JP6365291B2 - Voltage detection circuit - Google Patents

Description

  The present invention relates to a voltage detection circuit that detects a voltage generated in a detection target circuit.

  For example, such a voltage detection circuit may be configured to differentially amplify the voltage of a current detection resistor incorporated in the detection target circuit. In some cases, the voltage detection circuit is provided with a differential amplifier to input and amplify a differential signal. For example, a differential amplifier configured as in Patent Document 1 is provided as an example.

JP-A-8-307166

  For example, consider using such a differential amplifier in a vehicle device. In the vehicle, the ground of the power system circuit is body-grounded, and the ground of the low power circuit is a ground node (equivalent to the first reference node) different from the ground node (equivalent to the second reference node) of the power system circuit. )It is connected to the. Therefore, an impedance may be generated between these ground nodes, and in this case, a potential difference is generated between the ground nodes.

  In such a case, the potential of the reference node of the detection target circuit operated by the power system power supply circuit may be lower than the reference potential of the detection circuit operated by the low-power power supply circuit. For this reason, the voltage of the detection target circuit viewed from the detection circuit becomes lower than the original value, and there is a possibility that the operation of the detection circuit using the differential amplifier may be defective in a normal design. The same problem occurs if the system is not limited to a vehicle device but is supplied with power from a plurality of power supply circuits.

  An object of the present invention is to enable a differential amplifier to normally perform differential amplification even when the potential of the reference node of the detection target circuit is lower than the potential of the reference node of the power supply voltage of the detection circuit and outputs a negative potential. An object of the present invention is to provide a voltage detection circuit.

  According to invention of Claim 1, it acts as follows. The detection target circuit is a circuit that operates with a first power supply voltage using the potential of the first reference node as the reference potential and outputs a negative potential from the output terminal. The differential amplifier includes a differential input transistor. The differential amplifier operates with a second power supply voltage using the potential of the second reference node that can be changed to a potential different from the potential of the first reference node as a reference potential, and inputs a signal to the input node of the differential input transistor. Amplify differentially. At this time, the level shifter is disposed between the output terminal of the detection target circuit and the input node of the differential input transistor, and level-shifts the output voltage of the detection target circuit and inputs it to the input node of the differential input transistor. Let At this time, the level shifter inputs a negative potential from the output terminal of the detection target circuit, shifts the level in the positive voltage direction toward the input node of the differential input transistor, and outputs it to the input node of the differential input transistor.

Therefore, even when the potential of the first reference node of the detection target circuit is lower than the potential of the second reference node of the power supply voltage of the voltage detection circuit and outputs a negative potential, the level shifter outputs the output voltage of the detection target circuit. Since the level is shifted in the positive voltage direction and input to the input node of the differential input transistor, the differential amplifier can normally perform differential amplification. In addition, since the level shifter includes a diode, the switching on / off time when the level shifter is configured by a transistor or the like can be eliminated, and the response speed of the circuit can be improved.

Electrical configuration diagram schematically showing an example of the system of the first embodiment Electrical configuration diagram schematically showing a configuration example of the excitation coil drive unit and voltage detection circuit Electrical configuration diagram schematically showing a configuration example of a differential amplifier Electrical configuration diagram schematically showing a configuration example of a differential amplifier according to the second embodiment Electrical configuration diagram schematically showing a configuration example of a differential amplifier according to a third embodiment Electrical configuration diagram schematically showing a configuration example of a differential amplifier according to a fourth embodiment Electrical configuration diagram schematically showing a configuration example of a differential amplifier according to a fifth embodiment Electrical configuration diagram schematically showing a configuration example of a voltage detection circuit according to a sixth embodiment

  Hereinafter, several embodiments of the voltage detection circuit will be described with reference to the drawings. About the same or similar structure between each embodiment, the code | symbol same as the code | symbol attached | subjected to the previous embodiment is attached | subjected, and description is abbreviate | omitted as needed in subsequent embodiment.

