JP7360299B2 - Power supply and notification module - Google Patents

Description

The present invention relates to a power supply device and a notification module.

The application of vehicle emergency notification systems to vehicles such as automobiles is expanding. The vehicle emergency call system is also referred to as an e-call system. In a vehicle emergency notification system, when an emergency situation such as a vehicle accident occurs, an emergency notification signal is transmitted from an ECU for an e-call system mounted on a vehicle to an external device (such as a server device). The ECU for the e-call system basically operates by receiving driving power from the battery (lead acid battery, etc.) installed in the vehicle, but even if there is a disconnection between the battery and the ECU due to a vehicle accident, etc. It is equipped with a spare battery made of lithium ion, etc., so that it can send out emergency call signals.

Japanese Patent Application Publication No. 2018-148609

As an ECU for an e-call system equipped with a spare battery, an ECU 901 as shown in FIG. 15 is being considered. FIG. 15 shows a schematic configuration of an ECU 901 according to a reference configuration. The ECU 901 includes a step-down power supply circuit 910 that can generate a step-down output voltage by stepping down the output voltage (for example, 12V) of a voltage source 951 that is a main battery, and an output voltage (for example, 3V) of a voltage source 952 that is a backup battery. A boost power supply circuit 920 that can generate a boosted output voltage by boosting the voltage is provided. The step-down power supply circuit 910 is configured as a step-down switching regulator (step-down DC/DC converter), and the step-up power supply circuit 920 is configured as a step-up switching regulator (step-up DC/DC converter).

The output terminal of power supply circuit 910 is connected to main power supply line 971, and the output terminal of power supply circuit 920 is connected to main power supply line 971 via transistor M900. A CAN transceiver 961, an MPU 962, a communication module 963, and a GPS processing unit 964, which constitute circuit blocks for realizing the functions of the vehicle emergency notification system, are driven based on the main power supply voltage Vm on the main power supply line 971.

While the main battery (voltage source 951) is connected to the step-down power supply circuit 910, the stored energy of the spare battery (voltage source 952) is prevented from being consumed, but the wiring between the main battery and the step-down power supply circuit 910 is disconnected. In such a case, it is necessary to immediately supply power from a spare battery. Therefore, after the system is started, the boost power supply circuit 920 is always enabled (signal EN is asserted), the transistor M900 is turned on, and the target output of the boost power supply circuit 920 is set to the step-down power supply circuit 910. It is necessary to set it lower than that of . For example, if the main power supply voltage Vm is required to be "5V±5%", the output targets of the power supply circuits 910 and 920 are set to 5.14V and 4.85V, respectively.

It is necessary to always ensure that the boost power supply circuit 920 can operate without abnormality when the above-mentioned disconnection or the like occurs. However, unless a disconnection or the like occurs, the boost power supply circuit 920 does not actually perform a boost operation due to the relationship between the output target levels. Taking these into consideration, it is necessary to consider how to perform abnormality detection (failure detection) in the boost power supply circuit 920.

In this regard, in the configuration of FIG. 15, during abnormality diagnosis, transistor M900 is turned off to temporarily disconnect the output of boost power supply circuit 920 from main power supply line 971 while causing boost power supply circuit 920 to perform a boost operation. By monitoring the output voltage of the boost power supply circuit 920 at this time with the A/D converter of the MPU 962, it is possible to confirm whether a normal boost voltage is being output (that is, it is possible to confirm whether there is any abnormality in the boost power supply circuit 920). .

However, the configuration of FIG. 15 requires an expensive transistor M900 (P-channel MOSFET in FIG. 15) with low on-resistance. In addition, the voltage accuracy when generating the main power supply voltage Vm from the output of the boost power supply circuit 920 deteriorates by the voltage drop of the transistor M900 (for example, if the requirement for the main power supply voltage Vm is "5V ± 5%" is satisfied). At the same time, it is necessary to set the target output of the step-up power supply circuit 920 lower than that of the step-down power supply circuit 910, but it becomes difficult to satisfy this requirement).

SUMMARY OF THE INVENTION An object of the present invention is to provide a power supply device and a reporting module that are capable of diagnosing the presence or absence of an abnormality in a power supply circuit at low cost and with a simple configuration.

A power supply device according to the present invention includes a step-down power supply circuit that outputs a step-down output voltage from a step-down output terminal by stepping down the voltage of a first voltage source , and a step-up output terminal that steps up the voltage of a second voltage source. a step-up power supply circuit that outputs a step-up output voltage from the step-up output terminal; a main power supply line that is commonly connected to the step-down output terminal and the step-up output terminal and supplies the main power supply voltage ; and a step-down target voltage set higher than the step-up target voltage in normal mode. In a diagnostic mode for diagnosing the presence or absence of an abnormality in the step-up power supply circuit, a control section that lowers the step-down target voltage and increases the step-up target voltage to set the step-up target voltage higher than the step-down target voltage; This is a configuration (first configuration).

In the power supply device according to the first configuration, the step-down power supply circuit is a step-down switching regulator that includes a step-down transistor and generates the step-down output voltage by a step-down operation accompanied by switching of the step-down transistor, The step-up power supply circuit executes or stops the step-down operation depending on the relationship between the main power supply voltage and the step-down target voltage. The boost switching regulator may generate a voltage, and may have a configuration ( second configuration) that executes or stops the boost operation depending on the relationship between the main power supply voltage and the boost target voltage.

In the power supply device according to the second configuration, the step-down voltage divider circuit is composed of a series circuit of a plurality of voltage-dividing resistors, and generates a step-down feedback voltage by dividing the main power supply voltage; The step-down power supply circuit further includes a step-up voltage divider circuit, which is made up of a series circuit of piezoresistors and generates a step-up feedback voltage by dividing the main power supply voltage, and the step-down power supply circuit is configured such that the step-down feedback voltage is set to a predetermined step-down voltage. The step-up power supply circuit executes or stops the step-down operation so that the step-up feedback voltage matches or approaches a predetermined step-up reference voltage; The step-down voltage divider circuit and the step-up voltage divider circuit are each configured to have a variable voltage division ratio, and the control unit adjusts the step-down target voltage through variable setting of the voltage division ratio in the step-down voltage divider circuit. may be variably set, and the boost target voltage may be variably set through variable setting of the voltage division ratio in the boost voltage divider circuit ( third configuration).

The power supply device according to the second configuration includes a series circuit of a plurality of voltage dividing resistors, and divides the main power supply voltage at different voltage division ratios to generate a step-down feedback voltage and a step-up feedback voltage. Further comprising a circuit, the step-down power supply circuit executes or stops the step-down operation so that the step-down feedback voltage matches or approaches a predetermined step-down reference voltage, and the step-up power supply circuit performs or stops the step-down operation so that the step-up feedback voltage matches or approaches a predetermined step-down reference voltage. The step-up operation is executed or stopped so as to match or approach the step-up reference voltage of The voltage division ratio for obtaining the feedback voltage is configured to be variable, and the control unit simultaneously changes the voltage division ratio when switching between the normal mode and the diagnostic mode, thereby adjusting the step-down target voltage and the step-up target voltage. A configuration ( fourth configuration) in which the target voltages are changed simultaneously may also be used.

In the power supply device according to the fourth configuration, a series circuit of the plurality of voltage dividing resistors is inserted between the main power supply line and the ground, and in the voltage dividing circuit, some of the plurality of voltage dividing resistors A bypass circuit is connected in parallel to the voltage dividing resistor, the step-down feedback voltage and the step-up feedback voltage are generated at mutually different first and second nodes in the series circuit, and the bypass circuit is connected in parallel. A part of the voltage dividing resistor is interposed between the first node and the second node, and the control unit controls the connection between the part of the voltage dividing resistor and the bypass circuit by controlling the state of the bypass circuit. The resistance value of the parallel circuit is made variable, and the resistance value of the parallel circuit is changed when switching between the normal mode and the diagnostic mode, thereby obtaining the voltage division ratio and the main power supply voltage for obtaining the step-down feedback voltage from the main power supply voltage. A configuration ( fifth configuration) may be adopted in which the voltage division ratio for obtaining the boost feedback voltage from the power supply voltage is changed at the same time, thereby simultaneously changing the step-down target voltage and the boost target voltage.

In the power supply device according to any of the first to fifth configurations, the control unit may include a configuration ( sixth configuration) that diagnoses whether or not there is an abnormality in the booster power supply circuit based on the main power supply voltage in the diagnosis mode. ).

In the power supply device according to the sixth configuration, the control unit determines whether or not the main power supply voltage is within a predetermined normal voltage range corresponding to the boost target voltage in the diagnostic mode. A configuration ( seventh configuration) may be adopted in which the presence or absence of an abnormality in the step-up power supply circuit is diagnosed by detecting whether or not the boost power supply circuit is abnormal.

In the power supply device according to any of the second to fifth configurations, when the voltage boosting transistor is connected to the boosting transistor and the boosting operation is being performed, the voltage is a boosted voltage from the second voltage source; The control unit further includes a monitor circuit that generates a voltage different from the voltage at the boost output terminal on a predetermined monitor line, and in the diagnostic mode, the control unit controls the boost power supply circuit based on the voltage on the monitor line. It may be a configuration ( eighth configuration) that diagnoses the presence or absence of an abnormality.

In the power supply device according to the eighth configuration, the control unit is capable of executing a normal mode diagnosis process in the normal mode, and in the normal mode diagnosis process, the boost operation is executed based on the voltage of the monitor line. It may be a configuration ( ninth configuration) in which it is determined that there is an abnormality in the power supply device when it is determined that the voltage boosting operation is being performed.

In the power supply device according to the eighth or ninth configuration, the boost power supply circuit includes the boost transistor, an inductor connected in series with the boost transistor, and an anode connected to a connection node between the inductor and the boost transistor. and a smoothing capacitor inserted between the cathode of the freewheeling diode and the ground, the cathode of the freewheeling diode is connected to the main power supply line, and the inductor and the booster are connected. A voltage from the second voltage source is applied to a series circuit with the boost transistor, and the monitor circuit has an anode connected to a connection node between the inductor and the boost transistor, and a cathode connected to the monitor line. A configuration (fiftieth configuration) including a monitoring freewheeling diode and a monitoring smoothing capacitor inserted between the monitoring line and ground may be used.

In the power supply device according to any of the first to ninth and fiftieth configurations, a voltage accuracy specification that requires the main power supply voltage to fall within a predetermined voltage range is determined for the main power supply voltage. , the step-down target voltage and the step-up target voltage in the normal mode, and the step-down target voltage and the step-up target voltage in the diagnostic mode are all within the predetermined voltage range ( tenth structure). It's okay.

A reporting module according to the present invention is a reporting module that is equipped with a power supply device according to any one of the first to tenth and fiftieth configurations and is mounted on a vehicle, and acquires position information representing the position of the vehicle. an external communication device capable of wirelessly transmitting a predetermined emergency call signal including the location information to an external device when a predetermined notification condition is met; and another circuit mounted on the vehicle. an in-vehicle communication device that communicates with the vehicle, and the position information acquisition device, the external communication device, the in-vehicle communication device, and the control unit in the power supply device are driven based on the main power supply voltage. configuration ( eleventh configuration).

According to the present invention, it is possible to provide a power supply device and a reporting module that are capable of diagnosing the presence or absence of an abnormality in a power supply circuit with a low cost and simple configuration.

