Vehicle-mounted device

Abstract

This vehicle-mounted device is mounted on a vehicle, and is provided with: an input circuit that includes an input terminal to which an input voltage is input; the driving power supply circuit outputs driving voltage to the input circuit, the input circuit comprises a pnp type bipolar transistor, a pull-up circuit, a second pull-up resistor and a base resistor, the pull-up circuit comprises a pull-up power supply, a first pull-up resistor and a second diode which are connected in series, the anode of the second diode faces the first pull-up resistor, and the cathode of the second diode faces the base resistor. The pull-up circuit is arranged between the base electrode of the pnp type bipolar transistor and the input end, the second pull-up resistor is arranged between the base electrode of the pnp type bipolar transistor and the driving power supply circuit, and the base electrode resistor is arranged between the base electrode of the pnp type bipolar transistor and the second pull-up resistor. A first diode is arranged between the connection point of the second pull-up resistor and the base resistor and the input end, and the cathode of the first diode faces the input end.

Description

Technical Field

[0001] The present disclosure relates to a vehicle-mounted device.

[0002] This application claims the priority based on Japanese application No. 2022-109144 for which it applied on July 6, 2022, and cites all the contents described in the said Japanese application. Background Art

[0003] A constant current driving device for driving a load with current is disclosed (for example, Patent Document 1). The constant current driving device includes a first current driving circuit connected between a first terminal and a second terminal, and a second current driving circuit connected between a third terminal and the first terminal or the second terminal, so that the current flowing through the load is divided and flows through the first current driving circuit and the second current driving circuit. The first current driving circuit is composed of a first operational amplifier and a first transistor, and the first transistor is connected in a manner that a current flows between the first terminal and the second terminal.

[0004] Prior art literature Patent Literature Patent Document 1: Japanese Patent Application Publication No. 2008-161078 Summary of the invention

[0005] A vehicle-mounted device according to one embodiment of the present disclosure is mounted on a vehicle, wherein the vehicle-mounted device comprises: an input circuit including an input terminal to which an input voltage is input; and a drive power circuit outputting a drive voltage to the input circuit, the input circuit including a pnp-type bipolar transistor, a pull-up circuit, a second pull-up resistor, and a base resistor, the pull-up circuit including a pull-up power supply, a first pull-up resistor, and a second diode connected in series, the anode of the second diode facing the first pull-up resistor, the pull-up circuit being arranged between the base of the pnp-type bipolar transistor and the input terminal, the second pull-up resistor being arranged between the base of the pnp-type bipolar transistor and the drive power circuit, the base resistor being arranged between the base of the pnp-type bipolar transistor and the second pull-up resistor, a first diode being arranged between a connection point between the second pull-up resistor and the base resistor and the input terminal, the cathode of the first diode facing the input terminal. BRIEF DESCRIPTION OF THE DRAWINGS

[0006] Figure 1 This is a schematic diagram illustrating an outline of a vehicle-mounted device mounted on a vehicle according to the first embodiment. Figure 2 This is a circuit diagram illustrating the configuration of an input circuit and the like included in the vehicle-mounted device. Figure 3 This is an explanatory diagram (timing chart) for explaining the operation of the input circuit, etc. DETAILED DESCRIPTION

[0007] [Problems to be Solved by the Present Disclosure]

[0008] In the constant current driving device using a transistor described in Patent Document 1, when determining whether an input voltage is high or low based on a predetermined threshold, even when the threshold is small, it is not considered that the determination is performed efficiently.

[0009] The present disclosure has been made in view of such circumstances, and an object of the present disclosure is to provide an in-vehicle device including an input circuit capable of efficiently performing determination on an input voltage.

[0010] [Effects of the present disclosure]

[0011] According to one aspect of the present disclosure, it is possible to provide an in-vehicle device including an input circuit that efficiently performs determination on an input voltage.