(First embodiment)
1st Embodiment demonstrates the structural example applied to the electric power generation system 1 shown in FIG. As shown in FIG. 1, the power generation system 1 includes a control ECU 2 as a vehicle device, a motor unit 4, and drive units 5 and 6 that drive the motor unit 4. The motor unit 4 includes a stator 10 and a rotor 11, the stator 10 includes a stator coil, and the rotor 11 includes an exciting coil. The drive unit 5 can be energized and driven to the stator coil of the stator 10, and the drive unit 6 can be energized and driven to the excitation coil of the rotor 11.

  The ECU 2 includes, for example, a CPU 7 and a microcomputer including a ROM 8, a RAM 9, and a nonvolatile memory (not shown), and the CPU 7 executes a program stored in the memory so that the driving units 5 and 6 execute the program. Drive control of the motor unit 4 is performed. For example, in detail, the ECU 2 detects currents flowing through the drive units 5 and 6, the stator coil of the stator 10, and the field coil of the rotor 11, and outputs a control signal to the drive units 5 and 6 according to this detection signal. Thus, the motor unit 4 is driven and controlled.

  The stator coil drive unit 5 of the stator 10 and the field coil drive unit 6 of the rotor 11 are, for example, a lithium ion battery using a ground node PGND (corresponding to the first reference node) grounded to the vehicle body as a reference potential. The power supply voltage VB (for example, 12V: equivalent to the first power supply voltage) is configured to operate. Further, the ECU 2 is configured to operate by a power supply voltage VS (for example, 12 V: equivalent to the second power supply voltage) by a battery, for example, with a control analog ground node (conceived as a second reference node) AGND as a reference potential.

  Electrically, the driving nodes 5 and 6 and the reference nodes AGND and PGND of the ECU 2 have the same potential in principle, but the locations of the ground nodes AGND and PGND are different from each other. An impedance component on an electric circuit is provided between the nodes AGND and PGND. Therefore, the potentials of the ground nodes AGND and PGND can be changed to different potentials. The drive unit 5 has a rectifying function for regenerating the lithium ion battery that generates the power supply voltage VB with respect to the AC voltage generated in the stator coil of the stator 10.

  Further, the drive unit 6 mainly includes an H bridge circuit 12 as shown in FIG. The H bridge circuit 12 is configured, for example, by connecting N channel MOS transistors 13 to 16 in an H bridge connection. As shown in FIG. 2, when the control signal is input from the control ECU 2 by the on / off control signal, the driving unit 6 turns on / off the transistors 13 to 16 of the H bridge circuit 12 based on the control signal, Energize the exciting coil 11a of the rotor 11.

  The drive unit 6 includes a resistor 17 as a detection target circuit in the current supply path of the H bridge circuit 12 and outputs a voltage across the resistor 17 from the output terminal OH-OL. The energizing current of the exciting coil 11a has a current value of about several A, for example, and is detected through the detection resistor 17. A noise filter 18 is configured outside the drive unit 6. The noise filter 18 is configured by connecting resistors 19 and 20 and a capacitor 21 in the illustrated form, and low-pass-filters the voltage between the terminals of the resistor 17 and outputs it to the input terminal IH-IL of the voltage detection circuit 3 of the ECU 2. The noise filter 18 may or may not be provided. The voltage detection circuit 3 is configured by connecting an amplifier circuit 22 to its input terminal IH-IL. The amplifier circuit 22 is configured by a differential amplifier circuit, for example, and differentially amplifies the voltage across the resistor 17 and outputs the amplified voltage from the output terminal OUT1.

  The amplifier circuit 22 is configured by combining an operational amplifier 23 with an offset function and resistors 24-27 in the illustrated form. A resistor 24 is connected between the input terminal IH and the non-inverting input terminal of the operational amplifier 23, and a resistor 25 is connected between the input terminal IL and the inverting input terminal of the operational amplifier 23. A non-inverting input terminal of the operational amplifier 23 is given a positive predetermined voltage VT (<power supply voltage VS: 1 V, for example) via a resistor 26. The predetermined voltage VT is an offset DC voltage generated using the power supply voltage VS.

