Current detection circuit, semiconductor device, and semiconductor system

Abstract

Embodiments of the present disclosure relate to a current detection circuit, a semiconductor device, and a semiconductor system, which are suitable for improving current sensing accuracy. According to one embodiment, a current detection circuit 12 includes: a sensing transistor Tr11 through which a first sensing current proportional to a current flowing through a drive transistor MN1 flows; an operational amplifier AMP1 for amplifying a potential difference between a voltage of an external output terminal OUT and a source voltage of the sensing transistor Tr11 for outputting the first sensing current; a transistor Tr12 provided in series with the sensing transistor Tr11, and an output voltage of the operational amplifier AMP1 is applied to a gate of the transistor Tr12; and a switch SW3 provided between the external output terminal OUT and the source of the sensing transistor Tr11, the switch SW3 being turned on when the drive transistor MN1 is turned off.

Description

[0001] Cross-reference to related applications

[0002] The disclosure of Japanese Patent Application No. 2019-055993, filed on March 25, 2019, including its specification, drawings and abstract, is incorporated herein by reference in its entirety. Technical Field

[0003] This disclosure relates to current sensing circuits, semiconductor devices, and semiconductor systems, such as current sensing circuits, semiconductor devices, and semiconductor systems suitable for improving the accuracy of current sensing. Background Technology

[0004] The vehicle is equipped with an electronic control unit (ECU) that controls the current supply to the solenoid valve, which in turn controls the opening and closing of the clutch. The ECU controls the clutch's opening and closing by controlling the current supply to the solenoid valve, thereby transmitting engine power to the transmission during vehicle start-up, stopping, and gear shifting. Here, the ECU needs to accurately control the current supplied to the solenoid valve to accurately open and close the clutch.

[0005] Therefore, the electronic control unit is equipped with a current detection circuit to detect whether the value of the current output from the solenoid driver indicates a normal value. Of course, this current detection circuit needs to detect the current with high accuracy.

[0006] Current sensing circuits that use shunt resistors to detect the current flowing through a driver are known as current sensing circuits with high current sensing accuracy. However, current sensing circuits using the shunt resistor method suffer from increased circuit size. In particular, when multiple solenoid drivers need to be mounted on a single chip, multiple shunt resistor current sensing circuits are provided on one chip, resulting in a very large chip size.

[0007] The following is a list of publicly available technologies.

[0008] [Patent Document 1] US Patent Publication No. 6,377,034

[0009] Patent Document 1 discloses a solution to these problems. The current sensing circuit disclosed in Patent Document 1 detects the current flowing in the driver (transistor) using a sensing transistor, with a current proportional to the current flowing in the driver (transistor) flowing in the sensing transistor. As a result, this current sensing circuit can suppress the increase in circuit size compared to the circuit size of a shunt resistor type current sensing circuit. Summary of the Invention

[0010] Incidentally, the current sensing circuit disclosed in Patent Document 1 includes an amplifier and a voltage-controlled transistor such that the source voltage of the driver and the source voltage of the sensing transistor are equal. The amplifier amplifies the potential difference between the source voltage of the sensing transistor and the ground voltage. The voltage-controlled transistor is provided between the source of the sensing transistor and the current detection output terminal, and controls the current flowing between the source and drain based on the output voltage of the amplifier.

[0011] However, in the configuration of Patent Document 1, when the sensing transistor is in the off state, the current flowing through the voltage control transistor decreases to around 0A, causing a decrease in the gain of the loop formed by the amplifier and the voltage control transistor, and rendering the feedback through this loop ineffective. As a result, the voltage control transistor is not completely turned off, causing the source voltage of the sensing transistor in the off state to exhibit a voltage different from 0V. That is, the source-drain voltage of the driver in the off state is different from the source-drain voltage of the sensing transistor in the off state.

[0012] Here, when the source-drain voltage of the driver in the off state and the source-drain voltage of the sensing transistor in the off state have different values, the degree of degradation of the driver and sensing transistor caused by leakage current is different. As a result, in the configuration of Patent Document 1, the ratio of the current flowing in the driver to the current flowing in the sensing transistor in the on state fluctuates, making it impossible to accurately detect the current flowing in the driver. Other objects and novel features will become apparent from the description and drawings of this specification.

[0013] Problem Solving

[0014] According to one embodiment, a current detection circuit includes: a first sensing transistor, to which a voltage from a first power supply is supplied, and a first driving transistor, the first driving transistor being provided between the first power supply and an external output terminal, a load being connected to the external output terminal, a first sensing current flowing through the first sensing transistor, the first sensing current being proportional to the current flowing through the first driving transistor; a first amplifier amplifying the potential difference between the voltage at the external output terminal and the output terminal of the first sensing transistor that outputs the first sensing current; a first voltage control transistor being provided in series with the first sensing transistor at the output terminal of the first sensing transistor, the output voltage of the first amplifier being applied to the gate of the first voltage control transistor; the first voltage control transistor being provided between the external output terminal and the output terminal of the first sensing transistor, the first voltage control transistor being turned on when the first driving transistor is turned off; and a first switch being turned off when the first driving transistor is turned on, wherein the current detection circuit outputs the first sensing current as a detection current.

[0015] According to one embodiment, a current detection circuit includes: a first sensing transistor, to which a voltage from an external output terminal is supplied; a first driving transistor or a second driving transistor, wherein the first driving transistor is provided between a first power supply and the external output terminal, a load is connected to the external output terminal, the second driving transistor is provided between the external output terminal and the second power supply, and a first sensing current flows proportionally to the current flowing through the first driving transistor; a first amplifier for amplifying the potential difference between the voltage of the first power supply and the voltage at the output terminal of the first sensing transistor for outputting the first sensing current; a first voltage control transistor provided in series with the first sensing transistor on the output terminal side of the first sensing transistor and having a gate, to which the output voltage of the first amplifier is applied; and a first voltage control transistor provided between the first power supply and the output terminal of the first sensing transistor, wherein a first switch is turned on when the first driving transistor is turned off, and the first switch is turned off when the first driving transistor is turned on. The current detection circuit outputs the first sensing current as a detection current.

[0016] According to one embodiment, the current sensing circuit includes: a first sensing transistor, a first amplifier, a first voltage control transistor, a second sensing transistor, a second amplifier, a second voltage control transistor, a mirror transistor, a selection circuit, and a switch group including a plurality of switches. When the operating mode is a high-side drive mode, the current sensing circuit turns the switch group on / off. Therefore, the first sensing transistor, supplied with the voltage of a first power supply along with a first drive transistor, and having a first sensing current flowing proportional to the current flowing through the first drive transistor, is provided between the first power supply and an external output terminal, with a load connected to the external output terminal. The first amplifier is configured to amplify the potential difference between the voltage of the external output terminal and the voltage of the output terminal of the first sensing transistor used to output the first sensing current. The first voltage control transistor is provided in series with the first sensing transistor at the output terminal of the first sensing transistor and is configured such that the output voltage of the first amplifier is applied to the gate of the first voltage control transistor. A first switch is provided between the external output terminal and the output terminal of the first sensing transistor, and the first switch is part of the switch group. The first switch, being part of the switch group, is configured to turn on when the first drive transistor is off and turn off when the first drive transistor is on. A second sensing transistor, supplied with the voltage of an external output terminal together with a second driving transistor, is provided between the external output terminal and the second power supply in a complementary manner to the first driving transistor. The second sensing transistor is configured to allow a second sensing current to flow, the second sensing current being proportional to the current flowing through the second driving transistor. A second amplifier is configured to amplify the potential difference between the voltage of the second power supply and the voltage at the output terminal of the second sensing transistor that outputs the second sensing current. A second voltage control transistor is provided in series with the second sensing transistor at its output terminal. The second voltage control transistor is configured such that the output voltage of the second amplifier is applied to the gate of the second voltage control transistor. A second switch is provided between the second power supply and the output terminal of the second sensing transistor and is configured to turn on when the second driving transistor is off and turn off when the second driving transistor is on; the second switch is part of a switch group. A mirror transistor is configured to mirror the second sensing current flowing using the second sensing transistor to the second voltage control transistor. A selection circuit is configured to selectively output the first sensing current and the second sensing current mirrored by the mirror transistor as a detection current. When the operating mode is low-side drive mode, the current sensing circuit turns the switch group on / off. Therefore, the first sensing transistor, together with the first driving transistor, is supplied with the voltage of the external output terminal, and a first sensing current flows proportional to the voltage flowing through the first driving transistor. The first amplifier is configured to amplify the potential difference between the voltage of the first power supply and the voltage at the output terminal of the first sensing transistor that outputs the first sensing current.A first voltage control transistor is provided in series with a first sensing transistor at the output terminal of the first sensing transistor. The first voltage control transistor is configured such that the output voltage of a first amplifier is applied to the gate. A first switch is provided between a first power supply and the output terminal of the first sensing transistor, and is configured to turn on when the first driving transistor is off, and to turn off when the first driving transistor is on. A second sensing transistor is supplied with the voltage of a second power supply and the voltage of a second driving transistor, and a second sensing current flows through the second sensing transistor, the second sensing current being proportional to the current flowing through the second driving transistor. A second amplifier is configured to amplify the potential difference between the voltage of an external output terminal and the voltage of the output terminal of the second sensing transistor used to output the second sensing current. A second voltage control transistor is provided in series with the second sensing transistor at the output terminal of the second sensing transistor, and is configured such that the output voltage of the second amplifier is applied to the gate. A second switch is provided between the external output terminal and the output terminal of the second sensing transistor. The second switch is configured to turn on when the second driving transistor is off, and to turn off when the second driving transistor is on. A mirror transistor is configured to mirror the second sensing current flowing using the second sensing transistor to the second voltage control transistor. The selection circuit is configured to selectively output a first sensing current and a second sensing current mirrored by a mirror transistor as a detection current.

[0017] [The effects of the invention]

[0018] Current sensing circuits, semiconductor devices, and systems can be provided that are suitable for improving the accuracy of current sensing. Attached Figure Description

[0019] Figure 1 This is an external view of a vehicle on which an electronic control unit according to the first embodiment is mounted.

[0020] Figure 2 It is shown Figure 1 A block diagram showing an exemplary configuration of the electronic control unit.

[0021] Figure 3 It is shown Figure 2 The diagram shows a specific configuration example of the electronic control unit 1.

[0022] Figure 4 This is a diagram illustrating a specific configuration example of the current detection circuit according to the first embodiment.

[0023] Figure 5 It is shown Figure 4 The timing diagram of the operation of the current detection circuit shown is shown.

[0024] Figure 6 This is used to explain what happens when the high-side driver is turned on. Figure 4 The diagram shows the current flow in the current detection circuit.

[0025] Figure 7 This is used to explain what happens when the low-side driver is turned on. Figure 4 The diagram shows the current flow in the current detection circuit.

[0026] Figure 8 This is a diagram illustrating a specific configuration of a current detection circuit based on a concept prior to the implementation of the first embodiment.

[0027] Figure 9 This is used to explain what happens when the high-side driver is turned on. Figure 8 The diagram shows the current flow in the current detection circuit.

[0028] Figure 10 This is used to explain what happens when the low-side driver is turned on. Figure 8 The diagram shows the current flow in the current detection circuit.

[0029] Figure 11 This is a schematic cross-sectional view of a transistor, used to explain transistor degradation caused by leakage current.

[0030] Figure 12 This is a diagram illustrating an example configuration of the drive transistor and the sensing transistor in which gain degradation does not occur even when a shutdown state degradation occurs.

[0031] Figure 13 This is a diagram illustrating an example configuration of the drive transistor and the sensing transistor in which gain degradation occurs when a shutdown state degradation occurs.

[0032] Figure 14 It is shown Figure 12 The diagram shows the input current and current detection error for the configuration example shown.

[0033] Figure 15 It is shown Figure 13 The diagram shows the input current and current detection error for the configuration example shown.

[0034] Figure 16 This is a diagram illustrating a specific configuration example of the current detection circuit according to the second embodiment.

[0035] Figure 17 It is shown Figure 16 The timing diagram of the operation of the current detection circuit shown is shown.

[0036] Figure 18 This is used to explain what happens when the high-side driver is turned on. Figure 16 The diagram shows the current flow in the current detection circuit.

[0037] Figure 19 This is used to explain what happens when the low-side driver is turned on. Figure 16 The diagram shows the current flow in the current detection circuit.

[0038] Figure 20 This is a diagram used to explain the current flow according to the concept of a current detection circuit prior to the second embodiment when the high-side driver is turned on.