[0012] [Description of Embodiments of the Present Disclosure]

[0013] First, the embodiments of the present disclosure will be described by way of examples. In addition, at least a part of the embodiments described below may be arbitrarily combined.

[0014] (1) An in-vehicle device according to one aspect of the present disclosure is mounted on a vehicle, wherein the in-vehicle device comprises: an input circuit including an input terminal to which an input voltage is input; and a drive power circuit outputting a drive voltage to the input circuit, the input circuit including a pnp bipolar transistor, a pull-up circuit, a second pull-up resistor, and a base resistor, the pull-up circuit including a pull-up power supply, a first pull-up resistor, and a second diode connected in series, the anode of the second diode facing the first pull-up resistor, the pull-up circuit being arranged between the base of the pnp bipolar transistor and the input terminal, the second pull-up resistor being arranged between the base of the pnp bipolar transistor and the drive power circuit, the base resistor being arranged between the base of the pnp bipolar transistor and the second pull-up resistor, and a first diode being arranged between a connection point between the second pull-up resistor and the base resistor and the input terminal, the cathode of the first diode facing the input terminal.

[0015] In this embodiment, the vehicle-mounted device has an input circuit, a driving power supply circuit that outputs a driving voltage to the input circuit, and a voltage conversion circuit connected to the output end of the input circuit. The low-side input circuit device is constituted by these input circuits and the driving power supply circuit. The vehicle-mounted device including the low-side input circuit device functions as a body ECU, a CAN gateway or other relay device for driving control of a body system actuator mounted on a vehicle, or an electrical connection box with a semiconductor fuse. The vehicle-mounted device (low-side input circuit device) outputs a high or low signal (output voltage) according to the input voltage input from the input end (connector end connected to the input connector) of the input circuit. The high or low signal (output voltage) is output, for example, from a voltage conversion circuit connected to the output end of the input circuit to a microcomputer or the like. The microcomputer to which the high or low signal (output voltage) is input performs various control processes or calculation processes based on the signal (output voltage). The input circuit includes a pnp bipolar transistor, and a first conductive line extending from the input end (connector end) is connected to the base of the pnp bipolar transistor. The first diode and the base resistor are provided in the first conductive path. In this case, the voltage at the input end (V: input end voltage) becomes the value obtained by subtracting the voltage drop of the first diode (VfD: forward voltage) and the voltage drop between the emitter and base of the pnp bipolar transistor (Vbe) from the driving voltage (V_OUT) (V=V_OUT-Vf-Vbe). For the input voltage (Vin) input to the input end, when the threshold value (threshold value of the on / off voltage) when judging as low or high is a relatively small value (low voltage), the influence of the deviation caused by the temperature characteristics of each element that determines the input end voltage becomes large. In contrast, the voltage drop of the first diode provided in the second first conductive path and the voltage drop between the emitter and base of the pnp bipolar transistor affect the input end voltage (V), so the deviation can be reduced and the threshold can be made more accurate. For example, when using a digital transistor with built-in resistors, the voltage drop (Vbe×(Ri+Rb) / Ri) between the emitter and base of the pnp bipolar transistor is determined by the resistance divider ratio ((Ri+Rb) / Ri) between the internal resistance (Ri) of the digital transistor and the base resistance (Rb). In this case, the error (deviation) of the internal resistance (Ri) of the digital transistor is large, and the resistance divider ratio may vary significantly. In contrast, as described above, the input circuit uses a pnp bipolar transistor, and the second pull-up resistor and the base resistance are connected in parallel, thereby eliminating (making the resistance divider unnecessary), and reducing the deviation compared to the case of using a digital transistor. As a result, the threshold can be made more accurate, and relatively cheap components can be used, thereby reducing product costs.

[0016] (2) In an in-vehicle device according to one embodiment of the present disclosure, the driving power circuit includes a driving power supply, an npn-type bipolar transistor, a first resistor, and a second resistor, wherein the second resistor is connected in series with the first resistor, and the driving power circuit outputs the driving voltage corresponding to a resistance voltage division ratio between the first resistor and the second resistor.

