JP2008070951A - Microcomputer monitoring circuit - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a microcomputer monitoring circuit monitoring a microcomputer by use of a control signal output by a power source circuit itself. <P>SOLUTION: This microcomputer monitoring circuit 300 has a reset signal output part 303 acquiring the control signal L2 used inside the power source circuit 200, and outputting a reset signal L4 to the microcomputer 100 when the control signal shows abnormality of the power source circuit. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a microcomputer monitoring circuit, and more particularly to a microcomputer monitoring circuit that uses a control signal from a power supply circuit for supplying power to the microcomputer.

  In microcomputers and the like, the allowable operating voltage range is predetermined (for example, 5V ± 5%). If the supply voltage to the microcomputer is out of the allowable operating voltage range, the microcomputer may run away or the stored contents There is a risk of a problem such as being rewritten. Therefore, a reset circuit having a detection unit for detecting the supply voltage is provided, and when the detection unit detects that the supply voltage is outside the allowable operating voltage range, a reset signal is output from the reset circuit to the reset terminal of the microcomputer. It is known to do (for example, patent document 1).

  In addition, in microcomputers with built-in rewritable memory elements such as flash ROM, the minimum operating voltage is different between the normal operation mode and the memory element rewrite operation mode. It is known that the voltage detection unit is switched according to the mode and the rewrite operation mode, and a reset signal is output to the reset terminal of the microcomputer according to the voltage detection result by the different voltage detection unit (for example, Patent Document 2). ).

  FIG. 1 is a schematic block diagram showing the configuration of such a microcomputer, a power supply circuit, and a reset circuit.

  As shown in FIG. 1, a microcomputer 10 is connected to a power supply circuit 20 that outputs a constant voltage from the battery BATT to a predetermined voltage, and a reset circuit 30. The microcomputer 10 has a built-in flash ROM 11 which is a data rewritable storage means. The microcomputer 10 has a normal operation mode (for example, a minimum operating voltage of 3.5 V) for performing a normal operation, and a flash ROM 11. The rewrite operation mode (for example, the minimum operation voltage is 4.5 V) is set. The operation mode is set by the operation mode setting switching unit 12. The reset circuit 30 includes a WDT monitoring unit 32, a reset signal output unit 33, a first voltage detection unit 34 that detects a voltage drop in the normal operation mode, and a second voltage detection unit 35 that detects a voltage drop in the rewrite operation mode. The voltage detection unit switching unit 36 and the operation mode detection unit 37 are provided. The operation mode detection unit 37 detects the state of the operation mode setting switching unit 12, and the voltage detection unit switching unit 36 determines whether the first voltage detection unit 34 or the second voltage is based on the operation mode detected by the operation mode detection unit 37. The detection unit 35 is selected. The reset signal output unit 33 includes a NOR circuit 33a that outputs an H level only when both two inputs are at an L level.

  The reset signal output unit 33 detects the abnormality detection signal from the first voltage detection unit 34 or the second voltage detection unit 35 selected by the voltage detection unit switching unit 36 and / or the abnormality detection signal from the WDT monitoring unit 32. Then, a reset signal is output to the microcomputer 10 to reset the microcomputer 10. With the reset signal, the microcomputer 10 is configured to be able to return to a normal state even when the voltage drops or when the microcomputer 10 runs away due to the influence of electrical noise or the like.

JP 6-89709 (Fig. 13) JP 2005-30818 (FIG. 1)

  In this way, in a microcomputer monitoring circuit such as a reset circuit that monitors the voltage supplied to the microcomputer, when complex control is to be performed, multiple voltage detection units and switching according to the operation mode of the microcomputer There is a problem that an increase in circuit scale and associated cost increase occur.

  Therefore, an object of the present invention is to provide a microcomputer monitoring circuit that uses a control signal output from the power supply circuit itself.

  In order to solve the above problems, the microcomputer monitoring circuit according to the present invention acquires a control signal used in the power supply circuit, and outputs a reset signal to the microcomputer when the control signal indicates an abnormality in the power supply circuit. It has a reset signal output section.

  In order to solve the above problems, in the microcomputer monitoring system according to the present invention, a power supply circuit having a control signal output unit that outputs a control signal indicating abnormality of the power supply circuit, a microcomputer that receives power supply from the power supply circuit, And a microcomputer monitoring circuit having a reset signal output unit for outputting a reset signal to the microcomputer when the control signal indicates abnormality of the power supply circuit.

  Furthermore, in order to solve the above problems, the microcomputer monitoring circuit according to the present invention acquires a status signal indicating the status of the power supply sequence of the plurality of power supply circuits, and when the status signal indicates an abnormality in the power supply sequence, the reset signal Is provided with a reset signal output unit for outputting to the microcomputer.

  According to the present invention, the control signal output from the power supply circuit itself is used to monitor the voltage supplied to the microcomputer, so that a plurality of voltage detection units and switching according to the operation mode of the microcomputer can be performed separately. There is no need to provide a part or the like, and the circuit scale can be reduced and the cost can be reduced.

  A microcomputer monitoring circuit according to the present invention will be described below with reference to the drawings.

  FIG. 2 is a schematic block diagram showing a configuration of a microcomputer monitoring system 1 including a microcomputer monitoring circuit, a microcomputer, and a power supply circuit according to the present invention.

  The microcomputer monitoring system 1 includes a microcomputer 100, a power supply circuit 200 that outputs the power from the battery BATT at a constant voltage, and a microcomputer monitoring circuit 300 that monitors the microcomputer 100.

  Further, the microcomputer 100 has a built-in flash ROM 101 which is a data rewritable storage means. The microcomputer 100 has a normal operation mode in which normal operation is performed (for example, a minimum operating voltage is 3.5 V), and a flash ROM 101. The rewriting operation mode (for example, the minimum operating voltage is 4.5 V) is set.

  The power supply circuit (regulator) 200 includes a shunt resistor 201, a boost transistor 202, a voltage control transistor 203, an overcurrent detection unit 204, a voltage control amplifier 205, a reference voltage 206, resistors 207 and 208, and the like.

  In the power supply circuit 200, the voltage control amplifier 205 controls the operation of the voltage control transistor 203 in accordance with the comparison result between the value obtained by dividing the voltage of the power supply line L1 by the resistors 207 and 208 and the reference voltage 206, and the voltage control The boost transistor 202 is controlled according to the operation of the transistor 203 for controlling, so that the voltage of the power supply line L1 becomes a predetermined voltage.

  The overcurrent detection unit 204 monitors the sense current from the boost transistor 202 and, when detecting a sense current exceeding a predetermined value, the power supply circuit 200 supplies a current exceeding the rating. The operation is performed so as to suppress the output current of the power supply circuit 200 by outputting an overcurrent detection signal. Here, an overcurrent detection signal as a control signal for the power supply circuit is output from the power supply circuit 200 to the voltage monitoring circuit 300 described later via the signal line L2.

  The microcomputer monitoring circuit 300 includes a WDT (watch dock timer) monitoring unit 302, a voltage detection unit 304 that detects a voltage drop in the normal operation mode of the microcomputer 100, a reset signal output unit 303, and the like.

  The WDT monitoring unit 302 monitors a pulse signal output from the CPU of the microcomputer 100 via the signal line L3. If the pulse signal cannot be received within a predetermined time, the WDT monitoring unit 302 indicates that an abnormality has occurred in the microcomputer 100. It judges and outputs an abnormal signal (H level).

  The voltage detector 304 monitors the voltage of the power supply line L1, and if the voltage drops below the minimum operating voltage (for example, 3.5V) in the normal operation mode in which the microcomputer operates normally, an abnormal signal is detected. (H level) is output.