[0039] Figure 21 This is a diagram used to explain the flow of current according to the concept of a current detection circuit prior to the second embodiment when the low-side driver is turned on.

[0040] Figure 22 This is a diagram illustrating a specific configuration example of the current detection circuit according to the third embodiment.

[0041] Figure 23 This is used to explain what happens when the high-side driver is turned on. Figure 22 The diagram shows the current flow in the current detection circuit.

[0042] Figure 24 This is used to explain what happens when the low-side driver is turned on. Figure 22 The diagram shows the current flow in the current detection circuit.

[0043] Figure 25 This is a diagram illustrating a specific configuration example of the current detection circuit according to the fourth embodiment.

[0044] Figure 26 This is used to explain what happens when the high-side driver is turned on. Figure 25 The diagram shows the current flow in the current detection circuit.

[0045] Figure 27 This is used to explain what happens when the low-side driver is turned on. Figure 25 The diagram shows the current flow in the current detection circuit.

[0046] Figure 28 This is a diagram illustrating a specific configuration example of the current detection circuit according to the fifth embodiment.

[0047] Figure 29 This is used to explain when the high-side driver is turned on during high-side driving. Figure 28 The diagram shows the connection relationships of the components of the current detection circuit and the current flow.

[0048] Figure 30 This is used to explain when the low-side driver is turned on while the high-side driver is in operation. Figure 28 The diagram shows the connection relationships of the components of the current detection circuit and the current flow.

[0049] Figure 31This is used to explain when the high-side driver is turned on while the low-side driver is in operation. Figure 28 The diagram shows the connection relationships of the components of the current detection circuit and the current flow.

[0050] Figure 32 This is used to explain when the low-side driver is turned on during low-side driving. Figure 28 The diagram shows the connection relationships of the components of the current detection circuit and the current flow.

[0051] Figure 33 This is a diagram illustrating an example configuration of a current sensing circuit based on a comparative example.

[0052] Figure 34 This is used to explain when the high-side driver is turned on during high-side driving. Figure 33 The diagram shows the current flow in the current detection circuit.

[0053] Figure 35 This is used to explain when the low-side driver is turned on while the high-side driver is in operation. Figure 33 The diagram shows the current flow in the current detection circuit.

[0054] Figure 36 This is used to explain when the high-side driver is turned on while the low-side driver is in operation. Figure 33 The diagram shows the current flow in the current detection circuit.

[0055] Figure 37 This is used to explain when the low-side driver is turned on during low-side driving. Figure 33 The diagram shows the current flow in the current detection circuit.

[0056] Figure 38 This is a diagram illustrating the specific configuration of the current detection circuit according to the sixth embodiment.

[0057] Figure 39A and Figure 39B It is a diagram used to explain improvements in the dead zone region.

[0058] Figure 40 This is used to explain when the high-side driver is turned on during high-side driving. Figure 38 The diagram shows the connection relationships of the components of the current detection circuit and the current flow.

[0059] Figure 41 This is used to explain when the low-side driver is turned on while the high-side driver is in operation. Figure 38 The diagram shows the connection relationships of the components of the current detection circuit and the current flow.

[0060] Figure 42 This is used to explain when the high-side driver is turned on while the low-side driver is in operation. Figure 38 The diagram shows the connection relationships of the components of the current detection circuit and the current flow.

[0061] Figure 43 This is used to explain when the low-side driver is turned on during low-side driving. Figure 38 The diagram shows the connection relationships of the components of the current detection circuit and the current flow. Detailed Implementation

[0062] For clarity of explanation, the following description and figures have been appropriately omitted and simplified. Furthermore, the elements described in the figures as functional blocks for performing various processes can be configured as a CPU (Central Processing Unit), memory, and other hardware-based circuitry, and can be implemented by a software-based program loaded into memory. Therefore, those skilled in the art will understand that these functional blocks can be implemented in various forms by separate hardware, separate software, or combinations thereof, and the invention is not limited to any of them. In the figures, the same elements are indicated by the same reference numerals, and repeated descriptions are omitted where necessary.

[0063] Furthermore, the aforementioned programs can be stored and provided to a computer using various types of non-transitory computer-readable media. Non-transitory computer-readable media include various types of tangible storage media. Examples of non-transitory computer-readable media include magnetic recording media (e.g., floppy disks, magnetic tapes, hard disk drives), magneto-optical recording media (e.g., magneto-optical disks), CD-ROMs (read-only memory, CD-Rs, CD-R / Ws), and solid-state storage (e.g., mask ROMs, PROMs (programmable ROMs), EPROMs (erasable PROMs, flash memory ROMs, RAMs (random access memory)). Programs can also be provided to a computer using various types of transient computer-readable media. Examples of transient computer-readable media include electrical signals, optical signals, and electromagnetic waves. Transient computer-readable media can provide programs to a computer via wired or wireless communication paths such as electrical wires and optical fibers.

[0064] <First Embodiment> Figure 1 This is an external view of a vehicle on which an electronic control unit (ECU) according to the first embodiment is mounted.

[0065] like Figure 1 As shown, for example, engine 2, clutch 3, transmission 4, differential gear 5, tire 6, solenoid valve (load) 7 and electronic control unit 1 are installed on the vehicle.

[0066] For example, the electronic control unit 1 controls the current supply to the solenoid valve 7. The solenoid valve 7 converts the current supplied from the solenoid actuator into electromagnetic force via an inductor or the like, and then uses the electromagnetic force to control the opening and closing of the clutch 3. Therefore, the transmission of the driving force of the engine 2 to the transmission 4 is controlled during vehicle start-up, stopping, and gear shifting. The transmission 4 changes the driving force of the engine 2 into a rotational speed and torque corresponding to the operating conditions, and then transmits the torque to the differential gear 5 to rotate the tires 6.

[0067] Figure 2 This is a block diagram illustrating an exemplary configuration of the electronic control unit 1. Figure 2 As shown, the electronic control unit 1 includes a solenoid driver 11, a current detection circuit 12, and a control unit 13.

[0068] Solenoid driver 11 outputs current to solenoid valve 7. Current detection circuit 12 detects the value of the current output from solenoid driver 11. Control circuit 13, for example, is an MCU (microcontroller unit) and, based on the current value detected by current detection circuit 12, controls the output current of solenoid driver 11 by controlling the duty cycle of a control pulse signal (e.g., a control signal), so that the value of the output current of solenoid driver 11 falls within a normal range.

[0069] Here, the electronic control unit 1 needs to accurately open and close the clutch 3 by precisely controlling the current supplied to the solenoid valve 7. Therefore, the current detection circuit 12 needs to detect the current with high accuracy.

[0070] Figure 3 It is shown Figure 2 The diagram shows the specific configuration of the electronic control unit 1. (As shown...) Figure 3 As shown, in the electronic control unit 1, the solenoid driver 11 includes a driving transistor MN1 and a driving transistor MN2, and the current detection circuit 12 includes a sensing transistor Tr11, a sensing transistor Tr21, and a current monitor 121.

[0071] The driving transistor MN1 is, for example, an N-channel MOS transistor with a high withstand voltage, and serves as the high-side driver of the solenoid driver 11. Specifically, the driving transistor MN1 is supplied between the voltage supply terminal and the external output terminal OUT, the battery voltage Vbat is supplied to the voltage supply terminal (hereinafter referred to as the voltage supply terminal Vbat), the solenoid valve 7 as a load is connected to the external output terminal OUT, and the driving transistor MN1 is turned on / off based on the pulse signal S1 as a control signal from the control circuit 13.

[0072] The driving transistor MN2 is, for example, an N-channel MOS transistor with a high withstand voltage and serves as the low-side driver of the solenoid driver 11. Specifically, the driving transistor MN2 is provided between the external output terminal OUT and the reference voltage terminal (hereinafter referred to as the reference voltage terminal GND), and is turned on / off based on the pulse signal S2, to which the reference voltage GND, such as ground voltage, is supplied. The pulse signal S2 is a control signal from the control circuit 13.

[0073] The solenoid valve 7 has an inductor L1 and converts the current supplied from the solenoid actuator 11 into electromagnetic force. The solenoid valve 7 controls the hydraulic pressure by using electromagnetic force, thereby controlling the opening and closing of the clutch 3.

[0074] exist Figure 3 In this embodiment, the solenoid valve 7, which is the load, is provided between the external output terminal OUT of the electronic control unit 1 and the reference voltage GND. Therefore, in Figure 3 In this case, the driving transistor MN1, acting as a high-side driver, is used to drive the solenoid valve 7, and the driving transistor MN2, acting as a low-side driver, serves as the regenerative current path for the solenoid valve 7. In the following text, the fact that the high-side driver (driving transistor MN1) is used to drive the load (soleoid valve 7) is also referred to as high-side driving.

[0075] The solenoid valve 7 can be provided between the external output terminal OUT of the electronic control unit 1 and the voltage source of the battery voltage Vbat. In this case, the drive transistor MN2, acting as a low-side driver, is used to drive the solenoid valve 7, and the drive transistor MN1, acting as a high-side driver, serves as the regenerative current path for the solenoid valve 7. In the following text, the fact that the low-side driver (drive transistor MN2) is used to drive the load (soleoid valve 7) is also referred to as low-side driving.

[0076] For example, first, drive transistor MN1 is turned on and drive transistor MN2 is turned off. As a result, current flows from the voltage supply terminal Vbat through drive transistor MN1 to the inductor L1 of the solenoid valve 7. At this time, current energy is stored in inductor L1. Subsequently, drive transistor MN1 is turned off and drive transistor MN2 is turned on. As a result, the current flowing from the voltage supply terminal Vbat through drive transistor MN1 to the inductor L1 of the solenoid valve 7 is interrupted. Inductor L1 releases the stored current energy in an attempt to maintain the current value of the previously flowing current. As a result, current flows from the reference voltage terminal GND through drive transistor MN2 to the inductor L1 of the solenoid valve 7. This operation is repeated.

[0077] Similar to the driving transistor MN1, the sensing transistor Tr11 is formed from an N-channel MOS transistor with a high withstand voltage. For example, the transistor size of the sensing transistor Tr11 is 1 / 1000 times the transistor size of the driving transistor MN1.

[0078] Specifically, in the sensing transistor Tr11, the drain is connected to the voltage supply terminal Vbat, the source is connected to the current monitor 121, and a pulse signal S1 is supplied to the gate. Therefore, a current proportional to (i.e., 1 / 1000 times) the current flowing between the source and drain of the driving transistor MN1 flows between the source and drain of the sensing transistor Tr11.

[0079] Similar to the driving transistor MN2, the sensing transistor Tr21 is formed from an N-channel MOS transistor with a high withstand voltage. For example, the transistor size of the sensing transistor Tr21 is 1 / 1000 times the transistor size of the driving transistor MN2.

[0080] Specifically, in the sensing transistor Tr21, the drain is connected to the external output terminal OUT, the source is connected to the current monitor 121, and a pulse signal S2 is supplied to the gate. Therefore, a current proportional to (i.e., 1 / 1000 times) the current flowing between the source and drain of the driving transistor MN2 flows between the source and drain of the sensing transistor Tr21.

[0081] Current monitor 121 monitors the current flowing through sensing transistors Tr11 and Tr21, respectively. The monitoring results from current monitor 121 are output as the results detected by current detection circuit 12.

[0082] Control circuit 13 uses pulse signals S1 and S2 to alternately drive drive transistors MN1 and MN2. Here, control circuit 13 controls the duty cycle of pulse signals S1 and S2 based on the result detected by current detection circuit 12. As a result, the driving periods of drive transistors MN1 and MN2 can be adjusted with high accuracy. Consequently, for example, in a vehicle in which electronic control unit 1 is installed, vibrations during gear shifting in transmission 4 can be suppressed, enabling a comfortable ride with less vibration.

[0083] Before describing in detail the current detection circuit 12 installed on the electronic control unit 1, the inventor will first describe the current detection circuit 52 that has been previously studied by the inventor.

[0084] <<Configuration of Current Detection Circuit 52>> Figure 8 This is a diagram illustrating a configuration example of a current detection circuit 52 according to a concept prior to the first embodiment. Figure 8The solenoid driver 11, serving as the drive circuit, and the solenoid valve 7, serving as the load circuit, are also shown. Figure 8 In this process, the high-side drive of the solenoid valve 7 is performed by the solenoid actuator 11.