[0017] In this embodiment, the driving power supply circuit includes a driving power supply, an npn-type bipolar transistor, a first resistor, and a second resistor connected in series with the first resistor, for example, composed of an emitter follower circuit. By using the emitter follower circuit to constitute the driving power supply circuit, the output voltage can be adjusted by the resistance voltage divider ratio of the first resistor (R1) and the second resistor (R2), so that the output voltage (V_OUT) based on the driving power supply circuit is constant relative to the output voltage (V_OUT) of the driving power supply. In addition, by changing the resistance constants of these first resistors (R1) and second resistors (R2), the threshold value (threshold value of the on / off voltage) when judging as low or high can be adjusted, which can improve the availability of the driving power supply circuit.

[0018] (3) The vehicle-mounted device of one aspect of the present disclosure further includes a voltage conversion circuit, which performs voltage conversion between the input circuit and the microcomputer. The voltage conversion circuit is a level shift circuit, and the level shift circuit includes a level shift power supply and a digital transistor. The voltage converted by the level shift circuit is output to the microcomputer, and the microcomputer is connected to the collector of the digital transistor.

[0019] In this embodiment, the voltage conversion circuit is composed of a level shift circuit including a level shift power supply and a digital transistor, and the output voltage after the level shift (voltage conversion) by the level shift circuit is output from the voltage conversion circuit. In this way, the voltage conversion is performed between the input circuit and the microcomputer through the voltage conversion circuit. For example, in the case where an electronic component with a computing function such as a microcomputer, IC (Integrated Circuit), ASIC (Application Specific Integrated Circuit) or FPGA (Field-Programmable Gate Array) is connected to the output end (microcomputer end) of the voltage conversion circuit, it is also considered that the threshold voltage of the microcomputer does not correspond to the output voltage from the driving power supply circuit. Even in such a case, by using the output voltage of the level shift power supply of the voltage conversion circuit (level shift circuit), it is possible to correspond to (satisfy) the threshold voltage of the microcomputer without relying on the output voltage (pull-up voltage) from the driving power supply circuit.

[0020] [Details of the embodiments of the present disclosure]

[0021] The present disclosure is specifically described based on the drawings showing the embodiments of the present disclosure. Hereinafter, the vehicle-mounted device 1 of the embodiment of the present disclosure will be described with reference to the drawings. In addition, the present disclosure is not limited to these examples, but is indicated by the claims, and is intended to include all changes within the meaning and scope equivalent to the claims.

[0022] (Implementation method 1)

[0023] Hereinafter, embodiments will be described based on the drawings. Figure 1 This is a schematic diagram illustrating an outline of the vehicle-mounted device 1 mounted on the vehicle C according to the first embodiment. Figure 2 1 is a circuit diagram illustrating the structure of the input circuit 2 and the like included in the vehicle-mounted device 1. The vehicle-mounted device 1 can also be mounted on a vehicle C, and includes the input circuit 2 and a driving power circuit 4 that outputs a driving voltage to the input circuit 2, and further includes a voltage conversion circuit 5 connected to the output end of the input circuit 2. The vehicle-mounted device 1 can also further include a microcomputer 6 connected to the voltage conversion circuit 5. The driving power circuit 4 and the input circuit 2 are connected via a second conductive line 102. The input circuit 2 and the voltage conversion circuit 5 are connected via a third conductive line 103.

[0024] The input circuit 2, the drive power circuit 4 and the voltage conversion circuit 5 constitute a low-side input circuit device. The vehicle-mounted device 1, which functions as the low-side input circuit device, outputs a signal (output voltage) indicating high (Hi) or low (Lo) to the microcomputer 6 according to the voltage value of the input voltage input to the input circuit 2. The details will be described later. The threshold value (threshold value of the on / off voltage) for high / low judgment of the input voltage is determined by the input circuit 2 and the drive power circuit 4. The input circuit 2 has a pnp bipolar transistor T2, which is configured to eliminate the voltage division ratio of the base resistor R5, etc., so that a relatively low voltage threshold can be set, and the threshold value can be made more accurate, thereby reducing the deviation of the threshold value.