1 is a diagram schematically showing how an ECU is mounted on a vehicle according to an embodiment of the present invention. FIG. 2 is a diagram illustrating how bidirectional communication between an ECU and a server device becomes possible according to an embodiment of the present invention. FIG. 1 is a configuration diagram of an ECU according to a first embodiment of the present invention. 4 is a circuit diagram of the step-down power supply circuit of FIG. 3. FIG. 4 is a circuit diagram of the boost power supply circuit of FIG. 3. FIG. FIG. 2 is a diagram showing a relationship between a step-down target voltage and a step-up target voltage in a normal mode and a diagnostic mode according to the first embodiment of the present invention. FIG. 2 is a diagram showing a relationship between a step-down target voltage and a step-up target voltage in a normal mode and a diagnostic mode according to the first embodiment of the present invention. FIG. 2 is a diagram showing a range of variation in a step-down target voltage and a step-up target voltage in a normal mode and a diagnostic mode according to the first embodiment of the present invention. 3 is an operation flowchart of the ECU according to the first embodiment of the present invention. FIG. 4 is a waveform diagram of the main power supply voltage in a normal case according to the first embodiment of the present invention. FIG. 6 is a waveform diagram of the main power supply voltage in a step-up abnormality case according to the first embodiment of the present invention. FIG. 3 is a configuration diagram of an ECU according to a second embodiment of the present invention. FIG. 3 is a configuration diagram of an ECU according to a third embodiment of the present invention. FIG. 7 is a circuit diagram of a boost power supply circuit and a monitor circuit according to a third embodiment of the present invention. FIG. 3 is a configuration diagram of an ECU according to a reference configuration.

Examples of embodiments of the present invention will be specifically described below with reference to the drawings. In each referenced figure, the same parts are given the same reference numerals, and overlapping explanations regarding the same parts will be omitted in principle. In this specification, for the purpose of simplifying the description, by writing symbols or codes that refer to information, signals, physical quantities, elements, parts, etc., information, signals, physical quantities, elements, parts, etc. that correspond to the symbols or codes are indicated. Names such as names may be omitted or abbreviated. For example, the step-down power supply circuit referred to by "10" (see FIG. 3), which will be described later, may be written as the step-down power supply circuit 10 or may be abbreviated as the power supply circuit 10; refer to the same thing.

First, some terms used in the description of the embodiments of the present invention will be explained. In a circuit, lines and wiring are synonymous. The ground refers to a conductive part having a reference potential of 0V (zero volts), or refers to the 0V potential itself. The potential of 0V is sometimes referred to as a ground potential. In embodiments of the invention, voltages shown without particular reference represent potentials with respect to ground. Level refers to the level of potential, and for any signal or voltage, a high level has a higher potential than a low level. For any signal or voltage, a high level of the signal or voltage means that the level of the signal or voltage is high, and a low level of the signal or voltage means that the level of the signal or voltage is low. means that it is in The level of a signal may be expressed as a signal level, and the level of a voltage may be expressed as a voltage level.

Regarding any transistor configured as a FET (field effect transistor) including a MOSFET, an on state refers to a state in which the drain and source of the transistor are in a conductive state, and an off state refers to a state where the drain and source of the transistor are in a conductive state. Refers to a state of non-conduction (blocking state) between the source and the source. The same applies to transistors that are not classified as FETs. The MOSFET may be understood to be an enhancement type MOSFET unless otherwise specified. MOSFET is an abbreviation for "metal-oxide-semiconductor field-effect transistor."

Any switch can be composed of one or more FETs (field effect transistors), and when a switch is on, conduction occurs between both ends of the switch, while when the switch is off, the switch is electrically conductive. There is no conduction between both ends. Hereinafter, the on state and off state of any transistor or switch may be simply expressed as on or off. For any transistor or switch, switching from an off state to an on state is expressed as turn-on, and switching from an on state to an off state is expressed as turn-off. Furthermore, for any transistor or switch, a section in which the transistor or switch is in an on state may be referred to as an on section, and a section in which the transistor or switch is in an off state may be referred to as an off section.

<<First embodiment>>
A first embodiment of the present invention will be described. FIG. 1 is a diagram schematically showing how the ECU 1 is mounted on a vehicle CC. The voltage source VS1 is a battery mounted on the vehicle CC, and is constituted by an arbitrary secondary battery such as a lead-acid battery. Voltage source VS1 is externally connected to ECU1. In FIG. 1, a passenger car is shown as the vehicle CC, but the vehicle CC may be any vehicle (particularly, for example, a vehicle that can be driven on a road). The ECU 1 is an ECU (Electronic Control Unit) installed in a vehicle CC to realize the functions of a so-called vehicle emergency notification system, and functions as a notification module (vehicle emergency notification module).The vehicle emergency notification system is an e- Also called a call system.

As shown in FIG. 2, the vehicle emergency notification system includes an ECU 1 and an external device SV located outside the vehicle CC. The external device SV is, for example, a server device connected to a communication network such as the Internet network. The ECU 1 is capable of bidirectional communication with an external device SV via a predetermined mobile communication network.

In addition, the vehicle CC is equipped with a plurality of ECUs including ECU1 as a reporting module, and the plurality of ECUs communicate with each other in various ways via a CAN (Controller Area Network), which is a communication network provided in the vehicle CC. information can be sent and received.

FIG. 3 shows the configuration of the ECU 1a according to the first embodiment. In the first embodiment, the ECU 1a in FIG. 3 is used as the ECU 1 in FIG. The ECU 1a includes a voltage source VS2 different from the voltage source VS1, and also includes a step-down power supply circuit 10, a step-up power supply circuit 20, voltage dividing circuits DIV1, DIV2, and DIV3, a CAN transceiver 61, and an MPU (Micro-processing unit). 62, a communication module 63, and a GPS processing section 64.

The voltage source VS2 is a DC voltage source configured with a lithium ion battery or the like. The ECU 1 (ECU 1a here) is driven using the voltage source VS1 as a main voltage source, and the voltage source VS2 functions as a backup battery that effectively functions when power supply based on the voltage source VS1 is interrupted. The voltage source VS2 may be a primary battery or a secondary battery. The capacity of voltage source VS2 is smaller than the capacity of voltage source VS1. Further, the nominal voltage value of the output voltage of the voltage source VS1 (for example, 12V) is larger than the nominal voltage value of the output voltage of the voltage source VS2 (for example, 3V). In the following, the output voltage of the voltage source VS1 will be expressed as a voltage VA, and the output voltage of the voltage source VS2 will be expressed as a voltage VB.

The step-down power supply circuit 10 includes an input terminal 10 _IN that receives the output voltage VA of the voltage source VS1 and an output terminal 10 _OUT , and reduces the input voltage (therefore, the voltage VA) to the input terminal 10 _IN to output the output terminal 10 _OUT . It is possible to output its own output voltage (step-down output voltage) from A feedback voltage VfbA is input from the voltage dividing circuit DIV1 to the step-down power supply circuit 10, and the step-down power supply circuit 10 performs an operation of generating a step-down output voltage (corresponding to a step-down operation described below) based on the feedback voltage VfbA.

The boost power supply circuit 20 includes an input terminal 20 _IN that receives the output voltage VB of the voltage source VS2, and an output terminal 20 _OUT , and boosts the input voltage to the input terminal 20 _IN (therefore, the voltage VB) to output the output terminal 20 _OUT . It is possible to output its own output voltage (boosted output voltage) from A feedback voltage VfbB is input from the voltage dividing circuit DIV2 to the boost power supply circuit 20, and the boost power supply circuit 20 performs an operation of generating a boosted output voltage (corresponding to a boost operation described below) based on the feedback voltage VfbB.

However, since the output terminal 10 _OUT of the step-down power supply circuit 10 and the output terminal 20 _OUT of the step-up power supply circuit 20 are commonly connected to each other via the main power supply line LN1, the step-down output voltage generation operation and the step-up output voltage generation operation are different. Only one of the generation operations will be executed. The voltage applied to the main power line LN1 provided in the ECU 1a is referred to as main power voltage VM.

The voltage dividing circuit DIV1 includes voltage dividing resistors R1, R2, and R3, and a transistor M1 configured as an N-channel MOSFET. A series circuit of voltage dividing resistors R1 to R3 is placed between the main power line LN1 and the ground, and at this time, the voltage dividing resistors R1, R2, and R3 are placed in this order from the main power line LN1 to the ground. be done. More specifically, one end of the voltage dividing resistor R1 is connected to the main power supply line LN1, the other end of the voltage dividing resistor R1 is connected to one end of the voltage dividing resistor R2, and the other end of the voltage dividing resistor R2 is connected to the voltage dividing resistor R2. It is connected to one end of voltage dividing resistor R3, and the other end of voltage dividing resistor R3 is connected to ground. The drain of the transistor M1 is connected to the connection node between the voltage dividing resistors R1 and R2, and the source of the transistor M1 is connected to the connection node between the voltage dividing resistors R2 and R3. A feedback voltage VfbA is generated at the connection node between the voltage dividing resistors R2 and R3.

The voltage divider circuit DIV1 functions as a step-down voltage divider circuit that generates the feedback voltage VfbA to the step-down power supply circuit 10 by dividing the main power supply voltage VM. The partial pressure ratio is variable. That is, the voltage division ratio is made variable by turning on/off the transistor M1.

More specifically, when the resistance values of the voltage dividing resistors R1, R2, and R3 are represented by symbols "R1," "R2," and "R3," the feedback voltage VfbA is obtained by dividing the main power supply voltage VM. The voltage dividing ratio when generating is "R3/(R1+R2+R3)" when the transistor M1 is off, and "R3/(R1+R3)" when the transistor M1 is on. However, here, it is assumed that the on-resistance of the transistor M1 is sufficiently low and zero.

The voltage dividing circuit DIV2 includes voltage dividing resistors R4, R5, and R6, and a transistor M2 configured as an N-channel MOSFET. A series circuit of voltage dividing resistors R4 to R6 is placed between the main power line LN1 and the ground, and at this time, the voltage dividing resistors R4, R5, and R6 are placed in this order from the main power line LN1 to the ground. be done. More specifically, one end of the voltage dividing resistor R4 is connected to the main power supply line LN1, the other end of the voltage dividing resistor R4 is connected to one end of the voltage dividing resistor R5, and the other end of the voltage dividing resistor R5 is connected to the voltage dividing resistor R5. It is connected to one end of voltage dividing resistor R6, and the other end of voltage dividing resistor R6 is connected to ground. The drain of transistor M2 is connected to a connection node between voltage dividing resistors R5 and R6, and the source of transistor M2 is connected to ground. A feedback voltage VfbB is generated at the connection node between the voltage dividing resistors R4 and R5.

The voltage dividing circuit DIV2 functions as a voltage boosting voltage dividing circuit that generates the feedback voltage VfbB to the boosted power supply circuit 20 by dividing the main power supply voltage VM. The partial pressure ratio is variable. That is, the voltage division ratio is made variable by turning on/off the transistor M2.

More specifically, when the resistance values of voltage dividing resistors R4, R5, and R6 are represented by symbols "R4", "R5", and "R6", respectively, by dividing the main power supply voltage VM, the feedback voltage VfbB is The voltage division ratio when generating is "(R5+R6)/(R4+R5+R6)" when transistor M2 is off, and "R5/(R4+R5)" when transistor M2 is on. However, here, it is assumed that the on-resistance of the transistor M2 is sufficiently low and zero.