[0085] The current detection circuit 52 includes sensing transistors Tr11 and Tr21, transistors (voltage-controlled transistors) Tr12 and Tr22, transistor (mirror transistor) Tr23, operational amplifiers AMP1 and AMP2, and switches SW1 and SW2. Among the components of the current detection circuit 52, the current monitor 121 is composed of all components except for the sensing transistors Tr11 and Tr21. Switches SW1 and SW2 form a selection circuit.

[0086] Here, we will describe the case where transistors Tr12, Tr22, and Tr23 are P-channel MOS transistors. As mentioned above, transistors Tr11 and Tr21 are N-channel MOS transistors with high voltage tolerance, similar to driving transistors MN1 and MN2.

[0087] Sensing transistor Tr11 is supplied between the voltage supply terminal Vbat and node N11, and is turned on / off based on pulse signal S1. Operational amplifier AMP1 amplifies the potential difference between the source voltage of driving transistor MN1 (voltage at external output terminal OUT) and the source voltage of sensing transistor Tr11 (voltage at node N11). Transistor Tr12 is supplied between node N11 and switch SW1, and controls the current flowing between the source and drain based on the output voltage of operational amplifier AMP1. As a result, the source voltage of driving transistor MN1 and the source voltage of sensing transistor Tr11 (voltage at node N11) are maintained at substantially the same value. Battery voltage Vbat is supplied to the drains of driving transistor MN1 and sensing transistor Tr11, respectively. As a result, the ratio of the current flowing through driving transistor MN1 to the current flowing through sensing transistor Tr11 (and transistor Tr12) remains constant (e.g., 1000:1).

[0088] Sensing transistor Tr21 is provided between the external output terminal OUT and node N12, and is turned on and off based on the pulse signal S2. Operational amplifier AMP2 amplifies the potential difference between the source voltage of driving transistor MN2 (reference voltage GND) and the source voltage of sensing transistor Tr21 (voltage at node N12). Transistor Tr22 is provided between the power supply voltage terminal and node N12, and the current flowing between its source and drain is controlled based on the output voltage of operational amplifier AMP2, to which the power supply voltage VDD is supplied (hereinafter referred to as power supply voltage terminal VDD). As a result, the source voltage of driving transistor MN2 and the source voltage of sensing transistor Tr21 (voltage at node N12) are maintained at substantially the same value. Here, the voltage of the external output terminal OUT is provided to the corresponding drain of driving transistor MN2 and sensing transistor Tr21. As a result, the ratio of the current flowing through driving transistor MN2 to the current flowing through sensing transistor Tr21 (and transistor Tr22) remains constant (e.g., 1000:1).

[0089] Transistor Tr23 is provided between the power supply voltage terminal VDD and switch SW2, and together with transistor Tr22, controls the current flowing between the source and drain based on the output voltage of operational amplifier AMP2. In this embodiment, the same current flowing through transistor Tr22 flows through transistor Tr23. That is, transistor Tr23 mirrors the current flowing through transistor Tr22 and outputs a mirrored current.

[0090] Switches SW1 and SW2 constitute a selection circuit and selectively output the current flowing in sensing transistor Tr11 and the current flowing in sensing transistor Tr21 (more specifically, the current obtained by mirroring the current flowing in sensing transistor Tr21) as the detection current Iin of current detection circuit 52. Switches SW1 and SW2 are complementaryly turned on and off according to the on and off states of driving transistors MN1 and MN2.

[0091] Figure 9 This diagram illustrates the current flow in the current detection circuit 52 when the driving transistor MN1 is turned on. The driving transistor MN1 is a high-side driver. Figure 9 As shown, when driving transistor MN1 is turned on and driving transistor MN2 is turned off, switch SW1 is turned on and switch SW2 is turned off. As a result, the current flowing through transistors Tr11 and Tr12 is proportional to the current flowing through driving transistor MN1, and the current flowing through transistors Tr11 and Tr12 is output through switch SW1 as the detection current Iin of current detection circuit 52.

[0092] Figure 10This diagram illustrates the current flow in the current detection circuit 52 when the driving transistor MN2 is turned on. The driving transistor MN2 is a low-side driver. Figure 10 As shown, when driving transistor MN1 is turned off and driving transistor MN2 is turned on, switch SW1 is turned off and switch SW2 is turned on. As a result, the current flowing in transistors Tr21 and Tr22 is proportional to the current flowing in driving transistor MN2. The current flowing in transistors Tr21 and Tr22 is mirrored through transistor Tr23 and output via switch SW2 as the detection current Iin of the current detection circuit 52.

[0093] However, in the configuration of the current detection circuit 52, because the source-drain voltage of the off-state driving transistor MN2 is different from the source-drain voltage of the off-state sensing transistor Tr21, the degree of degradation caused by leakage current differs between each of the driving transistor MN2 and the sensing transistor Tr21. As a result, in the configuration of the current detection circuit 52, the ratio of the current flowing through the on-state driving transistor MN2 to the sensing transistor Tr21 varies from a constant value (e.g., 1000:1), and therefore the current flowing through the driving transistor MN2 cannot be accurately detected. Similarly, in the configuration of the current detection circuit 52, because the ratio of the current flowing through the on-state driving transistor MN1 to the sensing transistor Tr11 varies from a constant value (e.g., 1000:1), the current flowing through the driving transistor MN1 cannot be accurately detected. A detailed description of this problem will be given below.

[0094] Figure 11 This is a schematic cross-sectional view of a transistor, used to explain transistor degradation caused by leakage current. Figure 11 A schematic cross-sectional view of an N-channel MOS transistor is shown.

[0095] like Figure 11 As shown, four main leakage currents are generated in the N-channel MOS transistor in the off state. First, the first leakage current I1 is generated from an N-type diffusion region forming the source electrode to the P-well. The second leakage current I2 is generated from the P-well to the N-region, which is formed on another N-type diffusion region forming the drain electrode. The third leakage current I3 is generated from the gate electrode through the gate oxide film to the N-region. The fourth leakage current I4 is generated from the N-region to another N-type diffusion region forming the drain electrode.

[0096] Here, the fourth leakage current I4 is accelerated by the strong electric field between the drain and source, thereby generating hot carriers. These hot carriers are trapped at the interface between the N-region and the gate oxide. As a result, the on-resistance of the N-channel MOS transistor increases. That is, the characteristics of the N-channel MOS transistor deteriorate. For example, this property degradation is also known as off-state degradation.

[0097] Figure 12 This is a diagram illustrating an exemplary configuration of the drive transistor and the sensing transistor in which gain degradation does not occur even when a shutdown state degradation occurs. Figure 13 This is a diagram illustrating an exemplary configuration of the drive transistor and the sensing transistor in which gain degradation occurs when a shutdown state degradation occurs. Figure 14 It is shown Figure 12 A graph showing the relationship between input current and current detection error in the exemplary configuration shown. Figure 15 It is shown in Figure 13 The graph shows the relationship between input current and current detection error in the exemplary configuration shown.

[0098] First of all, Figure 12 In this configuration, the source-drain voltages of each of the drive transistor and the sensing transistor in the off state have the same value. As a result, when off-state degradation occurs, the degree of degradation of each of the drive transistor and the sensing transistor becomes the same, such that the ratio of the current flowing through each of the drive transistor and the sensing transistor in the on state is maintained at a constant value (e.g., 1000:1) (see...). Figure 14 As a result, in Figure 12 In this configuration, the current flowing through the driving transistor can be detected with high accuracy.

[0099] On the other hand, Figure 13 In this configuration, the source-drain voltages of each phase in the off-state driving transistor and sensing transistor are different. As a result, when off-state degradation occurs, the degree of degradation of the driving transistor and sensing transistor differs from each other, causing the ratio of current flowing through each phase in the on-state driving transistor and sensing transistor to change from a constant value (e.g., ...). Figure 15 As shown). The result, in Figure 13 In this configuration, the current flowing through the driving transistor cannot be accurately detected.

[0100] Here, in the current detection circuit 52 configuration, when the driving transistor MN2 is turned off, the sensing transistor Tr21 is also turned off, and the current flowing through transistor Tr22 decreases to near 0A. This reduces the gain of the loop formed by transistor Tr22 and operational amplifier AMP2, and the feedback through the loop becomes ineffective. As a result, transistor Tr22 is not completely turned off, causing the source voltage of the sensing transistor Tr21 in the off-state to be higher than 0V. That is, the source-drain voltage of the driving transistor MN2 in the off-state is different from the source-drain voltage of the sensing transistor Tr21 in the off-state.

[0101] In the configuration of the current detection circuit 52, when the driving transistor MN1 is turned off, the feedback loop formed by transistor Tr12 and the feedback loop formed by operational amplifier AMP1 do not operate until the source voltage of sensing transistor Tr11 drops to near 0V. Therefore, the source voltage of sensing transistor Tr11 in the off state is higher than 0V. That is, the source-drain voltage of driving transistor MN1 in the off state is different from the source-drain voltage of sensing transistor Tr11 in the off state.

[0102] Therefore, in the configuration of the current detection circuit 52, the current flowing through the driving transistors MN1 and MN2 cannot be accurately detected using the sensing transistors Tr11 and Tr21.

[0103] Therefore, the inventors of this invention have discovered a current detection circuit, semiconductor device, and semiconductor system that can accurately detect the current flowing through the drive transistors MN1 and MN2 even when a shutdown state degradation occurs.

[0104] <<Exemplary Configuration of Current Detection Circuit 12 According to the First Embodiment>> Figure 4 This is a diagram illustrating an exemplary configuration of the current detection circuit 12 according to the first embodiment. Figure 4 The solenoid driver 11, serving as the drive circuit, and the solenoid valve 7, serving as the load circuit, are also shown. Figure 4 In this process, the high-side drive of the solenoid valve 7 is performed by the solenoid actuator 11.

[0105] like Figure 4 As shown, compared to current detection circuit 52, current detection circuit 12 further includes switches SW3 and SW4. Switch SW3 is provided between the source of driving transistor MN1 (external output terminal OUT) and the source of sensing transistor Tr11 (node ​​N11). Switch SW4 is provided between the source of driving transistor MN2 (reference voltage terminal GND) and the source of sensing transistor Tr21 (node ​​N12). Switches SW3 and SW4 are complementaryly turned on and off according to the switching of the on and off states of driving transistors MN1 and MN2.

[0106] Since the remaining part of the configuration of current detection circuit 12 is the same as that of current detection circuit 52, its explanation is omitted.

[0107] <<Sequence Diagram>> Figure 5 This is a timing diagram showing the operation of the current detection circuit 12. Figure 5First, since pulse signal S1 indicates level L and pulse signal S2 indicates level H, driving transistor MN1 is turned off and driving transistor MN2 is turned on. As a result, the regenerative current of solenoid valve 7 flows through the current path of driving transistor MN2 in the on state (times t10 to t11).

[0108] At this time, in order to detect the current flowing through the on-state drive transistor MN2, switch SW4 is controlled to be off. On the other hand, in order to short-circuit the source of each of the off-state drive transistor MN1 and sensing transistor Tr11, switch SW3 is controlled to be on. Switch SW1 is controlled to be off, while switch SW2 is controlled to be on.

[0109] Subsequently, when pulse signal S2 switches from H level to L level, drive transistor MN2 switches from the ON state to the OFF state in response to pulse signal S2 (time t11). At this time, in order to short-circuit the source of each term in drive transistor MN2 (which is in the OFF state) and sensing transistor Tr21, switch SW4 switches from OFF to ON (time t11). Switch SW2 switches from ON to OFF (time t11).

[0110] Subsequently, when the pulse signal S1 switches from L level to H level, the gate-source voltage Vgs of the driving transistor MN1 begins to rise (time t12). When the gate-source voltage Vgs of the driving transistor MN1 reaches the threshold voltage, current flows through the driving transistor MN1, causing the voltage Vo at the external output terminal OUT to begin to rise. Since the current flowing through the driving transistor MN1 is constant while the voltage Vo is rising, the gate-source voltage Vgs of the driving transistor MN1 remains essentially constant. The gate-source voltage Vgs during this period is called the plateau voltage. Here, until the voltage Vo reaches the battery voltage Vbat, the sources of each of the partially turned-on driving transistor MN1 and sensing transistor Tr11 need to be short-circuited, so switch SW3 remains on.

[0111] Subsequently, when the voltage Vo reaches the battery voltage Vbat and the gate-source voltage Vgs of the driving transistor MN1 becomes higher than the plateau voltage, switch SW3 switches from on to off (time t13). As a result, the short circuit at the source of each of the driving transistor MN1 and the sensing transistor Tr11, which were in the on state, is released. Switch SW1 switches from off to on (time t13).

