Load drive control device

Abstract

To provide a load drive controller that can both reduce EMI noise and switching losses while maintaining a common IC configuration.SOLUTION: A pre-driver circuit 20, which controls the driver elements, has a slope control circuit that independently controls the current slope from the driver elements and the voltage slope from the driver circuit, respectively. The controller 30 controls the current slope from the driver elements and the voltage slope from the driver circuit respectively by outputting a current control signal selected from a plurality of current control signals and a voltage control signal selected from a plurality of voltage control signals to the pre-driver circuit 20, respectively.SELECTED DRAWING: Figure 5

Description

[Technical Field]

[0001] The technology disclosed herein belongs to the technical field of load drive control devices. [Background technology]

[0002] Solenoids (loads) installed in vehicles are generally driven by turning driver transistors on and off using PWM (Pulse Width Modulation) control.When turning the driver transistors on and off, it is necessary to switch the current and voltage used to drive the solenoid as quickly as possible to reduce switching loss.

[0003] However, increasing the switching speed increases the induced electromotive force generated by abrupt current changes and parasitic inductance, as well as EMI (Electro Magnetic Interference) noise caused by high-frequency components in the output voltage. For this reason, efforts are being made to reduce both EMI noise and switching loss as much as possible.

[0004] For example, Patent Document 1 discloses a load drive control device that changes the rising and falling slopes of an output voltage that drives a load by adjusting the amount of current of a current source that turns on and off a driver transistor. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] U.S. Patent No. 8,258,822 Summary of the Invention [Problem to be solved by the invention]

[0006] For example, in the case of a driver circuit that drives a device installed in a vehicle, the layout of the wire harness connected to the driver circuit varies depending on the vehicle's body configuration, etc. Different layouts of the wire harness change the length of the wire harness, which in turn changes the induced electromotive force due to the parasitic inductance of the wire harness, thereby changing the waveform of the output voltage output to the device. Furthermore, different layouts of the driver circuit depending on the vehicle's body configuration, etc., change the heat dissipation structure for heat generated by switching, etc., and therefore the allowable heat generation amount of the driver circuit. Therefore, to simultaneously reduce EMI noise and switching loss, it is necessary to tailor the current and voltage waveforms to suit each vehicle and each layout of the driver circuit within the vehicle. Meanwhile, there is also a demand for standardization of integrated circuits (ICs) equipped with driver circuits as much as possible to improve productivity.

[0007] Furthermore, in Patent Document 1, the slope of the rise and fall of the output voltage is changed, but since switching loss is the product of the voltage applied to the driver element and the current flowing through the driver element, it is necessary to also consider the output current. There is room for improvement in order to achieve both reductions in EMI noise and switching loss.

[0008] The technology disclosed herein has been developed in light of these points, and its purpose is to provide a load drive control device that can achieve both reduced EMI noise and reduced switching loss while standardizing the IC configuration. [Means for solving the problem]

[0009] In order to solve the above problems, the technology disclosed herein is directed to a load drive control device, and includes a driver circuit that drives a load, a pre-driver circuit that drives the driver circuit, and a controller that controls the drive state of the driver circuit by outputting a control signal to the pre-driver circuit, wherein the driver circuit has a high-side driver element and a low-side driver element, and the pre-driver circuit has slope control circuits that independently control the gradient of a current slope, which is the rise and fall of an output current output from at least one of the high-side driver element and the low-side driver element, and control the gradient of a voltage slope, which is the rise and fall of an output voltage output from the driver circuit, and the controller controls the current slope and the voltage slope by outputting to the pre-driver circuit a current control signal selected from a plurality of current control signals set for each current slope pattern and a voltage control signal selected from a plurality of voltage control signals set for each voltage slope pattern, respectively.

[0010] With this configuration, the controller simply selects the optimal pattern from multiple current slope patterns and multiple voltage slope patterns depending on the equipment in which the load drive control device is installed. The control signals indicating each pattern may be stored in a memory device within the IC or obtained from an external controller such as a microcontroller. This makes it possible to achieve both reduced EMI noise and reduced switching loss for each equipment while keeping the IC configuration common.