The voltage dividing circuit DIV3 consists of a series circuit of voltage dividing resistors R7 and R8. Specifically, one end of the voltage dividing resistor R7 is connected to the main power supply line LN1, the other end of the voltage dividing resistor R7 is connected to one end of the voltage dividing resistor R8, and the other end of the voltage dividing resistor R8 is connected to the ground. Ru. A voltage Vdet, which is a divided voltage of the main power supply voltage VM, is generated at the connection node between the voltage dividing resistors R7 and R8.

A plurality of load devices that operate using the main power supply voltage VM as a driving source are connected to the main power supply line LN1. Although the CAN transceiver 61, MPU 62, communication module 63, and GPS processing unit 64 are listed here as the plurality of load devices, load devices other than these may also be connected to the main power line LN1.

The CAN transceiver 61 is an ECU different from the ECU 1a and realizes two-way communication of arbitrary information with each ECU mounted on the vehicle CC via CAN.

The MPU 62 has a function of outputting the signals FET_EN and Boost_EN and a function of evaluating the voltage Vdet, and also controls the operation of each part within the ECU 1a in an integrated manner. Each of the signals FET_EN and Boost_EN is a binary signal that takes a low level or a high level signal level. In the ECU 1a, a signal FET_EN is supplied to each gate of the transistors M1 and M2. When the signal FET_EN is at a high level, the transistors M1 and M2 are turned on, and when the signal FET_EN is at a low level, the transistors M1 and M2 are turned off. The signal Boost_EN is an enable signal for the boost power supply circuit 20, and here it is assumed that the boost power supply circuit 20 is activated only when the signal Boost_EN is at a high level.

The communication module 63 realizes bidirectional communication of arbitrary information with the external device SV (see FIG. 2).

The GPS processing unit 64 detects the current position of the vehicle CC by receiving signals from a plurality of GPS satellites forming a GPS (Global Positioning System), and generates vehicle position information indicating the current position of the vehicle CC. In the vehicle position information, the current position of the vehicle CC is expressed by longitude and latitude on the earth.

In the vehicle emergency call function realized by the ECU 1a, when a predetermined emergency call condition is satisfied, a predetermined emergency call signal is transmitted to the external device SV using the communication module 63 under the control of the MPU 62. The emergency call signal includes the latest vehicle position information generated by the GPS processing unit 64, and may also include various types of registered information (such as the vehicle type of the vehicle CC and owner information of the vehicle CC). For example, the vehicle CC is provided with an airbag and an airbag ECU that controls the deployment of the airbag, and when the airbag is deployed, the airbag ECU sends a predetermined airbag deployment notification to the CAN transceiver 61. A signal is sent. When the CAN transceiver 61 receives the airbag deployment notification signal, the emergency call condition is established. In addition, the emergency call condition may also be satisfied when an impact sensor mounted on the vehicle CC detects an impact of a certain value or more.

FIG. 4 shows a specific configuration example of the step-down power supply circuit 10. The step-down power supply circuit 10 is a step-down switching regulator (step-down DC/DC converter) having a step-down transistor (step-down switching transistor), and converts a step-down output voltage based on the voltage VA by a step-down operation accompanied by switching of the step-down transistor. Generated at output terminal 10 _OUT .

The step-down power supply circuit 10 in FIG. 4 includes a transistor 11 configured as an N-channel MOSFET, a diode 12 functioning as a freewheeling diode (rectifier diode), an inductor 13, a smoothing capacitor 14, and a reference voltage source 15. A control circuit 16 is provided.

In the transistor 11, the drain is connected to the input terminal 10 _IN , and the source is commonly connected to the cathode of the diode 12 and one end of the inductor 13. The other end of the inductor 13 is connected to the output terminal 10 _OUT . One end of the smoothing capacitor 14 is connected to the output terminal 10 _OUT , and the other end of the smoothing capacitor 14 is connected to ground. The anode of diode 12 is connected to ground. Reference voltage source 15 generates reference voltage VrefA having a predetermined positive DC voltage value based on voltage VA.

The control circuit 16 switches the transistor 11 or maintains the transistor 11 in an off state based on the feedback voltage VfbA and the reference voltage VrefA so that the feedback voltage VfbA matches or approaches the reference voltage VrefA. Specifically, for example, the control circuit 16 includes an error amplifier 16a that generates an error signal according to the difference between the feedback voltage VfbA and the reference voltage VrefA, and a PWM comparator that compares the error signal with a triangular wave signal having a predetermined PWM frequency. 16b, and a driver 16c that turns on or turns on the transistor 11 by controlling the gate potential of the transistor 11 according to the output signal of the PWM comparator.

Although switching of the transistor 11 may be stopped depending on the states of the transistors M1 and M2 in FIG. 3 (details will be described later), a supplementary explanation will be provided regarding the step-down operation in which switching of the transistor 11 is performed. In the step-down operation, the transistor 11 is turned on and off alternately in a predetermined PWM cycle, and the on-duty of the transistor 11 is controlled so that the feedback voltage VfbA matches the reference voltage VrefA, thereby providing a step-down output to the output terminal 10 _OUT . A voltage is generated. In the step-down operation, the on-duty of the transistor 11 refers to the ratio of the on-period of the transistor 11 to the sum of the on-period and off-period of the transistor 11.

When the step-down operation is performed, the step-down output voltage generated at the output terminal 10 _OUT becomes the main power supply voltage VM. In the step-down operation, when the feedback voltage VfbA matches the reference voltage VrefA, the step-down output voltage (main power supply voltage VM) generated at the output terminal 10 _OUT matches the step-down target voltage, which is the target of the step-down output voltage. Therefore, in the step-down operation, the on-duty of the transistor 11 is controlled so that the step-down output voltage matches the step-down target voltage. The step-down target voltage is determined by the reference voltage VrefA and the voltage division ratio of the voltage divider circuit DIV1 (the voltage division ratio when obtaining the feedback voltage VfbA by dividing the main power supply voltage VM), so it depends on the state of the transistor M1. Change.

The control circuit 16 is activated when the value of the voltage VA exceeds a certain value, and enters a state in which it can perform the above-described step-down operation. Due to an accident in the vehicle CC, the wiring between the voltage source VS1 and the input terminal 10 _IN may be disconnected and the value of the voltage VA becomes less than a certain value. It is assumed that the voltage is greater than a certain value and that the control circuit 16 is in a state where it can perform a step-down operation.

FIG. 5 shows a specific configuration example of the boost power supply circuit 20. The step-up power supply circuit 20 is a step-up switching regulator (step-up DC/DC converter) having a step-up transistor (step-up switching transistor), and generates a step-up output voltage based on the voltage VB by a step-up operation accompanied by switching of the step-up transistor. Generated at output terminal 20 _OUT .

The boost power supply circuit 20 in FIG. 5 includes a transistor 21 configured as an N-channel MOSFET, a diode 22 functioning as a freewheeling diode (rectifier diode), an inductor 23, a smoothing capacitor 24, and a reference voltage source 25. A control circuit 26 is provided.

An inductor 23 is inserted between the drain of the transistor 21 and the input terminal 20 _IN . That is, one end of the inductor 23 is connected to the input terminal 20 _IN , and the other end of the inductor 23 is connected to the drain of the transistor 21. The source of transistor 21 is connected to ground. Therefore, voltage VB from voltage source VS2 is applied to the series circuit of inductor 23 and transistor 21. The anode of the diode 22 is connected to the drain of the transistor 21, and the cathode of the diode 22 is connected to the output terminal 20 _OUT . One end of the smoothing capacitor 24 is connected to the output terminal 20 _OUT , and the other end of the smoothing capacitor 24 is connected to ground. Reference voltage source 25 generates reference voltage VrefB having a predetermined positive DC voltage value based on voltage VB.

Based on the feedback voltage VfbB and the reference voltage VrefB, the control circuit 26 switches the transistor 21 or maintains the transistor 21 in an off state so that the feedback voltage VfbB matches or approaches the reference voltage VrefB. Specifically, for example, the control circuit 26 includes an error amplifier 26a that generates an error signal according to the difference between the feedback voltage VfbB and the reference voltage VrefB, and a PWM comparator that compares the error signal with a triangular wave signal having a predetermined PWM frequency. 26b, and a driver 26c that turns on or turns on the transistor 21 by controlling the gate potential of the transistor 21 according to the output signal of the PWM comparator. However, the control circuit 26 operates only when the signal Boost_EN is at a high level, and when the signal Boost_EN is at a low level, the control circuit 26 does not operate and the transistor 21 is maintained in an off state.

Although the switching of the transistor 21 may be stopped depending on the states of the transistors M1 and M2 in FIG. 3 or the level of the signal Boost_EN, a supplementary explanation will be given regarding the boosting operation in which the switching of the transistor 21 is performed. In the boost operation, the transistor 21 is alternately turned on and off in a predetermined PWM cycle, and the on-duty of the transistor 21 is controlled so that the feedback voltage VfbB matches the reference voltage VrefB, thereby providing a boost output to the output terminal 20 _OUT . A voltage is generated. In the boost operation, the on-duty of the transistor 21 refers to the ratio of the on-period of the transistor 21 to the sum of the on-period and off-period of the transistor 21.

When the boost operation is performed, the boosted output voltage generated at the output terminal 20 _OUT becomes the main power supply voltage VM. In the boosting operation, when the feedback voltage VfbB matches the reference voltage VrefB, the boosted output voltage (main power supply voltage VM) generated at the output terminal 20 _OUT matches the boosted target voltage that is the target of the boosted output voltage. Therefore, in the boosting operation, the on-duty of the transistor 21 is controlled so that the boosted output voltage matches the boosted target voltage. The boost target voltage is determined by the reference voltage VrefB and the voltage division ratio of the voltage divider circuit DIV2 (the voltage division ratio when obtaining the feedback voltage VfbB by dividing the main power supply voltage VM), so it depends on the state of the transistor M2. Change.

Note that the configurations of the power supply circuits 10 and 20 shown in FIGS. 4 and 5 are merely examples, and various modifications are possible. For example, a synchronous rectification method may be adopted in the step-down power supply circuit 10 or the step-up power supply circuit 20. Further, a single capacitor may also be used as the smoothing capacitors 14 and 24.

[Normal mode and diagnostic mode]
MPU 62 can operate in normal mode or diagnostic mode. Although the MPU 62 may operate in an operation mode different from both the normal mode and the diagnostic mode, only the normal mode and the diagnostic mode are focused here. It is also possible to adopt a concept in which the ECU 1a operates in a normal mode and a diagnostic mode, and the MPU 62 switches and controls the operation mode of the ECU 1a.

The MPU 62 turns off the transistors M1 and M2 by setting the signal FET_EN to a low level in the normal mode, and turns on the transistors M1 and M2 by setting the signal FET_EN to a high level in the diagnostic mode.

6 and 7 show the relationship between the step-down target voltage and the step-up target voltage in the normal mode and the diagnostic mode. Below, the step-down target voltage and step-up target voltage will be referred to by the symbols "VtgA" and "VtgB", respectively. In FIG. 7, for convenience of illustration, the solid line waveform representing the step-down target voltage VtgA and the broken line waveform representing the step-up target voltage VtgB are shown slightly shifted in the left-right direction. Further, the step-down target voltage and the step-up target voltage in the normal mode are represented by the symbols "VtgA_N" and "VtgB_N," respectively, and the step-down target voltage and the step-up target voltage in the diagnostic mode are represented by the symbols "VtgA_S" and ", respectively. It is expressed as "VtgB_S".

