JP6384393B2 - Microcomputer and electronic control device - Google Patents

Description

  The present invention relates to a microcomputer and an electronic control device including the microcomputer.

  A microcomputer (hereinafter referred to as a microcomputer) has an appropriate range of power supply voltage. For this reason, if the supplied power supply voltage is out of the proper range, the electric load controlled by the microcomputer may malfunction.

  On the other hand, for example, as an electronic control device for a vehicle, a configuration is known that includes a microcomputer monitoring device that monitors a power supply voltage supplied to the microcomputer together with the microcomputer. A microcomputer having a built-in monitoring circuit for monitoring the power supply voltage is also known. For example, Patent Document 1 discloses an electronic control device including a microcomputer monitoring device.

  As described above, in the configuration having the power supply voltage monitoring function, the microcomputer is reset when the power supply voltage supplied to the microcomputer is out of the proper range, so that malfunction of the electric load can be suppressed.

JP 2013-133089 A

  When power is supplied to the microcomputer, the load is higher than during normal operation. Therefore, the power supply voltage is stabilized by a capacitor in order to suppress a rapid fluctuation (drop) in the power supply voltage. The microcomputer also includes a plurality of modules having functional circuits such as an I / 0 port and a timer. Instead of starting all the modules at the same time when the power supply voltage is applied to the microcomputer, the power supply voltage is controlled by controlling the power supply voltage supply timing so that multiple modules are started one by one. It is conceivable to suppress rapid fluctuations in voltage.

  However, if the function of suppressing the load fluctuation of the power supply voltage is reduced due to the removal of the capacitor or the like, the power supply voltage does not return at the end of startup of each module, and the power supply voltage is reduced every time the module is started up. For this reason, the power supply voltage may fall below the threshold for resetting while starting up a plurality of modules, and the microcomputer may be reset.

  In view of the above problems, an object of the present invention is to provide a microcomputer and an electronic control device that can suppress resetting when a power supply voltage is turned on.

  The invention disclosed herein employs the following technical means to achieve the above object. Note that the reference numerals in parentheses described in the claims and in this section indicate a corresponding relationship with specific means described in the embodiments described later as one aspect, and limit the technical scope of the invention. Not what you want.

One of the disclosed inventions is a microcomputer that performs a predetermined process by being supplied with a power supply voltage via a capacitor (13, 14),
A monitoring circuit (20) for monitoring the supplied power supply voltage;
A plurality of modules (23) each having a functional circuit;
A control unit (24) for controlling the supply timing of the power supply voltage to the module for operating the module, and for controlling the supply timing so that when the power supply voltage is turned on, the plurality of modules rise one by one in order and start operation. And comprising
When the power supply voltage is turned on, when the power supply voltage monitored by the monitoring circuit falls below a predetermined second threshold (Vth2) that is set higher than the first threshold (Vth1) for resetting, the control unit The supply timing of the power supply voltage to the module that starts the operation next is delayed from the case where the power supply voltage does not fall below the second threshold value.

  According to this, when the power supply voltage falls below the second threshold when the power is turned on, the supply timing of the power supply voltage to the module to start the operation next is set to the time when the power supply voltage does not fall below the second threshold, that is, from the normal time. Can be delayed. In this way, the power supply voltage is restored to some extent, and then the next module is started. Thereby, for example, even if the function of suppressing the load fluctuation of the power supply voltage is reduced due to the removal of the capacitor, the microcomputer can be prevented from being reset in the middle of starting up the plurality of modules in order.

It is a figure which shows schematic structure of the electronic controller which concerns on 1st Embodiment. It is a flowchart which shows the process which a control part performs. It is a timing chart which shows a power supply voltage, the operation state of a some module, etc. It is a timing chart in a reference example. It is a timing chart in a reference example. It is a flowchart which shows the process which a control part performs in the electronic control apparatus which concerns on 2nd Embodiment. It is a timing chart which shows a power supply voltage, the operation state of a some module, etc.

It is a flowchart which shows the process which a control part performs in the electronic control apparatus which concerns on 3rd Embodiment. It is a timing chart which shows a power supply voltage, the operation state of a some module, etc. It is a flowchart which shows the process which a control part performs in the electronic control apparatus which concerns on 4th Embodiment. It is a timing chart which shows a power supply voltage, the operation state of a some module, etc.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In each embodiment, common or related elements are given the same reference numerals.

