vehicle-mounted device

Abstract

To provide an on-vehicle device that comprises an input circuit which performs determination to an input voltage efficiently.SOLUTION: An on-vehicle device comprises an input circuit 2, a drive power supply circuit 4, and a voltage conversion circuit 5. The input circuit comprises a pnp-type bipolar transistor T2, a second pull-up resistor R4, a base resistor R5, a pull-up circuit 3, and an input end 21. The pull-up circuit includes a pull-up power supply 31, a first pull-up resistor 3, and a second diode D2 that are connected in series, being provided between a base of the pnp-type bipolar transistor and an input end. The second pull-up resistor is provided between the base of the pnp-type bipolar transistor and the drive power supply circuit. The base resistor is provided between the base of the pnp-type bipolar transistor and the second pull-up resistor. A first diode D1 is interposed between a connection point between the second pull-up resistor and the base resistor, and the input end so that its cathode is directed to the input end.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to an in-vehicle device. [Background technology]

[0002] A constant current driver that drives a load with a current has been disclosed (for example, Patent Document 1). The constant current driver includes a first current driver circuit connected between a first terminal and a second terminal, and a second current driver circuit connected between a third terminal and the first terminal or the second terminal, and divides the current flowing through the load into the first current driver circuit and the second current driver circuit. The first current driver circuit includes a first operational amplifier and a first transistor, and the first transistor is connected so that a current flows between the first terminal and the second terminal. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2014-82226 Summary of the Invention [Problem to be solved by the invention]

[0004] However, in the constant current drive device using the transistor described in Patent Document 1, when determining whether the input voltage is high or low based on a predetermined threshold, no consideration is given to making this determination efficiently even when the threshold is small.

[0005] The present invention has been made in view of the above circumstances, and an object of the present invention is to provide an in-vehicle device equipped with an input circuit that can efficiently perform judgment on an input voltage. [Means for solving the problem]

[0006] an input terminal connected to the input terminal; a drive power supply circuit configured to output a drive voltage to the input circuit; and a PNP bipolar transistor, a pull-up circuit, a second pull-up resistor, and a base resistor. The pull-up circuit includes a pull-up power supply, a first pull-up resistor, and a second diode connected in series, the second pull-up resistor being connected between the base of the PNP bipolar transistor and the input terminal; the second pull-up resistor is connected between the base of the PNP bipolar transistor and the drive power supply circuit; the base resistor is connected between the base of the PNP bipolar transistor and the second pull-up resistor; and a first diode, with its cathode facing the input terminal, is interposed between the connection point of the second pull-up resistor and the base resistor and the input terminal. [Effects of the Invention]

[0007] According to one aspect of the present disclosure, it is possible to provide an in-vehicle device including an input circuit that efficiently performs a determination on an input voltage. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is a schematic diagram illustrating an overview of an in-vehicle device mounted on a vehicle according to a first embodiment. [Figure 2] 2 is a circuit diagram illustrating the configuration of an input circuit and the like included in the in-vehicle device. FIG. [Figure 3] 10 is an explanatory diagram (timing chart) explaining the operation of an input circuit and the like. DETAILED DESCRIPTION OF THE INVENTION

[0009] [Description of the embodiments of the present disclosure] First, embodiments of the present disclosure will be listed and described. At least some of the embodiments described below may be combined in any desired manner.

[0010] (1) An on-board device according to one aspect of the present disclosure is an on-board device mounted on a vehicle, comprising: an input circuit including an input terminal to which an input voltage is input; and a drive power supply circuit that outputs a drive voltage to the input circuit, wherein the input circuit includes a PNP bipolar transistor, a pull-up circuit, a second pull-up resistor, and a base resistor, wherein the pull-up circuit includes a pull-up power supply, a first pull-up resistor, and a second diode connected in series, the second pull-up resistor being connected between the base of the PNP bipolar transistor and the input terminal, the second pull-up resistor being connected between the base of the PNP bipolar transistor and the drive power supply circuit, the base resistor being connected between the base of the PNP bipolar transistor and the second pull-up resistor, and a first diode being connected between the input terminal and a connection point between the second pull-up resistor and the base resistor, the first diode having its cathode facing the input terminal.