[0025] The driving power circuit 4 includes a driving power 41, an npn bipolar transistor T1, a first resistor R1, and a second resistor R2. The driving power 41 outputs a predetermined voltage (e.g., 5 V) obtained by stepping down a voltage (e.g., 12 V) supplied from a power supply device such as a lead storage battery or an AC generator mounted on the vehicle C using a regulator or the like.

[0026] The driving power source 41 is connected to the npn bipolar transistor T1, and the npn bipolar transistor T1 is always applied with a voltage output from the driving power source 41. The wire extending from the driving power source 41 to the npn bipolar transistor T1 is branched into two, and the two branched ends are respectively connected to the collector and the base of the npn bipolar transistor T1.

[0027] A first resistor R1 is sandwiched between the driving power supply 41 and the base of the npn-type bipolar transistor T1. A second resistor R2 is sandwiched on the wire extending from the first resistor R1 to the ground. That is, the base of the npn-type bipolar transistor T1 is connected to a wire extending from the connection point of the first resistor R1 and the second resistor R2. Through such a connection method, the first resistor R1 and the second resistor R2 are connected in series, and the base of the npn-type bipolar transistor T1 is connected to the connection point of the first resistor R1 and the second resistor R2, so that the voltage output from the emitter of the npn-type bipolar transistor T1 becomes a voltage value corresponding to the resistance voltage divider ratio of the first resistor R1 and the second resistor R2.

[0028] In this way, the driving power supply circuit 4 is composed of an emitter follower circuit, which steps down the output voltage (VCC) from the driving power supply 41 to a specified voltage (V_OUT) according to the resistance voltage division ratio of the first resistor R1 and the second resistor R2. The stepped-down voltage is equivalent to the output voltage (V_OUT) of the driving power supply circuit 4. By using this emitter follower circuit, the npn bipolar transistor T1 can be used in a simulated manner based on the operating principle of the linear regulator to adjust the output voltage (V_OUT) by resistance voltage division. As a result, a relatively expensive comparator is not required, and the necessary functions can be achieved (satisfied) with a cheap structure.

[0029] The output voltage is adjusted by the resistance voltage division ratio (V_OUT=VCC*R2 / (R1+R1)-Vbe[the voltage drop between the emitter and the base of the npn bipolar transistor T1]) of the first resistor R1 (Ω: R1) and the second resistor R2 (Ω: R2) in such a way that the output voltage (V_OUT) of the driving power supply circuit 4 becomes constant relative to the output voltage (VCC) of the driving power supply 41. The resistance voltage division ratio can be changed by changing the resistance constants of the first resistor R1 and the second resistor R2, so the threshold value (threshold value of the on / off voltage) when making a high or low judgment can be effectively adjusted, thereby improving the availability of the driving power supply circuit 4.

[0030] The emitter of the npn bipolar transistor T1 is connected to the emitter of the pnp bipolar transistor T2 included in the input circuit 2 via the second conductive line 102. The output voltage (V_OUT) stepped down by the resistance voltage divider ratio is always applied from the driving power supply circuit 4 to the pnp bipolar transistor T2 of the input circuit 2.

[0031] The input circuit 2 includes a pnp bipolar transistor T2, a second pull-up resistor R4, a base resistor R5, a pull-up circuit 3, and an input terminal 21. The emitter of the pnp bipolar transistor T2 is connected to a second conductive path 102, and an output voltage (V_OUT) stepped down by a resistance voltage divider ratio is always applied from the driving power circuit 4 via the second conductive path 102.