[0011] In the load drive control device, the pre-driver circuit includes a high-side pre-driver circuit for driving the high-side driver element and a low-side pre-driver circuit for driving the low-side driver element, and the slope control circuit is provided in the high-side pre-driver circuit and independently controls the gradient of a current slope, which is the rise and fall of an output current output from the high-side driver element, and the gradient of a voltage slope, which is the rise and fall of an output voltage output from the driver circuit.

[0012] In other words, the operation of the high-side driver element in particular is related to EMI noise and switching loss. Therefore, by providing a slope control circuit in the high-side pre-driver circuit and controlling the current slope and voltage slope, it is possible to effectively reduce both EMI noise and switching loss.

[0013] The load drive control device may further include a memory device electrically connected to the controller and storing the plurality of current control signals and the plurality of voltage control signals, and the controller may read desired current control signals and voltage control signals from the plurality of current control signals and the plurality of voltage control signals stored in the memory device, and output the respective control signals to the pre-driver circuit.

[0014] According to this configuration, the control is completed within the driver circuit alone, so that the current slope and voltage slope can be controlled with high precision.

[0015] In the load drive control device equipped with the memory device, the memory device may be configured to pre-store combinations of the plurality of current control signals and the plurality of voltage control signals, and the controller may read the combinations of the current control signals and the voltage control signals from the memory device and output the respective control signals to the pre-driver circuit.

[0016] According to this configuration, the controller only needs to select a combination of a current control signal and a voltage control signal, which simplifies the control of the driver circuit.

[0017] In one embodiment of the load drive control device, the controller controls a current slope control period for controlling the current slope and a voltage slope control period for controlling the voltage slope, respectively, for each period of the current slope and the voltage slope so that the periods do not overlap with each other, and further the controller outputs a control signal to the slope control circuit to control the current slope during the current slope control period, and outputs a control signal to the slope control circuit to control the voltage slope during the voltage slope control period.

[0018] That is, because the rise and fall periods of the output current are different from the rise and fall periods of the output voltage, the current slope control period and the voltage slope control period can be set so that they do not overlap. This allows the current slope and voltage slope to be controlled separately. Therefore, the current slope and voltage slope can be tailored to be appropriate for each device, and EMI noise and switching loss can be reduced more effectively.

[0019] In the embodiment, the controller may be configured to output a control signal to the pre-driver circuit so that, when turning on the driver element, the voltage slope control period is followed by the current slope control period, and, when turning off the driver element, the controller may output a control signal to the pre-driver circuit so that the current slope control period is followed by the voltage slope control period.

[0020] In particular, when the driver element is a transistor, the current slope control period may be set to the period from when the driver element is turned on until the current output from the driver element reaches the load current when the driver element is turned on, and may be set to the period from when the driver element is turned on until the driver element is turned off when the driver element is turned off, after the voltage slope control period, and the voltage slope control period may be set to a period including mirror periods when the driver element is turned on and when it is turned off.

[0021] That is, the current slope control period is shorter than the voltage slope control period. Therefore, when the driver transistor is turned on, the current slope control is performed before the voltage slope control, and when the driver transistor is turned off, the current slope control is performed after the voltage slope control. This makes it possible to appropriately control the current slope while also controlling the voltage slope over as long a period as possible. In particular, if the period for adjusting the voltage slope is set to a period that includes the mirror period, the voltage slope can be controlled with almost no effect on the control of the current slope. As a result, EMI noise and switching loss can be reduced more effectively. [Effects of the Invention]

[0022] As described above, the technology disclosed herein allows the current slope and voltage slope to be selected from pre-stored patterns, thereby making it possible to achieve both reduced EMI noise and reduced switching loss for each device while keeping the configuration of the IC itself common. [Brief explanation of the drawings]