(First embodiment)
First, a schematic configuration of the electronic control device according to the present embodiment will be described with reference to FIG. The electronic control device of the present embodiment is configured as an engine ECU (Electronic Control Unit).

  When an ignition switch (not shown) is turned on by a passenger, the electronic control device 10 shown in FIG. 1 operates by receiving power from the battery 100 via a power relay (not shown). Then, a target torque to be output by an engine (not shown) is calculated. In addition, the electronic control unit 10 controls the throttle valve opening, the fuel injection amount, the ignition timing, and the like in order to generate the target torque required by the engine.

  The electronic control device 10 includes a microcomputer 11, a power supply IC 12, and capacitors 13 and 14.

  The microcomputer 11 is a microcomputer that includes a CPU, a ROM, a RAM, a register, an I / O port, and the like. In the microcomputer 11, the CPU performs signal processing according to a control program stored in advance in the ROM, various data acquired via the bus, and the like while using a temporary storage function of the RAM or the register. Further, the signal obtained by this signal processing is output to the bus. In this way, the microcomputer 11 executes the various functions described above. For example, the microcomputer 11 controls driving of the electric load 101.

  The power supply IC 12 steps down a DC voltage (hereinafter simply referred to as battery voltage) supplied from the battery 100 mounted on the vehicle, and supplies it to the microcomputer 11 as a power supply voltage for the microcomputer 11 to operate. For example, the battery voltage of 12V is stepped down to 5V by the power supply IC 12. As such a power supply IC 12, one having a known configuration, for example, one having a switching power supply circuit or a series power supply circuit can be adopted. The power supply voltage is stabilized by the capacitor 14 and supplied to the microcomputer 11. The battery voltage is stabilized by the capacitor 13. For this reason, the power supply voltage is also stabilized by the capacitor 13.

  As shown in FIG. 1, the microcomputer 11 includes a monitoring circuit 20, a reset circuit 21, an abnormality detection circuit 22, a plurality of modules 23, and a control unit 24.

  The monitoring circuit 20 monitors the power supply voltage supplied from the power supply IC 12 to the microcomputer 11 via the capacitor 14. The monitoring circuit 20 compares the supplied power supply voltage with a preset threshold value. The monitoring circuit 20 outputs a reset signal for resetting the microcomputer 11 when the power supply voltage falls below a predetermined first threshold value Vth1 in advance. In other words, the first threshold value Vth1 is a reset voltage threshold value. As the first threshold value Vth1, a value (eg, 3.3V) higher than an operation guarantee lower limit value (eg, 3V), which is a lower limit value that guarantees the operation of the microcomputer 11, is set. When the reset signal is input to the reset circuit 21, the microcomputer 11 is in a reset state.

  In addition, when the power supply voltage is applied to the microcomputer 11, the monitoring circuit 20 outputs a fail-safe signal when the power supply voltage falls below a preset second threshold value Vth2. In the present embodiment, when a fail safe signal is output from the monitoring circuit 20, the control unit 24 performs control different from that at the normal time (when no fail safe signal is output) on the module 23. In other words, the second threshold value Vth2 is a fail-safe voltage threshold value. As the second threshold Vth2, a value higher than the first threshold Vth1 (for example, 3.5 V to 3.7 V) is set.

  The fail safe signal is also output to the abnormality detection circuit 22. The abnormality detection circuit 22 outputs a diagnosis signal to an external device (not shown) when a fail-safe signal (for example, an H level signal) is input. The microcomputer 11 includes a power-on reset circuit (not shown). Therefore, a predetermined period after the power supply voltage is turned on and the reset of the microcomputer 11 is released, that is, a period immediately after the reset is released, is a time when the microcomputer 11 is turned on.

  Each of the plurality of modules 23 has a functional circuit. The microcomputer 11 has peripheral functions such as an I / O port function for input from a switch or sensor and an output to a display, a function for serial communication, a timer function for managing time, and an A / D conversion function. A circuit (interface circuit) is provided. Each module 23 has at least one of the peripheral function circuits described above. The peripheral function circuit is modularized so that it can be appropriately selected according to the type of the microcomputer 11. The number of modules 23 may be plural (two or more). In the present embodiment, the microcomputer 11 includes a group of n modules (n ≧ 4). In FIG. 1, the first module 23 indicates the module 23 that is activated first, and the n-th module 23 indicates the module 23 that is activated n-th. For example, the first module 23 has an I / O port function, and the second module 23 has a timer function.