  FIG. 3 shows an internal configuration example of the operational amplifier 23. The operational amplifier 23 includes a differential amplifier 32 having a pair of differential input transistors 28 and 29, a current generation circuit 30 and an active load 31 as input stages. The differential amplifier 32 includes an intermediate amplification stage and an output stage after the input stage, but this configuration is omitted in FIG. The pair of differential input transistors 28 and 29 are configured using, for example, PNP-type bipolar transistors. The emitters of the pair of differential input transistors 28 and 29 are commonly connected to each other. The current generation circuit 30 is configured using, for example, a current mirror circuit, generates a constant current based on the power supply voltage VS, and supplies the constant current to the common emitter node Na of the pair of differential input transistors 28 and 29. Note that the output stage of the current generation circuit 30 is configured using a current mirror circuit including, for example, a PNP-type bipolar transistor.

  The collectors of the pair of differential input transistors 28 and 29 are connected to the active load 31. The active load 31 is configured by using, for example, NPN bipolar transistors (hereinafter abbreviated as transistors) 33 and 34, the bases of the transistors 33 and 34 are connected in common, and the common base of the transistors 33 and 34 is connected. The node and the collector of one transistor 33 are connected in common.

  A plurality of (for example, three) diodes 35 to 37 are connected in the reverse direction from the input terminal IHa of the operational amplifier 23 (the output terminal OH of the driving unit 6) to the base (input node) of one differential input transistor 28. ing. That is, a plurality of diodes 35 to 37 are connected with the base side of the differential input transistor 28 as an anode and the input terminal side of the operational amplifier 23 as a cathode. A plurality of (for example, three) diodes 38 to 40 are connected in the reverse direction from the input terminal ILa of the operational amplifier 23 (the output terminal OL of the driving unit 6) to the base (input node) of the other differential input transistor 29. ing. That is, a plurality of diodes 38 to 40 are connected with the base side of the differential input transistor 29 as an anode and the input terminal side of the operational amplifier 23 as a cathode. The numbers of the diodes 35 to 37 and 38 to 40 connected to the one and other differential input transistors 28 and 29 are the same.

  A current source 41 is connected between a supply terminal of the power supply voltage VS and a base node N1 (input node) of one differential input transistor 28. The current source 41 includes diodes 35 to 37. It is configured to output a current (for example, several μ [A]) that can sufficiently decrease the forward voltage Vf (≈0.7 [V]). The output current value of the current source 41 is set to a current value that is significantly smaller than the detection current value detected by the detection resistor 17 of the drive unit 6, and the output current of the current source 41 is the input terminal IHa, Even if it flows to the drive unit 6 side through ILa, it is adjusted and set so that it can be ignored as an error.

  The plurality of diodes 35 to 37 are elements that act as a level shifter 43 for level-shifting the forward voltage Vf by the number of connections of the diodes 35 to 37, and the voltage input to the input terminal IHa of the operational amplifier 23 is The level is shifted and a level shift voltage is input to the input node N1 of the differential input transistor. The level shifters 43 and 44 are disposed between the input terminal IH-IL of the voltage detection circuit 3 and the input nodes N1 and N2 of the differential input transistors 28 and 29.

  Similarly, a current source 42 is connected between the supply terminal of the power supply voltage VS and the base node N2 (input node) of the other differential input transistor 29. The current source 42 includes diodes 38 to 40. Is configured to output a current that can sufficiently output the forward voltage Vf (≈0.7 [V]). The current sources 41 and 42 are set to have the same energization current amount.

  The plurality of diodes 38 to 40 are elements that act as a level shifter 44 for level-shifting the forward voltage Vf by the number of connected diodes 38 to 40, and the voltage input to the input terminal ILa of the operational amplifier 23 is obtained. The level is shifted and a level shift voltage is input to the input node N2 of the differential input transistor 29.

  The operation of the above configuration will be described. When the ECU 2 outputs an on / off control signal to the drive unit 6, the ECU 2 energizes the excitation coil 11 a of the rotor 11. Here, the energizing current of the exciting coil 11 a is detected by the detection resistor 17. When the drive unit 6 detects the voltage across the terminals of the detection resistor 17, the drive unit 6 outputs the detection voltage with reference to the ground node PGND serving as the first reference node.