  The reset signal output unit 303 includes a NOR circuit 303a that outputs an H level only when all three inputs are at an L level. The NOR circuit 303a includes an overcurrent detection signal (L2) from the overcurrent detection unit 204 of the power supply circuit 200, an abnormal signal (H level) from the WDT monitoring unit 302, and an abnormal signal (H level) from the voltage detection unit 304. ) Is input. When the reset signal output unit 303 detects an overcurrent detection signal from the overcurrent detection unit 204, an abnormal signal from the WDT monitoring unit 302, and / or an abnormal signal from the voltage detection unit 304, the reset signal output unit 303 receives the microcomputer 100 via the line L4. A reset signal (L level) is output to the reset terminal to reset the microcomputer 100. By this reset, the microcomputer 100 is configured to be able to return to a normal state even when the voltage drops or when it runs away due to the influence of electrical noise or the like.

  FIG. 3 is a diagram showing an example of signal output in the microcomputer monitoring system 1 shown in FIG.

  3A shows an example of a supply current of the power supply circuit 200, FIG. 3B shows an example of an overcurrent detection signal output from the overcurrent detection unit 204, and FIG. 3C shows a reset signal output. An example of a reset signal output from the unit 303 is shown.

  When the supply current exceeds the predetermined level s at time t1 (see FIG. 3 (a)), the overcurrent detection signal changes from the L level to the H level (see FIG. 3 (b)). Changing from the H level to the L level (see FIG. 3C), the microcomputer 100 is reset. Further, at time t2, when the supply current is reduced by the control by the overcurrent detection unit 204 and is suppressed below the predetermined level s, the overcurrent detection signal changes from the H level to the L level (see FIG. 3B). Accordingly, the reset signal changes from the L level to the H level (see FIG. 3C), and the reset of the microcomputer 100 is released.

  As described above, the microcomputer monitoring circuit 300 according to the present invention can quickly detect an abnormality in the power supply circuit 200 (an increase in supply current value) and reset the microcomputer 100, so that the microcomputer 100 can accurately detect abnormal operation or runaway. It becomes possible to prevent well. Furthermore, since the existing overcurrent detection signal from the overcurrent detection unit 204 originally provided in the power supply circuit 200 is used for resetting the microcomputer, abnormal operation of the microcomputer 100 can be performed without adding a new circuit. Or it becomes possible to prevent a runaway with high precision.

  Note that the circuit configuration for outputting the power from the battery BATT to a predetermined voltage in the power supply circuit 200 described above is an example, and the present invention can be applied to other types of power supply circuits. It is. Further, another method may be used as an overcurrent detection method in the overcurrent detection unit 204. Further, in the above example, the overcurrent detection signal from the overcurrent detection unit 204 is directly input to the NOR circuit 303a. However, the overcurrent detection signal from the overcurrent detection unit 204 is associated with the reset signal output unit 303. The current detection signal may be amplified, the voltage level may be adjusted, and the H and L levels may be inverted. Furthermore, although the microcomputer monitoring circuit 300 is configured to perform three types of microcomputer monitoring, the WDT monitoring unit 302 and the voltage detection unit 304 are not necessarily provided.

  FIG. 4 is a schematic block diagram showing the configuration of another microcomputer monitoring system 2.

  The microcomputer monitoring system 2 includes a microcomputer 100, a power supply circuit (regulator) 210 that outputs the power from the battery BATT to a predetermined voltage, and a microcomputer monitoring circuit 300 for monitoring the microcomputer 100. . In the microcomputer monitoring system shown in FIG. 4, the same components as those of the microcomputer monitoring system 2 shown in FIG.

  The microcomputer monitoring system 2 shown in FIG. 4 is different from the microcomputer monitoring system 1 shown in FIG. 2 in that the power supply circuit 210 includes a filter circuit 211 in advance, and the control signal for the power supply circuit output from the overcurrent detection unit 204. The overcurrent detection signal is input to the filter circuit 211, and the output signal of the filter circuit 211 is output to the microcomputer monitoring circuit 300 via the signal line L2. Therefore, the output signal of the filter circuit 211 is input to the NOR circuit 303a.

  The filter circuit 211 has a resistor 212, a capacitor 213, a buffer 214, etc., and when the overcurrent detection signal continues to be at H level for a predetermined period (T1), its output changes from L level to H level. And output.

  FIG. 5 is a diagram showing an example of signal output in the microcomputer monitoring system 2 shown in FIG.

  5A shows an example of the supply current of the power supply circuit 210, FIG. 5B shows an example of an overcurrent detection signal output from the overcurrent detection unit 204, and FIG. 5C shows the filter circuit 211. FIG. 5D shows an example of the reset signal output from the reset signal output unit 303.

  When the supply current exceeds the predetermined level s at time t3 (see FIG. 5A), the overcurrent detection signal changes from the L level to the H level (see FIG. 5B). After that, when the H-level overcurrent detection signal is continuously output for a predetermined period (T1), the output signal from the filter circuit 211 changes from the L level to the H level at time t4 (see FIG. 5C). Accordingly, the reset signal changes from the H level to the L level (see FIG. 5D), and the microcomputer 100 is reset.

  As described above, the microcomputer monitoring circuit 300 according to the present invention can quickly detect an abnormality (an increase in supply current value) of the power supply circuit 210 and reset the microcomputer 100, so that the microcomputer 100 can accurately detect abnormal operation or runaway. It becomes possible to prevent well. Furthermore, since the existing output signal from the filter circuit 211 originally provided in the power supply circuit 210 is used for resetting the microcomputer, it is possible to accurately detect abnormal operation or runaway of the microcomputer 100 without adding a new circuit. It becomes possible to prevent well.

  When the power supply circuit 210 has the filter circuit 211 shown in FIG. 4, the reset signal is output only when the H-level overcurrent detection signal continues for a predetermined period (T1). Therefore, when the supply current frequently fluctuates in the vicinity of the predetermined level s, the reset signal is not output unnecessarily.

  Note that the circuit configuration for outputting the power from the battery BATT to a predetermined voltage in the power supply circuit 210 described above is an example, and the present invention can be applied to other types of power supply circuits. It is. Further, another method may be used as an overcurrent detection method in the overcurrent detection unit. Furthermore, the circuit configuration example of the filter circuit 211 illustrated in FIG. 4 is also an example, and other circuit configurations can be used, or the predetermined period can be set to an optimum value according to the system. Further, in the above example, the output signal from the filter circuit 211 is directly input to the NOR circuit 303a. However, the signal is amplified or the voltage level is adjusted in accordance with the reset signal output unit 303. , H and L levels may be inverted. Further, when the power supply circuit is not provided with a filter circuit, a filter circuit may be provided in the microcomputer monitoring circuit 300.

  FIG. 6 is a schematic block diagram showing the configuration of still another microcomputer monitoring system 3.

  The microcomputer monitoring system 3 includes a microcomputer 100, a power supply circuit (regulator) 220 that outputs the power from the battery BATT to a predetermined voltage, and a microcomputer monitoring circuit 300 for monitoring the microcomputer 100. . In the microcomputer monitoring system 3 shown in FIG. 6, the same components as those in the microcomputer monitoring system 1 shown in FIG.

  The microcomputer monitoring system 3 shown in FIG. 6 is different from the microcomputer monitoring system 1 shown in FIG. 2 in that the power supply circuit 220 includes a timer circuit 221 in advance, and the control signal for the power supply circuit output from the overcurrent detection unit 204. The overcurrent detection signal is input to the timer circuit 221, and the output signal of the timer circuit 221 is output to the microcomputer monitoring circuit 300 via the signal line L2. Therefore, the output signal of the timer circuit 221 is input to the NOR circuit 303a.