  The control unit 24 controls the supply timing of the power supply voltage to the module 23 for operating the module 23. Therefore, the control unit 24 can also be said to be a module activation sequence control unit. The control unit 24 controls the supply timing so that when the power supply voltage is supplied to the microcomputer 11, the plurality of modules 23 start up one after another in order. The control unit 24 controls the supply timing of the power supply voltage to the module 23 based on the signal output from the monitoring circuit 20.

  A buffer 25 is provided on the input side of each module 23. When the control unit 24 outputs an instruction signal to the buffer 25 corresponding to the module 23 in the starting order, the power supply voltage is supplied to the corresponding module 23 via the buffer 25. For example, in the order of starting up the module 1, the power supply voltage is supplied through the buffer 25 corresponding to the module 1. In addition, the control unit 24 acquires a signal indicating the end of startup from each module 23. Thereby, the control part 24 can start up the several module 23 one by one in order.

  Next, based on FIGS. 2 and 3, processing executed by the control unit 24 and changes in the power supply voltage, the operation state of the module 23, and the like accompanying the processing will be described. In FIG. 3, as an example, a case where the capacitor 14 has dropped and the power supply voltage falls below the second threshold value Vth2 during the startup of the second module 23 will be described.

  When the power supply voltage is applied to the microcomputer 11 and the reset of the microcomputer 11 is released, the control unit 24 executes the following process. First, the control unit 24 sets X = 1 as an initial value in the counter (step S10). Next, the control unit 24 outputs an instruction signal to the corresponding buffer 25 in order to supply and start up the power supply voltage to the module 23 corresponding to the currently set count value X (step S20). The module 23 corresponding to the count value X is also referred to as the Xth module 23. Initially, since X = 1 is set in the counter, the power supply voltage is supplied to the first module 23. At time T10 shown in FIG. 3, start-up of the first module 23 begins. In order to start up the first module 23, the current flowing through the microcomputer 11 as a whole increases and the power supply voltage decreases from before the start-up.

  Next, the control unit 24 determines whether or not the power supply voltage is lower than the second threshold value Vth2 (step S30). The control unit 24 performs determination based on the signal output from the monitoring circuit 20. When the signal from the monitoring circuit 20 is an H level signal, that is, a fail-safe signal, the control unit 24 determines that the power supply voltage is lower than the second threshold Vth2 (power supply voltage <Vth2), and then performs the process of step S40 Execute. On the other hand, when the signal from the monitoring circuit 20 is an L level signal, the control unit 24 determines that the power supply voltage is not lower than the second threshold value Vth2, that is, power supply voltage ≧ Vth2, and then performs the process of step S50. Run. As shown in FIG. 3, during the start-up of the first module 23, since the power supply voltage> Vth <b> 2, the control unit 24 then executes the process of step S <b> 50.

  In step S50, the control unit 24 determines whether or not the startup of the Xth module 23 has been completed. Each module 23 outputs a signal notifying the end to the control unit 24 when the rise of the power supply voltage is completed. When the signal indicating the end of start-up of the X-th module 23 is not input, the control unit 24 returns to step S30 and executes the processes after step S30 again.

  On the other hand, when a signal indicating the end of startup of the Xth module 23 is input, the control unit 24 increments (+1) the count value of the counter (step S60). As shown in FIG. 3, when the start-up of the first module 23 is completed at time T20, the control unit 24 sets X = 2 in the counter. Since the capacitor 14 is removed, the power supply voltage drops rapidly and does not sufficiently recover even when the first module 23 is started up.

  Next, the control unit 24 determines whether or not the count value of the counter is X = (n + 1) (step S70). When the start up to the nth module 23 is completed, the count value of the counter is incremented in step S60, and X = (n + 1). That is, in step S70, it is determined whether or not all modules 23 have been started up. Since X = 2 at time T20, the process returns to step S20 to execute the subsequent processing. On the other hand, in the case of X = (n + 1), the start of all the modules 23 is completed, and thus a series of processing is completed.