[0032] The base of the pnp bipolar transistor T2 is connected to the input terminal 21 through the first conductive line 101. The input terminal 21 may also be composed of a connector terminal, etc., and function as a connector terminal. A high or low input voltage to be determined is input to the input terminal 21 (connector terminal). The collector of the pnp bipolar transistor T2 is connected to the voltage conversion circuit 5 through the third conductive line 103. The collector of the pnp bipolar transistor T2 is equivalent to the output terminal of the input circuit.

[0033] A second pull-up resistor R4 is disposed between the second conductive line 102 and the first conductive line 101. That is, the second pull-up resistor R4 is connected to the first conductive line 101 at the second connection point S2 and is connected to the second conductive line 102 at the third connection point S3.

[0034] The base resistor R5 is sandwiched between the base of the pnp bipolar transistor T2 and the third connection point S3 (the connection point between the second pull-up resistor R4 and the first conductive line 101). By setting such a structure, the voltage of the input terminal 21 (connector terminal) connected to the base of the pnp bipolar transistor T2 (V: input terminal 21 voltage) can be eliminated by resistor division. For example, in the case of using a digital transistor T3 with built-in resistors, the internal resistor is connected in series with the base resistor R5. Due to the deviation of the internal resistor, the resistor voltage division ratio varies, and the voltage of the input terminal 21 (connector terminal) (V: input terminal 21 voltage) may be deviated. In contrast, on the basis of using the pnp bipolar transistor T2, by connecting the second pull-up resistor R4 and the base resistor R5 in parallel, the resistor voltage division can be eliminated, and the accuracy of the threshold value when judging the high / low of the input voltage can be improved.

[0035] The pull-up circuit 3 includes a pull-up power supply 31, a first pull-up resistor R3, and a second diode D2. The pull-up power supply 31, the first pull-up resistor R3, and the second diode D2 are connected in series in the direction of the current flow from the pull-up power supply 31. The cathode of the second diode D2 is connected to the first conductive line 101 at the first connection point S1. A first diode D1 is sandwiched between the first connection point S1 and the second connection point S2 in the first conductive line 101, and the anode of the first diode D1 faces the second connection point S2 side (the base side of the pnp bipolar transistor T2). In this way, the first pull-up resistor R3 and the second pull-up resistor R4 of the pull-up circuit 3 are connected to the first conductive line 101, so that the potential of the first conductive line 101 can be prevented from becoming unstable, and can be effectively maintained in advance at a sufficiently high potential corresponding to the product specifications.

[0036] The input circuit 2 configured in this way functions as a low-side input circuit. The threshold value (threshold value of the on / off voltage) for determining whether the input voltage (Vin) input from the input terminal 21 (connector terminal) is low or high is based on the voltage of the input terminal 21 (V: voltage of the input terminal 21). The voltage of the input terminal 21 (V: voltage of the input terminal 21) is a value obtained by subtracting the voltage drop (VfD: forward voltage) of the first diode D1 and the voltage drop (Vbe) between the emitter and base of the pnp bipolar transistor T2 from the output voltage (V_OUT) from the drive power supply circuit 4 (V=V_OUT-Vf-Vbe).

[0037] When the threshold value (threshold value of the on / off voltage) for high / low judgment of the input voltage (Vin) input to the input terminal 21 becomes a relatively small value (low voltage), the temperature characteristics of each element such as the pnp bipolar transistor T2 and the first diode D1 will have an impact. In contrast, the input voltage (Vin) is affected by the voltage drop of the first diode D1 and the voltage drop between the emitter and the base of the pnp bipolar transistor T2, so the deviation can be reduced and the threshold can be made more accurate.

[0038] The voltage conversion circuit 5 is composed of a level shift circuit including a level shift power supply 51 and a digital transistor T3. The digital transistor T3 is an npn-type transistor having an internal resistor. A third conductive line 103 extending from the collector of the pnp-type bipolar transistor T2 of the input circuit 2 is connected to the base of the digital transistor T3. The collector of the digital transistor T3 is connected to the microcomputer 6 and the level shift power supply 51. The emitter of the digital transistor T3 is grounded.