Through state control of transistors M1 and M2, each voltage division ratio of voltage divider circuits DIV1 and DIV2 changes between normal mode and diagnostic mode. At this time, first,
The first inequality “VtgA_N>VtgA_S”, and
The second inequality “VtgB_N<VtgB_S” holds true. Also,
The third inequality “VtgA_N>VtgB_N”, and
The resistance values of the voltage dividing resistors R1 to R6 and the values of the reference voltages VrefA and VrefB are determined so that the fourth inequality "VtgA_S<VtgB_S" holds true. That is, by lowering the step-down target voltage and increasing the step-up target voltage based on the normal mode, the step-up target voltage is set higher than the step-down target voltage in the diagnostic mode.

Furthermore, the resistance values of the voltage dividing resistors R1 to R6 and the values of the reference voltages VrefA and VrefB are determined so that the four target voltages VtgA_N, VtgA_S, VtgB_N, and VtgB_S all fall within a predetermined specification voltage range RNG. There is. A voltage accuracy specification that requires the main power supply voltage VM to fall within a predetermined voltage range is defined for the main power supply voltage VM (in other words, for the ECU 1a), and the predetermined voltage range is within the specified voltage range RNG. be. The specification voltage range RNG is a voltage range from a predetermined lower limit voltage V _LL to a predetermined upper limit voltage V _HL (0<V _LL <V _HL ). The value of the upper limit voltage V _HL is lower than the nominal voltage value (for example, 12 V) of the output voltage VA of the voltage source VS1, and the value of the lower limit voltage V _LL is lower than the nominal voltage value (for example, 3 V) of the output voltage VB of the voltage source VS2. higher than

The voltage expected to appear at the output terminal 10 _OUT and the main power supply line LN1 when the step-down power supply circuit 10 performs a step-down operation in the normal mode is referred to as a normal step-down expected voltage. Normally, the expected step-down voltage has a constant voltage width. The designed upper limit voltage and lower limit voltage that the expected normal voltage step-down voltage can take are represented by symbols "VtgA_N_H" and "VtgA_N_L", respectively (see FIG. 8(a)). “VtgA_N_H>VtgA_N_L” holds true. Each value of the voltages VtgA_N_H and VtgA_N_L can be estimated based on the accuracy of each value of the voltage dividing resistors R1 to R3 and the reference voltage VrefA at the design stage of the ECU 1a. The voltage range from the upper limit voltage VtgA_N_H to the lower limit voltage VtgA_N_L can be said to represent the variation range of the step-down target voltage VtgA_N in the normal mode.

The voltage that is expected to appear at the output terminal 20 _OUT and the main power line LN1 when the boost power supply circuit 20 performs a boost operation in the normal mode is referred to as a normal boost expected voltage. Normally, the expected boost voltage has a constant voltage width. The designed upper limit voltage and lower limit voltage that the expected normal boost voltage can take are represented by symbols "VtgB_N_H" and "VtgB_N_L", respectively (see FIG. 8(a)). “VtgB_N_H>VtgB_N_L” holds true. Each value of the voltages VtgB_N_H and VtgB_N_L can be estimated based on the accuracy of each value of the voltage dividing resistors R4 to R6 and the reference voltage VrefB at the design stage of the ECU 1a. The voltage range from the upper limit voltage VtgB_N_H to the lower limit voltage VtgB_N_L can be said to represent the variation range of the boosted target voltage VtgB_N in the normal mode.

The voltage expected to appear at the output terminal 10 _OUT and the main power line LN1 when the step-down power supply circuit 10 performs a step-down operation in the diagnostic mode is referred to as a diagnostic step-down expected voltage. The estimated diagnostic step-down voltage has a constant voltage width. The design upper limit voltage and lower limit voltage that the expected diagnostic step-down voltage can take are represented by symbols "VtgA_S_H" and "VtgA_S_L", respectively (see FIG. 8(b)). “VtgA_S_H>VtgA_S_L” holds true. Each value of the voltages VtgA_S_H and VtgA_S_L can be estimated based on the accuracy of each value of the voltage dividing resistors R1 to R3 and the reference voltage VrefA at the design stage of the ECU 1a. It can be said that the voltage range from the upper limit voltage VtgA_S_H to the lower limit voltage VtgA_S_L represents the variation range of the step-down target voltage VtgA_S in the diagnostic mode.

The voltage that is assumed to appear at the output terminal 20 _OUT and the main power line LN1 when the boost power supply circuit 20 performs a boost operation in the diagnostic mode is referred to as a diagnostic boost expected voltage. The expected diagnostic boost voltage has a constant voltage width. The designed upper limit voltage and lower limit voltage that the expected diagnostic boost voltage can take are represented by symbols "VtgB_S_H" and "VtgB_S_L", respectively (see FIG. 8(b)). “VtgB_S_H>VtgB_S_L” holds true. Each value of the voltages VtgB_S_H and VtgB_S_L can be estimated based on the accuracy of each value of the voltage dividing resistors R4 to R6 and the reference voltage VrefB at the design stage of the ECU 1a. The voltage range from the upper limit voltage VtgB_S_H to the lower limit voltage VtgB_S_L can be said to represent the variation range of the boosted target voltage VtgB_S in the diagnostic mode.

8(a) and (b) show the upper and lower limit voltages of the normal step-down expected voltage, normal step-up expected voltage, diagnostic step-down expected voltage, and diagnostic step-up voltage, respectively, and the upper limit voltage V _HL in the specification voltage range RNG. The relationship between the voltage and the lower limit voltage _VLL is shown.

Regarding normal mode,
"V _HL >VtgA_N_H",
“VtgA_N_L>VtgB_N_H”, and
so that “VtgB_N_L>V _LL ” holds true, and
Regarding diagnostic mode,
"V _HL >VtgB_S_H",
"VtgB_S_L>VtgA_S_H", and
The ECU 1a is formed so that “VtgA_S_L>V _LL ” holds true.

In other words, even if errors in the resistance values of the voltage dividing resistors R1 to R6 and the values of the reference voltages VrefA and VrefB are included, as shown in FIGS. 8(a) and (b), the normal step-down expected voltage is always higher than the normal expected boost voltage, and in the diagnostic mode, the expected diagnostic boost voltage is always higher than the expected diagnostic step-down voltage. Furthermore, regarding the normal mode, even if the above error is included, as shown in Figure 8(a), the upper limit voltage _VHL of the specified voltage range RNG is higher than the expected normal step-down voltage, and the upper limit voltage VHL of the specified voltage range RNG is higher than the expected normal step-up voltage. The lower limit voltage _VLL of the voltage range RNG is lower. Similarly, regarding the diagnostic mode, even if the above error is included, as shown in FIG. 8(b), the upper limit voltage _VHL of the specification voltage range RNG is higher than the expected diagnostic boost voltage, and is higher than the expected diagnostic step-down voltage. The lower limit voltage _VLL of the specified voltage range RNG is lower.

A specific numerical example will be given. Here, it is assumed that the main power supply voltage VM (for example, the power supply voltage of the CAN transceiver 61) is required to be within the range of "5V±5%". Then, the lower limit voltage V _LL and upper limit voltage V _HL are set to 4.75V and 5.25V, respectively. In this case, for example, the step-down target voltage VtgA_N in normal mode is set to 5.14V, the step-up target voltage VtgB_N in normal mode is set to 4.85V, the step-down target voltage VtgA_S in diagnostic mode is set to 4.85V, and the step-down target voltage VtgA_S in diagnostic mode is set to 4.85V. The boost target voltage VtgB_S in the mode is set to 5.14V. Furthermore,
The range of fluctuation of the expected normal step-down voltage around the step-down target voltage VtgA_N (here 5.14 V) in normal mode,
The range of fluctuation of the expected normal boost voltage around the boost target voltage VtgB_N (here 4.85V) in normal mode,
The fluctuation range of the expected diagnostic step-down voltage around the step-down target voltage VtgA_S (here, 4.85 V) in the diagnostic mode, and
In the diagnostic mode, the range of fluctuation of the expected diagnostic boost voltage around the boost target voltage VtgB_S (here, 5.14 V) is all ±2% with respect to the center voltage.

This ensures the high-low relationship between each voltage as shown in FIGS. 8(a) and 8(b). In this numerical example, "VtgA_N=VtgB_S" and "VtgB_N=VtgA_S", but it does not matter whether the voltages VtgA_N and VtgB_S match or do not match, and it does not matter whether the voltages VtgB_N and VtgA_S match or do not match.

Note that the voltage dividing circuits DIV1 and DIV2 may have any configuration as long as the above-mentioned relationship between the step-down target voltage and the step-up target voltage in the normal mode and the diagnostic mode is satisfied.

For example, the transistor M1 constitutes a bypass circuit connected in parallel to the voltage dividing resistor R2, and in the voltage dividing circuit DIV1 of FIG. 3, when the transistor M1 is turned on, the parallel circuit of the voltage dividing resistor R2 and the bypass circuit The resistance value of becomes substantially zero, but if the resistance value of the parallel circuit of the voltage dividing resistor R2 and the bypass circuit becomes smaller when the transistor M1 is on than when the transistor M1 is off. , the configuration of the bypass circuit of the voltage dividing circuit DIV1 is arbitrary. For example, the bypass circuit of the voltage dividing circuit DIV1 may be a series circuit of the transistor M1 and a resistor.

Similarly, for example, the transistor M2 forms a bypass circuit connected in parallel to the voltage dividing resistor R6, and in the voltage dividing circuit DIV2 of FIG. 3, when the transistor M2 is turned on, the voltage dividing resistor R6 and the bypass circuit are connected. The resistance value of the parallel circuit becomes substantially zero, but the resistance value of the parallel circuit of the voltage dividing resistor R6 and the bypass circuit becomes smaller when transistor M2 is on compared to when transistor M2 is off. If so, the configuration of the bypass circuit of the voltage dividing circuit DIV2 is arbitrary. For example, the bypass circuit of the voltage dividing circuit DIV2 may be a series circuit of the transistor M2 and a resistor.

[Operation flowchart]
FIG. 9 is an operation flowchart of the ECU 1a. The flow of the operation of the ECU 1a will be explained along the operation flowchart of FIG. First, in step S11, a battery as a voltage source VS1 is installed in the vehicle CC. Then, in step S12, the step-down power supply circuit 10 is started and performs a step-down operation, and the step-down output voltage obtained by the step-down operation is applied to the main power supply line LN1 as the main power supply voltage VM, and the MPU 62 is started up in step S13.

By the way, each line (wiring) to which the signals FET_EN and Boost_EN are applied is pulled down to ground by a pull-down resistor provided within or outside the MPU 62. Therefore, before the MPU 62 is started, the signals FET_EN and Boost_EN are at low level, and after the step-down power supply circuit 10 is started, the step-down output voltage (main power supply voltage VM) is set to the step-down target voltage VtgA_N (for example, 5.14V), while the boost power supply circuit 20 stops boosting the voltage.

After starting up, the MPU 62 operates in a normal mode in principle, and operates in a diagnostic mode only when executing a boost diagnostic process in step S16, which will be described later. In the normal mode, the signal FET_EN is set to low level as described above.

The vehicle CC is provided with an ignition key (not shown). The ignition key is turned off or on in response to an operation by an operator (for example, a driver of the vehicle CC). When the ignition key is in the on state, the engine of the vehicle CC starts, and when the ignition key is in the off state, the engine of the vehicle CC does not start.

After the MPU 62 is started in step S13, it is checked in step S14 whether or not the ignition key is in the on state, and when the ignition key is in the on state, an engine start signal indicating this is sent to the ECU 1a. . When the engine start signal is received by the ECU 1a, the process proceeds to step S15. The engine start signal is transmitted to the ECU 1a from an ECU that detects the state of the ignition key, which is different from the ECU 1a (the same applies to the engine stop signal described later).