[0112] Subsequently, when pulse signal S1 switches from H level to L level, the gate-source voltage Vgs of driving transistor MN1 begins to decrease (time t14). Therefore, voltage Vo begins to decrease. At this time, in order to short-circuit the source of each term in driving transistor MN1 (which is in the off state) and sensing transistor Tr11, switch SW3 switches from off to on (time t14). Switch SW1 switches from on to off (time t14).

[0113] Subsequently, when pulse signal S2 switches from L level to H level, in response to pulse signal S2, drive transistor MN2 switches from the off state to the on state (time t15). At this time, switch SW4 switches from on to off (time t15). As a result, the short circuit at the source of each term in drive transistor MN2 and sensing transistor Tr21, which were in the on state, is released. Switch SW2 switches from off to on (time t15).

[0114] Next, refer to Figure 6 and Figure 7 The following will describe in more detail the current flow of the current detection circuit 12 and the switching states of switches SW3 and SW4 in the corresponding operating modes.

[0115] Figure 6 This is a diagram used to explain the current flow in the current detection circuit 12 when the driving transistor MN1 is turned on. The driving transistor MN1 is a high-side driver.

[0116] like Figure 6 As shown, when driving transistor MN1 is turned on and driving transistor MN2 is turned off, switch SW1 is turned on and switch SW2 is turned off. As a result, the current flowing through transistors Tr11 and Tr12 is proportional to the current flowing through driving transistor MN1, and the current flowing through transistors Tr11 and Tr12 is output through switch SW1 as the detection current Iin of current detection circuit 12.

[0117] At this time, switch SW3 is turned off and switch SW4 is turned on. As a result, the source of each of the driving transistor MN2 and sensing transistor Tr21 in the off state is short-circuited. Here, the voltage of the external output terminal OUT is supplied to the drain of each of the driving transistor MN2 and sensing transistor Tr21. Therefore, the source-drain voltage of each of the driving transistor MN2 and sensing transistor Tr21 in the off state presents the same value. As a result, when the off state degrades, the degree of degradation of each of the driving transistor MN2 and sensing transistor Tr21 becomes the same, so that the ratio of the current flowing through each of the driving transistor MN2 and sensing transistor Tr21 in the on state is maintained at a constant value (e.g., 1000:1). Therefore, the current detection circuit 12 can accurately detect the current flowing through the driving transistor MN2 by using the sensing transistor Tr21.

[0118] Figure 7 This is a diagram used to explain the current flow in the current detection circuit 12 when the driving transistor MN2 is turned on. The driving transistor MN2 is a low-side driver.

[0119] like Figure 7 As shown, when driving transistor MN1 is turned off and driving transistor MN2 is turned on, switch SW1 is turned off and switch SW2 is turned on. As a result, the current flowing in transistors Tr21 and Tr22 is proportional to the current flowing in driving transistor MN2. The current flowing in transistors Tr21 and Tr22 is mirrored through transistor Tr23 and output via switch SW2 as the detection current Iin of current detection circuit 12.

[0120] At this time, switch SW3 is turned on and switch SW4 is turned off. As a result, the source of each of the driving transistor MN1 and sensing transistor Tr11 in the off state is short-circuited. The battery voltage Vbat is supplied to the drain of the driving transistor MN1 and sensing transistor Tr11, respectively. Therefore, the source-drain voltage of each of the driving transistor MN1 and sensing transistor Tr11 in the off state exhibits the same value. As a result, when off-state degradation occurs, the degree of degradation of each of the driving transistor MN1 and sensing transistor Tr11 becomes the same, such that the ratio of the current flowing through each of the driving transistor MN1 and sensing transistor Tr11 in the on state is maintained at a constant value (e.g., 1000:1). Therefore, the current detection circuit 12 can accurately detect the current flowing through the driving transistor MN1 using the sensing transistor Tr11.

[0121] For example, when the solenoid driver 11 stops operating, both drive transistors MN1 and MN2 are turned off, causing switches SW3 and SW4 to turn on. In this case, even when the off-state degrades, the drive transistor MN1 and the sensing transistor Tr11 degrade to the same degree, and the drive transistor MN2 and the sensing transistor Tr21 degrade to the same degree. Therefore, the current detection circuit 12 can suppress the degradation of the detection accuracy of the current flowing through the drive transistors MN1 and MN2.

[0122] As described above, the current detection circuit 12 according to this embodiment includes switches SW3 and SW4. Switch SW3 is used to short-circuit the source of each of the driving transistor MN1 and sensing transistor Tr11 in the off state, and switch SW4 is used to short-circuit the source of each of the driving transistor MN2 and sensing transistor Tr21. As a result, when off-state degradation occurs, the degradation degree of driving transistor MN1 and sensing transistor Tr11 becomes the same, so that the ratio of the current flowing through driving transistor MN1 and sensing transistor Tr11 in the on state is maintained at a constant value. Similarly, when off-state degradation occurs, the degradation degree of each of driving transistor MN2 and sensing transistor Tr21 becomes the same, so that the ratio of the current flowing through driving transistor MN2 and sensing transistor Tr21 in the on state is maintained at a constant value. Therefore, the current detection circuit 12 applied in this embodiment can accurately detect the current flowing in driving transistors MN1 and MN2 by using sensing transistors Tr11 and Tr21.

[0123] In this embodiment, the current detection circuit 12 detects the current flowing through the driving transistors MN1 and MN2, but the invention is not limited thereto. The current detection circuit 12 can be suitably modified to detect the current flowing in only one of the driving transistors MN1 and MN2.

[0124] <Second Embodiment> Figure 16 This is a diagram illustrating an exemplary configuration of the current detection circuit 22 according to the second embodiment. Figure 16 The solenoid driver 11, serving as the drive circuit, and the solenoid valve 7, serving as the load circuit, are also shown. Figure 16 In the middle, the solenoid actuator 11 performs the low-side drive of the solenoid valve 7.

[0125] like Figure 16As shown, similar to current detection circuit 12, current detection circuit 22 includes sensing transistors Tr11 and Tr21, transistors (voltage-controlled transistors) Tr12 and Tr22, transistor (mirror transistor) Tr23, operational amplifiers AMP1 and AMP2, and switches SW1 to SW4. However, current detection circuit 22 and current detection circuit 12 differ in their circuit connections. A detailed description follows.

[0126] Sensing transistor Tr11 is provided between the external output terminal OUT and node N11, and is turned on / off based on pulse signal S1. Operational amplifier AMP1 amplifies the potential difference between the drain voltage of driving transistor MN1 (battery voltage Vbat) and the drain voltage of sensing transistor Tr11 (voltage of node N11). Transistor Tr12 is provided between node N11 and switch SW1, and controls the current flowing between the source and drain based on the output voltage of operational amplifier AMP1. As a result, the drain voltage of driving transistor MN1 and the drain voltage of sensing transistor Tr11 (voltage of node N11) are maintained at substantially the same value. Here, the voltage of external output terminal OUT is supplied to the source of each of driving transistor MN1 and sensing transistor Tr11. Therefore, the ratio of the current flowing through driving transistor MN1 to the current flowing through sensing transistor Tr11 (and transistor Tr12) remains constant (e.g., 1000:1).

[0127] Sensing transistor Tr21 is supplied between the reference voltage terminal GND and node N12, and is turned on and off based on the pulse signal S2. Operational amplifier AMP2 amplifies the potential difference between the drain voltage of driving transistor MN2 (voltage at external output terminal OUT) and the drain voltage of sensing transistor Tr21 (voltage at node N12). Transistor Tr22 is supplied between the power supply voltage terminal VDD and node N12, and the current flowing between the source and drain is controlled based on the output voltage of operational amplifier AMP2. As a result, the drain voltage of driving transistor MN2 and the drain voltage of sensing transistor Tr21 are maintained at substantially the same value. The reference voltage GND is supplied to the source voltages of driving transistor MN2 and sensing transistor Tr21. Therefore, the ratio of the current flowing through driving transistor MN2 to the current flowing through sensing transistor Tr21 (and transistor Tr22) remains constant (e.g., 1000:1).

[0128] Transistor Tr23 is provided between the power supply voltage terminal VDD and switch SW2, and together with transistor Tr22, controls the current flowing between the source and drain based on the output voltage of operational amplifier AMP2. In this embodiment, the same current flowing through transistor Tr22 flows through transistor Tr23. That is, transistor Tr23 mirrors the current flowing through transistor Tr22 and outputs the mirrored current.

[0129] Switches SW1 and SW2 constitute a selection circuit and selectively output the current flowing in sensing transistor Tr11 and the current flowing in sensing transistor Tr21 (more specifically, the current obtained by mirroring the current flowing in sensing transistor Tr21) as the detection current Iin of current detection circuit 22. Switches SW1 and SW2 are complementaryly turned on and off according to the on and off states of driving transistors MN1 and MN2.

[0130] Switch SW3 is provided between the drain of driving transistor MN1 (voltage supply terminal Vbat) and the drain of sensing transistor Tr11 (node ​​N11). Switch SW4 is provided between the drain of driving transistor MN2 (external output terminal OUT) and the drain of sensing transistor Tr21 (node ​​N12). Switches SW3 and SW4 are complementaryly turned on and off according to the switching of the on and off states of driving transistors MN1 and MN2, respectively.

[0131] <<Sequence Diagram>> Figure 17 This is a timing diagram showing the operation of the current detection circuit 22. Figure 17 In this case, firstly, since pulse signal S1 indicates H level and pulse signal S2 indicates L level, drive transistor MN1 is turned on and drive transistor MN2 is turned off. As a result, the regenerative current of solenoid valve 7 flows through the current path of drive transistor MN1 in the on state (times t20 to t21).

[0132] At this time, in order to detect the current flowing through the on-state drive transistor MN1, switch SW3 is controlled to be off. On the other hand, in order to short-circuit the drain of each of the off-state drive transistor MN2 and sensing transistor Tr21, switch SW4 is controlled to be on. Switch SW1 is controlled to be on, and switch SW2 is controlled to be off.

[0133] Subsequently, when pulse signal S1 switches from H level to L level, in response to pulse signal S1, drive transistor MN1 switches from the ON state to the OFF state (time t21). At this time, in order to short-circuit the drain of each of the phases of drive transistor MN1 and sensing transistor Tr11 which are in the OFF state, switch SW3 switches from OFF to ON (time t21). Switch SW1 switches from ON to OFF (time t21).

[0134] Subsequently, when pulse signal S2 switches from L level to H level, the gate-source voltage Vgs of driving transistor MN2 begins to rise (time t22). When the gate-source voltage Vgs of driving transistor MN2 reaches the threshold voltage, current flows through driving transistor MN2, causing the voltage Vo at the external output terminal OUT to begin to decrease. Since the current flowing through driving transistor MN2 remains constant while voltage Vo decreases, the gate-source voltage Vgs of driving transistor MN2 remains essentially constant. The gate-source voltage Vgs during this period is called the plateau voltage. Here, until voltage Vo reaches the reference voltage GND, the drains of each of the not fully turned-on driving transistor MN2 and sensing transistor Tr21 need to be short-circuited, so switch SW4 remains on.

[0135] Subsequently, when the voltage Vo reaches the reference voltage GND and the gate-source voltage Vgs of the driving transistor MN2 becomes higher than the plateau voltage, switch SW4 switches from on to off (time t23). As a result, the short circuit at the drain of each of the driving transistor MN2 and the sensing transistor Tr21, which were in the on state, is released. Switch SW2 switches from off to on (time t23).

[0136] Subsequently, when pulse signal S2 switches from H level to L level, the gate-source voltage Vgs of driving transistor MN2 begins to decrease (time t24). As a result, voltage Vo begins to rise. At this time, in order to short-circuit the drain of each of the phases of the off driving transistor MN2 and sensing transistor Tr21, switch SW4 switches from off to on (time t24). Switch SW2 switches from on to off (time t24).

[0137] Subsequently, when the pulse signal S1 switches from L level to H level, the driving transistor MN1 switches from off to on (time t25). At this time, the switch SW3 switches from on to off (time t25). As a result, the short circuit at the drain of each of the phases of the driving transistor MN1 and the sensing transistor Tr11, which were in the on state, is released. The switch SW1 switches from off to on (time t25).

[0138] Next, we will refer to Figure 18 and Figure 19The current flow of the current detection circuit 22 and the switching states of switches SW3 and SW4 in the corresponding operating modes are described in more detail.

[0139] Figure 18 This is a diagram used to explain the current flow in the current detection circuit 22 when the driving transistor MN1 is turned on. The driving transistor MN1 is a high-side driver.