[0011] In this aspect, the on-board device includes an input circuit, a drive power supply circuit that outputs a drive voltage to the input circuit, and a voltage conversion circuit connected to the output terminal of the input circuit. The input circuit and drive power supply circuit constitute a low-side input circuit device. An on-board device including the low-side input circuit device functions, for example, as a body ECU that controls the drive of body actuators mounted on a vehicle, a relay device such as a CAN gateway, or an electrical junction box equipped with a semiconductor fuse. The on-board device (low-side input circuit device) outputs a high or low signal (output voltage) in response to an input voltage input from an input terminal (connector terminal to which an input connector is connected) of the input circuit. The high or low signal (output voltage) is output to a microcomputer or the like from a voltage conversion circuit connected to the output terminal of the input circuit, for example. The microcomputer that receives the high or low signal (output voltage) performs various control processes or arithmetic processes based on the signal (output voltage). The input circuit includes a pnp bipolar transistor, and a first conductive path extending from the input terminal (connector terminal) is connected to the base of the pnp bipolar transistor. The first conduction path includes a first diode and a base resistor. In this case, the input voltage (V: input voltage) is calculated by subtracting the voltage drop (VfD: forward voltage) of the first diode and the emitter-base voltage drop (Vbe) of the pnp bipolar transistor from the drive voltage (V_OUT) (V=V_OUT-Vf-Vbe). When the threshold (ON / OFF voltage threshold) for determining whether the input voltage (Vin) applied to the input terminal is low or high is a relatively small value (low voltage), the influence of variations due to the temperature characteristics of each element that determines the input voltage becomes significant. In contrast, the input voltage (V) is affected only by the voltage drop of the first diode provided in the second first conduction path and the emitter-base voltage drop of the pnp bipolar transistor, thereby reducing variations and achieving high threshold accuracy.For example, when a digital transistor with a built-in resistor is used, the emitter-base voltage drop of a pnp bipolar transistor (Vbe × (Ri + Rb) / Ri) is determined by the resistor-division ratio ((Ri + Rb) / Ri) of the digital transistor's internal resistance (Ri) and base resistance (Rb). In this case, there is a concern that the error (variation) in the digital transistor's internal resistance (Ri) may be large, causing a significant change in the resistor-division ratio. In contrast, as described above, by using a pnp bipolar transistor in the input circuit and connecting the second pull-up resistor and base resistor in parallel, the resistor-division ratio can be eliminated (eliminated), thereby reducing variation compared to when using a digital transistor. This allows for high-precision threshold voltages and the use of relatively inexpensive components, thereby reducing product costs.

[0012] (2) In an in-vehicle device according to one embodiment of the present disclosure, the drive power supply circuit includes a drive power supply, an npn bipolar transistor, a first resistor, and a second resistor connected in series with the first resistor, and outputs the drive voltage according to a resistance voltage division ratio between the first resistor and the second resistor.

[0013] In this embodiment, the drive power supply circuit includes a drive power supply, an npn bipolar transistor, a first resistor, and a second resistor connected in series with the first resistor, and is configured, for example, as an emitter follower circuit. By configuring the drive power supply circuit using an emitter follower circuit in this manner, the output voltage (V_OUT) from the drive power supply circuit can be adjusted by the resistor voltage division ratio of the first resistor (R1) and the second resistor (R2) so that the output voltage (V_OUT) from the drive power supply is constant relative to the output voltage (V_OUT) of the drive power supply. Furthermore, by changing the resistance constants of the first resistor (R1) and the second resistor (R2), it is possible to adjust the threshold (ON / OFF voltage threshold) for determining whether the signal is low or high, thereby improving the usability of the drive power supply circuit.

[0014] (3) An in-vehicle device according to one embodiment of the present disclosure further includes a voltage conversion circuit that performs voltage conversion between the input circuit and a microcomputer, the voltage conversion circuit being a level shift circuit including a level shift power supply and a digital transistor, and outputting the voltage converted by the level shift circuit to the microcomputer connected to the collector of the digital transistor.

[0015] In this embodiment, the voltage conversion circuit is configured with a level shift circuit including a level shift power supply and a digital transistor, and an output voltage level-shifted (voltage-converted) by the level shift circuit is output from the voltage conversion circuit. In this manner, the voltage conversion circuit performs voltage conversion between the input circuit and the microcomputer. For example, if an electronic component with a computing function, such as a microcomputer, IC (Integrated Circuit), ASCI (Application Specific Integrated Circuit), or FPGA (Field-Programmable Gate Array), is connected to the output terminal (microcomputer terminal) of the voltage conversion circuit, the threshold voltage of the microcomputer or the like may not correspond to the output voltage from the drive 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 satisfy the threshold voltage of the microcomputer or the like without relying on the output voltage (pull-up voltage) from the drive power supply circuit.

