JP2017195654A - Protection circuit self-diagnosis device and protection circuit diagnostic method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a protection circuit self-diagnosis device and a protection circuit diagnostic method which allow for self-diagnosis of a protection circuit with simple configuration.SOLUTION: An overcurrent protection circuit self-diagnosis device includes a first comparator 10 for detecting abnormality, a second comparator 12 for detecting abnormality, and a control section for switching the self-diagnosis period of the first comparator 10 and the self-diagnosis period of the second comparator 12 alternately, performing self-diagnosis of the first comparator 10 by using an output signal OUTD1 therefrom while the second comparator 12 is performing abnormality detection operation, during self-diagnosis period of the first comparator 10, and performing self-diagnosis of the second comparator 12 by using an output signal OUTD2 therefrom while the first comparator 10 is performing abnormality detection operation, during self-diagnosis period of the second comparator 12.SELECTED DRAWING: Figure 1

Description

  The present embodiment relates to a protection circuit self-diagnosis device and a protection circuit diagnosis method for self-diagnosis of a protection circuit such as an overcurrent protection circuit and an overvoltage protection circuit.

  Standards for safety functions (for example, fail-safe functions, abnormality detection functions, safety stop functions, etc.) for all parts mounted on automobiles are being reviewed. In particular, many in-vehicle devices are electrically / electronically controlled, and not only high performance and high functionality but also safety are important needs.

  An international standard ISO 26262 that systematically summarizes development methods and management methods for safe in-vehicle devices has been formulated (for example, see Non-Patent Document 1).

"ISO 26262-1: 2011", [online], 2011-11-15, International Organization for Standardization, [Search February 17, 2016], Internet <URL: https://www.iso.org/obp / ui / # iso: std: iso: 26262: -1: ed-1: v1: en>

  Incidentally, the electronic circuit includes a protection circuit for detecting various abnormalities such as an overcurrent protection circuit and an overvoltage protection circuit. Since such a protection circuit operates only when there is an abnormality unlike a circuit that performs basic operations, it is very difficult to confirm that the protection circuit operates reliably after a shipping test. In the past, in order to ensure that the protection circuit operates in a mode that would cause a fatal operation failure if the protection circuit did not operate, it was necessary to arrange redundant circuits and monitor circuits separately and perform mutual monitoring There was a problem in terms of cost.

  The present embodiment provides a protection circuit self-diagnosis device and a protection circuit diagnosis method capable of self-diagnosis of the protection circuit with a simple configuration.

  According to one aspect of the present embodiment, a first protection circuit that detects an abnormality, a second protection circuit that detects the abnormality, a self-diagnosis period of the first protection circuit, and a self-diagnosis of the second protection circuit During the self-diagnosis period of the first protection circuit, the first protection circuit is self-examined using the output signal of the first protection circuit while the second protection circuit is performing an abnormality detection operation. Control for self-diagnosis of the second protection circuit using the output signal of the second protection circuit while the first protection circuit is performing an abnormality detection operation during the self-diagnosis period of the second protection circuit A protection circuit self-diagnosis device comprising a unit is provided.

  According to another aspect of the present embodiment, the switching step of alternately switching the self-diagnosis period of the first protection circuit and the second protection circuit for detecting an abnormality, and during the self-diagnosis period of the first protection circuit, The first protection circuit performs self-diagnosis using the output signal of the first protection circuit while the second protection circuit performs an abnormality detection operation, and the first protection circuit is in a self-diagnosis period of the second protection circuit. There is provided a protection circuit self-diagnosis method including a control step of self-diagnosis of the second protection circuit using an output signal of the second protection circuit while the circuit is performing an abnormality detection operation.

  According to the present embodiment, it is possible to provide a protection circuit self-diagnosis device and a protection circuit diagnosis method capable of self-diagnosis of the protection circuit with a simple configuration.

It is explanatory drawing of the overcurrent protection circuit self-diagnosis apparatus which concerns on embodiment, (a) Typical circuit block block diagram, (b) The graph which shows the relationship between a monitor voltage and a reference voltage. The flowchart which shows roughly the operation example of the overcurrent protection circuit self-diagnosis apparatus which concerns on embodiment. 1 is a schematic circuit block configuration diagram of an overcurrent protection circuit self-diagnosis device according to Embodiment 1. FIG. 4 is a timing chart when the overcurrent protection circuit self-diagnosis device shown in FIG. 3 performs self-diagnosis, and (a) monitor voltage ΔV, first reference voltage ΔV1, second reference voltage ΔV2, and (b) control. Signals IND1, IND2, (c) output signals OUTD1, OUTD2, (d) output signal OUT. FIG. 6 is a schematic circuit block configuration diagram of an overvoltage protection circuit self-diagnosis device according to a second embodiment. 6 is a timing chart when the overvoltage protection circuit self-diagnosis device shown in FIG. 5 performs self-diagnosis, in which (a) a monitor voltage Vm, a first reference voltage Vt1, a second reference voltage Vt2, and (b) control signals IND1, IND2; (C) Output signal OUTD1, OUTD2, (d) Output signal OUT. FIG. 3 is a schematic internal configuration diagram of a main part of an on-vehicle electronic control system to which the overcurrent protection circuit self-diagnosis device according to the first embodiment or the overvoltage protection circuit self-diagnosis device according to the second embodiment can be applied. FIG. 3 is a schematic configuration diagram of an example in which a switching power supply connected to an overcurrent protection circuit self-diagnosis device according to a first embodiment or an overvoltage protection circuit self-diagnosis device according to a second embodiment is applied to an I2C bus. FIG. 6 is a schematic configuration diagram in which the overcurrent protection circuit self-diagnosis device according to the first embodiment or the overvoltage protection circuit self-diagnosis device according to the second embodiment is applied to a system that supplies power to a load circuit.