  The ground node PGND is, for example, body grounded, and the ground node AGND is a ground position of the ECU 2. Therefore, an impedance is generated between the ground nodes PGND-AGND, and the potentials of the ground node AGND and the ground node PGND may be different.

  For example, a case will be described in which a negative voltage fluctuation of about −1V occurs from the ground node AGND to the ground node PGND, and the voltage detection circuit 3 inputs and detects a DC voltage of, for example, −1V to + 1V. For convenience of explanation, the DC level of each node when the drive unit 6 is not operating will be described. The forward voltage of each diode 35-40 is defined as Vf (≈0.7 V), and the saturation voltage between the collector emitters of the differential input transistors 28 and 29 is defined as Vce1 (≈0.1 V).

  For example, when the potential of the ground node PGND serving as the reference of the detection resistor 17 of the drive unit 6 constituting the detection target circuit is negative (for example, −1 V) when viewed from the ground node AGND of the voltage detection circuit 3, this negative potential. Is input to the voltage detection circuit 3 through the noise filter 18.

  At this time, since the amplifier circuit 22 includes the operational amplifier 23 and the resistors 24-27, a potential V1 (for example, −0.5 V) corresponding to the negative potential is input to the input terminal of the operational amplifier 23.

  Since the potential levels of the input terminals IHa and ILa are low, the current sources 41 and 42 normally supply current to the input terminals IHa and ILa through the level shifters 43 and 44. For this reason, the base voltages of the differential input transistors 28 and 29 become 3 × Vf + V1 [V] by the action of the level shifters 43 and 44. Assuming that the base-emitter voltage Vbe of the differential input transistors 28 and 29 matches Vf (≈0.7 [V]), the potential V2a of the emitter common connection node Na of the differential input transistors 28 and 29 is 4 ×. Vf + V1 [V] (≈2.3 [V]).

  In this case, since the potential V2 of the node Na exceeds Vf + Vce1 (≈0.8 [V]) that is the operation lower limit voltage of the operational amplifier 23, the operational amplifier 23 can be normally operated, and the voltage detection circuit 3 has the input potential. Can be detected. Further, even when a lower negative potential V3 (for example, -1 [V]) is input to the input terminals IHa and ILa of the operational amplifier 23, the potential V2b of the node Na is 4 × Vf + V3 [V] (≈1.8). [V]) and lower than V2a, but even in such a case, since it exceeds Vf + Vce, the operational amplifier 23 can normally operate, and the voltage detection circuit 3 can detect this input potential.

  At this time, when the current generation circuit 30 is configured by the output of a PNP bipolar transistor, the saturation voltage between the collector and emitter of the PNP transistor of the output current mirror circuit of the current generation circuit 30 is set to Vce2. Then, the common-mode input allowable range of the differential amplifier 32 serving as the first stage circuit of the operational amplifier 23 is the power supply side voltage Vs−Vce2−4 × Vf and the ground side voltage Vf + Vce1−4 × Vf. At this time, if Vf of the diode is 0.7 V and the collector-emitter saturation voltage Vce1 of the output PNP transistor is 0.1 V, the negative potential can be detected up to -2.2 V.

  For example, when amplifying by connecting the collector of the auxiliary PNP transistor in front of the differential input transistor 28 made of a PNP transistor as in the conventional operational amplifier, there is a parasitic diode between the collector base of the auxiliary PNP transistor. . At this time, when a negative potential is input from the drive unit 6 that is the detection target side when viewed from the detection side, the drive unit 6 side passes through a parasitic diode between the collector base of the auxiliary PNP transistor from the ground node AGND. A sneak current is generated. As a result, this sneak current flows to the drive unit 6 side, so that an error component is likely to be generated. For example, when −1V is input, it becomes 2 × Vf−1V, and this potential is equal to or lower than Vf + Vce. Therefore, a potential of about −1V is not within the allowable range.