[0016] [Details of the embodiments of the present disclosure] The present disclosure will be specifically described with reference to drawings showing embodiments thereof. An in-vehicle device 1 according to an embodiment of the present disclosure will be described below with reference to the drawings. Note that the present disclosure is not limited to these examples, but is defined by the claims, and is intended to include all modifications within the meaning and scope equivalent to the claims.

[0017] (Embodiment 1) Hereinafter, embodiments will be described with reference to the drawings. FIG. 1 is a schematic diagram illustrating an overview of an in-vehicle device 1 mounted on a vehicle C according to the first embodiment. FIG. 2 is a circuit diagram illustrating the configuration of an input circuit 2 and the like included in the in-vehicle device 1. The in-vehicle device 1 is mounted on the vehicle C and includes an input circuit 2 and a drive power supply circuit 4 that outputs a drive voltage to the input circuit 2, and may further include a voltage conversion circuit 5 connected to the output terminal of the input circuit 2. The in-vehicle device 1 may further include a microcomputer 6 connected to the voltage conversion circuit 5. The drive power supply circuit 4 and the input circuit 2 are connected by a second conductive path 102. The input circuit 2 and the voltage conversion circuit 5 are connected by a third conductive path 103.

[0018] The input circuit 2, drive power supply circuit 4, and voltage conversion circuit 5 constitute a low-side input circuit device. The in-vehicle device 1 functioning 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. As will be described in detail later, the input circuit 2 and drive power supply circuit 4 determine the threshold (ON / OFF voltage threshold) used to determine whether the input voltage is high or low. The input circuit 2 includes a pnp bipolar transistor T2 and is configured without a voltage division ratio using a base resistor R5 or the like, so that a relatively low threshold voltage can be set, and the threshold can be set with high precision and with reduced variation in the threshold.

[0019] The drive power supply circuit 4 includes a drive power supply 41, an npn bipolar transistor T1, a first resistor R1, and a second resistor R2. The drive power supply 41 outputs a predetermined voltage (e.g., 5V) obtained by stepping down a voltage (e.g., 12V) supplied from a power supply device such as a lead battery or an alternator mounted on the vehicle C using a regulator or the like.

[0020] An npn bipolar transistor T1 is connected to the drive power supply 41, and a voltage output from the drive power supply 41 is constantly applied to the npn bipolar transistor T1. An electric wire extending from the drive power supply 41 to the npn bipolar transistor T1 branches into two, and the two branched ends are connected to the collector and base of the npn bipolar transistor T1, respectively.

[0021] A first resistor R1 is interposed between the drive power supply 41 and the base of the npn bipolar transistor T1. A second resistor R2 is interposed in an electric wire extending from the first resistor R1 to ground. That is, an electric wire extending from the junction of the first resistor R1 and the second resistor R2 is connected to the base of the npn bipolar transistor T1. With this connection, the first resistor R1 and the second resistor R2 are connected in series, and the base of the npn bipolar transistor T1 is connected to the junction of the first resistor R1 and the second resistor R2. As a result, the voltage output from the emitter of the npn bipolar transistor T1 has a value corresponding to the resistance voltage division ratio of the first resistor R1 and the second resistor R2.

[0022] In this way, the drive power supply circuit 4 is configured with an emitter follower circuit that steps down the output voltage (VCC) from the drive power supply 41 to a predetermined voltage (V_OUT) according to the resistor voltage division ratio of the first resistor R1 and the second resistor R2. This stepped-down voltage corresponds to the output voltage (V_OUT) of the drive power supply circuit 4. By using this emitter follower circuit, the npn bipolar transistor T1 can be used in an analog manner based on the operating principle of a linear regulator, and the output voltage (V_OUT) can be adjusted by resistor voltage division. This eliminates the need for a relatively expensive comparator, making it possible to achieve (satisfy) the required functionality with an inexpensive configuration.

[0023] The output voltage (V_OUT) from the drive power supply circuit 4 is adjusted to be constant relative to the output voltage (VCC) of the drive power supply 41 by the resistor divider ratio (V_OUT=VCC*R2 / (R1+R1)-Vbe [emitter-base voltage drop of npn bipolar transistor T1]) of the first resistor R1 (Ω:R1) and the second resistor R2 (Ω:R2). The resistor divider ratio can be changed by changing the resistance constants of the first resistor R1 and the second resistor R2. Therefore, the threshold (ON / OFF voltage threshold) for determining whether a signal is high or low can be efficiently adjusted, thereby improving the availability of the drive power supply circuit 4.

[0024] The emitter of the npn bipolar transistor T1 and the emitter of the pnp bipolar transistor T2 included in the input circuit 2 are connected by a second conductive path 102. The output voltage (V_OUT) stepped down from the drive power supply circuit 4 at a resistive voltage division ratio is constantly applied to the pnp bipolar transistor T2 of the input circuit 2.