[0140] like Figure 18 As shown, when driving transistor MN1 is turned on and driving transistor MN2 is turned off, switch SW1 is turned on and switch SW2 is turned off. As a result, the current flowing through transistors Tr11 and Tr12 is proportional to the current flowing through driving transistor MN1, and the current flowing through transistors Tr11 and Tr12 is output through switch SW1 as the detection current Iin of current detection circuit 22.

[0141] At this time, switch SW3 is turned off and switch SW4 is turned on. As a result, the drain of each of the driving transistor MN2 and sensing transistor Tr21 in the off state is short-circuited. Here, the reference voltage GND is supplied to the source of each of the driving transistor MN2 and sensing transistor Tr21. Therefore, the source-drain voltage of each of the driving transistor MN2 and sensing transistor Tr21 in the off state presents the same value. As a result, when off-state degradation occurs, the degree of degradation of each of the driving transistor MN2 and sensing transistor Tr21 becomes the same, so that the ratio of the current flowing through each of the driving transistor MN2 and sensing transistor Tr21 in the on state is maintained at a constant value (e.g., 1000:1). Therefore, the current detection circuit 22 can accurately detect the current flowing through the driving transistor MN2 by using the sensing transistor Tr21.

[0142] Figure 19 This is a diagram used to explain the current flow in the current detection circuit 22 when the driving transistor MN2 is turned on. The driving transistor MN2 is a low-side driver.

[0143] like Figure 19 As shown, when driving transistor MN1 is turned off and driving transistor MN2 is turned on, switch SW1 is turned off and switch SW2 is turned on. As a result, the current flowing in transistors Tr21 and Tr22 is proportional to the current flowing in driving transistor MN2. The current flowing in transistors Tr21 and Tr22 is mirrored through transistor Tr23 and output via switch SW2 as the detection current Iin of current detection circuit 22.

[0144] At this time, switch SW3 is turned on and switch SW4 is turned off. As a result, the drain of each of the driving transistor MN1 and sensing transistor Tr11 in the off state is short-circuited. Here, the voltage of the external output terminal OUT is supplied to the source of each of the driving transistor MN1 and sensing transistor Tr11. Therefore, the source-drain voltage of each of the driving transistor MN1 and sensing transistor Tr11 in the off state presents the same value. As a result, when off-state degradation occurs, the degree of degradation of each of the driving transistor MN1 and sensing transistor Tr11 becomes the same, so that the ratio of the current flowing through each of the driving transistor MN1 and sensing transistor Tr11 in the on state remains constant (e.g., 1000:1). Therefore, the current detection circuit 22 can accurately detect the current flowing through the driving transistor MN1 using the sensing transistor Tr11.

[0145] For example, when the solenoid driver 11 stops operating, both drive transistors MN1 and MN2 are turned off, causing switches SW3 and SW4 to turn on. In this case, when turn-off degradation occurs, drive transistor MN1 and sensing transistor Tr11 degrade to the same degree, and drive transistor MN2 and sensing transistor Tr21 degrade to the same degree. Therefore, the current detection circuit 22 can suppress the degradation of the accuracy of the detection of the current flowing through drive transistors MN1 and MN2.

[0146] As described above, the current detection circuit 22 according to this embodiment includes switches SW3 and SW4. Switch SW3 is used to short-circuit the drain of each of the driving transistor MN1 (off state) and the sensing transistor Tr11, and switch SW4 is used to short-circuit the drain of each of the driving transistor MN2 (off state) and the sensing transistor Tr21. As a result, similar to the current detection circuit 12, the current detection circuit 22 in this embodiment can accurately detect the current flowing through the driving transistors MN1 and MN2 by using the sensing transistors Tr11 and Tr21.

[0147] In this embodiment, the current detection circuit 22 detects the current flowing through the driving transistors MN1 and MN2, but the invention is not limited thereto. The current detection circuit 22 can be suitably modified to a configuration for detecting the current flowing in only one of the driving transistors MN1 and MN2.

[0148] <<Refer to Current Detection Circuit 62 in Comparative Example>> Figure 20 and Figure 21 The following describes a current detection circuit 62 as a comparative example of current detection circuit 22. Compared to current detection circuit 22, current detection circuit 62 does not include switches SW3 and SW4.

[0149] Figure 20 This diagram illustrates the current flow in the current detection circuit 62 when the driving transistor MN1 is turned on. The driving transistor MN1 is a high-side driver. Figure 20 As shown, when driving transistor MN1 is turned on and driving transistor MN2 is turned off, switch SW1 is turned on and switch SW2 is turned off. As a result, the current flowing through transistors Tr11 and Tr12 is proportional to the current flowing through driving transistor MN1, and the current flowing through transistors Tr11 and Tr12 is output through switch SW1 as the detection current Iin of the current detection circuit 52.

[0150] However, in the current sensing circuit 62 configuration at this time, when the driving transistor MN2 is turned off, the sensing transistor Tr21 is also turned off, and the current flowing through the transistor Tr22 decreases to around 0A. This reduces the gain of the loop formed by the transistor Tr22 and the operational amplifier AMP2, and the loop feedback becomes ineffective. As a result, the transistor Tr22 is not completely turned off, causing the drain voltage of the sensing transistor Tr21 in the off state to increase to near the power supply voltage VDD. Here, when the power supply voltage VDD is equal to the battery voltage Vbat, since it takes time for the drain voltage of the sensing transistor Tr21 to reach near the battery voltage Vbat, the source-drain voltage of the driving transistor MN2 in the off state and the source-drain voltage of the sensing transistor Tr21 in the off state exhibit different values ​​during this period.

[0151] As a result, when the off-state deteriorates, the degree of degradation of each term in the driving transistor MN2 and the sensing transistor Tr21 is different, causing the ratio of the current flowing through each term in the on-state driving transistor MN2 and the sensing transistor Tr21 to change from a constant value.

[0152] Figure 21 This diagram illustrates the current flow in the current detection circuit 62 when the driving transistor MN2 is turned on. The driving transistor MN2 is a low-side driver. Figure 21 As shown, when driving transistor MN1 is turned off and driving transistor MN2 is turned on, switch SW1 is turned off and switch SW2 is turned on. As a result, the current flowing in transistors Tr21 and Tr22 is proportional to the current flowing in driving transistor MN2. The current flowing in transistors Tr21 and Tr22 is mirrored through transistor Tr23 and output via switch SW2 as the detection current Iin of the current detection circuit 52.

[0153] However, in the current sensing circuit 62 configuration at this time, when the driving transistor MN1 is turned off, the sensing transistor Tr11 is also turned off, and the current flowing through the transistor Tr12 decreases to near 0A. This reduces the gain of the loop formed by the transistor Tr12 and the operational amplifier AMP1, and the feedback through this loop becomes ineffective. As a result, the transistor Tr12 is not completely turned off, causing the drain voltage of the sensing transistor Tr11 in the off state to become less than the battery voltage Vbat. That is, the source-drain voltage of the driving transistor MN1 in the off state and the source-drain voltage of the sensing transistor Tr11 in the off state are different from each other.

[0154] As a result, when the off-state deteriorates, the degree of degradation of each term in the driving transistor MN1 and the sensing transistor Tr11 is different, causing the ratio of the current flowing through each term in the on-state driving transistor MN1 and the sensing transistor Tr11 to change from a constant value.

[0155] Therefore, the current detection circuit 62 cannot accurately detect the current flowing through the driving transistors MN1 and MN2 using sensing transistors Tr11 and Tr21. On the other hand, the current detection circuit 22 according to this embodiment can solve the problem that occurs in the current detection circuit 62 by providing switches SW3 and SW4.

[0156] <Third Embodiment> Figure 22 This is a diagram illustrating the specific configuration of the current detection circuit 12a according to the third embodiment. Figure 22 The solenoid driver 11, serving as the drive circuit, and the solenoid valve 7, serving as the load circuit, are also shown. Figure 22 In this process, the high-side drive of the solenoid valve 7 via the solenoid actuator 11 is executed.

[0157] Compared to the current detection circuit 12, the current detection circuit 12a also includes a switching circuit SW5. The switching circuit SW5 is configured to disconnect the external output terminal OUT and the source of the sensing transistor Tr11 from the two input terminals of the operational amplifier AMP1 when the driving transistor MN1 is turned off.

[0158] Specifically, the switching circuit SW5 includes switches SW51 to SW56. Switch SW51 is provided between the inverting terminal of operational amplifier AMP1 and the source of sensing transistor Tr11. Switch SW52 is provided between the non-inverting terminal of operational amplifier AMP1 and the source (external output terminal OUT) of driving transistor MN1. Switch SW53 is provided between the inverting terminal of operational amplifier AMP1 and the source of transistor Tr12. Switch SW54 is provided between the source of transistor Tr12 and the source of sensing transistor Tr11. Switch SW55 is provided between the source of transistor Tr12 and the voltage supply terminal Vbat. Switch SW56 is provided between the non-inverting terminal of operational amplifier AMP1 and the voltage supply terminal Vbat.

[0159] Figure 23 This is a diagram used to explain the current flow in the current detection circuit 12a when the driving transistor MN1 is turned on. The driving transistor MN1 is a high-side driver.

[0160] like Figure 23 As shown, when driving transistor MN1 is turned on and driving transistor MN2 is turned off, switch SW1 is turned on and switch SW2 is turned off. At this time, switches SW51, SW52, and SW54 are turned on, and switches SW53, SW55, and SW56 are turned off. Therefore, the source of driving transistor MN1 (external output terminal OUT) is connected to the non-inverting terminal of operational amplifier AMP1, and the source of sensing transistor Tr11 is connected to the inverting terminal of operational amplifier AMP1. As a result, in current detection circuit 12a, as in current detection circuit 12, the current flowing in transistors Tr11 and Tr12 is proportional to the current flowing in driving transistor MN1, and the current flowing in transistors Tr11 and Tr12 is output as the detection current Iin via switch SW1.

[0161] The on / off states of switches SW3 and SW4, as well as the operation of current detection circuit 12a, are thus identical to those in current detection circuit 12, and therefore their description is omitted.

[0162] Figure 24 This is a diagram used to explain the current flow in the current detection circuit 12a when the drive transistor MN2, which acts as the low-side driver, is turned on.

[0163] like Figure 24As shown, when driving transistor MN1 is turned off and driving transistor MN2 is turned on, switch SW1 is turned off and switch SW2 is turned on. Therefore, in current detection circuit 12a, similar to current detection circuit 12, the current flowing in transistors Tr21 and Tr22 is proportional to the current flowing in driving transistor MN2. The current flowing in transistors Tr21 and Tr22 is mirrored through transistor Tr23 and output as the detection current Iin via switch SW2.

[0164] The on / off states of switches SW3 and SW4, and the operation of current detection circuit 12a, are thus identical to those in current detection circuit 12, and therefore their description is omitted.

[0165] At this time, switches SW51, SW52, and SW54 are off, and switches SW53, SW55, and SW56 are on. Therefore, the voltage supply terminal Vbat is connected to both the non-inverting and inverting terminals of operational amplifier AMP1. This disconnects operational amplifier AMP1 from the external output terminal OUT, whose voltage varies over a wide range from the reference voltage GND to the battery voltage Vbat, allowing AMP1 to be configured with circuitry operating in a low voltage range around the battery voltage Vbat. This suppresses an increase in circuit size.

[0166] As described above, the current detection circuit 12a applied in this embodiment can exhibit the same effect as the current detection circuit 12. Furthermore, the current detection circuit 12a according to this embodiment is configured to disconnect the source of the driving transistor MN1 (external output terminal OUT) and the source of the sensing transistor Tr11 from the two input terminals of the operational amplifier AMP1 when the driving transistor MN1 is turned off. This disconnects the operational amplifier AMP1 from the external output terminal OUT, allowing AMP1 to be configured to operate in a low voltage range around the battery voltage Vbat, wherein the voltage of the external output terminal OUT varies over a wide range from the reference voltage GND to the battery voltage Vbat. This suppresses an increase in circuit size.

[0167] <Fourth Embodiment> Figure 25 This is a diagram showing the specific configuration of the current detection circuit 22a according to the fourth embodiment. Figure 25 The solenoid driver 11, serving as the drive circuit, and the solenoid valve 7, serving as the load circuit, are also shown. Figure 25 In the middle, the solenoid actuator 11 performs the low-side drive of the solenoid valve 7.