  The timer circuit 221 includes a resistor 222, a capacitor 223, a buffer 224, a diode 225, and the like so that the output is held at the H level for a predetermined period T2 after the overcurrent detection signal becomes the H level. It is configured. Note that the timer circuit 221 is a circuit originally provided in the power supply circuit 220 in order to output a signal for self-repair of the power supply circuit 220.

  FIG. 7 is a diagram showing an example of signal output in the microcomputer monitoring system 3 shown in FIG.

  7A shows an example of the supply current of the power supply circuit 220, FIG. 7B shows an example of the overcurrent detection signal output from the overcurrent detection unit 204, and FIG. 7C shows the timer circuit 221. FIG. 7D shows an example of the reset signal output from the reset signal output unit 303.

  When the supply current exceeds the predetermined level s at time t5 (see FIG. 7A), the overcurrent detection signal changes from the L level to the H level (see FIG. 7B). Thereafter, when the overcurrent detection signal changes from the L level to the H level, the timer circuit 221 holds the output at the H level for a predetermined period T2 (see FIG. 7C), and accordingly, the period T2 During the period (time t5 to t6), the reset signal changes to the L level (see FIG. 7D), and the microcomputer 100 is reset.

  As described above, in the microcomputer monitoring circuit 300 according to the present invention, the abnormality of the power supply circuit 220 (the increase in the supply current value) can be detected quickly and the microcomputer 100 can be reset. It becomes possible to prevent well. Further, since the existing output signal from the timer circuit 221 originally provided in the power supply circuit 220 is used for resetting the microcomputer, it is possible to accurately detect abnormal operation or runaway of the microcomputer 100 without adding a new circuit. It becomes possible to prevent well.

  When the power supply circuit 220 includes the timer circuit 221 shown in FIG. 6, the output of the timer circuit 221 is held at the H level for a predetermined period after the overcurrent detection signal changes to the H level. Therefore, there is a further effect that the reset signal can be reliably transmitted to the microcomputer.

  Note that the circuit configuration for outputting the power from the battery BATT to a predetermined voltage in the power supply circuit 220 described above is an example, and the present invention can be applied to other types of power supply circuits. It is. Further, another method may be used as an overcurrent detection method in the overcurrent detection unit. Further, the circuit configuration example of the timer circuit 221 shown in FIG. 6 is an example, and other circuit configurations may be used, or the period T2 during which the output signal is held at the H level is set to an optimum value according to the system. Is also possible. Further, in the above example, the output signal from the timer circuit 221 is configured to be input to the NOR circuit 303a as it is. However, the signal is amplified or the voltage level is adjusted in correspondence with the reset signal output unit 303. , H and L levels may be inverted. Furthermore, when the timer circuit is not provided in the power supply circuit, a timer circuit may be provided in the microcomputer monitoring circuit 300.

  FIG. 8 is a schematic block diagram showing the configuration of still another microcomputer monitoring system 4.

  The microcomputer monitoring system 4 includes a microcomputer 100, a power supply circuit (regulator) 230 that outputs the electric power from the battery BATT to a predetermined voltage, and a microcomputer monitoring circuit 300 for monitoring the microcomputer 100. . In the microcomputer monitoring system 4 shown in FIG. 8, the same components as those of the microcomputer monitoring system 1 shown in FIG.

  The microcomputer monitoring system 4 shown in FIG. 8 is different from the microcomputer monitoring system 1 shown in FIG. 2 in that the power supply circuit 230 includes a latch circuit 231 and a reset release signal generation circuit 233 in advance, and outputs from the overcurrent detection unit 204. The overcurrent detection signal as the control signal for the power supply circuit is input to the latch circuit 231, and the output signal (Q output) of the latch circuit 231 is output to the microcomputer monitoring circuit 300 via the signal line L2, and the NOR circuit 303a. Is input.

  The latch circuit 231 includes an RS flip-flop 232 so that an overcurrent detection signal is input to the S input of the RS flip-flop 232 and a reset release signal from the reset release signal generation circuit 233 is input to the R input. It is configured. The RS flip-flop 232 functions to hold the output (Q output) at the H level during a period (T4) from when the overcurrent detection signal becomes the H level until the reset release signal becomes the H level. Note that the latch circuit 231 and the reset release signal generation circuit 233 are circuits originally provided in the power supply circuit 230 in order to output a signal for self-repair of the power supply circuit 220 and the like.

  FIG. 9 is a diagram showing an example of signal output in the microcomputer monitoring system 4 shown in FIG.

  9A shows an example of a supply current of the power supply circuit 230, FIG. 9B shows an example of an overcurrent detection signal output from the overcurrent detection unit 204, and FIG. 9C shows a reset release signal. FIG. 9D shows an example of the output (Q output) of the latch circuit 231, and FIG. 9E shows the output of the reset signal output unit 303. An example of a reset signal is shown.

  When the supply current exceeds the predetermined level s at time t5 (see FIG. 9A), the overcurrent detection signal changes from the L level to the H level (see FIG. 9B). After a predetermined period T3 (time t8) after the overcurrent detection signal changes from L level to H level, the reset release signal output from the reset release signal generation circuit 232 changes from L level to H level (FIG. 9 (c)). The latch circuit 231 sets the output (Q output) to the H level during a period (T4) from when the overcurrent detection signal changes from the L level to the H level until the reset release signal changes from the L level to the H level. Since this is held (see FIG. 9D), the reset signal changes to L level (see FIG. 9D) during the period T4 (time t7 to t8), and the microcomputer 100 is reset. .

  As described above, the microcomputer monitoring circuit 300 according to the present invention can quickly detect an abnormality in the power supply circuit 230 (an increase in supply current value) and reset the microcomputer 100, so that the microcomputer 100 can accurately detect abnormal operation or runaway. It becomes possible to prevent well. Further, since the existing output signal from the latch circuit 231 originally provided in the power supply circuit 230 is used for resetting the microcomputer, it is possible to accurately detect abnormal operation or runaway of the microcomputer 100 without adding a new circuit. It becomes possible to prevent well.

  Incidentally, when the power supply circuit 230 includes the latch circuit 231 and the reset release signal generation circuit 233 shown in FIG. 8, only the predetermined period (T3 or T4) after the overcurrent detection signal changes to the H level. Since the output (Q output) of the latch circuit 231 is held at the H level, the reset signal can be reliably transmitted to the microcomputer.

  Note that the circuit configuration for outputting the power from the battery BATT to a predetermined voltage in the power supply circuit 230 described above is an example, and the present invention can also be applied to other types of power supply circuits. It is. Further, another method may be used as an overcurrent detection method in the overcurrent detection unit. Further, the circuit configuration example of the latch circuit 231 and the reset release signal generation circuit 233 illustrated in FIG. 8 is an example, and other circuit configurations may be used, or the period T3 or T4 in which the output signal is held at the H level may be used. It is also possible to set the optimum value according to the system. In the above example, the output (Q output) of the latch circuit 231 is directly input to the NOR circuit 303a. However, the signal is amplified and the voltage level is adjusted in correspondence with the reset signal output unit 303. Or the H and L levels may be inverted. Further, when the power supply circuit is not provided with the latch circuit and the reset release signal generation circuit, the latch circuit and the reset release signal generation circuit may be provided in the microcomputer monitoring circuit 300.

  FIG. 10 is a schematic block diagram showing the configuration of still another microcomputer monitoring system 5.

  The microcomputer monitoring system 5 includes a microcomputer 100, a power supply circuit (regulator) 240 that outputs the electric power from the battery BATT to a predetermined voltage, and a microcomputer monitoring circuit 300 for monitoring the microcomputer 100. . In the microcomputer monitoring system 5 shown in FIG. 10, the same components as those in the microcomputer monitoring system 1 shown in FIG.