[0039] The level shift power supply 51 and the level shift resistor R6 are connected in series, and the level shift resistor R6 is connected to the wire connecting the microcomputer 6 and the collector of the digital transistor T3. That is, one end of the level shift resistor R6 is connected to the level shift power supply 51, and the other end of the level shift resistor R6 is connected to the wire connecting the microcomputer 6 and the collector of the digital transistor T3.

[0040] The digital transistor T3 is turned on or off according to the voltage inputted through the third conductive line 103 connected to the base. When the digital transistor T3 is turned off, a high (Hi) voltage is inputted to the microcomputer 6 from the level shift power supply 51. When the digital transistor T3 is turned on, the microcomputer 6 becomes a ground potential, and a low (Lo) voltage is inputted to the microcomputer 6. By configuring the voltage conversion circuit 5 using the level shift circuit in this way, the threshold voltage of the microcomputer 6 and the like connected to the voltage conversion circuit 5 can be satisfied without depending on the output voltage (V_OUT) from the drive power supply circuit 4.

[0041] The microcomputer 6 is a computer having a control unit such as an MPU, a storage unit such as a RAM or a ROM, and input / output terminals, and having a computing function. The microcomputer 6 determines whether the input voltage input from the input terminal 21 (connector terminal) is high (Hi) or low (Lo) based on the output voltage output from the voltage conversion circuit 5. For example, a threshold voltage may be set in the microcomputer 6. When the output voltage output from the voltage conversion circuit 5 is above the threshold voltage, it is determined to be high (Hi), and when it is less than the threshold voltage, it is determined to be low (Lo). In the present embodiment, the microcomputer 6 is connected to the voltage conversion circuit 5, but it is not limited to this. For example, an electronic component having a computing function such as an IC (Integrated Circuit), an ASIC (Application Specific Integrated Circuit) or an FPGA (Field-Programmable Gate Array) may also be connected.

[0042] Figure 3 This is an explanatory diagram (timing chart) for explaining the operation of the input circuit 2, etc. In this explanatory diagram (timing chart), the operation of the input terminal 21 (connector terminal), the npn-type bipolar transistor T1 of the driving power supply circuit 4, the pnp-type bipolar transistor T2 of the input circuit 2, and the digital transistor T3 of the voltage conversion circuit 5 (microcomputer 6 terminal) is explained with voltage levels (Hi, Lo). Figure 3 The reference numerals A to D shown correspond to Figure 2 The symbols indicated by the arrows in the middle and the voltage levels (Hi, Lo) illustrate the voltage levels (Hi, Lo) at the locations indicated by the arrows.

[0043] The npn bipolar transistor T1 of the driving power circuit 4 is always turned on, and as described above, the driving voltage after being stepped down according to the resistance voltage division ratio is output (applied) to the pnp bipolar transistor T2 of the input circuit 2 via the first conductive line 101. The input terminal 21 (connector terminal) of the input circuit 2 changes according to the input voltage. The input voltage can also change from 12V to 0V, for example.

[0044] When the voltage level of the input voltage at the input terminal 21 (connector terminal) of the input circuit 2 is high (Hi), the pnp bipolar transistor T2 of the input circuit 2 is turned off, and the voltage level of the voltage output from the collector of the pnp bipolar transistor T2 is low (Lo). In this case, the digital transistor T3 of the voltage conversion circuit 5 is turned off, and the voltage level of the voltage at the emitter of the digital transistor T3, that is, the microcomputer 6 terminal connected to the microcomputer 6, is high (Hi).