[0023] [Figure 1] 1 is a block diagram illustrating an IC constituting a load drive control device according to a first exemplary embodiment. [Figure 2] FIG. 2 is a diagram illustrating a configuration of a driver circuit. [Figure 3]10 is a timing chart showing when a high-side transistor is turned on / off. [Figure 4] FIG. 2 is a block diagram illustrating a schematic configuration of a high-side pre-driver circuit. [Figure 5] 10 is a timing chart showing the relationship between the gate-source voltage and drain-source voltage of a high-side transistor, and the output voltage. [Figure 6] 10 is a graph showing the results of adjusting the gradient of the current slope at the time of rising and the gradient of the voltage slope at the time of rising. [Figure 7] FIG. 10 is a block diagram illustrating an IC constituting the load drive control device according to the second embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0024] Exemplary embodiments will now be described in detail with reference to the drawings.

[0025] (Embodiment 1) FIG. 1 shows a schematic configuration of a driver IC (Integrated Circuit) 1 as a load drive control device according to the first embodiment. This driver IC 1 is mounted on, for example, a vehicle. Specifically, it is used to electrically control a solenoid valve 100 for adjusting hydraulic pressure in a transmission mounted on the vehicle. In this case, the solenoid valve 100 corresponds to the load to be controlled. In the following explanation, the solenoid valve 100 is described as the load. Note that the load drive control device according to the first embodiment can be used to control not only the solenoid valve 100 but also other loads such as an injector or a motor.

[0026] The driver IC1 has a driver circuit 10 that actually drives the solenoid valve 100, a pre-driver circuit 20 that controls the operation of the driver circuit 10, and a pre-driver controller 30 (hereinafter referred to as the controller 30) that outputs a control signal to the pre-driver circuit 20. In the first embodiment, a setting signal related to the control of the pre-driver circuit 20 is input to the controller 30.

[0027] As shown in FIG. 2, the driver circuit 10 is configured as a half-bridge circuit. The driver circuit 10 has two driver elements. The two driver elements include a high-side driver element 11 connected to the high-voltage side and a low-side driver element 12 connected to the ground side. The high-side and low-side driver elements 11 and 12 are each configured, for example, with MOS transistors. In the following explanation, we will explain the case where N-type MOS transistors are used as the high-side and low-side driver elements 11 and 12. Note that the high-side driver element 11 may also be a P-type MOS transistor. Also, the low-side driver element 12 A diode may be used instead of a MOS transistor.

[0028] The solenoid valve 100 is operated and controlled by alternately turning on and off the high-side driver element 11 and the low-side driver element 12 so that their on periods do not overlap, thereby supplying current alternately from the high-side and low-side.

[0029] The pre-driver circuit 20 includes a high-side pre-driver circuit 21 and a low-side pre-driver circuit 22. The high-side pre-driver circuit 21 is connected to the gate of the high-side driver element 11 and controls the operation of the high-side driver element 11. The low-side pre-driver circuit 22 is connected to the gate of the low-side driver element 12 and controls the operation of the low-side driver element 12. As will be described in detail later, at least one of the high-side and low-side pre-driver circuits 21, 22 has a configuration for reducing EMI (Electro Magnetic Interference) noise and switching loss generated when the driver elements 11, 12 are turned on and off. Here, a case where the high-side pre-driver circuit 21 has the above-mentioned configuration will be described.

[0030] Fig. 3 is a timing chart in a steady state when the high-side driver element 11 and the low-side driver element 12 are turned on / off in the circuit configuration shown in Fig. 2. As mentioned above, this timing chart is an example of operation when N-type MOS transistors are used as the high-side and low-side driver elements 11 and 12.