  In the case of the configuration of the present embodiment, even if a negative potential is input to the input terminals IH and IL of the voltage detection circuit 3, the level shifters 43 and 44 shift the potential in the positive voltage direction. It can be adjusted to be within the common mode input tolerance. Therefore, even if the potential of the ground node PGND of the detection resistor 17 of the drive unit 6 is lower than the potential of the ground node AGND of the voltage detection circuit 3, the terminal potential level of the detection resistor 17 viewed from the voltage detection circuit 3 is a negative potential. Even in this case, since the level shifters 43 and 44 shift the output potential of the detection resistor 17 in the positive voltage direction and input it to the bases of the differential input transistors 28 and 29, the operational amplifier 23 is normally differentially amplified. become able to.

  The current generation circuit 30 outputs a current for outputting the forward voltage Vf of the diodes 35 to 40 before inputting the output voltage of the resistor 17 from the current detection resistor 17 of the driving unit 6. Is given in advance. Therefore, for example, the switching on / off time when the level shifters 43 and 44 are configured by transistors instead of the diodes 35 to 40 can be eliminated, and the response speed of the circuit can be improved.

(Second Embodiment)
FIG. 4 shows an additional explanatory diagram of the second embodiment. As shown in FIG. 4, instead of the operational amplifier 23 of FIG. 3, as the level shifter 143, five diodes 135 to 137 and 135 a and 136 a connected in series may be used. May use five diodes 138 to 140 and 138a and 139a connected in series. The number of diodes connected in series is not limited as long as it is one or more. Also according to this embodiment, the same or similar effects as those of the above-described embodiment can be obtained.

(Third embodiment)
FIG. 5 shows an additional explanatory diagram of the third embodiment. An operational amplifier 223 shown in FIG. 5 instead of the operational amplifier 23 shown in FIG. 3 includes a pair of differential input transistors 228 and 229, an active load 31, and a differential amplifier 232 using an auxiliary differential pair 245 as an input stage. The pair of differential input transistors 228 and 229 form a differential pair, for example, an NPN bipolar transistor.

  The auxiliary differential pair 245 includes PNP-type bipolar transistors (hereinafter abbreviated as transistors) 246 and 247, 248 and 249 as a pair of auxiliary input transistors, and the bases of these transistors 246 to 249 are connected in common. The current source 250 is configured to draw a constant current from the common connection node Nb to the ground node AGND. The pair of differential input transistors 228 and 229 constitutes an emitter follower, and drives the emitters of the auxiliary differential input transistors 246 to 249 constituting the base-grounded auxiliary differential pair 245. The active load 31 is an active load of these auxiliary differential input transistors 246 and 247.

  Also in the circuit configuration shown in FIG. 5 of the present embodiment, the diodes 235 to 237 and 235a serve as the level shifter 243 from the input terminal IHa of the operational amplifier 223 (the input terminal IH of the voltage detection circuit 3) to the base of the differential input transistor 228 ( It is connected in the reverse direction toward the input node. The diodes 238 to 240 and 238a are connected in the reverse direction as the level shifter 244 from the input terminal ILa of the operational amplifier 223 (input terminal IL of the voltage detection circuit 3) to the base (input node) of the differential input transistor 229. Yes. For this reason, there exists the same or similar effect as the above-mentioned embodiment.

(Fourth embodiment)
FIG. 6 shows an additional explanatory diagram of the fourth embodiment. An operational amplifier 323 shown in FIG. 6 instead of the operational amplifier 23 in FIG. 3 shows an example using elements 328 to 331, 341 and 342 having MOS transistors as constituent elements. As shown in FIG. 6, the operational amplifier 323 includes a differential amplifier 332 having a pair of differential input transistors 328 and 329, a current generation circuit 330, and an active load 331 as an input stage. The pair of differential input transistors 328 and 329 are configured using P-channel MOS transistors, and the active load 331 is configured using N-channel MOS transistors 333 and 334. The current generation circuit 330 is mainly composed of a current mirror circuit using MOS transistors, and although not shown, an output stage transistor is, for example, a P-channel type MOS transistor. The current source 341 in place of the current source 41 and the current source 342 in place of the current source 42 are also preferably composed mainly of MOS transistors. Also according to this embodiment, the same or similar effects as those of the above-described embodiment can be obtained.