In step S15, the MPU 62 switches the signal Boost_EN from low level to high level. Thereafter, the signal Boost_EN is maintained at a high level until the ignition key is turned off. After step S15, the process advances to step S16.

In step S16, the MPU 62 switches the operation mode from the normal mode to the diagnosis mode and performs a predetermined boost diagnosis process. In the diagnostic mode, the signal FET_EN is set to high level as described above. In the boost diagnosis process, the presence or absence of an abnormality in the boost power supply circuit 20 is diagnosed (the diagnosis method will be described later). For example, a failure in which the transistor 21 is fixed in an off state regardless of the gate potential of the transistor 21 (see FIG. 5) is one type of abnormality in the boost power supply circuit 20. After completing the boost diagnosis process in step S16, the process advances to step S17.

In step S17, the MPU 62 returns the operation mode from the diagnostic mode to the normal mode. Therefore, in step S17, the signal FET_EN is returned from the high level to the low level, and thereafter, the signal FET_EN is maintained at the low level unless there is a transition to the diagnostic mode again. After step S17, the process advances to step S18.

In step S18, the diagnosis result of the step-up diagnosis process in step S16 is confirmed, and if it is determined that there is no abnormality in the step-up power supply circuit 20 (in other words, if it is determined that there is no abnormality), the process advances to step S19. If it is determined that there is an abnormality in the boost power supply circuit 20, the process advances to step S30.

In step S19, it is checked whether the ignition key is in the OFF state, and when the ignition key is in the OFF state, an engine stop signal indicating this is transmitted to the ECU 1a. When the engine stop signal is received by the ECU 1a, the process proceeds to step S20.

In step S20, the MPU 62 switches the signal Boost_EN from high level to low level. After that, the process returns to step S14, and the above-described processes after step S14 are repeated.

In step S30, the MPU 62 performs predetermined error processing. In error processing, the MPU 62 transmits a predetermined error signal to an ECU different from the ECU 1a. The ECU that has received the error signal displays a predetermined warning on a display device provided in the vehicle CC, for example. After the error processing, the MPU 62 switches the signal Boost_EN from high level to low level and proceeds to step S19.

Note that a switch composed of a MOSFET or the like is inserted between the negative output terminal of voltage source VS2 and the ground, or between the positive output terminal of voltage source VS2 and input terminal 20 _IN . It's okay to stay. In this case, the MPU 62 preferably turns on the switch in synchronization with the switching of the signal Boost_EN to a high level, and turns off the switch in synchronization with the switching of the signal Boost_EN to a low level. In the following, it is assumed that the signal Boost_EN is at a high level unless otherwise specified.

[Normal case]
FIG. 10 shows a waveform 610 of the main power supply voltage VM in a normal case. The normal case is a case in which both the power supply circuits 10 and 20 operate as designed without any abnormality.

In the normal case shown in FIG. 10, a transition from the normal mode to the diagnostic mode occurs at timing Ta1 through the operation of the ignition key, after which the boost diagnostic process is performed between timings Ta1 and Ta2, and at timing Ta2, the transition is made to the diagnostic mode. A transition from to normal mode occurs.

After starting up, the boost power supply circuit 20 stops boosting operation in a state where the feedback voltage VfbB is higher than the reference voltage VrefB. That is, after the boost power supply circuit 20 starts up, when the main power supply voltage VM is higher than the boost target voltage VtgB, the boost power supply circuit 20 stops the boost operation. In the boost power supply circuit 20, the control circuit 26 controls the state of the transistor 21 so that the feedback voltage VfbB matches or approaches the reference voltage VrefB, but the boost operation is performed when the feedback voltage VfbB is higher than the reference voltage VrefB. This is because if this is done, the error between voltages VfbB and VrefB will increase. Stopping the boosting operation means maintaining the transistor 21 in an off state without switching the transistor 21.

In the normal mode before timing Ta1, the step-down target voltage VtgA (VtgA_N) is higher than the step-up target voltage VtgB (VtgB_N) (see FIGS. 6 and 7). This holds true even when their variation ranges are considered (see FIG. 8(a)). Therefore, in the normal mode before timing Ta1, the step-down power supply circuit 10 performs a step-down operation so that the main power supply voltage VM matches the step-down target voltage VtgA (VtgA_N), while the step-up power supply circuit 20 performs a step-up operation. will be stopped.

After starting up, the step-down power supply circuit 10 stops its step-down operation in a state where the feedback voltage VfbA is higher than the reference voltage VrefA. That is, after the step-down power supply circuit 10 starts up, when the main power supply voltage VM is higher than the step-down target voltage VtgA, the step-down power supply circuit 10 stops the step-down operation. In the step-down power supply circuit 10, the control circuit 16 controls the state of the transistor 11 so that the feedback voltage VfbA matches or approaches the reference voltage VrefA, but the step-down operation is performed when the feedback voltage VfbA is higher than the reference voltage VrefA. This is because if this is done, the error between voltages VfbA and VrefA will increase. Stopping the step-down operation means maintaining the transistor 11 in an off state without switching the transistor 11.

In the diagnostic mode between timings Ta1 and Ta2, boost target voltage VtgB (VtgB_S) is higher than step-down target voltage VtgA (VtgA_S) (see FIGS. 6 and 7). This holds true even when their variation ranges are considered (see FIG. 8(b)). Therefore, in the diagnostic mode between timings Ta1 and Ta2, the step-up power supply circuit 20 performs a step-up operation so that the main power supply voltage VM matches the step-up target voltage VtgB (VtgB_S), while the step-down power supply circuit 10 performs a step-down operation. will be stopped.

The normal mode returns at timing Ta2, but the normal mode operation after timing Ta2 is the same as the normal mode operation before timing Ta1. That is, in the normal mode after timing Ta2, the step-down power supply circuit 10 performs step-down operation so that the main power supply voltage VM matches the step-down target voltage VtgA (VtgA_N), while the step-up power supply circuit 20 stops the step-up operation. be done.

Immediately after the operation mode is switched, the step-down operation and the step-up operation may be performed together for a short time, and some disturbance may occur in the main power supply voltage VM.

Between timings Ta1 and Ta2, the boost diagnosis process of step S16 (see FIG. 9) is executed. In the diagnostic mode, a voltage based on the boost operation and expected to match the boost target voltage VtgB_S should appear as the main power supply voltage VM. Therefore, the MPU 62 obtains the voltage Vdet in the diagnosis mode (see FIG. 3) as the evaluation voltage Vdet. At this time, in order to exclude the influence of fluctuations in the main power supply voltage VM due to mode transition, the voltage Vdet after a predetermined stabilization time has elapsed after the transition from the normal mode to the diagnostic mode is acquired as the evaluation voltage Vdet. For example, the voltage Vdet immediately before timing Ta2 may be acquired as the evaluation voltage Vdet.

Then, based on the evaluation voltage Vdet, the MPU 62 determines whether the main power supply voltage VM in the diagnostic mode has a voltage within the fluctuation range of the boost target voltage VtgB_S in the diagnostic mode, and based on this, the boost power supply circuit Diagnose the presence or absence of 20 abnormalities. That is, in the boost diagnostic process, it is determined based on the evaluation voltage Vdet whether the boost normal condition that the main power supply voltage VM in the diagnostic mode is equal to or lower than the voltage VtgB_S_H and equal to or higher than the voltage VtgB_S_L is satisfied ( (See FIG. 8(b)). It is possible to determine whether or not the boosting normal condition is met based on the known information, the resistance value ratio between the voltage dividing resistors R7 and R8, and the evaluation voltage Vdet. If the normal boosting conditions are satisfied, it is determined that there is no abnormality in the boosting power supply circuit 20, and if the normal boosting conditions are not satisfied, it is determined that there is an abnormality in the boosting power supply circuit 20. In the normal case of FIG. 10, the normal pressurization condition is satisfied.

The MPU 62 includes an A/D converter. The MPU 62 converts the analog evaluation voltage Vdet into a digital voltage value using an A/D converter, and determines whether the normal boost condition is satisfied or not based on the obtained voltage value. Alternatively, instead of the A/D converter, a window comparator including a plurality of comparators may be provided in the ECU 1a, and the window comparator may be used to determine whether the boost normal condition is met or not.

If a disconnection between the voltage source VS1 and the input terminal 10 _OUT occurs at any timing after timing Ta2 due to an accident in the vehicle CC, etc., the main power supply voltage VM will decrease as the step-down operation stops. The main power supply voltage VM decreases from around the step-down target voltage VtgA_N (for example, 5.14 V), but when the main power supply voltage VM decreases to around the step-up target voltage VtgB_N (for example, 4.85 V), the step-up operation with switching of the transistor 21 starts. As a result, the main power supply voltage VM is maintained near the boosted target voltage VtgB_N. In other words, the continuous operation of the CAN transceiver 61, the communication module 63, etc. is ensured based on the output power of the voltage source VS2 as a backup battery, and the functions of the vehicle emergency notification system can be effectively operated.

[Volume boost abnormality case]
FIG. 11 shows a waveform 620 of the main power supply voltage VM in the step-up abnormal case. In the step-up abnormality case illustrated in FIG. 11, the step-down power supply circuit 10 operates as designed without any abnormality, but the step-up power supply circuit 20 is unable to perform a step-up operation due to a failure.

In the voltage increase abnormality case shown in FIG. 11, a transition from normal mode to diagnostic mode occurs at timing Tb1 through the operation of the ignition key, and thereafter, voltage increase diagnostic processing is performed between timings Tb1 and Tb2, and the transition is performed at timing Tb2. A transition from mode to normal mode occurs.

In the normal mode before timing Tb1, the step-down target voltage VtgA (VtgA_N) is higher than the step-up target voltage VtgB (VtgB_N) (see FIGS. 6 and 7). This holds true even when their variation ranges are considered (see FIG. 8(a)). Therefore, in the normal mode before timing Tb1, the step-down power supply circuit 10 performs a step-down operation so that the main power supply voltage VM matches the step-down target voltage VtgA (VtgA_N), while the step-up power supply circuit 20 performs a step-up operation. will be stopped.

In the diagnostic mode between timings Tb1 and Tb2, boost target voltage VtgB (VtgB_S) is higher than step-down target voltage VtgA (VtgA_S) (see FIGS. 6 and 7). However, in the boost abnormality case shown in FIG. 11, the boosting operation of the boosting power supply circuit 20 is disabled due to a failure, so the boosting operation is stopped in the diagnostic mode between timings Tb1 and Tb2. Then, in the diagnostic mode between timings Tb1 and Tb2, the step-down power supply circuit 10 performs a step-down operation so that the main power supply voltage VM and the step-down target voltage VtgA (VtgA_S) match. Even in the normal mode after timing Tb2, the step-down power supply circuit 10 performs the step-down operation so that the main power supply voltage VM and the step-down target voltage VtgA (VtgA_N) match.

Since the step-down target voltage VtgA changes with mode switching, in the step-up abnormal case shown in FIG. 11, starting from timing Tb1, the main power supply voltage VM changes from a relatively high step-down target voltage VtgA_N to a relatively low step-down target voltage VtgA_S. After the main power supply voltage VM decreases, it stabilizes at the step-down target voltage VtgA_S, and then, starting from timing Tb2, the main power supply voltage VM increases from the relatively low step-down target voltage VtgA_S to the relatively high step-down target voltage VtgA_N, and then the step-down target voltage Stabilizes at VtgA_N.