  Next, embodiments of the present invention will be described with reference to the drawings. In the following description of the drawings, the same or similar parts are denoted by the same or similar reference numerals. However, it should be noted that the drawings are schematic, and the relationship between the thickness and the planar dimensions, the ratio of the thickness of each layer, and the like are different from the actual ones. Therefore, specific thicknesses and dimensions should be determined in consideration of the following description. Moreover, it is a matter of course that portions having different dimensional relationships and ratios are included between the drawings.

  Further, the embodiments described below exemplify apparatuses and methods for embodying the technical idea of the present invention, and the embodiments of the present invention include the material, shape, structure, The layout is not specified as follows. Various modifications can be made to the embodiment of the present invention within the scope of the claims.

[Embodiment]
(Overcurrent protection circuit)
First, the overcurrent protection circuit will be described. Overcurrent protection (OCP: Over Current Protection) is a function that limits the output current when the output current flows more than a limit value to prevent IC or load burnout.

Specifically, as shown in FIG. 1A, the power supply voltage Vcc is divided by resistors R1 and R2 to obtain a voltage V ′, and the monitor voltage ΔV generated by the current I flowing through the resistor Rm is changed to two. The signals are input to the comparators (comparators) 10 and 12 and compared with the reference voltages ΔV1 and ΔV2. The values of the reference voltages ΔV1 and ΔV2 can be adjusted by control signals ΔV1_CTR and ΔV2_CTR from a control unit (not shown) such as a microcomputer. As shown in FIG. 1B, when the monitor voltage ΔV exceeds the value _VMON of the reference voltages ΔV1 and ΔV2, the output current is limited to prevent IC and load burnout.

  Since such an overcurrent protection circuit operates only when there is an abnormality, unlike a circuit that performs basic operations, it is very difficult to confirm that it operates reliably after a shipping test. In the present embodiment, the following configuration is employed to perform self-diagnosis of the overcurrent protection circuit with a simple configuration.

(Overcurrent protection circuit self-diagnosis device)
An overcurrent protection circuit self-diagnosis device according to an embodiment includes a first protection circuit that detects an abnormality, a second protection circuit that detects an abnormality, a self-diagnosis period of the first protection circuit, and a self-diagnosis of the second protection circuit. During the self-diagnosis period of the first protection circuit, the first protection circuit performs self-diagnosis using the output signal of the first protection circuit while the second protection circuit performs an abnormality detection operation. And a control unit that self-diagnose the second protection circuit using the output signal of the second protection circuit while the first protection circuit is performing an abnormality detection operation during the self-diagnosis period of the two protection circuit.

  Specifically, as shown in FIG. 1A, the first protection circuit is a first comparator 10 that compares the first reference voltage ΔV1 and the monitor voltage ΔV, and the second protection circuit is a second protection circuit. The second comparator 12 compares the reference voltage ΔV2 with the monitor voltage ΔV, and the control unit variably controls the first reference voltage ΔV1 during the self-diagnosis period of the first comparator 10, and outputs the first comparator 10 The first comparator 10 is self-diagnosed using the signal OUTD1, the second reference voltage ΔV2 is variably controlled during the self-diagnosis period of the second comparator 12, and the second comparator 12 is output using the output signal OUTD2 of the second comparator 12. May be self-diagnosed.

  Further, the first AND circuit 14 to which the output signal OUTD1 of the first comparator 10 and the control signal IND1 of the control unit are input, and the second AND circuit 16 to which the output signal OUTD2 of the second comparator 12 and the control signal IND2 of the control unit are input. And an OR circuit 18 to which the output signal of the first AND circuit 14 and the output signal of the second AND circuit 16 are input, and the control unit may detect an abnormality using the output signal OUT of the OR circuit 18.