[0031] When the low-side driver element 12 is in an off state, that is, when the gate-source voltage (Vgs_L) of the low-side driver element is lower than the threshold voltage (Vth), and an on signal is output for the high-side driver element 11, a current is input to the gate of the high-side driver element 11 via the high-side pre-driver circuit 21. When the current is input to the gate of the high-side driver element 11 and the gate is charged, the gate-source voltage (Vgs_H) of the high-side driver element 11 rises. At this time, a current flows from ground (GND) to the solenoid valve 100 via the body diode of the low-side driver element to maintain the current flowing through the solenoid until the voltage reaches the threshold voltage (Vth) of the MOS transistor. Due to the influence of this current, the high-side driver element 11, the low-side driver element 12, and the solenoid valve 100 are electrically connected, and the output voltage (Vload) becomes lower than zero. In addition, the drain-source voltage (Vds_H) is the difference between the power supply voltage (VB) and the output voltage.

[0032] At time t1, when the gate-source voltage of the high-side driver element 11 exceeds the threshold voltage (Vth), the high-side driver element 11 turns on, and a current (Ids_H) begins to flow between the drain and source of the high-side driver element 11. This causes a current to flow to the solenoid valve 100 via the transistor of the high-side driver element 11. The drain-source current rises sharply and increases until it reaches the load current value (Iload) flowing through the solenoid valve 100.

[0033] At time t2, when the drain-source current of the high-side driver element 11 reaches the load current value flowing through the solenoid valve 100, the gate-source voltage of the high-side driver element 11 rises again after a mirror period (from time t2 to time t3).

[0034] On the other hand, when a current flows between the drain and source of the high-side driver element 11 and reaches the load current value, the drain-source voltage of the high-side driver element 11 drops. The potential on the source side is lower than that on the drain side by the on-voltage (Von) of the high-side driver element 11, so the drain-source voltage drops to the on-voltage. The on-voltage is expressed as the product of the on-resistance of the high-side driver element 11 and the drain-source current.

[0035] The output voltage rises as a current flows between the drain and source of the high-side driver element 11. The output voltage rises sharply during the mirror period and then becomes VB-Von. This voltage causes a current to flow through the solenoid valve 100, driving it.

[0036] When a signal to turn off the high-side driver element 11 is input, the gate is discharged and the gate-source voltage of the high-side driver element 11 decreases. Accordingly, the drain-source voltage of the high-side driver element 11 increases slightly, causing a slight decrease in the output voltage. The gate-source voltage then decreases further after a mirror period (between time t4 and time t5). During this time, the drain-source voltage increases and reaches the power supply voltage.

[0037] After the mirror period has elapsed, the drain-source current of the high-side driver element 11 decreases. At this time, current is supplied to the solenoid valve 100 via the body diode of the low-side driver element 12 so as to keep the load current flowing through the solenoid valve 100 constant. This causes the output voltage to fall below 0 again.

[0038] Then, at time t6, when the gate-source voltage of the high-side driver element 11 reaches the threshold voltage, the drain-source current of the high-side driver element 11 becomes 0. Thereafter, until the low-side driver element 12 is turned on, current is supplied to the solenoid 100 via the body diode of the low-side driver element 12. After the low-side driver element 12 is turned on, current is supplied to the solenoid 100 via the transistor of the low-side driver element 12.

[0039] Here, power during the rise and fall periods of the drain-source current waveforms of the high-side driver element and the low-side driver element, and during the rise and fall periods of the output voltage waveform, constitutes switching loss due to heat. This switching loss is expressed as the product of each current value during the current slope, which is the rise and fall of the current waveform of each driver element 11, 12, and the drain-source voltage value of each driver element 11, 12 during the voltage slope, which is the rise and fall of the output voltage waveform. In particular, the switching loss in the high-side driver element 11 exhibits the changes shown in Figure 3.

[0040] One possible way to reduce this switching loss is to make the current slope and voltage slope as steep as possible and shorten the period of each slope. However, making the current slope steeper increases noise due to induced electromotive force generated by parasitic inductance, while making the voltage slope steeper increases EMI (Electro Magnetic Interference) noise due to high-frequency components in the output voltage of the driver element. Therefore, it is necessary to control the current slope and voltage slope in a way that reduces both this noise and switching loss.