  Next, the control unit 24 executes the process of step S20. Since X = 2 is set, the control unit 24 outputs an instruction signal to the buffer 25 corresponding to the second module 23 in order to supply the second module 23 with a power supply voltage and start up. As a result, the power supply voltage is supplied to the second module 23. The start-up of the second module 23 is almost the same as the start-up end of the first module 23, that is, time T20. In order to start up the second module 23, the current flowing through the entire microcomputer 11 further increases. In addition, the power supply voltage is further reduced.

  Next, the control unit 24 executes Step S30. As shown in FIG. 3, the power supply voltage falls below the second threshold value Vth2 during the startup of the second module 23, specifically at time T30. The controller 24 waits for a predetermined time t1 after determining that the power supply voltage has fallen below the second threshold value Vth2 (step S40). The predetermined time t1 is set so that a predetermined waiting time is formed between the end of the start-up of any module 23 and the start-up of the next module 23. For example, several ms is set as the predetermined time t1. During the predetermined time t1, the start-up of the second module 23 is completed at time T40. However, since the predetermined time t1 has not elapsed, the start-up of the third module 23 is not started at time T40. As shown in FIG. 3, the power supply voltage largely recovers by waiting for a predetermined time t1.

  When the predetermined time t1 has elapsed, the control unit 24 then executes step S50. Since the start-up of the second module 23 has been completed, the control unit 24 then executes step S60 and increments the count value of the counter. Thereby, X = 3. In step S70, a NO determination is made, and the control unit 24 executes step S20 again.

  Since X = 3 is set, the control unit 24 outputs an instruction signal to the buffer 25 corresponding to the third module 23 in order to supply the third module 23 with a power supply voltage and start up. As a result, the power supply voltage is supplied to the third module 23. At time T50, the start-up of the third module 23 starts. Since the third module 23 is started up, the current flowing through the entire microcomputer 11 further increases. Although the power supply voltage also decreases, the voltage at the start of startup is sufficiently restored (for example, around 5 V) due to the standby for the predetermined time t1 described above, so even if the third module 23 is started up, the power supply voltage Does not drop to the second threshold value Vth2, and thus the first threshold value Vth1 at which the microcomputer 11 is reset.

  Therefore, the control part 24 performs the process of step S50-S70. When a signal indicating the start-up end is input from the third module 23, the control unit 24 increments the count value of the counter to X = 4. Since X = 4 is not X = (n + 1), the control unit 24 executes Step S20 again.

  Since X = 4 is set, the control unit 24 outputs an instruction signal to the buffer 25 corresponding to the fourth module 23 in order to supply the fourth module 23 with a power supply voltage and start up. As a result, the power supply voltage is supplied to the fourth module 23. At time T60, the startup of the fourth module 23 starts. Since the fourth module 23 is started up, the current flowing through the entire microcomputer 11 further increases. Although the power supply voltage also decreases, the power supply voltage does not decrease to the second threshold value Vth2 and thus the first threshold value Vth1 at which the microcomputer 11 is reset even if the fourth module 23 is started by waiting for the predetermined time t1. .

  The control unit 24 repeatedly executes the above-described processing until it is determined in step S70 that the count value of the counter is X = (n + 1).

  Next, effects of the microcomputer 11 and the electronic control device 10 will be described.

  4 and 5 show a reference example (comparative example). In the description of the reference example, the same name is given to an element related to the element of this embodiment. In the reference example, regardless of the monitoring result of the monitoring circuit, the control unit controls the supply timing of the power supply voltage so that when a power supply voltage is turned on, a plurality of modules rises one by one in order and starts operation. FIG. 4 shows a state in which the capacitor is not detached and the function of suppressing the load fluctuation of the power supply voltage is normal. As shown in FIG. 4, if the function for suppressing the load fluctuation of the power supply voltage is normal, the power supply voltage is reduced to the first threshold value Vth1 even if the modules are sequentially started up without providing a standby time. do not do. That is, the microcomputer is not reset.

  However, for example, in a state where the function of suppressing the load fluctuation of the power supply voltage is reduced due to the removal of the capacitor, as shown in FIG. 5, the power supply voltage does not return at the end of the start-up of each module. The power supply voltage will drop. For this reason, the power supply voltage falls below the first threshold value Vth1 while starting up the plurality of modules, and the microcomputer is reset. FIG. 5 shows an example in which the power supply voltage falls below the first threshold value Vth1 and the microcomputer resets during the startup of the third module.