  More specifically, the control unit inputs a control signal IND1 having a low level “0” to the first AND circuit 14 and changes the first reference voltage ΔV1 during the self-diagnosis period of the first comparator 10. As a result of inputting ΔV1_CTR to the first comparator 10, if the output signal OUTD1 of the first comparator 10 has a period of high level “1”, it is self-diagnosed that there is no problem in the operation of the first comparator 10, and the second During the self-diagnosis period of the comparator 12, the control signal IND2 having a low level “0” is input to the second AND circuit 16, and the control signal ΔV2_CTR for changing the second reference voltage ΔV2 is input to the second comparator 12. When the output signal OUTD2 of the second comparator 12 has a high level “1” period, the second comparator That there is no problem with the operation of the motor 12 may be self-diagnosis.

  Further, the control unit may detect an abnormality when the output signal OUT of the OR circuit 18 is at a high level “1”.

  In addition, when a problem occurs in the operation of one of the first protection circuit and the second protection circuit, the control unit may continue the protection function using only the other protection circuit.

  The first protection circuit and the second protection circuit may include an overcurrent protection circuit that detects an overcurrent.

  The first protection circuit and the second protection circuit may include an overvoltage protection circuit that detects an overvoltage.

  The first protection circuit and the second protection circuit may include a low voltage protection circuit that detects a low voltage.

  The first protection circuit and the second protection circuit may include an overtemperature protection circuit that detects overtemperature.

(Operation example of overcurrent protection circuit self-diagnosis device)
FIG. 2 schematically shows an operation example of the overcurrent protection circuit self-diagnosis device according to the embodiment.

  First, the control unit starts supplying the power supply voltage Vcc (step S101) and starts a timer operation (step S102). Then, the self-diagnosis period of the first comparator 10 and the self-diagnosis period of the second comparator 12 are alternately switched based on the count value of the timer (step S103).

  Specifically, during the self-diagnosis period of the first comparator 10, the first comparator 10 is self-diagnosed using the output signal OUTD1 of the first comparator 10 while the second comparator 12 is performing an abnormality detection operation (step S1). S104, S107). The abnormality detection operation means an original operation (normal operation) of the protection circuit. If it is found that there is a problem with the operation of the first comparator 10 during the self-diagnosis period of the first comparator 10, a response process when the problem occurs is executed (steps S105 → S106 → S103). When the second comparator 12 detects an abnormality, a response process when the abnormality occurs is executed (steps S108 → S109 → S103).

  On the other hand, during the self-diagnosis period of the second comparator 12, the second comparator 12 is self-diagnosed using the output signal OUTD2 of the second comparator 12 while the first comparator 10 is performing an abnormality detection operation (steps S110 and S113). ). If it is found that there is a problem in the operation of the second comparator 12 during the self-diagnosis period of the second comparator 12, a response process when the problem occurs is executed (steps S114 → S115 → S103). Further, when the first comparator 10 detects an abnormality, a response process when the abnormality occurs is executed (steps S111 → S112 → S103).

[Example 1]
Next, the overvoltage protection circuit self-diagnosis device according to the first embodiment will be described.

(Overcurrent protection circuit diagnostic device)
As illustrated in FIG. 3, the overcurrent protection circuit diagnostic device according to the first embodiment compares the first reference voltage ΔV1 with the monitor voltage ΔV, the second reference voltage ΔV2, and the monitor voltage ΔV. The second comparator 12, the first AND circuit 14 to which the output signal OUTD1 of the first comparator 10 and the control signal IND1 of the control unit are input, the output signal OUTD2 of the second comparator 12 and the control signal IND2 of the control unit are input. A second AND circuit 16, an OR circuit 18 to which the output signal of the first AND circuit 14 and the output signal of the second AND circuit 16 are input, and a control unit (not shown) such as a microcomputer are provided. The basic configuration is as described with reference to FIG.

(Operation example of overcurrent protection circuit diagnostic device)
FIG. 4 is a timing chart when the overcurrent protection circuit self-diagnosis device shown in FIG. 3 performs self-diagnosis. Specifically, FIG. 4A shows the monitor voltage ΔV, the first reference voltage ΔV1 of the first comparator 10, and the second reference voltage ΔV2 of the second comparator 12. FIG. 4B shows the control signals IND1 and IND2. FIG. 4C shows the output signal OUTD1 of the first comparator 10 and the output signal OUTD2 of the second comparator 12. FIG. 4D shows the output signal OUT of the OR circuit 18.

  First, as shown in FIG. 4A, the control unit sets the first reference voltage ΔV1 of the first comparator 10 to a range of, for example, 0V to 1.5V using the control signal ΔV1_CTR during the time t1 to t4. Sweep with. The range to be swept is not particularly limited as long as there is a time during which the monitor voltage ΔV exceeds the first reference voltage ΔV1. Here, the case where the monitor voltage ΔV is higher than the first reference voltage ΔV1 is illustrated for the time t2 to t3. On the other hand, during the time t1 to t4, the second reference voltage ΔV2 of the second comparator 12 is set to a value at the time of abnormality detection operation such as 1.5V, for example.

