimum input voltage is a ground voltage in a drive power source of the microcomputer, and the maximum input voltage is a drive voltage of the microcomputer. 2. The microcomputer self-diagnosis apparatus according to claim 1, wherein the microcomputer self-diagnosis is performed at predetermined time intervals. A main power supply for supplying power to the load;
A power storage device connected between the main power source and the load;
The power storage device is connected to the main power source and stores a power of the main power source,
A power storage unit voltage detection circuit connected to the power storage unit and detecting a voltage (Vc) of the power storage unit;
A main power supply voltage detection circuit connected to the main power supply and detecting a voltage (Vb) of the main power supply;
An output voltage detection circuit connected to the output of the power storage device and detecting an output voltage (Vd) of the power storage device;
A changeover switch connected between the power storage unit and the load, and supplying power of the power storage unit to the load;
The power storage unit voltage detection circuit, the main power supply voltage detection circuit, the output voltage detection circuit, and a changeover switch, and a microcomputer having the self-diagnosis device according to claim 1,
Only when the microcomputer is normal as a result of self-diagnosis, the main power supply voltage detection circuit detects the voltage (Vb) of the main power supply, and the voltage (Vb) of the main power supply falls below a threshold value. A power supply device that turns on the changeover switch so that the power storage unit supplies power to the load. The power supply device according to claim 6, wherein the microcomputer outputs a microcomputer abnormality signal if it is abnormal as a result of the self-diagnosis.

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