  On the other hand, in the present embodiment, the control unit 24 executes different control between the normal time and the control time of the power supply voltage based on the signal output from the monitoring circuit 20. If the power supply voltage falls below the second threshold value Vth2 when the microcomputer 11 is turned on, the control unit 24 will not supply the power supply voltage to the module 23 to be started next, and the power supply voltage will not fall below the second threshold value Vth. Delay than if. In particular, in this embodiment, the power supply voltage is supplied to the next module 23 after waiting for a predetermined time t1 from the time when it is determined that the power supply voltage has fallen below the second threshold value Vth2. That is, a predetermined standby time is provided between the end timing of the currently started module 23 and the start timing of the next started module. As a result, even if the function of suppressing the load fluctuation of the power supply voltage is reduced due to the removal of the capacitor 14, the power supply voltage is restored (increased) by the standby time. Therefore, even if the function of suppressing the load fluctuation of the power supply voltage is lowered, it is possible to prevent the microcomputer 11 from being reset due to a sudden voltage drop caused by sequentially starting up the plurality of modules 23.

(Second Embodiment)
In the present embodiment, descriptions of parts common to the microcomputer 11 and the electronic control device 10 shown in the first embodiment are omitted.

  In the first embodiment, an example in which the power supply voltage is supplied to the next module 23 after waiting for the elapse of the predetermined time t1 from the time when it is determined that the power supply voltage is lower than the second threshold value Vth2 has been described. On the other hand, in the present embodiment, when it is determined that the power supply voltage has fallen below the second threshold value Vth2, the next module is waited for a predetermined time after the startup of the module 23 being started up is completed. A power supply voltage is supplied to 23.

  As illustrated in FIG. 6, the control unit 24 executes the processes of steps S <b> 10 to S <b> 30 as in the first embodiment (FIG. 2). If it is determined in step S30 that the power supply voltage has fallen below the second threshold value Vth2, the control unit 24 determines whether or not the startup of the Xth module 23 has been completed (step S41). Step S41 is repeatedly executed until a signal indicating the end of startup of the Xth module 23 is input. When a signal indicating the end of startup of the X-th module 23 is input, the control unit 24 waits for a predetermined time t2 (step 42). The predetermined time t <b> 2 is set such that a predetermined standby state is formed between the end of the start-up of an arbitrary module 23 and the start-up of the next module 23. For example, several ms is set as the predetermined time t2.

  When the predetermined time t2 has elapsed, the control unit 24 then executes step S60. If it is determined in step S30 that the power supply voltage ≧ the second threshold value Vth2, step S50 is performed as in the first embodiment. The other points are the same as in the first embodiment.

  In FIG. 7, as in the first embodiment (FIG. 3), the capacitor 14 has dropped off, and the power supply is turned on at the time T30 during the start-up of the second module 23, specifically during the start-up of the second module 23. The case where the voltage falls below the second threshold value Vth2 is shown. As described above, in the present embodiment, when it is determined that the power supply voltage has fallen below the second threshold value Vth2, waiting for a predetermined time t2 to elapse after the startup of the second module 23 being started up is completed. Thus, the power supply voltage is supplied to the next third module 23. That is, a predetermined standby time is provided between the end timing of the second module 23 that is currently started up and the start timing of the third module that is started up next. As a result, even if the function of suppressing the load fluctuation of the power supply voltage is reduced due to the removal of the capacitor 14, the power supply voltage is restored (increased) by the standby time. Therefore, even if the function of suppressing the load fluctuation of the power supply voltage is lowered, it is possible to prevent the microcomputer 11 from being reset due to a sudden voltage drop caused by sequentially starting up the plurality of modules 23.

  In particular, in the present embodiment, when it is determined that the power supply voltage has fallen below the second threshold value Vth2, the next module 23 waits for the elapse of a predetermined time t2 after the start-up of the module 23 being started up is completed. Supply the power supply voltage. Therefore, a predetermined standby time can be more reliably provided between the end timing of the currently started module 23 and the start start timing of the next started module. Thereby, it can suppress more effectively that the microcomputer 11 resets.