  The microcomputer monitoring system 5 shown in FIG. 10 is different from the microcomputer monitoring system 1 shown in FIG. 2 not based on the overcurrent detection signal of the overcurrent detection unit 204 but based on the output signal of the voltage control amplifier 205. The microcomputer 100 is reset. Therefore, in the microcomputer monitoring system 5 shown in FIG. 10, the power supply circuit 240 has the voltage control amplifier output monitor circuit 241, and the output signal of the voltage control amplifier output monitor circuit 241 as the control signal of the power supply circuit is a signal. The signal is output to the microcomputer monitoring circuit 300 via the line L2, and is input to the NOR circuit 303a.

  The voltage control amplifier output monitor circuit 241 includes an OP amplifier 242 and a reference voltage 243. The OP amplifier 242 outputs the output voltage of the voltage control amplifier 205 when the output voltage of the voltage control amplifier 205 is equal to or lower than the reference voltage 243. Since it is expected that the power supply circuit 240 will not operate normally due to an abnormality, it is configured to output an H level output signal. The voltage control amplifier output monitor circuit 241 is a circuit originally provided with the power supply circuit 240 in order to display an output abnormality of the voltage control amplifier 205 on a display unit (not shown) included in the power supply circuit 240.

  FIG. 11 is a diagram showing an example of signal output in the microcomputer monitoring system 5 shown in FIG.

  11A shows an example of an output voltage of the voltage control amplifier 205, FIG. 11B shows an example of an output signal from the voltage control amplifier output monitor circuit 241, and FIG. 11C shows a reset signal output unit. An example of the reset signal output from 303 is shown.

  When the output voltage of the voltage control amplifier 205 becomes equal to or lower than the predetermined level s at time t9 (see FIG. 11A), the output signal of the voltage control amplifier output monitor circuit 241 changes from the L level to the H level indicating the lower limit abnormality. (Refer FIG.11 (b)). When the output signal of the voltage control amplifier output monitor circuit 241 changes from L level to H level, the reset signal changes to L level (see FIG. 11C), and the microcomputer 100 is reset.

  As described above, in the microcomputer monitoring circuit 300 according to the present invention, the abnormality of the power supply circuit 240 (decrease in the output voltage of the voltage control amplifier 205) can be quickly detected and the microcomputer 100 can be reset. Or it becomes possible to prevent a runaway with high precision. Further, since the existing output signal from the voltage control amplifier output monitor circuit 241 originally provided in the power supply circuit 240 is used for resetting the microcomputer, abnormal operation of the microcomputer 100 can be performed without adding a new circuit. Or it becomes possible to prevent a runaway with high precision.

  Note that the circuit configuration for outputting the power from the battery BATT to a predetermined voltage in the power supply circuit 240 described above is an example, and the present invention can also be applied to other types of power supply circuits. It is. Another method may be used as a method for detecting the output voltage of the voltage control amplifier 205. Furthermore, the circuit configuration example of the voltage control amplifier output monitor circuit 241 illustrated in FIG. 10 is an example, and other circuit configurations may be used. Further, in the above example, the output signal of the voltage control amplifier output monitor circuit 241 is input to the NOR circuit 303a as it is. However, the signal is amplified or the voltage level is set corresponding to the reset signal output unit 303. It may be adjusted or the H and L levels may be inverted. Further, when the power supply circuit is not originally provided with the voltage control amplifier output monitor circuit, a voltage control amplifier output monitor circuit may be provided in the microcomputer monitoring circuit 300.

  By the way, if the predetermined level (threshold) s that determines the lower limit abnormality of the output of the voltage control amplifier 205 is set so as to correspond to, for example, the minimum operating voltage (4.5 V) in the rewriting operation mode in which the rewriting operation of the flash ROM 101 is performed. If the output signal of the voltage control amplifier output monitor circuit in the power supply circuit 240 is used in place of the second voltage detection unit 35 shown in FIG. 1, the voltage detection switching unit 36 and the operation mode detection unit 37 shown in FIG. 1 is provided, the microcomputer monitoring circuit 300 can have the same function as the reset circuit 30 shown in FIG.

  Further, the output signal of the voltage control amplifier output monitor circuit 241 is input to the filter circuit 211 shown in FIG. 4, the timer circuit 221 shown in FIG. 6 or the latch circuit 231 shown in FIG. 8, and the output signal from each circuit is reset. You may comprise so that it may input into the output part 303. FIG.

  FIG. 12 is a schematic block diagram showing the configuration of still another microcomputer monitoring system 6.

  The microcomputer monitoring system 6 includes a microcomputer 100, a power supply circuit (regulator) 250 that outputs the electric power from the battery BATT to a predetermined voltage, and a microcomputer monitoring circuit 300 for monitoring the microcomputer 100. . In the microcomputer monitoring system 6 shown in FIG. 12, the same components as those of the microcomputer monitoring system 1 shown in FIG.

  The microcomputer monitoring system 6 shown in FIG. 12 is different from the microcomputer monitoring system 1 shown in FIG. 2 not based on the overcurrent detection signal of the overcurrent detection unit 204 but based on the output signal of the voltage control amplifier 205. The microcomputer 100 is reset. Therefore, in the microcomputer monitoring system 6 shown in FIG. 12, the power supply circuit 250 has the voltage control amplifier output monitor circuit 251, and the output signal of the voltage control amplifier output monitor circuit 251 as the control signal of the power supply circuit is a signal. The signal is output to the microcomputer monitoring circuit 300 via the line L2, and is input to the NOR circuit 303a.

  The voltage control amplifier output monitor circuit 251 includes an OP amplifier 252 and a reference voltage 253. The OP amplifier 252 outputs the output voltage of the voltage control amplifier 205 when the output voltage of the voltage control amplifier 205 is equal to or higher than the reference voltage 253. Since it is expected that the power supply circuit 250 will not operate normally due to an abnormality, the power supply circuit 250 is configured to output an H level output signal. The voltage control amplifier output monitor circuit 251 is a circuit originally provided with the power supply circuit 250 in order to display an output abnormality of the voltage control amplifier 205 on a display unit (not shown) included in the power supply circuit 250.

  FIG. 13 is a diagram showing an example of signal output in the microcomputer monitoring system 6 shown in FIG.

  13A shows an example of an output voltage of the voltage control amplifier 205, FIG. 13B shows an example of an output signal from the voltage control amplifier output monitor circuit 251, and FIG. 13C shows a reset signal output unit. An example of the reset signal output from 303 is shown.

  When the output voltage of the voltage control amplifier 205 becomes equal to or higher than the predetermined level s at time t10 (see FIG. 13A), the output signal of the voltage control amplifier output monitor circuit 251 changes from the L level to the H level indicating the upper limit abnormality. (See FIG. 13B). When the output signal of the voltage control amplifier output monitor circuit 251 changes from L level to H level, the reset signal changes to L level (see FIG. 13C), and the microcomputer 100 is reset.

  As described above, in the microcomputer monitoring circuit 300 according to the present invention, an abnormality in the power supply circuit 250 (an increase in the output voltage of the voltage control amplifier 205) can be detected quickly and the microcomputer 100 can be reset. Or it becomes possible to prevent a runaway with high precision. Further, since the existing output signal from the voltage control amplifier output monitor circuit 251 originally provided in the power supply circuit 250 is used for resetting the microcomputer, abnormal operation of the microcomputer 100 can be performed without adding a new circuit. Or it becomes possible to prevent a runaway with high precision.