  Further, as shown in FIG. 4B, the control unit sets the control signal IND1 input to the first AND circuit 14 to the low level “0” during the time t1 to t4. In this way, a period in which the control signal IND1 is at the low level “0” is referred to as “a self-diagnosis period of the first comparator 10”. During the self-diagnosis period t1 to t4 of the first comparator 10, the control signal IND2 input to the second AND circuit 16 is set to the high level “1”.

  As a result, as shown in FIG. 4C, the output signal OUTD1 of the first comparator 10 is at the high level “1” only during the times t2 to t3 among the times t1 to t4. In this case, since the times t2 to t3 when the monitor voltage ΔV exceeds the first reference voltage ΔV1 are correctly detected, the self-diagnosis can be performed if there is no problem in the operation of the first comparator 10. On the other hand, during the time t1 to t4, the second comparator 12 is performing an abnormality detection operation, and the monitor voltage ΔV is always lower than the second reference voltage ΔV2. Therefore, the output signal OUTD2 of the second comparator 12 is low level “ It remains “0”.

  As a result, as shown in FIG. 4D, the output signal OUT of the OR circuit 18 remains at the low level “0” during the time t1 to t4, and the overcurrent occurrence report signal ND cannot be obtained. Since the output signal OUTD1 of the first comparator 10 during the self-diagnosis is not transmitted to the subsequent stage from the OR circuit 18, it does not affect the detection of the overcurrent.

  When it is found that there is no problem in the operation of the first comparator 10, the control unit causes the first comparator 10 to perform an abnormality detection operation and self-diagnose the second comparator 12. Specifically, as shown in FIG. 4A, the second reference voltage ΔV2 of the second comparator 12 is set within a range of 0V to 1.5V, for example, using the control signal ΔV2_CTR during the time t4 to t7. Sweep. The range to be swept is not particularly limited as long as there is a time during which the monitor voltage ΔV exceeds the second reference voltage ΔV2. Here, the case where the monitor voltage ΔV exceeds the second reference voltage ΔV2 is illustrated for the time t5 to t6. On the other hand, during the time t4 to t7, the first reference voltage ΔV1 of the first comparator 10 is set to a value at the time of the abnormality detection operation such as 1.5V, for example.

  Further, as shown in FIG. 4B, the control unit sets the control signal IND2 input to the second AND circuit 16 to the low level “0” during the time t4 to t7. In this way, a period in which the control signal IND2 is at the low level “0” is referred to as “a self-diagnosis period of the second comparator 12”. During the self-diagnosis period t4 to t7 of the second comparator 12, the control signal IND1 input to the first AND circuit 14 is kept at the high level “1”.

  As a result, as shown in FIG. 4C, the output signal OUTD2 of the second comparator 12 is at the high level “1” only during the time t5 to t6 in the time t4 to t7. In this case, since the times t5 to t6 when the monitor voltage ΔV exceeds the second reference voltage ΔV2 are correctly detected, it is possible to make a self-diagnosis if there is no problem in the operation of the second comparator 12. On the other hand, during the time t4 to t7, the first comparator 10 is performing an abnormality detection operation, and the monitor voltage ΔV is always lower than the first reference voltage ΔV1, so the output signal OUTD1 of the first comparator 10 is low level “ It remains “0”.

  As a result, as shown in FIG. 4D, the output signal OUT of the OR circuit 18 remains at the low level “0” during the time t4 to t7, and the overcurrent occurrence report signal ND cannot be obtained. Since the output signal OUTD2 of the second comparator 12 during the self-diagnosis is not transmitted to the subsequent stage from the OR circuit 18, it does not affect the detection of the overcurrent.

  When it is found that there is no problem in the operation of the second comparator 12, the control unit causes the second comparator 12 to perform an abnormality detection operation and self-diagnose the first comparator 10. Thereafter, the same operation is repeated until a problem is found in the operation of the first comparator 10 or the second comparator 12.

  As described above, according to the overcurrent protection circuit self-diagnosis device according to the first embodiment, the operation of the other comparator is checked while monitoring the current by causing one comparator to detect an abnormality. An overcurrent can be detected by using a comparator that has taken off. Further, since the number of parts required for checking the operation is small and the configuration is simple, the cost is excellent.

[Example 2]
Next, an overvoltage protection circuit self-diagnosis device according to Embodiment 2 will be described. Overvoltage protection (OVP) is a function that protects the output voltage so that it does not exceed the load withstand voltage for some reason.

(Overvoltage protection circuit self-diagnosis device)
As shown in FIG. 5, the overvoltage protection circuit self-diagnosis device according to the second embodiment compares the first reference voltage Vt1 and the monitor voltage Vm, the second reference voltage Vt2 and the monitor voltage Vm. The second comparator 12, the first AND circuit 14 to which the output signal OUTD1 of the first comparator 10 and the control signal IND1 of the control unit are input, the output signal OUTD2 of the second comparator 12 and the control signal IND2 of the control unit are input. A second AND circuit 16, an OR circuit 18 to which the output signal of the first AND circuit 14 and the output signal of the second AND circuit 16 are input, and a control unit (not shown) such as a microcomputer are provided. Except for detecting the overvoltage, it is the same as the first embodiment.