Between timings Tb1 and Tb2, the boost diagnosis process of step S16 (see FIG. 9) is executed. In the diagnostic mode, a voltage based on the boost operation and expected to match the boost target voltage VtgB_S should appear as the main power supply voltage VM. Therefore, the MPU 62 obtains the voltage Vdet in the diagnosis mode (see FIG. 3) as the evaluation voltage Vdet. At this time, in order to exclude the influence of fluctuations in the main power supply voltage VM due to mode transition, the voltage Vdet after a predetermined stabilization time has elapsed after the transition from the normal mode to the diagnostic mode is acquired as the evaluation voltage Vdet. For example, the voltage Vdet immediately before timing Tb2 may be acquired as the evaluation voltage Vdet.

Then, the MPU 62 determines whether the main power supply voltage VM in the diagnosis mode has a voltage within the fluctuation range of the boost target voltage VtgB_S in the diagnosis mode based on the evaluation voltage Vdet, and thereby the boost power supply circuit 20 Diagnose whether there is any abnormality. The method for this judgment and diagnosis is as described above in connection with the normal case in FIG. In the abnormal voltage step-up case of FIG. 11, a relatively low voltage corresponding to the target voltage step-down voltage VtgA_S is obtained as the evaluation voltage Vdet, so the normal voltage step-up condition is not satisfied. Therefore, it is determined that there is an abnormality in the boost power supply circuit 20.

Even if the boost power supply circuit 20 does not perform a boost operation in the diagnostic mode, no problem occurs because the step-down target voltage VtgA_S in the diagnostic mode satisfies the voltage accuracy required for the main power supply voltage VM.

The power supply device W according to the present invention, which is embodied in this embodiment, will be considered. The power supply device W in the ECU 1a has a step-down output terminal (10 _OUT ), and is a step-down power supply circuit (10) capable of outputting a step-down output voltage from the step-down output terminal by stepping down the voltage from the first voltage source (VS1). a step-up power supply circuit (20) having a step-up output terminal (20 _OUT ) and capable of outputting a step-up output voltage from the step-up output terminal by boosting the voltage from the second voltage source (VS2); and a main power supply line (LN1) to which the step-up output terminals are commonly connected and to which the main power supply voltage (VM) based on the output of the step-down power supply circuit or the output of the step-up power supply circuit is applied; VtgA) and a control unit (62) that sets a boost target voltage (VtgB) that is a target for the boost output voltage, the control unit setting the step-down target voltage (VtgA) higher than the boost target voltage (VtgB). It can operate in a normal mode or a diagnostic mode in which the boost target voltage (VtgB) is set higher than the step-down target voltage (VtgA), and is characterized in that it diagnoses whether there is an abnormality in the boost power supply circuit in the diagnostic mode.

If the wiring between the first voltage source and the step-down power supply circuit is disconnected even though the stored energy of the second voltage source as a spare battery is not consumed while the main first voltage source is connected to the step-down power supply circuit. Therefore, it is necessary to immediately supply power from a backup battery. The power supply device W can basically meet this demand by operating in the normal mode. Furthermore, by enabling operation in the diagnostic mode, it becomes possible to easily diagnose whether or not there is an abnormality in the booster power supply circuit. At this time, an expensive transistor (corresponding to M900 in FIG. 15) that was necessary in the configuration of FIG. 15 is not necessary. Further, deterioration in voltage accuracy due to the installation of such a transistor is avoided.

In the power supply device W (see FIG. 6), the control unit lowers the step-down target voltage and increases the step-up target voltage based on the normal mode, thereby increasing the step-up target voltage to the step-down target voltage in the diagnostic mode. It is better to set it higher than the target voltage.

This makes it possible to relatively easily satisfy the voltage accuracy required for the main power supply voltage in both the normal mode and the diagnostic mode.

More specifically, in the power supply device W, the step-down power supply circuit (10) is a step-down switching regulator that includes a step-down transistor (11) and generates a step-down output voltage through a step-down operation accompanied by switching of the step-down transistor. The step-up power supply circuit (20) executes or stops the step-down operation according to the relationship between the main power supply voltage (VM) and the step-down target voltage (VtgA). This is a boost switching regulator that generates a boosted output voltage through a boost operation that involves switching, and executes or stops the boost operation depending on the relationship between the main power supply voltage (VM) and the boost target voltage (VtgB).

As a result, for example, in the normal mode, the step-down power supply circuit performs step-down operation so that the main power supply voltage matches the step-down target voltage (VtgA_N; for example, 5.14V), while the step-up power supply circuit performs "main power supply voltage ≒ step-down target voltage". > Boost target voltage”, so the boost operation is stopped. In the diagnostic mode, the step-up power supply circuit performs step-up operation so that the main power supply voltage matches the step-up target voltage (VtgB_S; for example, 5.14V), while the step-down power supply circuit performs the step-up operation so that the main power supply voltage matches the step-up target voltage (VtgB_S; for example, 5.14 V), while the step-down power supply circuit ” Therefore, the step-down operation is stopped.

In the power supply device W according to the first embodiment, a step-down voltage divider circuit (DIV1) is formed of a series circuit of a plurality of voltage-dividing resistors and generates a step-down feedback voltage (VfbA) by dividing the main power supply voltage. and a step-up voltage divider circuit (DIV2) which is composed of a series circuit of a plurality of other voltage-dividing resistors and generates a step-up feedback voltage (VfbB) by dividing the main power supply voltage, and the step-down power supply circuit performs or stops the step-down operation so that the step-down feedback voltage matches or approaches a predetermined step-down reference voltage (VrefA); The step-down voltage divider circuit and the step-up voltage divider circuit are each configured such that the voltage division ratio is variable, and the control unit (62) The step-down target voltage (VtgA) can be variably set through the variable setting of the voltage division ratio in the step-up voltage divider circuit, and the step-up target voltage (VtgB) can be variably set through the variable setting of the voltage division ratio in the step-up voltage divider circuit.

In the power supply device W according to the first embodiment, the control unit (62) diagnoses whether or not there is an abnormality in the boost power supply circuit based on the main power supply voltage (VM) in the diagnosis mode.

In the diagnostic mode, the voltage based on the boost operation of the boost power supply circuit should appear as the main power supply voltage, so with this configuration, it is possible to correctly diagnose whether there is an abnormality in the boost power supply circuit.

More specifically, for example, in the diagnostic mode, the control unit (62) determines whether the main power supply voltage (VM) is within a predetermined normal voltage range corresponding to the boost target voltage (VtgB_S) in the diagnostic mode. By detecting this, it is possible to diagnose whether there is an abnormality in the booster power supply circuit. The normal voltage range here may be, for example, a voltage range below voltage VtgB_S_H and above voltage VtgB_S_L (see FIG. 8(b)).

Further, in the power supply device W, a voltage accuracy specification that requires the main power supply voltage (VM) to fall within a predetermined voltage range (RNG) is defined for the main power supply voltage, and the step-down target voltage in the normal mode is It is preferable that the boost target voltage, the step-down target voltage and the step-up target voltage in the diagnostic mode all fall within the predetermined voltage range.

This makes it possible to satisfy the voltage accuracy required for the main power supply voltage in both normal mode and diagnostic mode.

The reporting module according to the present invention including the power supply device W is a reporting module (1; 1a in the first embodiment) mounted on a vehicle (CC), and acquires position information representing the position of the vehicle. and an external communication device (63) capable of wirelessly transmitting a predetermined emergency call signal including the location information to an external device when a predetermined notification condition is met, and installed in the vehicle. an in-vehicle communication device (61) that communicates with other circuits connected to the main power supply voltage. (VM).

Thereby, a reporting module that includes the advantages of the power supply device W can be formed.

<<Second embodiment>>
A second embodiment of the present invention will be described. The second embodiment and the third and fourth embodiments described later are embodiments based on the first embodiment, and unless there is a contradiction, matters not specifically stated in the second to fourth embodiments are based on the first embodiment. The description of the embodiments also applies to the second to fourth embodiments. When interpreting the description of the second embodiment, the description of the second embodiment may take precedence regarding matters that are inconsistent between the first and second embodiments (the same applies to the third and fourth embodiments described later). . Any plurality of embodiments among the first to fourth embodiments may be combined as long as there is no contradiction. When the matters described in the first embodiment are applied to the second embodiment, the description "ECU1a" in the first embodiment is read as "ECU1b" in the second embodiment.

FIG. 12 shows the configuration of the ECU 1b according to the second embodiment. In the second embodiment, ECU 1b in FIG. 12 is used as ECU 1 in FIG. ECU 1b in FIG. 12 is a partially modified version of ECU 1a in FIG. That is, the ECU 1b is formed by removing the voltage dividing circuits DIV1 and DIV2 from the ECU 1a in FIG. 3 and providing a voltage dividing circuit DIV4 instead. In other respects, since the ECU 1a and the ECU 1b have the same configuration, redundant explanation of the same parts will be omitted.

The voltage dividing circuit DIV4 provided in the ECU 1b includes voltage dividing resistors R11 to R14 and a transistor M3 configured as an N-channel MOSFET. A series circuit of voltage dividing resistors R11 to R14 is arranged between the main power supply line LN1 and the ground. It will be placed in More specifically, one end of voltage dividing resistor R11 is connected to main power supply line LN1, the other end of voltage dividing resistor R11 is connected to one end of voltage dividing resistor R12 at node ND11, and the other end of voltage dividing resistor R11 is connected to one end of voltage dividing resistor R12. is connected to one end of voltage dividing resistor R13 at node ND12, the other end of voltage dividing resistor R13 is connected to one end of voltage dividing resistor R14 at node ND13, and the other end of voltage dividing resistor R14 is connected to ground. . The drain of transistor M3 is connected to node ND12, and the source of transistor M3 is connected to node ND13.

In ECU1b, the voltage generated at node ND13 is inputted to step-down power supply circuit 10 as feedback voltage VfbA, and the voltage generated at node ND11 is inputted to boosted power supply circuit 20 as feedback voltage VfbB. In this way, the voltage divider circuit DIV4 has a function of generating feedback voltages VfbA and VfbB by dividing the main power supply voltage VM at different voltage division ratios, and divides the main power supply voltage VM when generating the feedback voltage VfbA from the main power supply voltage VM. The voltage ratio and the voltage division ratio when generating the feedback voltage VfbB from the main power supply voltage VM are configured to be changed simultaneously by turning on/off the transistor M3.

More specifically, if the resistance values of the voltage dividing resistors R11, R12, R13, and R14 are represented by the symbols "R11", "R12", "R13", and "R14", respectively, then the main power supply voltage VM is divided into The voltage division ratio when generating the feedback voltage VfbA by increasing the voltage is "R14/(R11+R12+R13+R14)" when the transistor M3 is off, and "R14/(R11+R12+R14)" when the transistor M3 is on. The voltage division ratio when generating the feedback voltage VfbB by dividing the main power supply voltage VM is "(R12+R13+R14)/(R11+R12+R13+R14)" when the transistor M3 is off, and "(R11+R12+R13+R14)" when the transistor M3 is on. R12+R14)/(R11+R12+R14)". However, here, it is assumed that the on-resistance of the transistor M3 is sufficiently low and is zero.