(Fifth embodiment)
FIG. 7 shows an additional explanatory diagram of the fifth embodiment. An operational amplifier 423 shown in FIG. 7 instead of the operational amplifier 23 shown in FIG. 3 includes a pair of differential input transistors 428 and 429, and a differential amplifier 432 having a current generation circuit 430 and an active load 431 as input stages. The pair of differential input transistors 428 and 429 are configured by, for example, N-channel MOS transistors, and the drains of these transistors 428 and 429 are commonly connected. Current generation circuit 430 draws a constant current to ground node AGND. The active load 431 includes P channel type MOS transistors 433 and 434. The MOS transistors 433 and 434 have their common source connected to the supply terminal of the power supply voltage VS, and the MOS transistors 433 and 434 have their gates commonly connected to each other. This common gate connection node N3a is connected to the drain of one MOS transistor 433. This active load 431 becomes an active load of the pair of differential input transistors 428 and 429.

  Also in the circuit configuration shown in FIG. 7 of the present embodiment, the diodes 35 to 37 are directed from the input terminal IHa of the operational amplifier 423 (input terminal IH of the voltage detection circuit 3) to the gate (input node) of the differential input transistor 428. Are connected in the reverse direction, and are configured as a level shifter 43. Diodes 38 to 40 are connected in the reverse direction from the input terminal ILa of the operational amplifier 423 (input terminal IL of the voltage detection circuit 3) to the gate (input node) of the differential input transistor 429, and are configured as a level shifter 44. ing. For this reason, there exists the same or similar effect as the above-mentioned embodiment.

(Sixth embodiment)
FIG. 8 shows an additional explanatory diagram of the sixth embodiment. In the sixth embodiment, a form is provided that includes a first adjustment unit that acquires a value corresponding to the power supply voltage VS and adjusts the level shift voltage of the level shifter according to the acquired value. In addition, a mode in which a value corresponding to the potential of the ground node PGND is acquired and a second adjustment unit that adjusts the level shift voltage of the level shifter according to the acquired value is shown. In addition, a mode in which a value corresponding to the operating environment temperature of the differential amplifier is acquired and a third adjustment unit that adjusts the level shift voltage of the level shifter according to the acquired value is shown.

  FIG. 8 schematically shows a configuration example near the input stage of the operational amplifier 523 and an electrical configuration block example for adjusting the level shift voltage by the level shifters 43 and 44. As shown in FIG. 8, the operational amplifier 523 includes a differential amplifier 32. The differential amplifier 32 is a circuit similar to that shown in FIG. Control switches 51 to 53 are connected in parallel to the diodes 35 to 37 constituting the level shifter 43, respectively. Control switches 54 to 56 are connected in parallel to the diodes 38 to 40 constituting the level shifter 44, respectively. These control switches 51 to 56 are configured to be able to be turned on / off by an adjustment unit 57.

  The control switches 51 to 56 are configured to be able to simultaneously turn on / off the same number of diodes 35 to 37 on the non-inverting input terminal IHa side of the operational amplifier 523 and the diodes 38 to 40 on the inverting input terminal ILa side. Yes. In the present embodiment, one control switch is connected in parallel to one diode. The control switches 51 to 56 are configured to be turned on and off simultaneously for each of the diodes 35 to 37 and 38 to 40 on the non-inverting input terminal IHa side and the inverting input terminal ILa side of the operational amplifier 523.

  The adjustment unit 57 is provided with detection results of a power supply voltage detection unit 58 as a first acquisition unit, a ground potential detection unit 59 as a second acquisition unit, and a temperature detection unit 60 as a third acquisition unit. The adjustment part 57 is comprised, for example with a microcomputer, and is provided with the function as a 1st-3rd adjustment part by executing the program memorize | stored. Although the adjustment part 57 shows the form provided with the function as a 1st-3rd adjustment part together, you may provide with the separate body separately, Furthermore, a 1st adjustment part, a 2nd adjustment part, a 3rd adjustment Only one of the units or a function as two adjustment units may be provided.