(Operation example of overvoltage protection circuit diagnostic device)
FIG. 6 is a timing chart when the overvoltage protection circuit self-diagnosis device shown in FIG. 5 performs self-diagnosis. Specifically, FIG. 6A shows the monitor voltage Vm, the first reference voltage Vt1 of the first comparator 10, and the second reference voltage Vt2 of the second comparator 12. FIG. 6B shows the control signals IND1 and IND2. FIG. 6C shows the output signal OUTD1 of the first comparator 10 and the output signal OUTD2 of the second comparator 12. FIG. 6D shows the output signal OUT of the OR circuit 18.

  First, as shown in FIG. 6A, the control unit uses the control signal Δt1_CTR to set the first reference voltage Vt1 of the first comparator 10 in the range of 0V to 1.5V, for example, during the time t1 to t4. Sweep. The range to be swept is not particularly limited as long as the monitor voltage Vm exceeds the first reference voltage Vt1. Here, a case where the monitor voltage Vm exceeds the first reference voltage Vt1 during the time t2 to t3 is illustrated. On the other hand, during the time t1 to t4, the second reference voltage Vt2 of the second comparator 12 is set to a value at the time of abnormality detection operation such as 1.5V, for example.

  Further, as shown in FIG. 6B, the control unit sets the control signal IND1 input to the first AND circuit 14 to the low level “0” during the time t1 to t4. In this way, a period in which the control signal IND1 is at the low level “0” is referred to as “a self-diagnosis period of the first comparator 10”. During the self-diagnosis period t1 to t4 of the first comparator 10, the control signal IND2 input to the second AND circuit 16 is set to the high level “1”.

  Accordingly, as shown in FIG. 6C, the output signal OUTD1 of the first comparator 10 is at the high level “1” only during the time t2 to t3 in the time t1 to t4. In this case, since the times t2 to t3 when the monitor voltage Vm exceeds the first reference voltage Vt1 are correctly detected, it is possible to make a self-diagnosis if there is no problem in the operation of the first comparator 10. On the other hand, during the time t1 to t4, the second comparator 12 is performing an abnormality detection operation, and the monitor voltage Vm is always lower than the second reference voltage Vt2. Therefore, the output signal OUTD2 of the second comparator 12 is low level “0”. It remains.

  As a result, as shown in FIG. 6D, the output signal OUT of the OR circuit 18 remains at the low level “0” during the time t1 to t4, and the overvoltage occurrence report signal ND cannot be obtained. Since the output signal OUTD1 of the first comparator 10 during the self-diagnosis is not transmitted to the subsequent stage from the OR circuit 18, it does not affect the detection of the overvoltage.

  When it is found that there is no problem in the operation of the first comparator 10, the control unit causes the first comparator 10 to perform an abnormality detection operation and self-diagnose the second comparator 12. Specifically, as shown in FIG. 6A, the second reference voltage Vt2 of the second comparator 12 is swept in the range of 0V to 1.5V, for example, using the control signal Δt2_CTR during the time t4 to t7. Let The sweep range is not particularly limited as long as the monitor voltage Vm exceeds the second reference voltage Vt2. Here, a case where the monitor voltage Vm exceeds the second reference voltage Vt2 during the time t5 to t6 is illustrated. On the other hand, during the time t4 to t7, the first reference voltage Vt1 of the first comparator 10 is set to a value at the time of abnormality detection operation such as 1.5V, for example.

  Further, as shown in FIG. 6B, the control unit sets the control signal IND <b> 2 input to the second AND circuit 16 to the low level “0” during the time t <b> 4 to t <b> 7. In this way, a period in which the control signal IND2 is at the low level “0” is referred to as “a self-diagnosis period of the second comparator 12”. During the self-diagnosis period t4 to t7 of the second comparator 12, the control signal IND1 input to the first AND circuit 14 is kept at the high level “1”.

  Accordingly, as shown in FIG. 6C, the output signal OUTD2 of the second comparator 12 is at the high level “1” only during the time t5 to t6 in the time t4 to t7. In this case, since the times t5 to t6 when the monitor voltage Vm exceeds the second reference voltage Vt2 are correctly detected, it is possible to make a self-diagnosis if there is no problem in the operation of the second comparator 12. On the other hand, during the time t4 to t7, the first comparator 10 is performing an abnormality detection operation, and the monitor voltage Vm is always lower than the first reference voltage Vt1, and therefore the output signal OUTD1 of the first comparator 10 is at the low level “0”. It remains.

  As a result, as shown in FIG. 6D, the output signal OUT of the OR circuit 18 remains at the low level “0” between the times t4 and t7, and the overvoltage occurrence report signal ND cannot be obtained. Since the output signal OUTD2 of the second comparator 12 during self-diagnosis is not transmitted to the subsequent stage from the OR circuit 18, it does not affect the detection of overvoltage.