[0168] Compared to the current detection circuit 22, the current detection circuit 22a also includes a switching circuit SW6. The switching circuit SW6 is configured to disconnect the external output terminal OUT and the drain of the sensing transistor Tr21 from the two input terminals of the operational amplifier AMP2 when the driving transistor MN2 is turned off.

[0169] Specifically, the switching circuit SW6 includes switches SW61 to SW66. Switch SW61 is provided between the inverting terminal of operational amplifier AMP2 and the drain of sensing transistor Tr21. Switch SW62 is provided between the non-inverting terminal of operational amplifier AMP2 and the drain (external output terminal OUT) of driving transistor MN2. Switch SW63 is provided between the inverting terminal of operational amplifier AMP2 and the drain of transistor Tr22. Switch SW64 is provided between the drain of transistor Tr22 and the drain of sensing transistor Tr21. Switch SW65 is provided between the inverting terminal of operational amplifier AMP2 and the reference voltage terminal GND. Switch SW66 is provided between the non-inverting terminal of operational amplifier AMP2 and the reference voltage terminal GND.

[0170] Figure 26 This is a diagram used to explain the current flow in the current detection circuit 22a when the driving transistor MN1 is turned on. The driving transistor MN1 is a high-side driver.

[0171] like Figure 26 As shown, when driving transistor MN1 is turned on and driving transistor MN2 is turned off, switch SW1 is turned on and switch SW2 is turned off. As a result, in current detection circuit 22a, the current flowing through transistors Tr11 and Tr12 is proportional to the current flowing through driving transistor MN1, and the current flowing through transistors Tr11 and Tr12 is output as the detection current Iin via switch SW1 in the same manner as in current detection circuit 22.

[0172] The on / off states of switches SW3 and SW4, as well as the operation of current detection circuit 22a, are therefore the same as those in current detection circuit 22, and their description is omitted.

[0173] At this time, switches SW61, SW62, and SW64 are off, and switches SW63, SW65, and SW66 are on. Therefore, the reference voltage terminal GND is connected to both the non-inverting and inverting terminals of operational amplifier AMP2. As a result, operational amplifier AMP2 is disconnected from the external output terminal OUT, and thus AMP2 can be configured to operate within a low voltage range, where the voltage at the external output terminal OUT varies over a wide range from the reference voltage GND to the battery voltage Vbat. This suppresses an increase in circuit size.

[0174] Figure 27 This is a diagram used to explain the current flow in the current detection circuit 22a when the driving transistor MN2 is turned on. The driving transistor MN2 is a low-side driver.

[0175] like Figure 27 As shown, when driving transistor MN1 is turned off and driving transistor MN2 is turned on, switch SW1 is turned off and switch SW2 is turned on. At this time, switches SW61, SW62, and SW64 are turned on, and switches SW63, SW65, and SW66 are turned off. Therefore, the drain of driving transistor MN2 (external output terminal OUT) is connected to the non-inverting terminal of operational amplifier AMP2, and the drain of sensing transistor Tr21 is connected to the inverting terminal of operational amplifier AMP2. As a result, in current detection circuit 22a, as in current detection circuit 22, the current flowing in transistors Tr21 and Tr22 is proportional to the current flowing in driving transistor MN2. The current flowing in transistors Tr21 and Tr22 is mirrored through transistor Tr23 and output as the detection current Iin via switch SW2.

[0176] The on / off states of switches SW3 and SW4, and the operation of current detection circuit 22a, are thus identical to those in current detection circuit 12, and therefore their description is omitted.

[0177] As described above, the current detection circuit 22a applied in this embodiment can exhibit the same effect as the current detection circuit 22. Furthermore, the current detection circuit 22a according to this embodiment is configured to disconnect the drain of the driving transistor MN2 (external output terminal OUT) and the drain of the sensing transistor Tr21 from the two input terminals of the operational amplifier AMP2 when the driving transistor MN2 is turned off. As a result, the operational amplifier AMP2 is disconnected from the external output terminal OUT, and therefore the operational amplifier AMP2 can be configured by a circuit operating in a low voltage range, wherein the voltage of the external output terminal OUT varies over a wide range from the reference voltage GND to the battery voltage Vbat. This suppresses an increase in circuit size.

[0178] <Fifth Embodiment> Figure 28 This is a diagram illustrating a specific configuration example of the current detection circuit 32 according to the fifth embodiment. The current detection circuit 32 according to this embodiment can detect the current flowing through the solenoid driver 11 by switching the connection relationship of the components when the solenoid valve 7 is driven by the solenoid driver 11 in either high-side drive or low-side drive. A detailed description will be given below.

[0179] like Figure 28As shown, the current detection circuit 32 includes sensing transistors Tr11 and Tr21, transistors Tr12 and Tr22, operational amplifiers AMP1 and AMP2, transistor Tr23, switches SW1 to SW4, and current detection circuits SW5 and SW6, which are similar to, for example, switch circuits 12a and 22a. The current detection circuit 32 also includes a switch group (hereinafter referred to as switch group SWG) for switching the connections of these components. Hereinafter, switch group SWG includes switches SW1 to SW4, and a plurality of switches constituting switch circuits SW5 and SW6.

[0180] exist Figure 28 In this configuration, sensing transistor Tr11a is provided as sensing transistor Tr11 used during high-side driving, and sensing transistor Tr11b is provided as sensing transistor Tr11 used during low-side driving. Furthermore, in... Figure 28 In one embodiment, transistor Tr12a is provided as transistor Tr12 used during high-side driving, and transistor Tr12b is provided as transistor Tr12 used during low-side driving. Furthermore, in Figure 28 In one embodiment, sensing transistor Tr21a is provided as sensing transistor Tr21 used when driven on the high side, and sensing transistor Tr21b is provided as sensing transistor Tr21 used when driven on the low side.

[0181] Figure 29 This diagram illustrates the connections of the components in the current detection circuit 32 and the current flow when the driving transistor MN1 is turned on in high-side driving mode. The driving transistor MN1 is the high-side driver. Figure 29 In the diagram, the thick dashed arrow indicates the path through which the solenoid current flows, while the thin dashed arrow indicates the path through which the detection current flows.

[0182] At this time, the current detection circuit 32 configures the circuit by turning the switch group SWG on and off. Figure 23 The equivalent circuit of the current detection circuit 12a shown is illustrated. Figure 29 In the above, the sensing transistor Tr11a for high-side driving is used as sensing transistor Tr11, and the transistor Tr12a for high-side driving is used as transistor Tr12.

[0183] At this time, the source of each of the driving transistor MN2 and sensing transistors Tr21a and Tr21b in the off state is short-circuited, and the drain of each is short-circuited by the switch corresponding to switch SW4 in the on / off switch group SWG. As a result, when off-state degradation occurs, the degradation degree of each of the driving transistor MN2 and sensing transistors Tr21a and Tr21b becomes the same, so that the ratio of the current flowing through each of the driving transistor MN2 in the on state and the sensing transistors Tr21a and Tr21b is maintained at a constant value. Therefore, the current detection circuit 32 can use sensing transistors Tr21a and Tr2b to accurately detect the current flowing through the driving transistor MN2.

[0184] Figure 30 This diagram illustrates the connections of the components of the current detection circuit 32 and the current flow when the driving transistor MN2 is turned on in high-side driving mode. The driving transistor MN2 is a low-side driver. Figure 30 In the diagram, the thick dashed arrow indicates the path through which the solenoid current flows, while the thin dashed arrow indicates the path through which the detection current flows.

[0185] At this time, the current detection circuit 32 achieves the following by turning the switch group SWG on and off: Figure 24 The equivalent circuit of the current detection circuit 12a shown is illustrated. Figure 30 In the above, the sensing transistor Tr21a for high-side driving is used as the sensing transistor Tr21.

[0186] At this time, by turning the switch corresponding to switch SW3 in the switch group SWG on and off, the source of each of the driving transistor MN1 and sensing transistors Tr11a and Tr11b in the off state is short-circuited, and each drain is short-circuited. As a result, when off-state degradation occurs, the degradation degree of driving transistor MN1, sensing transistors Tr11a and Tr11b becomes the same, so that the ratio of the current flowing through driving transistor MN1, sensing transistors Tr11a and Tr11b in the on state is maintained at a constant value. Therefore, the current detection circuit 32 can accurately detect the current flowing through driving transistor MN1 using sensing transistors Tr11a and Tr11b.

[0187] Figure 31 This diagram illustrates the connections of the components of the current detection circuit 32 and the current flow when the driving transistor MN1 is turned on in low-side driving mode. The driving transistor MN1 is a high-side driver. Figure 31 In the diagram, the thick dashed arrow indicates the path through which the solenoid current flows, while the thin dashed arrow indicates the path through which the detection current flows.

[0188] At this time, the current detection circuit 32 achieves the following by turning the switch group SWG on and off: Figure 26 The equivalent circuit of the current detection circuit 22a shown is illustrated. Figure 31 In the above, the sensing transistor Tr11b for low-side driving is used as sensing transistor Tr11, and the transistor Tr12b for low-side driving is used as transistor Tr12.

[0189] At this time, the source of each of the driving transistor MN2 in the off state and the sensing transistors Tr21a and Tr21b is short-circuited, and each drain is short-circuited by the switch corresponding to switch SW4 in the on / off switch group SWG. As a result, when off-state degradation occurs, the degree of degradation of each of the driving transistor MN2 and the sensing transistors Tr21a and Tr21b becomes the same, so that the ratio of the current flowing through each of the driving transistor MN2 in the on state and the sensing transistors Tr21a and Tr21b is maintained at a constant value. Therefore, the current detection circuit 32 can use the sensing transistors Tr21a and Tr21b to accurately detect the current flowing through the driving transistor MN2.

[0190] Figure 32 This diagram illustrates the connections of the components of the current detection circuit 32 and the current flow when the driving transistor MN2 is turned on in low-side driving mode. The driving transistor MN2 is the low-side driver. Figure 32 In the diagram, the thick dashed arrow indicates the path through which the solenoid current flows, while the thin dashed arrow indicates the path through which the detection current flows.

[0191] At this time, the current detection circuit 32 achieves this by turning the switch group SWG on and off. Figure 27 The equivalent circuit of the current detection circuit 22a shown is illustrated. Figure 32 In the middle, the sensing transistor Tr21b for low-side driving is used as the sensing transistor Tr21.

[0192] At this time, by turning the switch corresponding to switch SW3 in the switch group SWG on and off, the source of each of the three transistors in the off state—drive transistor MN1, sensing transistors Tr11a and Tr11b—is short-circuited, and each drain is short-circuited. As a result, when off-state degradation occurs, the degradation degree of drive transistor MN1, sensing transistors Tr11a and Tr11b becomes the same, so that the ratio of the current flowing through drive transistor MN1, sensing transistors Tr11a and Tr11b in the on state is maintained at a constant value. Therefore, the current detection circuit 32 can use sensing transistors Tr11a and Tr11b to accurately detect the current flowing through drive transistor MN1.

[0193] As described above, the current detection circuit 32 according to this embodiment can detect the current flowing through the solenoid driver 11 by switching the connection relationship of the components using the switch group SWG when the solenoid valve 7 is driven by the solenoid driver 11 through high-side drive or low-side drive.

[0194] Furthermore, according to this embodiment, the current detection circuit 32 switches the connection of components by using a switch group SWG, such that the source of each of the drive transistor MN1, sensing transistors Tr11a and Tr11b in the off state is short-circuited, and each drain is short-circuited. As a result, when off-state degradation occurs, the degradation degree of drive transistor MN1, sensing transistors Tr11a and Tr11b becomes the same, so that the ratio of the current flowing through drive transistor MN1, sensing transistors Tr11a and Tr11b in the on state is maintained at a constant value.

[0195] Similarly, the current detection circuit 32 connected to this embodiment switches the connection of the components using a switch group SWG, such that the source of each of the drive transistor MN2, sensing transistors Tr21a and Tr21b in the off state is short-circuited, and each drain is short-circuited. As a result, when off-state degradation occurs, the degree of degradation of each of the drive transistor MN2, sensing transistors Tr21a and Tr21b becomes the same, so that the ratio of the current flowing through each of the drive transistor MN2 and sensing transistors Tr21a and Tr21b in the on state is maintained at a constant value.

[0196] Therefore, the current detection circuit 32 applied in this embodiment can accurately detect the current flowing through the driving transistors MN1 and MN2 by using sensing transistors Tr11a, Tr11b, Tr21a and Tr21b.