(Third embodiment)
In the present embodiment, descriptions of parts common to the microcomputer 11 and the electronic control device 10 shown in the second embodiment are omitted.

  In this embodiment, after the power supply voltage falls below the second threshold value Vth2, the power supply voltage is supplied to the next module 23 after waiting for a predetermined time after the power supply voltage returns to the second threshold value Vth2.

  As illustrated in FIG. 8, the control unit 24 executes the processes of steps S <b> 10 to S <b> 30 as in the first embodiment (FIG. 2). If it is determined in step S30 that the power supply voltage has fallen below the second threshold Vth2, the control unit 24 determines whether or not the power supply voltage is equal to or higher than the second threshold Vth2 (step S43). That is, it is determined whether or not the power supply voltage has returned to the second threshold value Vth2. Step S43 is repeatedly executed until it is determined that the power supply voltage is equal to or higher than the second threshold value Vth2. When it is determined that the power supply voltage is equal to or higher than the second threshold Vth2, the control unit 24 waits for a predetermined time t3 (step S44). The predetermined time t3 is set so that a predetermined standby state is formed between the end of the start-up of an arbitrary module 23 and the start-up of the next module 23. For example, several ms is set as the predetermined time t3.

  When the predetermined time t3 has elapsed, the control unit 24 then executes step S60 as in the second embodiment. The other points are the same as in the second embodiment.

  In FIG. 9, as in the first embodiment (FIG. 3), the capacitor 14 has fallen off, and the power supply is at the time T30 during the start-up of the second module 23, specifically during the start-up of the second module 23. The case where the voltage falls below the second threshold value Vth2 is shown. In addition, the power supply voltage returns to the second threshold value Vth2 at time T41 after time T40 when the second module start-up ends. As described above, in the present embodiment, after the power supply voltage falls below the second threshold value Vth2, the next third module is waited for a predetermined time t3 after the power supply voltage returns to the second threshold value Vth2. A power supply voltage is supplied to 23. That is, a predetermined standby time is provided between the end timing of the second module 23 that is currently started up and the start timing of the third module that is started up next. As a result, even if the function of suppressing the load fluctuation of the power supply voltage is reduced due to the removal of the capacitor 14, the power supply voltage is restored (increased) by the standby time. Therefore, even if the function of suppressing the load fluctuation of the power supply voltage is lowered, it is possible to prevent the microcomputer 11 from being reset due to a sudden voltage drop caused by sequentially starting up the plurality of modules 23.

  In particular, in this embodiment, the power supply voltage is supplied to the next module 23 after waiting for a predetermined time t3 after the power supply voltage returns to the second threshold value Vth2. Therefore, the power supply voltage can be reliably increased with respect to the second threshold value Vth2 by the predetermined time t3. Thereby, it can suppress more effectively that the microcomputer 11 resets.

(Fourth embodiment)
In the present embodiment, descriptions of parts common to the microcomputer 11 and the electronic control device 10 shown in the second embodiment are omitted.

  In the present embodiment, after the power supply voltage falls below the second threshold value Vth2, when the power supply voltage returns to a predetermined third threshold value Vth3 that is set to a value higher than the second threshold value Vth2, the power supply voltage is supplied to the next module 23. Supply.

  As illustrated in FIG. 10, the control unit 24 performs the processes of steps S <b> 10 to S <b> 30 as in the first embodiment (FIG. 2). If it is determined in step S30 that the power supply voltage has fallen below the second threshold value Vth2, the control unit 24 determines whether or not the power supply voltage is greater than or equal to the third threshold value Vth3 (step S45). That is, it is determined whether or not the power supply voltage has returned to the third threshold value Vth3. In other words, the third threshold value Vth3 is a voltage stabilization threshold value. As the third threshold Vth3, a value (for example, 4V) higher than the second threshold Vth2 is set.

  Step S45 is repeatedly executed until it is determined that the power supply voltage is equal to or higher than the third threshold value Vth3. When it is determined that the power supply voltage is equal to or higher than the third threshold value Vth3, the control unit 24 executes Step S50 as in the first embodiment. The other points are the same as in the first embodiment.