A signal FET_EN from the MPU 62 is input to the gate of the transistor M3. When the signal FET_EN is at a low level, the transistor M3 is off, and when the signal FET_EN is at a high level, the transistor M3 is on. The method of controlling the level of signal FET_EN is as shown in the first embodiment. Therefore, in the normal mode, the signal FET_EN is set to a low level, and in the diagnostic mode, the signal FET_EN is set to a high level.

Therefore, in the ECU 1b, the feedback voltage VfbA is higher in the diagnostic mode than in the normal mode, and the feedback voltage VfbB is lower in the diagnostic mode than in the normal mode. As a result, in the ECU 1b, the step-down target voltage VtgA is lower in the diagnostic mode than in the normal mode, and the step-up target voltage VtgB is higher in the diagnostic mode than in the normal mode.

The characteristics of the step-down target voltage VtgA and the step-up target voltage VtgB, including that the first to fourth inequalities described above are satisfied and that the four target voltages VtgA_N, VtgA_S, VtgB_N, and VtgB_S all fall within the predetermined specification voltage range RNG. are as described in the first embodiment (the resistance values of the voltage dividing resistors R11 to R14 and the values of the reference voltages VrefA and VrefB are determined so as to be as described in the first embodiment).

In the ECU 1b, since the voltage dividing resistor ladder for setting the step-down target voltage and the step-up target voltage is shared, the potential difference between the step-down target voltage and the step-up target voltage is Accuracy can be improved (variations in the voltage dividing resistance of the voltage dividing circuit DIV1 and voltage dividing resistance of the voltage dividing circuit DIV2, which occur in the configuration of FIG. 3, appear to be canceled out in the configuration of FIG. 12) . As a result, the requirements for the step-down target voltage and the step-up target voltage as shown in FIGS. 6, 7, and 8(a) and (b) can be easily met. Furthermore, the number of transistors used for switching the voltage division ratio can be reduced (the configuration in FIG. 3 requires two transistors M1 and M2, while the configuration in FIG. 12 requires only one transistor M3).

Note that as long as the above-described relationship between the step-down target voltage and the step-up target voltage in each of the normal mode and the diagnostic mode is satisfied, the configuration of the voltage dividing circuit DIV4 is arbitrary.

For example, the transistor M3 constitutes a bypass circuit connected in parallel to the voltage dividing resistor R13, and in the voltage dividing circuit DIV4 of FIG. 12, when the transistor M3 is turned on, the parallel circuit of the voltage dividing resistor R13 and the bypass circuit The resistance value of becomes substantially zero, but if the resistance value of the parallel circuit of voltage dividing resistor R13 and the bypass circuit becomes smaller when transistor M3 is on than when transistor M3 is off. , the configuration of the bypass circuit of the voltage dividing circuit DIV4 is arbitrary. For example, the bypass circuit of the voltage dividing circuit DIV4 may be a series circuit of the transistor M3 and a resistor.

In other words, it can be said that the power supply device W according to the second embodiment employs the following configuration. The power supply device W is a voltage dividing circuit that is composed of a series circuit of a plurality of voltage dividing resistors, and generates a step-down feedback voltage (VfbA) and a step-up feedback voltage (VfbB) by dividing the main power supply voltage at mutually different voltage division ratios. (DIV4), and in this voltage dividing circuit (DIV4), a bypass circuit (M3 in the example of FIG. 12) is connected in parallel to some of the voltage dividing resistors (R13 in the example of FIG. 12). By controlling the state of the bypass circuit, the control unit (62) makes the resistance value of the parallel circuit between some of the voltage dividing resistors and the bypass circuit variable, and changes the resistance value of the parallel circuit when switching between the normal mode and the diagnostic mode. By changing the resistance value, the voltage division ratio for obtaining the step-down feedback voltage from the main power supply voltage and the voltage division ratio for obtaining the step-up feedback voltage from the main power supply voltage are simultaneously changed, and thereby the step-down target voltage and the step-up target voltage change at the same time.

<<Third Embodiment>>
A third embodiment of the present invention will be described. The description in the first or second embodiment is applicable to the third embodiment, and when the matters described in the first or second embodiment are applied to the third embodiment, the description in the first embodiment ""ECU1a" or "ECU1b" in the second embodiment is read as "ECU1c" in the third embodiment.

FIG. 13 shows the configuration of an ECU 1c according to the third embodiment. In the third embodiment, the ECU 1c in FIG. 13 is used as the ECU 1 in FIG. The ECU 1c in FIG. 13 is a partially modified version of the ECU 1b in FIG. 12. That is, the ECU 1c is formed by removing the voltage dividing circuit DIV3 from the ECU 1b in FIG. 12 and providing the monitor circuit 30 in its place. In other respects, since the ECU 1b and the ECU 1c have the same configuration, redundant explanation of the same parts will be omitted. In the ECU 1c of FIG. 13, it is also possible to adopt the method of generating the reference voltages VrefA and VrefB of the first embodiment instead of the method of generating the reference voltages VrefA and VrefB of the second embodiment (i.e., (The ECU 1c may be formed by removing the voltage dividing circuit DIV3 based on the ECU 1a of ECU 3 and providing the monitor circuit 30 instead.)

The monitor circuit 30 is connected to the boost power supply circuit 20 and derives a voltage Vdet2 depending on whether or not the boost power supply circuit 20 is performing a boost operation.

FIG. 14 shows a configuration example of the boost power supply circuit 20 and the monitor circuit 30. The boost power supply circuit 20 in FIG. 14 is the same as the boost power supply circuit 20 in FIG. The monitor circuit 30 includes a diode 31 functioning as a freewheeling diode (rectifier diode), a smoothing capacitor 32, and voltage dividing resistors 33 and 34. The anodes of diode 22 and diode 31 are commonly connected to the drain of transistor 21 . The cathode of the diode 31 is connected to the monitor line LN1'. One end of the smoothing capacitor 32 is connected to the monitor line LN1', and the other end of the smoothing capacitor 32 is connected to ground. One end of the voltage dividing resistor 33 is connected to the monitoring line LN1', and the other end of the voltage dividing resistor 33 is connected to the ground via the voltage dividing resistor 34. The voltage applied to the monitor line LN1' is referred to as voltage VMdmy. A voltage Vdet2, which is a divided voltage of the voltage VMdmy, is generated at the connection node between the voltage dividing resistors 33 and 34.

With the above configuration, when the boost operation is not performed, the voltage VMdmy becomes a voltage (VB-Vf) lower than the output voltage VB of the voltage source VS2 by the forward voltage Vf of the diode 31. When the boost operation is performed, a voltage that is a boosted voltage of the voltage VB and which is different from the voltage at the output terminal 20 _OUT (that is, the main power supply voltage VM) appears as the voltage VMdmy. The voltage VMdmy corresponds to a voltage imitating the main power supply voltage VM, and when the boost operation is performed, the voltage VMdmy has substantially the same voltage value as the voltage at the output terminal 20 _OUT (i.e., the main power supply voltage VM). It is expected that Therefore, by observing the voltage VMdmy, it is possible to diagnose whether the boosting operation is being performed normally. In the configurations of FIGS. 13 and 14, voltage VMdmy is evaluated using voltage Vdet2, which is a divided voltage of voltage VMdmy.

[Using monitor circuit in diagnostic mode]
A boost diagnosis process in the diagnosis mode using the monitor circuit 30 will be described. For concrete explanation, referring again to FIG. 10 or 11, the pressurization diagnosis processing in the above-mentioned normal case or abnormal pressurization case will be explained. In the normal case of FIG. 10, in the diagnostic mode between timings Ta1 and Ta2, as described in the first embodiment, the boost power supply circuit 20 operates so that the main power supply voltage VM matches the boost target voltage VtgB (VtgB_S). While the step-up operation is performed, the step-down power supply circuit 10 stops the step-down operation. In the step-up abnormality case in FIG. 11, in the diagnostic mode between timings Tb1 and Tb2, the step-up operation has stopped due to a failure, as described in the first embodiment, and the main power supply voltage VM and step-down target voltage VtgA (VtgA_S) The step-down power supply circuit 10 performs the step-down operation so that the values match.

The boost diagnosis process in step S16 (see FIG. 9) is executed between timings Ta1 and Ta2 in the normal case, and between timings Tb1 and Tb2 in the abnormal boost case. In the diagnostic mode, the voltage based on the boost operation and expected to match the boost target voltage VtgB_S should appear as the main power supply voltage VM, and in conjunction with this, the boost target voltage VtgB_S and The voltage that is expected to match should appear as the voltage VMdmy. Therefore, the MPU 62 obtains the voltage Vdet2 in the diagnosis mode as the evaluation voltage Vdet2. At this time, in order to exclude the influence of fluctuations in voltages VM and VMdmy due to mode transition, voltage Vdet2 after a predetermined stabilization time has elapsed after transition from normal mode to diagnostic mode is acquired as evaluation voltage Vdet2. For example, the voltage Vdet2 immediately before timing Ta2 or Tb2 may be acquired as the evaluation voltage Vdet2.

The MPU 62 diagnoses whether or not there is an abnormality in the boost power supply circuit 20 by determining whether a predetermined normal boost condition is met or not based on the evaluation voltage Vdet2. If the normal boosting conditions are satisfied, it is determined that there is no abnormality in the boosting power supply circuit 20, and if the normal boosting conditions are not satisfied, it is determined that there is an abnormality in the boosting power supply circuit 20.

The determination of success or failure of the normal boost condition (determination of sufficiency/insufficiency) is performed under the assumption that voltages VM and VMdmy have the same voltage value. The boost normal condition is a condition that the voltage VMdmy in the diagnostic mode is within a predetermined normal voltage range. The normal voltage range here is a voltage range corresponding to the boosted target voltage (VtgB_S) in the diagnostic mode, and therefore may be a voltage range from voltage VtgB_S_L to voltage VtgB_S_H (see FIG. 8(b)). However, it is also possible to set the lower limit of the normal voltage range lower than the voltage VtgB_S_L (however, it should be at least the lower limit voltage _LL of the specified voltage range RNG), and the upper limit of the normal voltage range can be set higher than the voltage VtgB_S_H. (However, the voltage should be at least lower than the upper limit voltage _HL of the specification voltage range RNG).

It is possible to determine whether or not the boosting normal condition is satisfied based on the resistance value ratio between the voltage dividing resistors R7 and R8, which are known information, and the evaluation voltage Vdet2. Note that the value of the lower limit voltage _VLL of the specified voltage range RNG is higher than the nominal voltage value (for example, 3V) of the output voltage VB of the voltage source VS2, so if the boost operation has stopped in the diagnostic mode, the boost Normal conditions are never satisfied.

In the normal case of FIG. 10, the normal pressurization condition is satisfied. In the abnormal boosting case shown in FIG. 11, the boosting operation is stopped due to a failure in the boosting power supply circuit 20, so the normal boosting condition is not satisfied.

When monitoring the main power supply voltage VM as in the configuration of the first or second embodiment, the output of each power supply circuit is It is required to improve the voltage accuracy and the reading accuracy of the voltage Vdet. In the third embodiment, such a requirement is relaxed because the voltage VMdmy of the monitor line LN1' which is DC-separated from the main power supply line LN1 is monitored.

The MPU 62 includes an A/D converter. The MPU 62 converts the analog evaluation voltage Vdet2 into a digital voltage value using an A/D converter, and determines whether the normal boost condition is satisfied or not based on the obtained voltage value. Alternatively, instead of the A/D converter, a window comparator including a plurality of comparators may be provided in the ECU 1c, and the window comparator may be used to determine whether the boost normal condition is met or not.