[0197] In this embodiment, the current detection circuit 32 implements one of the equivalent circuits of the current detection circuit 12a and the current detection circuit 22a as an operating mode, but the present invention is not limited thereto. For example, the current detection circuit 32 may be configured to implement the equivalent circuit of the current detection circuit 12 or the equivalent circuit of the current detection circuit 22 corresponding to the operating mode.

[0198] The current detection circuit 72 according to the comparison example will be described next. Figure 33 This is a diagram illustrating an example configuration of the current detection circuit 72 according to a comparative example. When the solenoid valve 7 is driven by the solenoid driver 11 in a high-side drive or a low-side drive manner, the current detection circuit 72 can detect the current flowing in the solenoid driver 11.

[0199] like Figure 33As shown, the current detection circuit 72 includes a sensing transistor Tr21a used during high-side driving, a sensing transistor Tr21b used during low-side driving, an operational amplifier AMP2, a transistor Tr22, a transistor Tr23, and switches SW71 to SW73.

[0200] Sensing transistors Tr21a and Tr21b are connected in series between the external output terminal OUT and the reference voltage terminal GND. Switch SW71 is provided between node N71 and the reference voltage terminal GND; node N71 is the node between sensing transistors Tr21a and Tr21b. Switch SW72 is provided between node N72 and the reference voltage terminal GND. Switch SW73 is provided between node N72 and the external output terminal OUT. Operational amplifier AMP2 amplifies the potential difference between the voltage at node N71 and the voltage at node N72. Transistor Tr22 is provided between the power supply voltage terminal VDD and node N71, and controls the current flowing between the source and drain nodes based on the output voltage of operational amplifier AMP2. Transistor Tr23 is provided between the power supply voltage terminal VDD and the current-sensing output terminal, and controls the current flowing through transistor Tr22 and the current flowing between the source and drain nodes based on the output voltage of operational amplifier AMP2. In this embodiment, the same current flowing through transistor Tr22 flows through transistor Tr23. That is, transistor Tr23 mirrors the current flowing through transistor Tr22 and outputs the mirrored current as the detection current Iin.

[0201] Figure 34 This diagram illustrates the current flow in the current detection circuit 72 when the driving transistor MN1 is turned on in the high-side drive mode. The driving transistor MN1 is the high-side driver.

[0202] At this time, switches SW71 and SW72 are turned on, and switch SW73 is turned off. However, in the current detection circuit 72 configuration at this time, the source-drain voltage of the drive transistor MN2 in the off state and the source-drain voltage of the sensing transistor Tr21a in the off state show the same value (Vbat), while the source-drain voltage of the sensing transistor Tr21b in the off state shows a different value (0V).

[0203] As a result, when the off-state deteriorates, the degree of degradation of each term in the driving transistor MN2 and the sensing transistor Tr21b is different, causing the ratio of the current flowing through each term in the on-state driving transistor MN2 and the sensing transistor Tr21b to change from a constant value.

[0204] Figure 35This diagram illustrates the current flow in the current detection circuit 72 when the driving transistor MN2 is turned on in high-side driving mode. The driving transistor MN2 is a low-side driver.

[0205] At this time, switch SW71 is turned off, switch SW72 is turned on, and switch SW73 is turned off. As a result, the current flowing in transistors Tr21a and Tr22 is proportional to the current flowing in drive transistor MN2. The current flowing in transistors Tr21a and Tr22 is mirrored by transistor Tr23 and output as the detection current Iin of current detection circuit 72.

[0206] Figure 36 This diagram illustrates the current flow in the current detection circuit 72 when the driving transistor MN1 is turned on in the low-side driving mode. The driving transistor MN1 is the high-side driver.

[0207] At this time, switches SW71 and SW72 are turned on, and switch SW73 is turned off. However, in the current detection circuit 72 configuration at this time, the source-drain voltage of the drive transistor MN2 in the off state and the source-drain voltage of the sensing transistor Tr21a in the off state show the same value (Vbat), while the source-drain voltage of the sensing transistor Tr21b in the off state shows a different value (0V).

[0208] As a result, when the off-state deteriorates, the degree of degradation of each term in the driving transistor MN2 and the sensing transistor Tr21b is different, causing the ratio of the current flowing through each term in the on-state driving transistor MN2 and the sensing transistor Tr21b to change from a constant value.

[0209] Figure 37 This diagram illustrates the current flow in the current detection circuit 72 when the driving transistor MN2 is turned on in low-side driving mode. The driving transistor MN2 is the low-side driver.

[0210] At this time, switches SW71 and SW72 are turned off, and switch SW73 is turned on. As a result, the current flowing in transistors Tr21a and Tr22 is proportional to the current flowing in the driving transistor MN2. The current flowing in transistors Tr21a and Tr22 is mirrored through transistor Tr23, and the output is the detection current Iin of the current detection circuit 72.

[0211] As described above, the current detection circuit 72 cannot accurately detect the current flowing through the driving transistor MN2 using the sensing transistor Tr21b. On the other hand, the current detection circuit 32 according to this embodiment can solve the problem that occurs in the current detection circuit 72.

[0212] <Fifth Embodiment> Figure 38 This is a diagram illustrating a specific configuration example of the current detection circuit 32a according to the sixth embodiment. Compared to the current detection circuit 32, the current detection circuit 32a further includes constant current sources I1 and I2.

[0213] A constant current source I1 generates a constant current IshH, which is an intentionally offset current. The current obtained by adding the constant current IshH to the current flowing through sensing transistors Tr11a and Tr11b (the first sensing current) is output as the detection current Iin of the current detection circuit 32a. As a result, when there is a change in the first sensing current (input current), the current detection circuit 32a can output the detection current Iin without causing a dead zone (see [link]). Figure 39A and Figure 39B ).

[0214] A constant current source I2 generates a constant current IshL, which is an intentionally offset current. The current obtained by adding the constant current IshL to the current flowing through sensing transistors Tr21a and Tr21b (the second sensing current) is output as the detection current Iin of the current sensing circuit 32a. Figure 38 In this circuit, a constant current IshL is supplied to the non-inverting terminal of operational amplifier AMP2. Consequently, some of the switches surrounding operational amplifier AMP2 are replaced with MOS transistors. As a result, when the second sensed current (input current) exhibits a shift, the current detection circuit 32a can output the sensed current Iin without inducing a dead zone (see [reference]). Figure 39A and Figure 39B ).

[0215] Figure 40 This diagram illustrates the connection of the components of the current detection circuit 32a and the current flow when the driving transistor MN1 is turned on in high-side driving mode. The driving transistor MN1 is the high-side driver. Figure 40 In the diagram, the thick dashed arrow indicates the path through which the solenoid current flows, while the thin dashed arrow indicates the path through which the detection current flows.

[0216] Figure 41 This diagram illustrates the connection of the components of the current detection circuit 32a and the current flow when the driving transistor MN2 is turned on in high-side driving mode. The driving transistor MN2 is a low-side driver. Figure 41 In the diagram, the thick dashed arrow indicates the path through which the solenoid current flows, while the thin dashed arrow indicates the path through which the detection current flows.

[0217] Figure 42This diagram illustrates the connection of the components of the current detection circuit 32a and the current flow when the driving transistor MN1 is turned on in low-side driving mode. The driving transistor MN1 is a high-side driver. Figure 42 In the diagram, the thick dashed arrow indicates the path through which the solenoid current flows, while the thin dashed arrow indicates the path through which the detection current flows.

[0218] Figure 43 This diagram illustrates the connection of the components of the current detection circuit 32a and the current flow when the driving transistor MN2 is turned on in low-side driving mode. The driving transistor MN2 is the low-side driver. Figure 43 In the diagram, the thick dashed arrow indicates the path through which the solenoid current flows, while the thin dashed arrow indicates the path through which the detection current flows.

[0219] Figures 40 to 43 The connection relationship of the components of the current detection circuit 32a shown, and the current flow and Figures 29 to 32 The connection relationships of the constituent components and the current flow of the current detection circuit 32 shown are the same, so its description is omitted.

[0220] As described above, the current detection circuit 32a applied in this embodiment can exhibit the same effect as the current detection circuit 32. Furthermore, the current detection circuit 32a applied in this embodiment can add a constant current IshH to a first sensing current, or add a constant current IshL to a second sensing current, thereby outputting a detection current Iin without causing a dead zone when there is a shift in the first sensing current and the second sensing current.

[0221] Although the invention made by the inventors has been specifically described based on the embodiments, the invention is not limited to the described embodiments, and various modifications can obviously be made without departing from its spirit.

[0222] For example, in the semiconductor device according to the above embodiments, the conductivity type (p-type or n-type) of the semiconductor substrate, semiconductor layer, diffusion layer (diffusion region), etc., can be reversed. Therefore, when one conductivity type of n-type or p-type is the first conductivity type and the other conductivity type is the second conductivity type, the first conductivity type can be p-type and the second conductivity type can be n-type, or conversely, the first conductivity type can be n-type and the second conductivity type can be p-type.

[0223] In the above embodiments, the corresponding switches can be configured, for example, using MOS transistors. For example, by using high-voltage-tolerant MOS transistors only in one of the multiple switches, in which a high voltage is applied, the increase in circuit size can be suppressed.

[0224] Some or all of the above embodiments may be described in the following additional statements, but the invention is not limited thereto.

[0225] (Additional Statement 1)

[0226] A current detection circuit includes:

[0227] The first sensing transistor and the first driving transistor are both supplied with the voltage of the first power supply. The first driving transistor is provided between the first power supply and the external output terminal, and a first sensing current flows through the first sensing transistor. The first sensing current is proportional to the current flowing through the first driving transistor.

[0228] The first amplifier amplifies the potential difference between the voltage at the external output terminal and the voltage at the output terminal of the first sensing transistor that outputs the first sensing current.

[0229] A first voltage-controlled transistor is provided in series with a first sensing transistor on one side of the output terminal of the first sensing transistor, and the output voltage of the first amplifier is added to the gate of the first voltage-controlled transistor.

[0230] A first switch is provided between an external output terminal and the output terminal of a first sensing transistor, which is turned on when the first driving transistor is turned off and turned off when the first driving transistor is turned on.

[0231] The current detection circuit outputs the first sensing current as the detection current.

[0232] (Additional Statement 2)

[0233] The current detection circuit according to Additional Statement 1 further includes:

[0234] The second sensing transistor is provided between the external output terminal and the second power supply, and the second sensing transistor and the second driving transistor are jointly supplied with the voltage of the external output voltage. The second driving transistor is complementary to the first driving transistor in turning on and off, and a sensing current proportional to the current flowing through the second driving transistor flows through the second sensing transistor.

[0235] A second voltage-controlled transistor is provided in series with a second sensing transistor on the output terminal side of the second sensing transistor, and the output voltage of the second amplifier is added to the gate of the second voltage-controlled transistor;

[0236] A second switch is provided between the output terminals of the second power supply and the second sensing transistor, and the second switch is turned on when the second driving transistor is off, and turned off when the second driving transistor is on; and

[0237] The selection circuit selectively outputs either the first sensing current or the second sensing current as the detection current.

[0238] (Additional Statement 3)

[0239] The current sensing circuit according to Additional Statement 1 further includes a first constant current source that adds a first constant current to the first sensing current.

[0240] (Additional Statement 4)

[0241] The current detection circuit according to Additional Statement 2 further includes:

[0242] A first constant current source, the first constant current source adds a first constant current to a first sensed current; and

[0243] The second constant current source adds a second constant current to the second sensing current.

[0244] (Additional Statement 5)

[0245] A semiconductor device, comprising:

[0246] The current detection circuit as described in Additional Statement 1;

[0247] A first driving transistor is provided between a first power supply and an external output terminal; and

[0248] The second driving transistor is provided between the second power supply and the external output terminal, and is turned on and off complementary to the first driving transistor.

[0249] (Additional Statement 6)

[0250] A semiconductor system, comprising:

[0251] The first driving transistor controls the supply of current to the load based on pulse signals;

[0252] According to the current detection circuit described in Supplementary Statement 1, the current flowing through the first driving transistor is detected; and

[0253] The control circuit controls the duty cycle of the pulse signal based on the detection results of the current detection circuit.

[0254] (Additional Statement 7)

[0255] The semiconductor system described in Additional Statement 6, wherein the load is a solenoid valve.

[0256] (Additional Statement 8)

[0257] A current detection circuit, comprising:

[0258] The voltage of the external output terminal is supplied to the first sensing transistor, and the first driving transistor is provided between the first power supply and the external output terminal. The load is connected to the external terminal, and the second driving transistor is provided between the external output terminal and the second power supply. A first sensing current proportional to the current flowing through the first driving transistor flows through the first sensing transistor.