[0041] In the case of a driver IC 1 that drives a solenoid valve 100 mounted on a vehicle, as in this embodiment, the layout of the wire harness connecting the battery to the driver circuit 10 (particularly the high-side transistor) varies depending on the vehicle body configuration, etc. If the layout of the wire harness differs, the length of the wire harness changes, which in turn changes noise due to the influence of parasitic inductance. This causes fluctuations in the drain potential of the high-side driver element 11, which in turn changes the waveform of the output voltage output to the solenoid valve 100. Furthermore, if the layout of the driver IC differs depending on the vehicle body configuration, etc., the heat dissipation structure for heat generated by switching, etc., differs, which changes the amount of heat that can be dissipated by the driver circuit. Therefore, to simultaneously reduce EMI noise and switching loss, it is necessary to adjust the current slope and voltage slope appropriately for each vehicle and for each layout of the driver IC 1 within the vehicle.

[0042] However, adjusting the current slope and voltage slope for each vehicle and each installation requires changing the driver IC specifications according to each condition, which can lead to a decrease in productivity. For this reason, there is a demand to standardize driver ICs as much as possible to improve productivity.

[0043] Therefore, in this embodiment, the configuration of the pre-driver circuit 20, particularly the high-side pre-driver circuit 21, is devised so that the driver IC 1 can be standardized while the slope of the current (Ids_H) flowing between the drain and source of the high-side driver element 11 and the slope of the output voltage (Vload) can be set to an appropriate state depending on the conditions.

[0044] 4 shows the configuration of the high-side pre-driver circuit 21. The high-side pre-driver circuit 21 includes a current supply circuit 21a for supplying a current to the gate of the high-side driver element 11, a current slope control circuit 21b for controlling the slope of the current flowing between the drain and source of the high-side driver element 11, and a voltage slope control circuit 21c for controlling the slope of the output voltage. The high-side pre-driver circuit 21 also includes a boost circuit 21d for supplying a large current to the gate of the high-side driver element 11. A first switch 21e is provided between the current supply circuit 21a and the current slope control circuit 21b. A second switch 21f is provided between the current supply circuit 21a and the voltage slope control circuit 21c. A third switch 21g is provided between the current supply circuit 21a and the boost circuit 21d. The current supply circuit 21a, the current slope control circuit 21b, the voltage slope control circuit 21c, the boost circuit 21d, the first switch 21e, the second switch 21f, and the third switch 21g are each connected to the controller 30, and control signals are input from the controller 30. Note that the configuration shown in Fig. 4 only illustrates a portion of the configuration of the high-side pre-driver circuit 21, and does not exclude the inclusion of other elements in the high-side pre-driver circuit 21.

[0045] In this embodiment, the current supplied to the gate of the high-side driver element 11 is controlled to adjust the rate of charging and discharging the gate, thereby controlling the slope of the current flowing between the drain and source of the high-side driver element 11 and the slope of the output voltage. The current slope control circuit 21b and the voltage slope control circuit 21c are each composed of, for example, a plurality of current mirror circuits, and are able to control the current supplied to the gate of the high-side driver element 11 according to the number of transistors connected in parallel in the current mirror circuit to be operated.

[0046] The current supply circuit 21a is configured, for example, as a current mirror circuit, and is capable of inputting and outputting the current generated by the current slope control circuit 21b, the voltage slope control circuit 21c, and the boost circuit 21d to the gate of the high-side driver element 11. In other words, the current supply circuit 21a is configured to be capable of both charging and discharging the gate of the high-side driver element 11.

[0047] When the first switch 21e is turned on, the current slope control circuit 21b is connected to the current supply circuit 21a, and is able to supply to the high-side driver element 11 a control current for controlling the slope of the current flowing between the drain and source of the high-side driver element 11. When the second switch 21f is turned on, the voltage slope control circuit 21c is connected to the current supply circuit 21a, and is able to supply to the high-side driver element 11 a control current for controlling the slope of the output voltage.