[Using the monitor circuit in normal mode (normal mode diagnostic processing)]
The monitor circuit 30 can function effectively even in normal mode. A normal mode diagnostic process that can be performed by the MPU 62 using the monitor circuit 30 in the normal mode will be described.

In the normal mode diagnosis process, the MPU 62 monitors whether or not the boost operation is being performed based on the voltage VMdmy (actually, based on the voltage Vdet2), and when it determines that the boost operation is being performed, It is determined that there is an abnormality (hereinafter referred to as a specific abnormality for convenience) in the power supply device. The power supply device included in the ECU 1c includes power supply circuits 10 and 20 as well as a circuit (voltage dividing circuit DIV4 in FIG. 13) that generates feedback voltages VfbA and VfbB. The specific abnormality is mainly an abnormality in either of the power supply circuits 10 and 20, but an abnormality in a circuit that generates the feedback voltages VfbA and VfbB may also belong to the specific abnormality.

Basically, no boosting operation is performed in the normal mode, and the voltage VMdmy should be lower than the output voltage VB of the voltage source VS2. However, if the boost operation is performed in the normal mode due to some abnormality, the voltage VMdmy will be higher than when the boost operation is stopped. Therefore, in the normal mode diagnostic process, the MPU 62 compares the voltage Vdet2 with a predetermined determination voltage Vth, and determines that there is a specific abnormality if the voltage Vdet2 is equal to or higher than the determination voltage Vth (if the voltage Vdet2 is less than the determination voltage Vth) (If so, it will not be determined that there is a specific abnormality.) For example, the determination voltage Vth may be determined so that when "VMdmy≧V _LL ", "Vdet2≧Vth" is satisfied.

As cases in which a specific abnormality occurs, the following first specific abnormality case and second specific abnormality case are mainly assumed.
The first specific abnormality case is a case in which, in the normal mode, the step-down power supply circuit 10 stops the step-down operation due to a failure, and the step-up power supply circuit 20 performs the step-up operation instead.
The second specific abnormality case is a case in which no failure occurs in the step-down power supply circuit 10 in the normal mode, but the step-up power supply circuit 20 performs a step-up operation. For example, a case in which the boosted target voltage VtgB excessively increases beyond the design value applies to the second specific abnormal case. If an abnormality occurs such that the node to which the feedback voltage VfbB is to be applied is short-circuited to ground, the boost power supply circuit 20 will perform a boost operation regardless of the main power supply voltage VM.

If it is determined that there is a specific abnormality, the MPU 62 performs predetermined error processing. The error handling here may be the same as or similar to the error handling in step S30 (see FIG. 9).

The normal mode diagnostic process makes it possible to monitor whether there is an abnormality in the power supply device (mainly an abnormality in the power supply circuit 10 or 20) even in the normal mode.

However, even if the MPU 62 is in the normal mode, it is preferable that the normal mode diagnostic process is not executed when the voltage VA decreases. The reason why the voltage boosting operation is performed when the main power supply voltage VM decreases as the voltage VA decreases is because this is the correct behavior. Specifically, the ECU 1c is provided with a voltage detection circuit (not shown) that detects the voltage VA, and when the voltage VA detected by the voltage detection circuit is below a predetermined drop judgment voltage Vth2, the normal mode diagnosis is performed. It is better to set the process to non-execution. Considering the characteristics of the step-down power supply circuit 10, for example, a voltage equal to or higher than the voltage VtgB_N_H is set as the drop determination voltage Vth2. If the voltage VA recovers (rises) and exceeds the drop judgment voltage Vth2 from a state in which the normal mode diagnostic processing is not executed due to the voltage VA falling below the predetermined drop judgment voltage Vth2, the normal mode is activated. You can restart the diagnostic process.

<<Fourth embodiment>>
A fourth embodiment of the present invention will be described. In the fourth embodiment, supplementary matters, modification techniques, etc. for the first to third embodiments will be explained.

For any signal or voltage, the relationship between high and low levels may be reversed without detracting from the spirit described above.

The types of channels of FETs (field effect transistors) shown in each embodiment are merely examples, and an N-channel FET may be changed to a P-channel FET, or a P-channel FET may be changed to an N-channel FET. The configuration of the circuit containing the FET can be modified to change the type of FET.

Any transistor mentioned above may be any type of transistor. For example, it is also possible to replace any transistor mentioned above as a MOSFET (in particular, for example, the switching transistor M1) by a junction FET, an IGBT (Insulated Gate Bipolar Transistor) or a bipolar transistor. Any transistor has a first electrode, a second electrode, and a control electrode. In a FET, one of the first and second electrodes is the drain, the other is the source, and the control electrode is the gate. In an IGBT, one of the first and second electrodes is the collector, the other is the emitter, and the control electrode is the gate. In a bipolar transistor that does not belong to an IGBT, one of the first and second electrodes is the collector, the other is the emitter, and the control electrode is the base.

The embodiments of the present invention can be appropriately modified in various ways within the scope of the technical idea shown in the claims. The above embodiments are merely examples of the embodiments of the present invention, and the meanings of the terms of the present invention and each component are not limited to those described in the above embodiments. The specific numerical values shown in the above-mentioned explanatory text are merely examples, and it goes without saying that they can be changed to various numerical values.

1, 1a, 1b, 1c ECU
10 Step-down power supply circuit 20 Step-up power supply circuit 30 Monitor circuit 61 CAN transceiver 62 MPU
63 Communication module 64 GPS processing unit VS1 Voltage source (first voltage source)
VS2 voltage source (second voltage source)
LN1 Main power supply line LN1' Monitor line DIV1 to DIV4 Voltage divider circuit

Claims (11)

a step-down power supply circuit that outputs a step-down output voltage from a step-down output terminal by stepping down the voltage of the first voltage source;
a boosting power supply circuit that outputs a boosted output voltage from a boosted output terminal by boosting the voltage of a second voltage source ;
a main power line that is commonly connected to the step-down output terminal and the step-up output terminal and supplies a main power voltage ;
In the normal mode, the step-down target voltage is set higher than the step-up target voltage, and in the diagnostic mode for diagnosing the presence or absence of an abnormality in the step-up power supply circuit, the step-down target voltage is lowered and the step-up target voltage is increased, so that the step-up target voltage is set higher than the step-up target voltage. and a control unit that sets the step-down target voltage higher than the target voltage.
power supply. The step-down power supply circuit is a step-down switching regulator that includes a step-down transistor and generates the step-down output voltage through a step-down operation that involves switching of the step-down transistor, and the step-down switching regulator has a relationship between the main power supply voltage and the step-down target voltage. performing or stopping the step-down operation according to the step;
The step-up power supply circuit is a step-up switching regulator that includes a step-up transistor and generates the step-up output voltage through a step-up operation accompanied by switching of the step-up transistor, and has a relationship between the main power supply voltage and the step-up target voltage. Execute or stop the boost operation according to the
, The power supply device according to claim 1 . a step-down voltage divider circuit comprising a series circuit of a plurality of voltage-dividing resistors and generates a step-down feedback voltage by dividing the main power supply voltage;
further comprising a voltage boosting voltage dividing circuit which is made up of a series circuit of a plurality of other voltage dividing resistors and generates a boosting feedback voltage by dividing the main power supply voltage;
The step-down power supply circuit executes or stops the step-down operation so that the step-down feedback voltage matches or approaches a predetermined step-down reference voltage;
The boosting power supply circuit executes or stops the boosting operation so that the boosting feedback voltage matches or approaches a predetermined boosting reference voltage,
The step-down voltage divider circuit and the step-up voltage divider circuit are each configured to have a variable voltage division ratio,
The control unit variably sets the step-down target voltage through variable setting of a voltage division ratio in the step-down voltage divider circuit, and variably sets the step-up target voltage through variable setting of a voltage division ratio in the step-up voltage divider circuit.
, The power supply device according to claim 2 . further comprising a voltage dividing circuit that is composed of a series circuit of a plurality of voltage dividing resistors and that generates a step-down feedback voltage and a step-up feedback voltage by dividing the main power supply voltage at mutually different voltage division ratios,
The step-down power supply circuit executes or stops the step-down operation so that the step-down feedback voltage matches or approaches a predetermined step-down reference voltage;
The boosting power supply circuit executes or stops the boosting operation so that the boosting feedback voltage matches or approaches a predetermined boosting reference voltage,
The voltage divider circuit is configured such that a voltage division ratio for obtaining the step-down feedback voltage from the main power supply voltage and a voltage division ratio for obtaining the step-up feedback voltage from the main power supply voltage are variable,
The control unit simultaneously changes the step-down target voltage and the step-up target voltage by changing these voltage division ratios simultaneously when switching between the normal mode and the diagnostic mode.
, The power supply device according to claim 2 . The series circuit of the plurality of voltage dividing resistors is inserted between the main power supply line and ground,
In the voltage dividing circuit, a bypass circuit is connected in parallel to some voltage dividing resistors of the plurality of voltage dividing resistors,
The step-down feedback voltage and the step-up feedback voltage are generated at mutually different first and second nodes in the series circuit, and the partial voltage dividing resistor to which the bypass circuit is connected in parallel is connected to the first node. interposed between the second node and the second node;
The control unit is configured to vary the resistance value of a parallel circuit between the partial voltage dividing resistor and the bypass circuit by controlling the state of the bypass circuit, and to change the resistance value of the parallel circuit between the normal mode and the diagnostic mode. By changing the resistance value of Simultaneously changing the target voltage and the boosted target voltage
, The power supply device according to claim 4 . In the diagnosis mode, the control unit diagnoses whether or not there is an abnormality in the boost power supply circuit based on the main power supply voltage.
, the power supply device according to any one of claims 1 to 5 . In the diagnostic mode, the control unit detects whether the main power supply voltage is within a predetermined normal voltage range corresponding to the boost target voltage in the diagnostic mode, thereby controlling the boost power supply circuit. Diagnose whether there is an abnormality in
, The power supply device according to claim 6 . Connected to the boosting transistor, when the boosting operation is being performed, a voltage that is a boosted voltage from the second voltage source and which is different from the voltage at the boosting output terminal is connected to a predetermined monitoring line. It is further equipped with a monitor circuit that generates
In the diagnosis mode, the control unit diagnoses whether or not there is an abnormality in the boost power supply circuit based on the voltage of the monitor line.
, the power supply device according to any one of claims 2 to 5 . The control unit is capable of executing a normal mode diagnosis process in the normal mode, and in the normal mode diagnosis process, monitors whether or not the boost operation is being performed based on the voltage of the monitor line, and determines whether the boost operation is being performed or not. When it is determined that an operation is being performed, it is determined that there is an abnormality in the relevant power supply device.
9. The power supply device according to claim 8 . Voltage accuracy specifications are defined for the main power supply voltage that require the main power supply voltage to fall within a predetermined voltage range;
The step-down target voltage and the step-up target voltage in the normal mode and the step-down target voltage and the step-up target voltage in the diagnostic mode all fall within the predetermined voltage range.
The power supply device according to any one of claims 1 to 9 . A reporting module equipped in a vehicle, comprising the power supply device according to any one of claims 1 to 10,
a position information acquisition device that acquires position information representing the position of the vehicle;
an external communication device capable of wirelessly transmitting a predetermined emergency call signal including the location information to an external device when a predetermined report condition is satisfied;
an in-vehicle communication device that communicates with other circuits mounted on the vehicle,
The position information acquisition device, the external communication device, the in-vehicle communication device, and the control section in the power supply device are driven based on the main power supply voltage.
, reporting module.

Images