  When it is found that there is no problem in the operation of the second comparator 12, the control unit causes the second comparator 12 to perform an abnormality detection operation and self-diagnose the first comparator 10. Thereafter, the same operation is repeated until a problem is found in the operation of the first comparator 10 or the second comparator 12.

  As described above, according to the overvoltage protection circuit self-diagnosis device according to the second embodiment, the operation of the other comparator is confirmed while the voltage is monitored by causing one comparator to perform an abnormality detection operation. An overvoltage can be detected using a comparator. Further, since the number of parts required for checking the operation is small and the configuration is simple, the cost is excellent.

  Here, the case where there is no problem in the operation of the first comparator 10 and the second comparator 12 is illustrated, but when a problem occurs, this is immediately detected on the control unit side, and the part is immediately replaced. be able to. In addition, the protection function can be continued using only a comparator without any problem until the parts are replaced.

  Further, the current monitor circuit and the voltage monitor circuit can be used together, or the difference between the value of the first comparator 10 and the value of the second comparator 12 can be detected. Therefore, it is possible to construct a highly reliable system with a small number of redundant circuits.

  Further, here, the first comparator 10 and the second comparator 12 are exemplified, but the number of protection circuits is not limited to two, and may be three or more. Of course, in terms of a simple configuration with a small number of parts, it is preferable to alternately switch the two protection circuits.

  In addition, although overcurrent protection (OCP) and overvoltage protection (OVP) are illustrated here, protection circuits such as undervoltage protection (UVLO) and overtemperature protection (OTP) It is possible to apply to the same.

[Application example]
(Electronic control system for vehicles)
FIG. 7 schematically illustrates a configuration example of an on-vehicle electronic control system to which the overcurrent protection circuit self-diagnosis device according to the first embodiment or the overvoltage protection circuit self-diagnosis device according to the second embodiment can be applied.

  The in-vehicle electronic control system includes an SoC (System-on-Chip) 200 in which necessary systems are integrated on one semiconductor chip, and a microcomputer (microcomputer) connected to the SoC 200 via an SoC system bus 90. ) A (50A), microcomputer B (50B), microcomputer C (50C), microcomputer A (50A), microcomputer B (50B), power supply unit A (100A) connected to microcomputer C (50C), power supply A supply unit B (100B) and a power supply unit C (100C) are provided.

  The power supply unit A (100A) supplies the voltage V1 to the power IC (1A), supplies the voltage V2 to the power IC (2A), and supplies the voltage V3 to the power IC (3A). Similarly, the power supply unit B (100B) supplies the voltage V1 to the power IC (1B), supplies the voltage V2 to the power IC (2B), and supplies the voltage V3 to the power IC (3B). The power supply unit C (100C) supplies the voltage V1 to the power IC (1C), supplies the voltage V2 to the power IC (2C), and supplies the voltage V3 to the power IC (3C).

  Here, the voltage V1 is, for example, 3.3V, the voltage V2 is, for example, 1.8V, and the voltage V3 is, for example, 1.2V.

  The power supply unit A (100A), the power supply unit B (100B), and the power supply unit C (100C) are respectively the power supply unit 110, the control circuit 20, the timer 30, and the voltage comparators C1 and C2. And a determination unit 40.

  In normal times, the microcomputer A (50A), the microcomputer B (50B), and the microcomputer C (50C) are respectively connected to the power supply unit A (100A), the power supply unit B (100B), and the power supply unit C (100C). Enable signals ENA, ENB, and ENC, which are control signals for enabling the power supply function, are output to the enable terminal EN.

  Further, when the power supply units A (100A), B (100B), and C (100C) detect an abnormality (a sign) during the power supply operation, the microcomputers A (50A), B (50B), and C (50C) In response to this, an abnormality occurrence report signal (not shown) for reporting the occurrence of the abnormality is output. In response to the abnormality occurrence report signal, the microcomputers A (50A), B (50B), and C (50C) output the interrupt signal IRQ to the SoC 200 and the power supply units A (100A) and B (100B). ), A disable signal (not shown), which is a control signal for invalidating the power supply function, is output to C (100C). The power supply units A (100A), B (100B), and C (100C) that have received the disable signal are power ICs (1A, 2A, 3A), (1B, 2B, 3B), (1C, 2C, 3C). Stop power supply to.

  FIG. 8 schematically illustrates a configuration example in which the switching power supply 100 connected to the overcurrent protection circuit self-diagnosis device according to the first embodiment or the overvoltage protection circuit self-diagnosis device according to the second embodiment is applied to an I2C bus.