  The circuit configuration for outputting the power from the battery BATT to a predetermined voltage in the power supply circuit 250 described above is an example, and the present invention can be applied to other types of power supply circuits. It is. Another method may be used as a method for detecting the output voltage of the voltage control amplifier 205. Furthermore, the circuit configuration example of the voltage control amplifier output monitor circuit 251 shown in FIG. 12 is an example, and other circuit configurations may be used. Further, in the above example, the output signal of the voltage control amplifier output monitor circuit 251 is input to the NOR circuit 303a as it is. However, the signal is amplified or the voltage level is set corresponding to the reset signal output unit 303. It may be adjusted or the H and L levels may be inverted. Further, when the power supply circuit is not originally provided with the voltage control amplifier output monitor circuit, a voltage control amplifier output monitor circuit may be provided in the microcomputer monitoring circuit 300.

  Further, the output signal of the voltage control amplifier output monitor circuit 251 is input to the filter circuit 211 shown in FIG. 4, the timer circuit 221 shown in FIG. 6, or the latch circuit 231 shown in FIG. 8, and the output signal from each circuit is reset. You may comprise so that it may input into the output part 303. FIG.

  FIG. 14 is a schematic block diagram showing the configuration of still another microcomputer monitoring system 7.

  The microcomputer monitoring system 7 includes a microcomputer 100, a power supply circuit (regulator) 260 that outputs the power from the battery BATT to a predetermined voltage, and a microcomputer monitoring circuit 300 that monitors the microcomputer 100. . In the microcomputer monitoring system 7 shown in FIG. 14, the same components as those in the microcomputer monitoring system 1 shown in FIG.

  The microcomputer monitoring system 7 shown in FIG. 14 differs from the microcomputer monitoring system 1 shown in FIG. 2 not based on the overcurrent detection signal of the overcurrent detection unit 204 but on the output signal of the overheat detection circuit of the power supply circuit. Thus, the microcomputer 100 is reset. Therefore, in the microcomputer monitoring system 7 shown in FIG. 14, the power supply circuit 260 has the overheat detection circuit 261, and the output signal of the overheat detection circuit 261 as a control signal for the power supply circuit is sent to the microcomputer via the signal line L2. It is output to the monitoring circuit 300. Therefore, the output signal of the overheat detection circuit 261 is input to the NOR circuit 303a.

  The overheat detection circuit 261 includes an inverter 262, a temperature sensor 263 as a current source, a transistor 264, resistors 265 and 266, a reference voltage 267, and the like. When the output current from the temperature sensor 263 exceeds a predetermined value, The output of the voltage control amplifier 205 is reduced so that an output that prevents overheating of the power supply circuit 260 is performed. The overheat detection circuit 261 is a circuit originally provided in the power supply circuit 260 as one of safety measures for the power supply circuit 260.

  FIG. 15 is a diagram showing an example of signal output in the microcomputer monitoring system 7 shown in FIG.

  15A shows an example of a temperature change of the power supply circuit 260, FIG. 15B shows an example of an output signal from the overheat detection circuit 261, and FIG. 15C is output from the reset signal output unit 303. An example of the reset signal is shown.

  When the temperature of the power supply circuit 260 becomes equal to or higher than the predetermined level s at time t11 (see FIG. 15A), the output signal of the overheat detection circuit 261 changes from L level to H level indicating a temperature abnormality (FIG. 15B). )reference). When the output signal of the overheat detection circuit 261 changes from the L level to the H level, the reset signal changes accordingly to the L level (see FIG. 15C), and the microcomputer 100 is reset.

  As described above, in the microcomputer monitoring circuit 300 according to the present invention, the abnormality (temperature rise) of the power supply circuit 260 can be detected quickly and the microcomputer 100 can be reset. It becomes possible. Furthermore, since the existing output signal from the overheat detection circuit 261 originally provided in the power supply circuit 260 is used for resetting the microcomputer, abnormal operation or runaway of the microcomputer 100 can be performed without adding a new circuit. It becomes possible to prevent with high accuracy.

  Note that the circuit configuration for outputting the power from the battery BATT to a predetermined voltage in the power supply circuit 260 described above is an example, and the present invention can be applied to other types of power supply circuits. It is. Further, other methods may be used as the temperature detection method of the power supply circuit. Furthermore, the circuit configuration example of the overheat detection circuit 261 is an example, and other circuit configurations may be used. Further, in the above example, the output signal of the overheat detection circuit 261 is configured to be input to the NOR circuit 303a as it is. However, the signal is amplified or the voltage level is adjusted in correspondence with the reset signal output unit 303. , H and L levels may be inverted. Furthermore, if the power supply circuit is not provided with an overheat detection circuit, an overheat detection circuit may be provided in the microcomputer monitoring circuit 300.

  Further, the output signal of the overheat detection circuit 261 is input to the filter circuit 211 shown in FIG. 4, the timer circuit 221 shown in FIG. 6 or the latch circuit 231 shown in FIG. 8, and the output signal from each circuit is reset signal output unit 303. You may comprise so that it may input into.

  FIG. 16 is a schematic block diagram showing the configuration of still another microcomputer monitoring system 8.

  The microcomputer monitoring system 8 includes a microcomputer 100, a power supply circuit (switching regulator) 400, and a microcomputer monitoring circuit 300 for monitoring the microcomputer 100. In the microcomputer monitoring system 8 shown in FIG. 16, the same components as those in the microcomputer monitoring system 1 shown in FIG.

  The microcomputer monitoring system 8 shown in FIG. 16 is different from the microcomputer monitoring system 1 shown in FIG. 2 in that the type of the power supply circuit 400 is different and not based on the overcurrent detection signal of the overcurrent detection unit. The microcomputer 100 is reset based on the output signal of the charge pump output monitor circuit 430 that monitors the charge pump power source 405. Therefore, in the microcomputer monitoring system 8 shown in FIG. 16, the power supply circuit 400 has the charge pump output monitor circuit 430, and the output signal of the charge pump output monitor circuit 430 as the control signal of the power supply circuit is the signal line L2. Are output to the microcomputer monitoring circuit 300 and input to the NOR circuit 303a.

  A power supply circuit (switching regulator) 400 includes a pulse power supply 401, an OP amplifier 402, an overcurrent detection unit 403, a logic circuit 404, a charge pump power supply 405, a buffer 406, a MOS switching transistor 407, an input voltage source 408, and a Schottky barrier diode. 409, a coil 410, a smoothing capacitor 411, a voltage control circuit 420, a charge pump output monitor circuit 430, and the like. The voltage control circuit 420 includes a voltage control amplifier 421, resistors 422 and 423, a reference voltage 424, and the like.

In the power supply circuit 400, the switching transistor 407 is controlled so as to switch power at a high frequency, and DC power smoothed by the smoothing capacitor 411 is supplied through a filter including a diode 409 and a coil 410. Further, the voltage control circuit 420 compares the voltage of the output signal line L1 with the resistance-divided reference voltage, and outputs a control signal to the OP amplifier 402 so as to be a predetermined voltage.
The charge pump output monitor circuit 430 includes resistors 431 and 432, an OP amplifier 433, a reference voltage 434, and the like. The charge pump output monitor circuit 430 determines that the power supply circuit 400 may not be able to supply power normally when the output of the charge pump power supply 405 falls below a predetermined level. It is configured to output a monitor signal. The charge pump output monitor circuit 430 is a circuit originally intended for maintenance provided in the power supply circuit 400 in order to monitor the output abnormality of the charge pump power supply 405.

  FIG. 17 is a diagram showing an example of signal output in the microcomputer monitoring system 8 shown in FIG.

  17A shows an example of the output voltage of the charge pump power supply 405, FIG. 17B shows an example of the charge pump output monitor signal from the charge pump output monitor circuit 430, and FIG. 17C shows the reset signal. An example of a reset signal output from the output unit 303 is shown.