  The power supply voltage detector 58 detects the power supply voltage VS applied to the power supply terminal of the power supply voltage VS using, for example, a resistor (not shown). The ground potential detector 59 detects the potential of the ground node PGND serving as a body earth, and detects the relative potential of the ground node PGND with respect to the potential of the ground node AGND. The temperature detector 60 detects the operating environment temperature of the operational amplifier 523 (differential amplifier 32) using, for example, a temperature sensor.

  For example, when the power supply voltage detection unit 58 detects the normal standard voltage VS0 as the power supply voltage VS as 12 V, for example, and the adjustment unit 57 acquires a value corresponding to this detection value, the total number (for example, 3) Some predetermined (for example, one) control switches (for example, 52 and 55) are turned on, and the remaining control switches (for example, 51, 53, 54, and 56) are turned off. Thereafter, when the power supply voltage detection unit 58 detects that the power supply voltage VS is higher than the standard voltage VS0, the control switch 51 is configured to increase the level shift voltage and increase the number of diodes connected to the level shifters 43 and 44 in series. Turn on and off -56. On the other hand, when the power supply voltage detector 58 detects that the voltage drops below the standard voltage VS0, the control switches 51 to 56 are set so as to reduce the level shift voltage and reduce the number of series-connected diodes of the level shifters 43 and 44. Turn on and off. Thereby, the level shift voltages of the level shifters 43 and 44 can be adjusted according to the change of the power supply voltage VS.

  Further, for example, when the ground potential detection unit 59 detects a potential substantially the same as the ground node AGND as the potential of the ground node PGND, and the adjustment unit 57 acquires a value corresponding to this detection value, a part of the total number A predetermined number (for example, one) of control switches (for example, 52 and 55) are turned on, and the remaining control switches (for example, 51, 53, 54, and 56) are turned off. After that, when the ground potential detection unit 59 detects the potential of the ground node PGND higher than the potential of the ground node AGND, the control switch 51 is configured so as to reduce the level shift voltage and reduce the number of series-connected diodes of the level shifters 43 and 44. Turn on and off -56. Conversely, when the ground potential detection unit 59 detects the potential of the ground node PGND lower than the potential of the ground node AGND, the control switch is configured to increase the level shift voltage and increase the number of series-connected diodes of the level shifters 43 and 44. Turn on 51-56. Thereby, the level shift voltages of the level shifters 43 and 44 can be adjusted according to the relative change between the potential of the ground node AGND and the potential of the ground node PGND.

  For example, when the temperature detection unit 60 detects a standard temperature (for example, 25 ° C.) as the operating environment temperature of the operational amplifier 523 (differential amplifier 32), and the adjustment unit 57 acquires a value corresponding to this detection value. A predetermined number (for example, one) of the total number of control switches (for example, 52, 55) is turned on, and the remaining control switches (for example, 51, 53, 54, 56) are turned off. After that, when the temperature detection unit 60 detects a temperature higher than the standard temperature as the operating environment temperature of the operational amplifier 523 (differential amplifier 32), the forward voltage Vf decreases due to the temperature characteristics of the diodes 35-40. The control switches 51 to 56 are turned on and off so as to increase the number of diodes 35 to 40 connected in series. Conversely, when the temperature detection unit 60 detects a temperature lower than the standard temperature as the operating environment temperature of the operational amplifier 523 (differential amplifier 32), the forward voltage Vf increases due to the temperature characteristics of the diodes 35-40. The control switches 51 to 56 are turned on and off so as to reduce the number of diodes 35 to 40 connected in series. As a result, the level shift voltages of the level shifters 43 and 44 can be adjusted in accordance with changes in the operating environment temperature of the operational amplifier 523 (differential amplifier 32).

  As described above, according to the present embodiment, the level shift voltages of the level shifters 43 and 44 are adjusted by adjusting the number of diodes 35 to 40 connected in series, so that various parameters (power supply voltage VS, ground voltage) are adjusted. The level shift voltage can be adjusted according to the potential of the node PGND and the operating environment temperature of the operational amplifier 523 (differential amplifier 32).

(Other embodiments)
The present invention is not limited to the above-described embodiment, and for example, the following modifications or expansions are possible. Although the diodes 35 to 40, 135 to 137, 135a, 136a, 138 to 140, 138a, 139a, 235 to 237, 235a, 238 to 240, and 238a are shown, transistors (MOS transistors, bipolar transistors, etc.) are shown. A diode-connected circuit may be used.