  The switching power supply 100 includes a power supply unit (Vcc) 110, a control circuit 20, a timer 30, a voltage comparator C (C1, C2), and an abnormality determination unit (abnormality determination block) 40. The switching power supply 100 supplies power to the power IC1 and IC2 via the I2C bus. An overcurrent occurrence report signal ND may be input to the switching power supply 100 from the overcurrent protection circuit self-diagnosis device (OCP) according to the first embodiment, or the overvoltage protection circuit self according to the second embodiment. An overvoltage occurrence report signal ND may be input from the diagnostic device (OVP).

  FIG. 9 schematically illustrates an example in which the overcurrent protection circuit self-diagnosis device according to the first embodiment or the overvoltage protection circuit self-diagnosis device according to the second embodiment is applied to a system that supplies power to the load 15. The power supply system includes an engine control unit (ECU) microcomputer 50, a control circuit 20, a power supply unit 110, a low-pass filter (L1 · Co), and a load 15 such as a speaker. The overcurrent occurrence report signal ND may be input to the control circuit 20 in FIG. 9 from the overcurrent protection circuit self-diagnosis device (OCP) according to the first embodiment, or the overvoltage according to the second embodiment. An overvoltage occurrence report signal ND may be input from the protection circuit self-diagnosis device (OVP). The output of the control circuit 20 is connected to the positive (+) input of the comparator 111, while the negative (−) input of the comparator 111 is supplied with an output voltage as the reference voltage VREF.

  The power supply unit 110 includes a comparator 111, a PWM modulator 112, a driver 113, and a driver output stage 114.

  In normal times, the ECU microcomputer 50 outputs an enable signal ENS, which is a control signal for enabling the power supply function, to the control circuit 20 from the enable terminal EN. Upon receiving the enable signal ENS, the control circuit 20 supplies a control signal for enabling the power supply function to the comparator 111.

  When the control circuit 20 detects an abnormality (a sign) during the power supply operation, the control circuit 20 notifies the ECU microcomputer 50 of the abnormality occurrence report signal (overcurrent occurrence report signal ND or overvoltage occurrence report signal ND). Etc.) is output. In response to the abnormality occurrence report signal, the ECU microcomputer 50 outputs a disable signal (not shown), which is a control signal for invalidating the power supply function, to the control circuit 20. Upon receiving the disable signal, the control circuit 20 supplies a control signal that disables the power supply function to the comparator 111, thereby stopping the power supply.

  As described above, according to the present embodiment, it is possible to provide a protection circuit self-diagnosis device and a protection circuit diagnosis method capable of self-diagnosis of the protection circuit with a simple configuration.

[Other embodiments]
As described above, the embodiments have been described. However, it should not be understood that the description and drawings constituting a part of this disclosure limit the present invention. From this disclosure, various alternative embodiments, examples and operational techniques will be apparent to those skilled in the art.

  As described above, the present invention naturally includes various embodiments not described herein. Therefore, the technical scope of the present invention is defined only by the invention specifying matters according to the scope of claims reasonable from the above description.

  The protection circuit self-diagnosis device according to the present embodiment can be applied to an overcurrent protection circuit, an overvoltage protection circuit, a low voltage protection circuit, and an overtemperature protection circuit. In addition, the present invention can be applied to electronic devices in various fields such as automobiles, aircraft, ships, railways, rockets, medical equipment, industrial machines, and robots.

10: First comparator (first protection circuit)
12 ... Second comparator (second protection circuit)
DESCRIPTION OF SYMBOLS 14 ... 1st AND circuit 16 ... 2nd AND circuit 18 ... OR circuit IND1 ... Control signal IND2 of control part ... Control signal OUTD1 of control part ... Output signal OUTD2 of 1st comparator ... Output signal (DELTA) V, Vm ... of 2nd comparator Voltages ΔV1, Vt1... First reference voltage ΔV2, Vt2... Second reference voltage

Claims (20)