[0048] The amount of current adjusted by the current slope control circuit 21b and the voltage slope control circuit 21c, i.e., the number of current mirror circuits to be operated among the multiple current mirror circuits constituting the current slope control circuit 21b and the voltage slope control circuit 21c, is determined by a control signal input from the controller 30 to the high-side pre-driver circuit 21. The control signal includes multiple current control signals set for each current slope pattern and multiple voltage control signals set for each voltage slope pattern. These current control signals and voltage control signals indicate the number of current mirror circuits to be operated in the current slope control circuit 21b and the voltage slope control circuit 21c. The current control signals and voltage control signals are examples of setting signals input to the controller 30 from outside.

[0049] In the first embodiment, the controller 30 inputs an externally input current control signal to the current slope control circuit 21b, and inputs an externally input voltage control signal to the voltage slope control circuit 21c.

[0050] In this embodiment, in order to adjust the current slope and the voltage slope, the timing at which the first switch 21e is turned on and the timing at which the second switch 21f is turned on are shifted.

[0051] The configuration of the high-side pre-driver circuit 21 described here can also be adopted in the low-side pre-driver circuit 22 to control the low-side driver element 12.

[0052] 5 shows the drive timing of the current slope control circuit 21b, the voltage slope control circuit 21c, and the boost circuit 21d during the rise of the current (Ids_H) flowing between the drain and source of the high-side driver element 11 and the output voltage (Vload). Note that times t1 to t6 shown in FIG. 5 correspond to times t1 to t6 shown in FIG.

[0053] When the low-side driver element 12 is in an off state, a signal to turn on the high-side driver element 11 is input, which places the current supply circuit 21a in a mode for charging the gate of the high-side driver element 11. At this time, the third switch 21g is turned on to connect the boost circuit 21d to the current supply circuit 21a, thereby supplying a relatively large current to the gate of the high-side driver element 11. This charges the gate in as short a period as possible, and increases the gate-source voltage to the threshold voltage as quickly as possible.

[0054] At time t1, when the gate-source voltage reaches the threshold voltage, the third switch 21g is turned off and the first switch 21e is turned on. As a result, a current adjusted by the current slope control circuit 21b is supplied to the gate of the high-side driver element 11. By increasing or decreasing the current adjusted by the current slope control circuit 21b, the slope of the slope of the current flowing through the high-side driver element 11 is adjusted. Specifically, if the amount of current supplied to the gate is increased, the gate is charged more quickly, and the slope of the rising current slope between the gate and drain can be made larger. Conversely, if the amount of current supplied to the gate is decreased, the gate is charged more slowly, and the slope of the current slope can be made smaller.

[0055] At time t2, the drain-source current (Ids_H) of the high-side driver element 11 reaches the load current value flowing through the solenoid valve 100, and the gate-source current enters the mirror period. The first switch 21e is turned off and the second switch 21f is turned on. This causes a current adjusted by the voltage slope control circuit 21c to be supplied to the gate of the high-side driver element 11. The slope of the voltage slope is adjusted by increasing or decreasing the current adjusted by the voltage slope control circuit 21c. Specifically, increasing the amount of current supplied to the gate speeds up gate charging, thereby increasing the slope of the rising voltage slope. Conversely, decreasing the amount of current supplied to the gate slows down gate charging, thereby decreasing the slope of the voltage slope. At this time, the current (Ids_H) flowing through the high-side driver element 11 reaches the load current value (Iload) flowing through the solenoid during steady-state operation, allowing the slope of the output voltage to be adjusted independently.

[0056] Then, at time t3, when the mirror period is completed, the second switch 21f is turned off and the third switch 21g is turned on. As a result, a current adjusted by the boost circuit 21d is supplied to the gate of the high-side driver element 11. This makes it possible to maintain the gate voltage at a high level so that the high-side driver element 11 is maintained in an on state.