[0025] 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. A second conductive path 102 is connected to the emitter of the pnp bipolar transistor T2, and an output voltage (V_OUT) stepped down by a resistor voltage division ratio from the drive power supply circuit 4 is constantly applied via the second conductive path 102.

[0026] The base of the pnp bipolar transistor T2 is connected to the input terminal 21 via a first conductive path 101. The input terminal 21 may be configured, for example, as a connector terminal or the like and function as a connector terminal. An input voltage to be determined as high or low 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 via a third conductive path 103. The collector of the pnp bipolar transistor T2 corresponds to the output terminal of the input circuit.

[0027] A second pull-up resistor R4 is provided between the second conductive path 102 and the first conductive path 101. That is, the second pull-up resistor R4 is connected to the first conductive path 101 at a second connection point S2 and is connected to the second conductive path 102 at a third connection point S3.

[0028] The base resistor R5 is interposed 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 path 101). This configuration eliminates the need for resistor division for the voltage (V: input terminal 21 voltage) at the input terminal 21 (connector terminal) connected to the base of the pnp bipolar transistor T2. For example, when a digital transistor T3 with a built-in resistor is used, the internal resistor and the base resistor R5 are connected in series. Variations in the internal resistance can fluctuate the resistor division ratio, resulting in variations in the voltage (V: input terminal 21 voltage) at the input terminal 21 (connector terminal). In response to this issue, by using the pnp bipolar transistor T2 and connecting the second pull-up resistor R4 and the base resistor R5 in parallel, the resistor division can be eliminated, improving the accuracy of the threshold for determining whether the input voltage is high or low.

[0029] 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 this order in the direction of current flow from the pull-up power supply 31. The cathode of the second diode D2 is connected to a first conduction path 101 at a first connection point S1. A first diode D1 is interposed between the first connection point S1 and the second connection point S2 in the first conduction path 101, with its anode facing the second connection point S2 (the base side of the PNP bipolar transistor T2). Since the first pull-up resistor R3 and the second pull-up resistor R4 of the pull-up circuit 3 are connected to the first conduction path 101 in this manner, the potential of the first conduction path 101 is prevented from becoming unstable and can be efficiently maintained at a sufficiently high potential corresponding to product specifications.

[0030] The input circuit 2 configured in this manner functions as a low-side input circuit. The threshold (ON / OFF voltage threshold) for determining whether the input voltage (Vin) input from the input terminal 21 (connector terminal) is low or high is based on the voltage at the input terminal 21 (V: input terminal 21 voltage). The voltage at the input terminal 21 (V: input terminal 21 voltage) is the output voltage (V_OUT) from the drive power supply circuit 4 minus the voltage drop (VfD: forward voltage) of the first diode D1 and the emitter-base voltage drop (Vbe) of the pnp bipolar transistor T2 (V=V_OUT-Vf-Vbe).

[0031] When the threshold (ON / OFF voltage threshold) for determining whether the input voltage (Vin) input to the input terminal 21 is a relatively small value (low voltage), it is affected by the temperature characteristics of each element, such as the pnp bipolar transistor T2 and the first diode D1. In contrast, what affects the input voltage (Vin) are the voltage drop of the first diode D1 and the emitter-base voltage drop of the pnp bipolar transistor T2, so variations can be reduced and high accuracy of the threshold can be achieved.

[0032] The voltage conversion circuit 5 is configured as 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 with an internal resistor. A third conductive path 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 connected to ground.

[0033] 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.

[0034] The digital transistor T3 is turned on or off depending on the voltage input via the third conduction path 103 connected to the base. When the digital transistor T3 is off, a high (Hi) voltage is input to the microcomputer 6 from the level shift power supply 51. When the digital transistor T3 is on, the microcomputer 6 is at ground potential, and a low (Lo) voltage is input to the microcomputer 6. By configuring the voltage conversion circuit 5 using a level shift circuit in this way, it is possible to satisfy the threshold voltage of the microcomputer 6 and the like connected to the voltage conversion circuit 5 without depending on the output voltage (V_OUT) from the drive power supply circuit 4.