A first protection circuit for detecting an abnormality;
A second protection circuit for detecting the abnormality;
The self-diagnosis period of the first protection circuit and the self-diagnosis period of the second protection circuit are alternately switched, and during the self-diagnosis period of the first protection circuit, the second protection circuit is performing an abnormality detection operation. Self-diagnosis of the first protection circuit is performed using an output signal of the first protection circuit, and during the self-diagnosis period of the second protection circuit, the second protection circuit operates while detecting an abnormality. A control circuit self-diagnosis device comprising: a control unit that performs self-diagnosis of the second protection circuit using an output signal of the protection circuit. The first protection circuit includes a first comparator that compares a first reference voltage and a monitor voltage,
The second protection circuit includes a second comparator that compares the second reference voltage with the monitor voltage,
The controller is
In the self-diagnosis period of the first comparator, the first reference voltage is variably controlled, and the first comparator is self-diagnosed using an output signal of the first comparator,
The self-diagnosis of the second comparator is performed by variably controlling the second reference voltage during the self-diagnosis period of the second comparator and using the output signal of the second comparator. The protective circuit self-diagnosis device described. A first AND circuit to which an output signal of the first comparator and a control signal of the control unit are input;
A second AND circuit to which the output signal of the second comparator and the control signal of the control unit are input;
An OR circuit to which an output signal of the first AND circuit and an output signal of the second AND circuit are input;
The protection circuit self-diagnosis device according to claim 2, wherein the control unit detects the abnormality using an output signal of the OR circuit. The controller is
In the self-diagnosis period of the first comparator, as a result of inputting a low level control signal to the first AND circuit and inputting a control signal for changing the first reference voltage to the first comparator, the first comparator If there is a high level period in the output signal of the comparator, self-diagnosis that there is no problem in the operation of the first comparator,
In the self-diagnosis period of the second comparator, a low level control signal is input to the second AND circuit, and a control signal for changing the second reference voltage is input to the second comparator. 4. The protection circuit self-diagnosis device according to claim 3, wherein when a high-level period exists in the output signal of the comparator, self-diagnosis is performed if there is no problem in the operation of the second comparator. 5.   5. The protection circuit self-diagnosis device according to claim 4, wherein the controller detects the abnormality when an output signal of the OR circuit is at a high level.   2. The control unit according to claim 1, wherein when a problem occurs in the operation of one of the first protection circuit and the second protection circuit, the control unit continues the protection function using only the other protection circuit. The protective circuit self-diagnosis device according to any one of?   The protection circuit self-diagnosis device according to claim 1, wherein the first protection circuit and the second protection circuit include an overcurrent protection circuit that detects an overcurrent.   The protection circuit self-diagnosis device according to claim 1, wherein the first protection circuit and the second protection circuit include an overvoltage protection circuit that detects an overvoltage.   The protection circuit self-diagnosis device according to any one of claims 1 to 6, wherein the first protection circuit and the second protection circuit include a low voltage protection circuit that detects a low voltage.   The protection circuit self-diagnosis device according to any one of claims 1 to 6, wherein the first protection circuit and the second protection circuit include an overtemperature protection circuit that detects an overtemperature. A switching step of alternately switching the self-diagnosis periods of the first protection circuit and the second protection circuit for detecting an abnormality;
During the self-diagnosis period of the first protection circuit, the first protection circuit performs self-diagnosis using the output signal of the first protection circuit while the second protection circuit performs an abnormality detection operation, and the second protection circuit A control step of performing self-diagnosis of the second protection circuit using the output signal of the second protection circuit during the abnormality detection operation of the first protection circuit during the self-diagnosis period of the protection circuit. A protection circuit self-diagnosis method characterized. The first protection circuit includes a first comparator that compares a first reference voltage and a monitor voltage,
The second protection circuit includes a second comparator that compares the second reference voltage with the monitor voltage,
In the control step,
In the self-diagnosis period of the first comparator, the first reference voltage is variably controlled, and the first comparator is self-diagnosed using an output signal of the first comparator,
The self-diagnosis of the second comparator is performed by variably controlling the second reference voltage and using the output signal of the second comparator during a self-diagnosis period of the second comparator. The protection circuit self-diagnosis method described. A first AND circuit to which an output signal of the first comparator and a control signal of the control unit are input;
A second AND circuit to which the output signal of the second comparator and the control signal of the control unit are input;
An OR circuit to which an output signal of the first AND circuit and an output signal of the second AND circuit are input;
The protection circuit self-diagnosis method according to claim 12, wherein in the control step, the abnormality is detected using an output signal of the OR circuit. In the control step,
In the self-diagnosis period of the first comparator, as a result of inputting a low level control signal to the first AND circuit and inputting a control signal for changing the first reference voltage to the first comparator, the first comparator If there is a high level period in the output signal of the comparator, self-diagnosis that there is no problem in the operation of the first comparator,
In the self-diagnosis period of the second comparator, a low level control signal is input to the second AND circuit, and a control signal for changing the second reference voltage is input to the second comparator. 14. The protection circuit self-diagnosis method according to claim 13, wherein when there is a high level period in the output signal of the comparator, self-diagnosis is performed if there is no problem in the operation of the second comparator.   15. The protection circuit self-diagnosis method according to claim 14, wherein, in the control step, the abnormality is detected when an output signal of the OR circuit is at a high level.   12. In the control step, when a problem occurs in one of the first protection circuit and the second protection circuit, the protection function is continued using only the other protection circuit. The protection circuit self-diagnosis method according to any one of -15.   The protection circuit self-diagnosis method according to any one of claims 11 to 16, wherein the first protection circuit and the second protection circuit include an overcurrent protection circuit that detects an overcurrent.   The protection circuit self-diagnosis method according to any one of claims 11 to 16, wherein the first protection circuit and the second protection circuit include an overvoltage protection circuit that detects an overvoltage.   The protection circuit self-diagnosis method according to any one of claims 11 to 16, wherein the first protection circuit and the second protection circuit include a low voltage protection circuit that detects a low voltage.   17. The protection circuit self-diagnosis method according to claim 11, wherein the first protection circuit and the second protection circuit include an overtemperature protection circuit that detects an overtemperature.

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