[0057] On the other hand, when the high-side driver element 11 is turned off, the current supply circuit 21a is switched to the side discharging the gate of the high-side driver element 11. As a result, current flows in the discharge direction, and the output voltage begins to drop. At this time, turning on the third switch 21g reduces switching loss. When the gate-source mirror period (from time t4 to time t5) begins, the third switch 21g is turned off and the second switch 21f is turned on. This allows the gradient of the falling voltage slope to be adjusted. After the mirror period is completed, the second switch 21f is turned off and the first switch 21e is turned on. This allows the gradient of the falling current slope flowing through the high-side driver element 11 to be adjusted. When the output current becomes zero, the first switch 21e is turned off. Note that to ensure that the gate discharge is completely completed, the third switch 21g may be turned on again after the first switch 21e is turned off.

[0058] As described above, by setting the current slope control period for controlling the slope of the current flowing through the high-side driver element 11 and the voltage slope control period for controlling the voltage slope so that they do not overlap, it is possible to adjust both the current slope and the voltage slope, thereby achieving both a reduction in EMI noise and a reduction in switching loss.

[0059] Figure 6 shows the results of a simulation performed on the circuit according to this embodiment, in which the slope of the current flowing through the driver element and the slope of the output voltage are controlled as described above. Figure 6(a) shows the results for the slope of the current flowing through the driver element, and Figure 6(b) shows the results for the slope of the output voltage. In Figure 6(a), the horizontal axis is stretched compared to Figure 6(b) to make the changes easier to understand.

[0060] As shown in Figure 6(a), the current slope control circuit 21b changes the current supplied to the gate, thereby changing the slope of the current flowing through the driver element. Here, four current slope patterns are used, but five or more patterns can be formed by adjusting the number of current mirror circuits that make up the current slope control circuit 21b. Note that, although not shown in Figure 6(a), when discharging the gate of the driver element, the slope of the current slope at the falling edge can also be changed by changing the current drawn from the gate.

[0061] As shown in FIG. 6(b), the slope of the output voltage can be changed by changing the current supplied to the gate by the voltage slope control circuit 21c. Here, as with the current slope shown in FIG. 6(a), four voltage slope patterns are used, but five or more patterns can be formed by adjusting the number of current mirror circuits that make up the current slope control circuit 21b. Note that, although not shown in FIG. 6(b), when discharging the gate of the driver element, the slope of the voltage slope at the falling edge can also be changed by changing the current drawn from the gate.

[0062] In this way, the slope of the current (Ids_H) flowing through the high-side driver element and the slope of the output voltage (Vload) can be controlled independently, making it possible to select appropriate current slope patterns and voltage slope patterns depending on the layout of the wire harness connected to the driver circuit 10. For example, when a long wire harness is required, a current slope with a gentle slope can be selected. When the wire harness is located near the engine or in a position where heat dissipation is difficult, current slopes and voltage slopes with steep slopes within the allowable range of EMI noise can be selected. In this case, signals for selecting the current slope and voltage slope are input externally, so that appropriate current slopes and voltage slopes can be achieved depending on the vehicle configuration and the layout of the driver IC1 while keeping the configuration of the driver IC1 the same.

[0063] Therefore, in the first embodiment, the driver IC1 serving as a load drive control device includes a driver circuit 10 having a high-side driver element 11 that drives a load (solenoid valve 100), a high-side pre-driver circuit 21 for driving the high-side driver element 11, and a controller 30 that controls the drive state of the high-side driver element 11 by outputting a control signal to the high-side pre-driver circuit 21. The high-side pre-driver circuit 21 includes slope control circuits (a current slope control circuit 21b and a voltage slope control circuit 21c) that independently control the gradient of the current slope, which is the rise and fall of the current flowing through the high-side driver element 11, and the gradient of the voltage slope, which is the rise and fall of the output voltage output from the driver circuit 10. The controller 30 controls the current slope from the high-side driver element 11 and the voltage slope from the driver circuit 10 by outputting to the high-side pre-driver circuit 21 a current control signal selected from a plurality of current control signals set for each current slope pattern and a voltage control signal selected from a plurality of voltage control signals set for each voltage slope pattern. In this way, the controller 30 only needs to input to the high-side pre-driver circuit 21 a signal related to an optimal pattern selected from each slope pattern depending on the ambient conditions of the device in which the driver IC 1 is mounted. This makes it possible to achieve both reduced EMI noise and reduced switching loss for each device while keeping the configuration of the driver IC itself common.