  As long as the level shifters 43 and 44 are disposed between the output terminal OH-OL of the inter-terminal voltage of the resistor 17 and the input nodes N1 and N2 of the differential input transistors 28 and 29, any position is possible. May be arranged. The same applies to the level shifters 143 and 144, 243, and 244.

  The level shifters 43 and 44, 143 and 144, 243 and 244 are preferably set to have the same amount of voltage for level shift between the terminals (non-inverting input terminal IHa and inverting input terminal ILa). Further, it may be set in consideration of variation between elements. The configurations of the embodiments can be applied in combination as appropriate.

  In the drawing, 2 is an ECU (vehicle device), 3 is a voltage detection circuit, 17 is a resistor (detection target circuit), 28, 29, 228, 229, 328, 329, 428, 429 are differential input transistors, 32, 232, 332, 432 are differential amplifiers, 35-40, 135-140, 135a, 136a, 138a, 139a, 235-240, 235a, 238a are diodes, 43, 44, 143, 144, 243, 244 are level shifters, 57 is an adjustment unit (first to third adjustment units), 58 is a power supply voltage detection unit (first acquisition unit), 59 is a ground potential detection unit (second acquisition unit), and 60 is a temperature detection unit (third acquisition unit). ), N1 and N2 are input nodes of the differential input transistor, VB is a power supply voltage (first power supply voltage), VS is a power supply voltage (second power supply voltage), and PGND is a ground node (first reference voltage). De), AGND ground node (second reference node) shows.

Claims (6)

The second reference node (AGND) can be changed to a potential different from the potential of the first reference node (PGND).
Detection target circuit (17) is, when said first reference node potential of (PGND) operated by a first power supply voltage and the reference potential (VB), and the 0 reference potential of the second reference node from the output terminal When the circuit outputs a negative potential of
Differential input transistors (28, 29; 228, 229; 328, 329; 428, 429), operated by a second power supply voltage (VS) with the potential of the second reference node (AGND) as a reference potential; A differential amplifier (32; 232; 332; 432) for differentially amplifying a signal by inputting a signal to input nodes (N1, N2) of the differential input transistor;
It is disposed between the output terminal of the detection target circuit and the input node of the differential input transistor, and level-shifts the output voltage of the detection target circuit to the input node of the differential input transistor. Level shifters (43, 44; 143, 144; 243, 244),
The level shifter inputs the negative potential from the output terminal of the detection target circuit is level-shifted to the positive voltage direction toward the input node of the differential input transistors, you output to an input node of the differential input transistors Configured as
The level shifter includes diodes (35 to 37, 38 to 40; 135 to 137, 135a, 136a, 138 to 140, 138a, and 139a) that are connected in the reverse direction from the detection target circuit toward the input node of the differential input transistor. 235-237, 235a, 238-240, 238a);
The detection target circuit includes a resistor (17), and the resistor is directly connected to the diode . A first acquisition unit (58) for acquiring a value corresponding to the second power supply voltage;
The voltage detection circuit according to claim 1 , further comprising: a first adjustment unit (57) that adjusts a level shift voltage of the level shifter according to an acquired value of the first acquisition unit. A second acquisition unit (59) for acquiring a value corresponding to the potential of the first reference node;
The voltage detection circuit according to claim 1 , further comprising: a second adjustment unit that adjusts a level shift voltage of the level shifter according to an acquired value of the second acquisition unit. A third acquisition unit (60) for acquiring a value corresponding to the operating environment temperature of the differential amplifier;
According to any one of claims 1-3, characterized in that it comprises a third adjustment part (57), for adjusting the level shift voltage of the level shifter according to by that obtain values in the third acquisition unit Voltage detection circuit. When the front Symbol detection target circuit outputs said negative potential, according to any one of claims 1 to 4, characterized in that outputs the negative potential via the resistor relative to the first reference node Voltage detection circuit. The voltage detection circuit according to any one of claims 1 to 5, wherein the voltage detection circuit is used for a vehicle device (2).

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