  When the output voltage of the charge pump power supply 405 becomes equal to or lower than the predetermined level s at time t12 (see FIG. 17A), the charge pump output monitor signal changes from L level to H level indicating an output voltage abnormality (FIG. 17 ( b)). When the charge pump output monitor signal changes from L level to H level, the reset signal changes to L level (refer to FIG. 17C), and the microcomputer 100 is reset.

  As described above, in the microcomputer monitoring circuit 300 according to the present invention, the abnormality of the power supply circuit 400 (decrease in the output voltage of the charge pump power supply 405) can be quickly detected and the microcomputer 100 can be reset. Or it becomes possible to prevent a runaway with high precision. Further, since the existing charge pump output monitor signal from the charge pump output monitor circuit 430 originally provided in the power supply circuit 400 is used for resetting the microcomputer, there is no need to add a new circuit. Abnormal operation or runaway can be accurately prevented.

  Note that the circuit configuration for outputting the power to a predetermined voltage in the power supply circuit 400 described above is an example, and the present invention can be applied to other types of power supply circuits. Another method may be used as a method for detecting the output voltage of the charge pump power supply 405. Furthermore, the circuit configuration example of the charge pump output monitor circuit 430 illustrated in FIG. 16 is merely an example, and other circuit configurations may be used. Further, in the above example, the output signal of the charge pump output monitor circuit 430 is directly input to the NOR circuit 303a. However, the signal is amplified or the voltage level is adjusted in accordance with the reset signal output unit 303. Or the H and L levels may be inverted. Further, when the power supply circuit is not provided with a charge pump output monitor circuit, a charge pump output monitor circuit may be provided in the microcomputer monitoring circuit 300.

  Further, the output signal of the charge pump output monitor circuit 430 is input to the filter circuit 211 shown in FIG. 4, the timer circuit 221 shown in FIG. 6, or the latch circuit 231 shown in FIG. 8, and the output signal from each circuit is output as a reset signal. It may be configured to input to the unit 303.

  FIG. 18 is a schematic block diagram showing the configuration of still another microcomputer monitoring system 9.

  The microcomputer monitoring system 9 includes a microcomputer 100, a power supply circuit (switching regulator) 500, and a microcomputer monitoring circuit 300 for monitoring the microcomputer 100. In the microcomputer monitoring system 9 shown in FIG. 18, the same components as those of the microcomputer monitoring system 8 shown in FIG.

  The microcomputer monitoring system 9 shown in FIG. 18 differs from the microcomputer monitoring system 8 shown in FIG. 16 on the basis of the switching pulse monitor signal, not the output signal of the charge pump output monitor circuit 430 that monitors the charge pump power supply 405. The microcomputer 100 is reset. Therefore, in the microcomputer monitoring system 9 shown in FIG. 18, the power supply circuit 500 has the switching pulse monitor circuit 510, and the switching pulse monitor signal as the control signal of the power supply circuit is transmitted via the signal line L2. 300 is input to the NOR circuit 303a.

  The switching pulse monitor circuit 510 includes a frequency / voltage conversion circuit 511, a first OP amplifier 512, a first reference voltage 513, a second OP amplifier 514, a second reference voltage 515, an OR circuit 516, and the like. The switching pulse monitor circuit 510 is configured to monitor the switching pulse of the pulse power supply 401 and change and output the switching pulse monitor signal from the L level to the H level when a frequency abnormality occurs. In the frequency / voltage conversion circuit 511, the switching pulse of the pulse power supply 401 is changed to a voltage corresponding to the frequency, the first OP amplifier 512 compares the voltage with the first reference voltage, and the voltage is larger than the first reference voltage. In other words, when the output pulse frequency of the pulse power supply 401 is higher than a predetermined range, the first OP amplifier 512 outputs an H level, the second OP amplifier 514 compares the voltage with the second reference voltage, and the second reference When the voltage is smaller than the voltage (that is, the output pulse frequency of the pulse power supply 401 is smaller than the predetermined range), the second OP amplifier 514 outputs an H level. When the H level signal is output from the first or second OP amplifier, the output of the OR circuit 516 becomes H level. The switching pulse monitor circuit 510 is a circuit originally intended for maintenance provided in the power supply circuit 500 in order to monitor the output abnormality of the output pulse of the pulse power supply 401.

  FIG. 19 is a diagram showing a signal output example in the microcomputer monitoring system 9 shown in FIG.

  19A shows an example of an output pulse of the pulse power supply 401, FIG. 19B shows an example of a switching pulse monitor signal from the switching pulse monitor circuit 510, and FIG. 19C shows a reset signal output unit 303. 2 shows an example of a reset signal output from.

  When the output of the pulse power supply 401 becomes lower than the predetermined frequency at time t13 (see FIG. 19A), the switching pulse monitor signal changes from L level to H level indicating frequency abnormality (see FIG. 19B). Further, when the output of the pulse power supply 401 becomes higher than a predetermined frequency at time t14 (see FIG. 19A), the switching pulse monitor signal changes from L level to H level indicating frequency abnormality (see FIG. 19B). ). When the switching pulse monitor signal changes from L level to H level, the reset signal changes to L level (see FIG. 19C), and the microcomputer 100 is reset.

  As described above, in the microcomputer monitoring circuit 300 according to the present invention, the abnormality of the power supply circuit 500 (the abnormality of the frequency of the output pulse of the pulse power supply 405) can be quickly detected and the microcomputer 100 can be reset. Or it becomes possible to prevent a runaway with high precision. Furthermore, since the existing switching pulse monitor signal from the switching pulse monitor circuit 510 originally provided in the power supply circuit 500 is used for resetting the microcomputer, abnormal operation of the microcomputer 100 can be performed without adding a new circuit. Or it becomes possible to prevent a runaway with high precision.

  Note that the circuit configuration for outputting the power to a predetermined voltage in the power supply circuit 500 described above is an example, and the present invention can be applied to other types of power supply circuits. Further, another method may be used as a frequency detection method of the output pulse of the pulse power supply 401. Further, the circuit configuration example of the switching pulse monitor circuit 510 illustrated in FIG. 18 is an example, and other circuit configurations may be used. Further, in the above example, the output signal of the switching pulse monitor circuit 510 is directly input to the NOR circuit 303a. However, the signal is amplified or the voltage level is adjusted in accordance with the reset signal output unit 303. Alternatively, the H and L levels may be inverted. Further, when the switching pulse monitor circuit is not provided in the power supply circuit, the switching pulse monitor circuit may be provided in the microcomputer monitoring circuit 300.

  Further, the output signal of the switching pulse monitor circuit 510 is input to the filter circuit 211 shown in FIG. 4, the timer circuit 221 shown in FIG. 6, or the latch circuit 231 shown in FIG. 8, and the output signal from each circuit is reset signal output unit It may be configured to input to 303.

  FIG. 20 is a schematic block diagram showing the configuration of still another microcomputer monitoring system 10.

  The microcomputer monitoring system 10 includes a microcomputer 100, a power supply circuit (switching regulator) 600, and a microcomputer monitoring circuit 300 for monitoring the microcomputer 100. In the microcomputer monitoring system 10 shown in FIG. 20, the same components as those in the microcomputer monitoring system 8 shown in FIG.

  The microcomputer monitoring system 10 shown in FIG. 20 is different from the microcomputer monitoring system 8 shown in FIG. 16 in that it is not the output signal of the charge pump output monitor circuit 430 that monitors the charge pump power supply 405 but the output pulse of the pulse power supply 405 and switching. The microcomputer 100 is reset based on a pulse monitor signal for monitoring the synchronization deviation with the gate signal pulse of the transistor 407. When the output pulse of the pulse power supply 405 and the gate signal pulse of the switching transistor 407 are out of synchronization, the power supply circuit 600 may not operate normally, and the microcomputer is controlled to be reset. Therefore, in the microcomputer monitoring system 10 shown in FIG. 20, the power supply circuit 600 has the pulse monitor circuit 610, and the pulse monitor signal as the control signal of the power supply circuit is sent to the microcomputer monitoring circuit 300 via the signal line L2. Is output and input to the NOR circuit 303a.