[0045] When the voltage level of the input voltage at the input terminal 21 (connector terminal) of the input circuit 2 is low (Lo), the pnp bipolar transistor T2 is turned on, and the voltage level of the voltage output from the collector of the pnp bipolar transistor T2 is high (Hi). In this case, the digital transistor T3 of the voltage conversion circuit 5 is turned on, and the voltage level of the voltage at the collector of the digital transistor T3, i.e., the terminal of the microcomputer 6 connected to the microcomputer 6, is low (Lo).

[0046] The input circuit 2 (low-side input circuit), the drive power circuit 4 (emitter follower circuit), and the voltage conversion circuit 5 (level shift circuit) provided in the vehicle-mounted device 1 perform high / low determination of the input voltage input to the input terminal 21 (connector terminal) as described above. In this way, the input circuit 2 (low-side input circuit), the drive power circuit 4 (emitter follower circuit), and the voltage conversion circuit 5 (level shift circuit) are each appropriately configured, and by combining them, determination of the input voltage can be performed efficiently.

[0047] Multiple claims recorded in the claims can be combined with each other regardless of the form of citation. In the claims, multiple dependent claims that are subordinate to multiple claims can also be recorded. Multiple dependent claims that are subordinate to multiple dependent claims can also be recorded. Even if multiple dependent claims that are subordinate to multiple dependent claims are not recorded, this does not limit the recording of multiple dependent claims that are subordinate to multiple dependent claims.

[0048] The embodiments disclosed this time should be considered as illustrative in all aspects and not restrictive. The scope of the present invention is indicated by the claims rather than the above, and is intended to include all modifications within the meaning and scope equivalent to the claims.

[0049] Description of symbols C. Vehicle 1 Vehicle-mounted device 101 First Conductive Circuit 102 second conductive circuit 103 Third conductive line 2 Input circuit (low-side input circuit) 21 Input terminal (connector side) T2 pnp bipolar transistor R4 Second pull-up resistor S2 Second connection point S3 Third connection point R5 Base resistor 3 Pull-up circuit 31 Pull-up power supply R3 First pull-up resistor D2 Second diode S1 First connection point D1 First diode 4 Driving power circuit (emitter follower circuit) 41. Driving power supply T1 npn bipolar transistor R1 First resistor R2 Second resistor 5 Voltage conversion circuit (level shift circuit) 51 Level Shifter Power Supply T3 Digital Transistor R6 Level shift resistor 6 Microcomputer.

Claims

1. A vehicle-mounted device, mounted on a vehicle, wherein: The vehicle-mounted device comprises: an input circuit including an input terminal to which an input voltage is input; and a driving power supply circuit, outputting a driving voltage to the input circuit, The input circuit includes a pnp bipolar transistor, a pull-up circuit, a second pull-up resistor and a base resistor. The pull-up circuit comprises a pull-up power supply, a first pull-up resistor and a second diode connected in series, the anode of the second diode faces the first pull-up resistor, and the pull-up circuit is arranged between the base of the pnp bipolar transistor and the input terminal. The second pull-up resistor is arranged between the base of the pnp bipolar transistor and the driving power circuit. The base resistor is arranged between the base of the pnp bipolar transistor and the second pull-up resistor. A first diode is provided between a connection point between the second pull-up resistor and the base resistor and the input end, and a cathode of the first diode faces the input end.

2. The vehicle-mounted device according to claim 1, wherein: The driving power circuit includes a driving power supply, an npn bipolar transistor, a first resistor and a second resistor, wherein the second resistor is connected in series with the first resistor. The driving power circuit outputs the driving voltage corresponding to a resistance voltage division ratio of the first resistor and the second resistor.

3. The vehicle-mounted device according to claim 1 or 2, wherein: The vehicle-mounted device further includes a voltage conversion circuit that performs voltage conversion between the input circuit and the microcomputer. The voltage conversion circuit is a level shift circuit, and the level shift circuit includes a level shift power supply and a digital transistor. The voltage converted by the level shift circuit is output to the microcomputer, and the microcomputer is connected to the collector of the digital transistor.

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