[0259] The first amplifier amplifies the potential difference between the voltage of the first power supply and the voltage of the first sensing transistor that outputs the first sensing current.

[0260] A first voltage-controlled transistor is provided in series with a first sensing transistor on one side of the output terminal of the first sensing transistor, and the output voltage of the first amplifier is added to the gate of the first voltage-controlled transistor.

[0261] A first switch is provided between an external output terminal and the output terminal of a first sensing transistor. The first switch is turned on when the first driving transistor is turned off and turned off when the first driving transistor is turned on.

[0262] The current detection circuit outputs the first sensing current as the detection current.

[0263] (Additional Statement 9)

[0264] According to the current detection circuit described in Statement 8

[0265] The first power source is the low-potential side power source.

[0266] The load is provided between the external output terminal and the low-potential side power supply.

[0267] The current detection circuit also includes a mirror transistor, which mirrors the first sensed current. The first sensed current flows through the first sensing transistor and the first voltage control transistor.

[0268] The current sensing circuit outputs the first sensed current, which is mirrored by the mirror transistor, as the sensed current.

[0269] (Additional Statement 10)

[0270] According to the current detection circuit described in Additional Statement 8

[0271] The first power source is the high-potential side power source.

[0272] The load is provided between the external output terminal and the high potential power supply.

[0273] (Additional Statement 11)

[0274] A semiconductor device, comprising:

[0275] The current detection circuit as described in Additional Statement 8;

[0276] A first driving transistor is provided between a first power supply and an external output terminal; and

[0277] The second driving transistor is provided between the second power supply and the external output terminal, and is turned on and off complementary to the first driving transistor.

[0278] (Additional Statement 12)

[0279] A semiconductor system, comprising:

[0280] The first driving transistor controls the supply of current to the load based on pulse signals;

[0281] According to the current detection circuit described in Additional Statement 8, the current flowing through the first driving transistor is detected;

[0282] The control circuit controls the duty cycle of the pulse signal based on the detection results of the current detection circuit.

[0283] (Additional Statement 13)

[0284] The semiconductor system described in Additional Statement 12, wherein the load is a solenoid valve.

Claims

1. A semiconductor device, comprising: The first driving transistor has a drain supplied by a first power supply voltage and a source connected to an output terminal, wherein an external load is connected to the output terminal. The first sensing transistor has a drain that is supplied using the first power supply voltage; A first voltage control circuit controls a first sensing current flowing out of the first sensing transistor based on the potential difference between the source voltage of the first driving transistor and the source voltage of the first sensing transistor. as well as A first connection control circuit is configured to connect the source of the first driving transistor and the source of the first sensing transistor. The sensed current is output as the detection current. When the first driving transistor is turned off, the source of the first driving transistor and the source of the first sensing transistor are short-circuited through the first connection control circuit. The first driving current flows out from the first driving transistor. The first sensing current is proportional to the first driving current. The first connection control circuit includes a switch. The first voltage control circuit includes: A first amplifier outputs an amplified potential difference between the source voltage of the first driving transistor and the source voltage of the first sensing transistor. as well as A first voltage-controlled transistor has a gate supplied by the output of the first amplifier, and one of its source or drain is connected to the source of the first sensing transistor. The semiconductor device further includes a first switching circuit that disconnects the output terminal and the source of the first sensing transistor from the two input terminals of the first amplifier.

2. The semiconductor device according to claim 1, The first power supply voltage is the high potential side power supply voltage. The external load is connected between the output terminal and the low-potential side power supply voltage.

3. The semiconductor device according to claim 1, further comprising: A first mirror transistor, which mirrors the first sensed current; The first power supply voltage is the low potential side power supply voltage. The external load is connected between the output terminal and the high-potential side power supply voltage, and The semiconductor device outputs a mirrored first sensing current, which is mirrored by the first mirror transistor, as the detection current.

4. The semiconductor device according to claim 1, further comprising: The second driving transistor has a source supplied by a second power supply voltage and a drain connected to the output terminal, and the second driving transistor is complementary to the first driving transistor in turning on and off. The second sensing transistor has a drain that is connected to the output terminal; The second amplifier amplifies the potential difference between the second power supply voltage and the source voltage of the second sensing transistor. The second voltage-controlled transistor has a gate supplied by the output of the second amplifier, and one of its source or drain is connected to the source of the second sensing transistor. The second connection control circuit is connected to the source of the second driving transistor and the source of the second sensing transistor, and the second connection control circuit is turned off when the second driving transistor is turned on, and turned on when the second driving transistor is turned off. as well as The selection circuit selectively outputs either the first sensing current or the second sensing current as the detection current.

5. The semiconductor device of claim 4, further comprising a second mirror transistor, the second mirror transistor mirroring the second sensed current. The first power supply voltage is the high potential side power supply voltage. The second power supply voltage is the low potential side power supply voltage. The external load is connected between the output terminal and the low-potential side power supply voltage, and The selection circuit selectively outputs either the first sensing current or the second sensing current as the detection current.

6. The semiconductor device of claim 4, further comprising a second mirror transistor that mirrors the first sensing current. The first power supply voltage is the low potential side power supply voltage. The second power supply voltage is the high potential side power supply voltage. The external load is connected between the output terminal and the high-potential side power supply voltage, and The selection circuit selectively outputs either the first sensing current or the second sensing current as the detection current.

7. The semiconductor device according to claim 1, When the first driving transistor is turned on, the switching circuit connects one of the two input terminals of the first amplifier to the output terminal, and connects the other input terminal of the first amplifier to the source of the first sensing transistor. When the first driving transistor is turned off, the switching circuit connects each of the two input terminals of the first amplifier to the first power supply voltage.

8. A semiconductor system, comprising: The semiconductor device according to claim 1, and A control circuit that controls the duty cycle of the pulse signal. The first driving transistor is controlled by the pulse signal.

9. A current detection circuit, comprising: First sensing transistor; First amplifier; First voltage-controlled transistor; Second sensing transistor; Second amplifier; Second voltage-controlled transistor; Mirror transistor; Select circuit; as well as A switch group, comprising multiple switches; When the operating mode is in high-side drive mode, the plurality of switches in the switch group are turned on or off. The first sensing transistor is configured to be supplied with a first power supply voltage together with a first driving transistor, the first driving transistor being provided between the first power supply and an external output terminal, the load being connected to the external output terminal, and... A first sensing current flows through the first sensing transistor, and the first sensing current is proportional to the current flowing through the first driving transistor; The first amplifier is configured to amplify the potential difference between the voltage at the external output terminal and the voltage at the output terminal of the first sensing transistor that outputs the first sensing current. The first voltage-controlled transistor is configured to be connected in series with the first sensing transistor on one side of the output terminal of the first sensing transistor, and the output voltage of the first amplifier is supplied to the gate of the first voltage-controlled transistor. A first switch is configured to be provided between the external output terminal and the output terminal of the first sensing transistor, the first switch being part of the switch group, and being turned on when the first driving transistor is turned off; And when the first driving transistor is turned on, the first switch is turned off. The second sensing transistor is configured to be supplied with the voltage of the external output terminal together with the second driving transistor. The second driving transistor is provided between the external output voltage and the second power supply voltage. The second driving transistor is configured to be turned on or off complementary to the first driving transistor, and a second sensing current flows through the second sensing transistor, the second sensing current being proportional to the current flowing through the second driving transistor. The second amplifier is configured to amplify the potential difference between the second power supply voltage and the voltage at the output terminal of the second sensing transistor, which outputs the second sensing current. The second voltage control transistor is configured to be connected in series with the second sensing transistor on one side of the output terminal of the second sensing transistor, and the output voltage of the second amplifier is supplied to the gate of the second voltage control transistor. A second switch is configured to be provided between the second power supply and the output terminal of the second sensing transistor. The second switch is part of the switch group, and is turned on when the second driving transistor is off, and turned off when the second driving transistor is on. The mirror transistor is configured to mirror the second sensing current flowing through the second voltage control transistor and the second sensing transistor. The selection circuit is configured to selectively output either the first sensing current or a mirrored second sensing current, which is mirrored by the mirror transistor, as the detection current. When the operating mode is in low-side drive mode, the plurality of switches in the switch group are turned on or off. The first sensing transistor is configured to be supplied with the voltage of the external output terminal together with the first driving transistor, and a first sensing current flows through the first sensing transistor, the first sensing current being proportional to the current flowing through the first driving transistor. The first amplifier is configured to amplify the potential difference between the first power supply voltage and the voltage at the output terminal of the first sensing transistor that outputs the first sensing current. The first voltage-controlled transistor is configured to be connected in series with the first sensing transistor on one side of the output terminal of the first sensing transistor, and the output voltage of the first amplifier is supplied to the gate of the first voltage-controlled transistor. The first switch is configured to be provided between the first power supply and the output terminal of the first sensing transistor, and the first switch is turned on when the first driving transistor is in the off state, and turned off when the first driving transistor is in the on state. The second sensing transistor is configured to be supplied with the second power supply voltage together with the second driving transistor, and a second sensing current flows through the second sensing transistor, the second sensing current being proportional to the current flowing through the second driving transistor. The second amplifier is configured to amplify the potential difference between the voltage at the external output terminal and the voltage at the output terminal of the second sensing transistor that outputs the second sensing current. The second voltage control transistor is configured to be connected in series with the second sensing transistor on one side of the output terminal of the second sensing transistor, and the output voltage of the second amplifier is supplied to the gate of the second voltage control transistor. The second switch is configured to be provided between the external output terminal and the output terminal of the second sensing transistor, and the second switch is turned on when the second driving transistor is turned off, and turned off when the second driving transistor is turned on. The mirror transistor is configured to mirror the second sensing current flowing through the second voltage control transistor and the second sensing transistor, and The selection circuit is configured to selectively output either the first sensing current or a mirrored second sensing current, which is mirrored by the mirror transistor, as the detection current. The current detection circuit mentioned above also includes: First switching circuit; and Second switching circuit, When the operating mode is in high-side drive mode, the plurality of switches in the switch group are turned on or off. The first switching circuit is configured to disconnect the external output terminal and the output terminal of the first sensing transistor from the two input terminals of the first amplifier when the first driving transistor is turned off. When the operating mode is in low-side drive mode, the plurality of switches in the switch group are turned on or off. The second switching circuit is configured to disconnect the external output terminal and the output terminal of the second sensing transistor from the two input terminals of the second amplifier when the second driving transistor is turned off.

10. The current detection circuit according to claim 9, The first sensing transistor is configured to have two transistors, which are complementaryly switched to be active or inactive corresponding to the operating mode. The second sensing transistor is configured to have two transistors, which are complementaryly switched to be active or inactive corresponding to the operating mode. The first switch is configured such that when the first driving transistor is turned off, each of the sources constituting the first driving transistor and the first sensing transistor is short-circuited, and The second switch is configured to short-circuit each of the sources constituting the second driving transistor and the second sensing transistor when the second driving transistor is turned off.

11. The current detection circuit according to claim 9, When the operating mode is in the high-side drive mode, the plurality of switches in the switch group are turned on or off. The first switching circuit is configured to connect one of the two input terminals of the first amplifier to the external output terminal, and to connect the other of the two input terminals of the first amplifier to the output terminal of the first sensing transistor. When the first driving transistor is turned off, the switching circuit connects each of the two input terminals of the first amplifier to the first power supply voltage. When the operating mode is in the low-side drive mode, the plurality of switches in the switch group are turned on or off. The second switching circuit is configured to connect one of the two input terminals of the second amplifier to the external output terminal, and to connect the other of the two input terminals of the second amplifier to the output terminal of the second sensing transistor. When the second driving transistor is turned off, the switching circuit connects each of the two input terminals of the second amplifier to the second power supply voltage.

12. The current detection circuit according to claim 9, further comprising: A first constant current source adds a first constant current to the first sensed current, and A second constant current source adds a second constant current to the second sensed current.

13. A semiconductor device, comprising: The current detection circuit according to claim 9; The first driving transistor is provided between the first power supply and the external output terminal; as well as The second driving transistor is provided between the second power supply and the external output terminal, and is turned on or off in a complementary manner to the first driving transistor.

14. A semiconductor system, comprising: The first driving transistor controls the supply of current flowing through the load based on a pulse signal; According to claim 9, the current detection circuit detects the current flowing through the first driving transistor; and A control circuit that controls the duty cycle of the pulse signal based on the detection result of the current detection circuit.

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