  The pulse monitor circuit 610 includes a phase comparator 611, a transistor 612, a drive power supply 614, a resistor 613, a capacitor 615, a reference voltage 616, and an OP amplifier that compare the phases of the output pulse of the pulse power supply 405 and the gate signal pulse of the switching transistor 407. When the phase comparator detects a phase shift, the transistor 612 is turned on and the output of the OP amplifier 617 (that is, the pulse monitor signal) is changed to the H level. Note that the pulse monitor circuit 610 is a circuit originally intended for maintenance provided in the power supply circuit 600 in order to monitor a synchronization error between the output pulse of the pulse power supply 405 and the gate signal pulse of the switching transistor 407.

  FIG. 21 is a diagram showing an example of signal output in the microcomputer monitoring system 10 shown in FIG.

  21A shows an example of an output pulse of the pulse power supply 401, FIG. 21B shows an example of a gate signal pulse of the switching transistor 407, and FIG. 21C shows a pulse monitor signal from the pulse monitor circuit 610. FIG. 21D shows an example of the reset signal output from the reset signal output unit 303.

  When a synchronization error between the output pulse of the pulse power source 405 and the gate signal pulse of the switching transistor 407 is detected at time t15 (see FIGS. 21A and 21B), the pulse monitor signal is synchronized from the L level. It changes to the H level indicating the deviation (see FIG. 21C). When the pulse monitor signal changes from L level to H level, the reset signal changes to L level (see FIG. 21D), and the microcomputer 100 is reset.

  As described above, in the microcomputer monitoring circuit 300 according to the present invention, the abnormality (pulse synchronization shift) of the power supply circuit 600 can be detected quickly and the microcomputer 100 can be reset, so that the abnormal operation or runaway of the microcomputer 100 can be accurately detected. It becomes possible to prevent. Further, since the existing pulse monitor signal from the pulse monitor circuit 610 originally provided in the power supply circuit 600 is used for resetting the microcomputer, abnormal operation or runaway of the microcomputer 100 can be performed without adding a new circuit. Can be accurately prevented.

  Note that the above-described power supply circuit 600 has an example of a circuit configuration for outputting electric power after making the voltage constant to a predetermined voltage, and the present invention can be applied to other types of power supply circuits. Also, other methods may be used as a method for detecting synchronization loss. Further, the circuit configuration example of the pulse monitor circuit 610 illustrated in FIG. 20 is an example, and other circuit configurations may be used. Furthermore, in the above example, the output signal of the pulse monitor circuit 610 is directly input to the NOR circuit 303a. However, the signal is amplified or the voltage level is adjusted in correspondence with the reset signal output unit 303. , H and L levels may be inverted. Further, when the power supply circuit is not provided with a pulse monitor circuit, a pulse monitor circuit may be provided in the microcomputer monitoring circuit 300.

  Further, the output signal of the pulse monitor circuit 610 is input to the filter circuit 211 shown in FIG. 4, the timer circuit 221 shown in FIG. 6 or the latch circuit 231 shown in FIG. 8, and the output signal from each circuit is reset signal output unit 303. You may comprise so that it may input into.

  FIG. 22 is a schematic block diagram showing the configuration of still another microcomputer monitoring system 11.

  The microcomputer monitoring system 11 includes a microcomputer 100, a first power supply circuit 700, a second power supply circuit 701, a third power supply circuit 703, and a microcomputer monitoring circuit 310 for monitoring the microcomputer 100.

  The first power supply circuit 700 is a power supply circuit for supplying, for example, a backup 1.5V voltage to the microcomputer 100 via the first power supply line L1, and the second power supply circuit 701 is, for example, a main 1 The third power supply circuit 702 supplies, for example, the main 5V voltage to the microcomputer 100 via the second power supply line L2, and the third power supply circuit 702 supplies the main 5V voltage to the microcomputer 100 via the third power supply line L3. It is a power supply circuit for providing. The configurations of the first to third power supply circuits 700 to 702 are the same as those of the power supply circuit 200 shown in FIG.

  The microcomputer monitoring circuit 310 includes a WDT monitoring circuit 312, a reset signal output unit 313, and a sequence control unit 314.

  The WDT monitoring unit 312 monitors a pulse signal output from the CPU of the microcomputer 100 via the signal line L4. If the pulse signal cannot be received within a predetermined time, an abnormality has occurred in the microcomputer 100. It judges and outputs an abnormal signal (H level).

  The sequence control unit 314 is configured to monitor and activate the first to third power supply circuits and to output an abnormality signal (H level) when an abnormality such as a power supply sequence as described later is detected. ing.

  The reset signal output unit 313 includes a NOR circuit 313a that outputs an H level only when both inputs are at an L level. The NOR circuit 313a is configured to receive an abnormal signal (H level) from the WDT monitoring unit 312 and an abnormal signal (H level) from the sequence control unit 314. When the reset signal output unit 313 detects an abnormal signal from the WDT monitoring unit 312 and / or an abnormal signal from the sequence control unit 314, the reset signal output unit 313 sends a reset signal (L level) to the reset terminal of the microcomputer 100 via the signal line L5. To output and reset the microcomputer 100. By this reset, the microcomputer 100 is configured to be able to return to a normal state even when the voltage drops or when it runs away due to the influence of electrical noise or the like.

  The sequence control unit 314 detects the start permission signal to the first to third power supply circuits and / or the output voltage of the first to third power supply circuits as a status signal, and at the time of starting the first to third power supply circuits, When the output voltage of any of the first to third power supply circuits decreases after startup and when the startup permission to the first to third power supply circuits is lost, the status signal indicates an abnormality in the power supply sequence. An abnormal signal (H level) is output. The sequence control unit 314 controls the activation order of the first to third power supply circuits according to the power supply sequence. The power supply sequence is, for example, first permitting activation of the first power supply circuit, and then permitting activation of the second power supply circuit when the output voltage of the first power supply circuit becomes a predetermined value or higher, and then secondly. When the output voltage of the power supply circuit becomes equal to or higher than a predetermined value, the third power supply circuit is allowed to start up. The control operation such as completing.

  FIG. 23 is a diagram showing an example of signal output in the microcomputer monitoring system 11 shown in FIG.

  FIG. 23A shows an example of a start permission signal from the sequence control unit 314 to the first power supply circuit 700, FIG. 23B shows an example of the output voltage of the first power supply circuit 700, and FIG. Shows an example of a start permission signal from the sequence control unit 314 to the second power supply circuit 701, FIG. 23 (d) shows an example of the output voltage of the second power supply circuit 701, and FIG. 23 (e) shows the sequence control unit 314. FIG. 23F shows an example of the output voltage of the third power supply circuit 702, and FIG. 23G is outputted from the reset signal output unit 313. An example of a reset signal is shown.

  23, at time t16, the output voltage of the first power supply circuit 700 starts to rise in synchronization with the activation permission signal to the first power supply circuit 700 becoming H level (see FIG. 23A). . At time t17, in synchronization with the output voltage of the first power supply circuit 700 reaching the predetermined level s1 (see FIG. 23B), the activation permission signal to the second power supply circuit 701 becomes H level (see FIG. 23). 23 (c)), the output voltage of the second power supply circuit 701 starts to rise in synchronization with it. At time t18, in synchronization with the output voltage of the second power supply circuit 701 reaching the predetermined level s2 (see FIG. 23D), the activation permission signal to the third power supply circuit 702 becomes H level (see FIG. 23). 23 (e)), the output voltage of the third power supply circuit 702 starts to rise in synchronization with the above. At time t19, the sequence control unit 314 changes the abnormal signal from the H level to the L level in synchronization with the output voltage of the third power supply circuit 702 reaching the predetermined level s3 (see FIG. 23 (f)). In synchronization therewith, the reset signal changes from the L level to the H level (see FIG. 23G), and the reset of the microcomputer 100 is released.