[0035] The microcomputer 6 is a computer having a control unit such as an MPU, a storage unit such as RAM or ROM, and input / output terminals or connectors, and is equipped with a calculation function. The microcomputer 6 determines whether the input voltage input from the input terminal 21 (connector terminal) is high (Hi) or low (Lo) depending on the output voltage output from the voltage conversion circuit 5. For example, a threshold voltage may be set in the microcomputer 6, and the output voltage output from the voltage conversion circuit 5 may be determined to be high (Hi) when it is equal to or higher than the threshold voltage, and determined to be low (Lo) when it is lower than the threshold voltage. In this embodiment, the microcomputer 6 is connected to the voltage conversion circuit 5, but this is not limited thereto. For example, an electronic component having a calculation function, such as an integrated circuit (IC), an application specific integrated circuit (ASCI), or a field-programmable gate array (FPGA), may be connected.

[0036] 3 is an explanatory diagram (timing chart) 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 bipolar transistor T1 of the drive power supply circuit 4, the pnp bipolar transistor T2 of the input circuit 2, and the digital transistor T3 (microcomputer 6 terminal) of the voltage conversion circuit 5 is explained using voltage levels (Hi, Lo). The symbols A to D shown in FIG. 3 correspond to the symbols indicated by the arrows in FIG. 2, and each voltage level (Hi, Lo) illustrates the voltage level (Hi, Lo) at the location indicated by the arrow.

[0037] The npn bipolar transistor T1 of the drive power supply circuit 4 is always on, and outputs (applies) the drive voltage stepped down in accordance with the resistive voltage division ratio as described above to the pnp bipolar transistor T2 of the input circuit 2 via the first conductive path 101. The input terminal 21 (connector terminal) of the input circuit 2 changes in accordance with the input voltage. The input voltage may change, for example, from 12 V to 0 V.

[0038] 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 emitter of the digital transistor T3, i.e., the voltage at the microcomputer 6 terminal to which the microcomputer 6 is connected, is high (Hi).

[0039] 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 emitter of the digital transistor T3, i.e., the voltage at the microcomputer 6 terminal to which the microcomputer 6 is connected, is low (Lo).

[0040] As described above, the input circuit 2 (low-side input circuit), drive power supply circuit 4 (emitter follower circuit), and voltage conversion circuit 5 (level shift circuit) provided in the in-vehicle device 1 make a high / low determination of the input voltage input to the input terminal 21 (connector terminal). As described above, the input circuit 2 (low-side input circuit), drive power supply circuit 4 (emitter follower circuit), and voltage conversion circuit 5 (level shift circuit) are each suitably configured, and by combining these, it is possible to efficiently perform a determination of the input voltage.

[0041] Multiple claims may be combined with each other regardless of the form of reference. Multiple dependent claims may be included in the claims, depending on multiple claims. Multiple dependent claims may be included in a multiple dependent claim. If multiple dependent claims are not included in a multiple dependent claim, this does not limit the number of multiple dependent claims that are included in a multiple dependent claim.

[0042] The embodiments disclosed herein are to be considered as illustrative in all respects and not restrictive. The scope of the present disclosure is defined by the claims, not by the above meaning, and is intended to include all modifications within the meaning and scope equivalent to the claims. [Explanation of symbols]

[0043] C vehicle 1 On-vehicle device 101 First conductive path 102 Second conductive path 103 Third Conduction Path 2 Input circuit (low-side input circuit) 21 Input end (connector end) 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. Drive power supply circuit (emitter follower circuit) 41 Drive power supply T1 npn bipolar transistor R1 First resistor R2 2nd resistor 5 Voltage conversion circuit (level shift circuit) 51 Level shift power supply T3 digital transistor R6 Level shift resistor 6 Microcomputer

Claims

1. An in-vehicle device mounted on a vehicle, an input circuit including an input terminal to which an input voltage is input; a drive power supply circuit that outputs a drive 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 includes a pull-up power supply, a first pull-up resistor, and a second diode connected in series, the anode of which faces the first pull-up resistor, and the cathode of the second diode is provided between the base of the pnp bipolar transistor and the input terminal; the second pull-up resistor is provided between the drive power supply circuit and a connection point between the base of the pnp bipolar transistor and the pull-up circuit, the base resistor is provided between the base of the pnp bipolar transistor and the second pull-up resistor, A first diode is interposed between the connection point of the second pull-up resistor and the base resistor and the pull-up circuit, with the cathode facing the input terminal. In-vehicle device.

2. The drive 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; The drive voltage is output according to a resistance voltage division ratio between the first resistor and the second resistor. The in-vehicle device according to claim 1 .

3. a voltage conversion circuit for converting voltage between the input circuit and the microcomputer; The voltage conversion circuit a level shift circuit including a level shift power supply and a digital transistor; The voltage converted by the level shift circuit is output to the microcomputer connected to the collector of the digital transistor. The in-vehicle device according to claim 1 or 2.

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