  In FIG. 11, as in the first embodiment (FIG. 3), the capacitor 14 has been dropped, and the power supply is turned on at the time T30 during the start-up of the second module 23, specifically during the start-up of the second module 23. The case where the voltage falls below the second threshold value Vth2 is shown. As described above, in this embodiment, after the power supply voltage falls below the second threshold value Vth2, the power supply voltage is returned to (increased) to the third threshold value Vth3, and then the power supply voltage is applied to the next third module 23. Supply. Thereby, even if the function of suppressing the load fluctuation of the power supply voltage is reduced due to the removal of the capacitor 14, the power supply voltage is restored (increased) to the third threshold value Vth3. Therefore, even if the function of suppressing the load fluctuation of the power supply voltage is lowered, it is possible to prevent the microcomputer 11 from being reset due to a sudden voltage drop caused by sequentially starting up the plurality of modules 23.

  In particular, in the present embodiment, the power supply voltage is supplied to the next module 23 after waiting for the power supply voltage to return to the third threshold value Vth3. That is, the next module 23 is started after the power supply voltage returns to a predetermined value. Thereby, it can suppress more effectively that the microcomputer 11 resets.

  The preferred embodiments of the present invention have been described above, but the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the spirit of the present invention.

  The electronic control device 10 is not limited to the engine ECU.

  The buffer 25 may be provided in the control unit 24.

  The example in which the function of suppressing the load fluctuation of the power supply voltage is reduced by removing the capacitor 14 is shown. However, even if the capacitor 13 is removed, the function of suppressing the load fluctuation of the power supply voltage is degraded. That is, when at least one of the capacitors 13 and 14 is disconnected, the function of suppressing the load fluctuation of the power supply voltage is degraded. In addition, the function of suppressing the load fluctuation of the power supply voltage also decreases due to a decrease in the performance of the battery 100 such as aged deterioration.

DESCRIPTION OF SYMBOLS 10 ... Electronic control device, 11 ... Microcomputer, 12 ... Power supply IC, 13, 14 ... Capacitor, 20 ... Monitoring circuit, 21 ... Abnormality detection circuit, 22 ... Reset circuit, 23 ... Module, 24 ... Control part, 25 ... Buffer, 100 ... battery, 101 ... electric load

Claims (6)

A microcomputer that is supplied with a power supply voltage via a capacitor (13, 14) and executes a predetermined process,
A monitoring circuit (20) for monitoring the supplied power supply voltage;
A plurality of modules (23) each having a functional circuit;
Controls the supply timing of the power supply voltage to the module for operating the module, and controls the supply timing so that when the power supply voltage is turned on, the plurality of modules start up one after another in sequence. A control unit (24) for performing,
When the power supply voltage monitored by the monitoring circuit falls below a predetermined second threshold value (Vth2) that is set higher than the first threshold value for resetting (Vth1) at the time of turning on the power supply voltage, The microcomputer is characterized in that the control unit delays the supply timing of the power supply voltage to the module to start the operation next than the case where the power supply voltage does not fall below the second threshold value.   The control unit controls the supply timing of the power supply voltage so as to supply the power supply voltage to the next module when a predetermined time elapses after the power supply voltage monitored by the monitoring circuit falls below the second threshold value. The microcomputer according to claim 1.   When the power supply voltage monitored by the monitoring circuit is lower than the second threshold, the control unit sends the power to the next module after a predetermined time has elapsed since the start-up of the currently started up module is completed. 2. The microcomputer according to claim 1, wherein a supply timing of the power supply voltage is controlled so as to supply a voltage.   The control unit supplies the power supply voltage to the next module when a predetermined time elapses after the power supply voltage monitored by the monitoring circuit falls below the second threshold and then returns to the second threshold. 2. The microcomputer according to claim 1, wherein a supply timing of the power supply voltage is controlled.   After the power supply voltage monitored by the monitoring circuit falls below the second threshold value, the control unit returns to a predetermined third threshold value (Vth3) set to a value higher than the second threshold value. 2. The microcomputer according to claim 1, wherein a supply timing of the power supply voltage is controlled so as to supply the power supply voltage to the module. A microcomputer (11) according to any one of claims 1 to 5,
A power supply circuit (12) for outputting the power supply voltage;
Capacitors (13, 14) for stabilizing the power supply voltage;
An electronic control device comprising:

Images