  As described above, the sequence control unit 314 activates the first to third power supply circuits in accordance with the power supply sequence when the first to third power supply circuits are activated, and outputs an abnormal signal (H level) during that time to the reset output unit. It outputs to 313 and the microcomputer 100 is maintained in a reset state.

  In addition, the sequence control unit 314 monitors the output voltage of the first to third power supply circuits after the first to third power supply circuits are activated, and also when any of the output voltages decreases (for example, at time t20). ), An abnormal signal (H level) is output to the reset output unit 313, and the microcomputer 100 is reset (see FIGS. 23B and 23G).

  FIG. 24 is a diagram showing another example of signal output in the microcomputer monitoring system 11 shown in FIG.

  FIG. 24A shows an example of a start permission signal from the sequence control unit 314 to the first power supply circuit 700, FIG. 24B shows an example of the output voltage of the first power supply circuit 700, and FIG. Shows an example of a start permission signal from the sequence control unit 314 to the second power supply circuit 701, FIG. 24D shows an example of the output voltage of the second power supply circuit 701, and FIG. 24E shows the sequence control unit 314. FIG. 24F shows an example of the output voltage of the third power supply circuit 702, and FIG. 24G is output from the reset signal output unit 313. An example of a reset signal is shown.

  The power supply sequence until the first to third power supply circuits in FIG. 24 are activated is the same as that in FIG. In FIG. 24, even when the activation permission signal to the second power supply circuit drops to L level for some reason (see FIG. 24C), the sequence control unit 314 changes the abnormal signal from L level to H level. Therefore, the reset signal is changed from the H level to the L level in synchronization therewith (see FIG. 24G), and the microcomputer 100 is reset.

  As described with reference to FIG. 22 to FIG. 24, the sequence control unit 314 includes the plurality of power supply circuits when the output voltage of any of the plurality of power supply circuits is reduced at the time of starting the plurality of power supply circuits and after the start-up. When the activation permission is lost, an abnormal signal (H level) is output, so that the microcomputer monitoring circuit 310 can properly monitor the plurality of power supply circuits and appropriately reset the microcomputer 100. .

It is the schematic block diagram which showed the structure of the conventional power supply circuit and a reset circuit. It is the schematic block diagram which showed the structure of the microcomputer monitoring system containing the microcomputer monitoring circuit which concerns on this invention. It is the figure which showed the signal output example in the microcomputer monitoring system shown in FIG. It is the schematic block diagram which showed the structure of the other microcomputer monitoring system containing the microcomputer monitoring circuit which concerns on this invention. It is the figure which showed the signal output example in the microcomputer monitoring system shown in FIG. It is the schematic block diagram which showed the structure of the further another microcomputer monitoring system containing the microcomputer monitoring circuit which concerns on this invention. It is the figure which showed the example of a signal output in the microcomputer monitoring system shown in FIG. It is the schematic block diagram which showed the structure of the further another microcomputer monitoring system containing the microcomputer monitoring circuit which concerns on this invention. It is the figure which showed the signal output example in the microcomputer monitoring system shown in FIG. It is the schematic block diagram which showed the structure of the further another microcomputer monitoring system containing the microcomputer monitoring circuit which concerns on this invention. It is the figure which showed the example of a signal output in the microcomputer monitoring system shown in FIG. It is the schematic block diagram which showed the structure of the further another microcomputer monitoring system containing the microcomputer monitoring circuit which concerns on this invention. It is the figure which showed the signal output example in the microcomputer monitoring system shown in FIG. It is the schematic block diagram which showed the structure of the further another microcomputer monitoring system containing the microcomputer monitoring circuit which concerns on this invention. It is the figure which showed the signal output example in the microcomputer monitoring system shown in FIG. It is the schematic block diagram which showed the structure of the further another microcomputer monitoring system containing the microcomputer monitoring circuit which concerns on this invention. It is the figure which showed the signal output example in the microcomputer monitoring system shown in FIG. It is the schematic block diagram which showed the structure of the further another microcomputer monitoring system containing the microcomputer monitoring circuit which concerns on this invention. It is the figure which showed the example of a signal output in the microcomputer monitoring system shown in FIG. It is the schematic block diagram which showed the structure of the further another microcomputer monitoring system containing the microcomputer monitoring circuit which concerns on this invention. It is the figure which showed the example of a signal output in the microcomputer monitoring system shown in FIG. It is the schematic block diagram which showed the structure of the other microcomputer monitoring system containing the other microcomputer monitoring circuit which concerns on this invention. It is the figure which showed the example of a signal output in the microcomputer monitoring system shown in FIG. It is the figure which showed the other signal output example in the microcomputer monitoring system shown in FIG.

Explanation of symbols

1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11 Microcomputer monitoring system 100 Microcomputer 200, 210, 220, 230, 240, 250, 260, 400, 500, 600, 700, 701, 702 Power supply circuit 204 Overcurrent detection unit 211 Filter circuit 221 Timer circuit 231 Latch circuit 241 251 Voltage control amplifier output monitor circuit 261 Overheat detection circuit 300 Microcomputer monitoring circuit 302 WDT monitoring unit 303 Reset signal output unit 304 Voltage detection unit 314 Sequence control Unit 410 charge pump output monitor circuit 510 switching pulse monitor circuit 610 pulse monitor circuit

Claims (10)

A microcomputer monitoring circuit for monitoring a microcomputer supplied with power from a power circuit,
A microcomputer monitor, comprising: a reset signal output unit that obtains a control signal used in the power supply circuit and outputs a reset signal to the microcomputer when the control signal indicates an abnormality in the power supply circuit circuit.   The microcomputer monitoring circuit according to claim 1, wherein the control signal is an overcurrent detection signal of the power supply circuit.   The microcomputer monitoring circuit according to claim 1, wherein the control signal is a voltage control amplifier output monitor signal of the power supply circuit.   The microcomputer monitoring circuit according to claim 1, wherein the control signal is an overheat detection signal of the power supply circuit.   The microcomputer monitoring circuit according to claim 1, wherein the control signal is a charge pump output monitor signal of the power supply circuit.   The microcomputer monitoring circuit according to claim 1, wherein the control signal is a switching pulse monitor signal of the power supply circuit. A microcomputer monitoring circuit for monitoring a microcomputer supplied with power from a plurality of power supply circuits,
It has a reset signal output unit that obtains a status signal indicating the status of a power supply sequence of the plurality of power supply circuits, and outputs a reset signal to the microcomputer when the status signal indicates an abnormality in the power supply sequence. A microcomputer monitoring circuit.   The reset signal output unit outputs the reset signal to the microcomputer in response to an output signal of a filter circuit that outputs a signal only when the control signal continuously shows a malfunction for a predetermined period. The microcomputer monitoring circuit according to any one of 7.   The reset signal output unit outputs the reset signal to the microcomputer according to an output signal of a timer circuit that continuously outputs a signal for a predetermined period when the control signal indicates abnormality. A microcomputer monitoring circuit according to any one of the above.   The reset signal output unit outputs the reset signal to the microcomputer according to an output signal of a latch circuit that continuously outputs a signal for a predetermined period when the control signal indicates abnormality. A microcomputer monitoring circuit according to any one of the above.

Images