[0064] In the first embodiment, the controller 30 sets the current slope control period for controlling the slope of the current flowing through the high-side driver element 11 and the voltage slope control period for controlling the voltage slope so that the periods do not overlap. Furthermore, the controller 30 outputs a control signal to the current slope control circuit 21b to control the current slope during the current slope control period, and outputs a control signal to the voltage slope control circuit 21c to control the voltage slope during the voltage slope control period. That is, because there is a gap between the rising period of the output current and the rising period of the output voltage, and between the falling period of the output current and the falling period of the output voltage, the current slope control period and the voltage slope control period can be set so that they do not overlap. This allows the current slope and the voltage slope to be controlled independently. This effectively reduces EMI noise and switching loss.

[0065] In particular, in the first embodiment, when the high-side driver element 11 is a MOS transistor, the current slope control period is set to the period from when the high-side driver element 11 is turned on until the current flowing through the high-side driver element 11 reaches the load current when the high-side driver element 11 is turned on. Meanwhile, the current slope control period is set to the period from when the high-side driver element 11 is turned on until the high-side driver element 11 is turned off when the high-side driver element 11 is turned off. The voltage slope control period is set to a period including the mirror period when the high-side driver element 11 is turned on and when it is turned off. This allows the voltage slope to be controlled over as long a period as possible while appropriately controlling the slope of the current flowing through the high-side driver element 11. In particular, if the period for adjusting the voltage slope is set to a period including the mirror period, the voltage slope can be controlled with almost no effect on the output current. As a result, EMI noise and switching loss can be reduced more effectively.

[0066] (Embodiment 2) Hereinafter, the second embodiment will be described in detail with reference to the drawings. In the following description, parts common to the first embodiment will be given the same reference numerals and detailed description thereof will be omitted.

[0067] The second embodiment differs from the first embodiment in that a memory device 240 is mounted on the driver IC 201. The memory device 240 stores in advance a plurality of current control signals set for each current slope pattern and a plurality of voltage control signals set for each voltage slope pattern. More specifically, the memory device 240 stores in advance combinations of a plurality of current control signals and a plurality of voltage control signals in a table format.

[0068] In this embodiment 2, the controller 30 reads a signal corresponding to a combination of a current control signal and a voltage control signal from the memory device 240, inputs the current control signal corresponding to the signal to the current slope control circuit 21b, and inputs the voltage control signal corresponding to the signal to the voltage slope control circuit 21c.

[0069] As described above, in the second embodiment, the driver IC 201 is provided with a memory device 240 in which a plurality of current control signals set for each current slope pattern and a plurality of voltage control signals set for each voltage slope pattern are pre-stored. Therefore, the control is completed within the driver IC 201 alone, and the current slope and voltage slope can be controlled with high precision.

[0070] In particular, in this embodiment, the memory device 240 pre-stores combinations of multiple current control signals and multiple voltage control signals, and the controller 30 reads the combinations of current control signals and voltage control signals from the memory device 240 and outputs the respective control signals to the high-side pre-driver circuit 21. This simplifies the control of the driver circuit 10 because the controller 30 only needs to select a combination of current control signals and voltage control signals. Note that the controller 30 can also change the combination of current control signals and voltage control signals read from the memory device 240 by inputting a setting signal from the outside, and output a control signal to the pre-driver circuit. This allows the driver IC to be adjusted to have appropriate current and voltage waveforms even after it is installed in equipment such as a vehicle, making it possible to more effectively reduce EMI noise and switching loss.

[0071] (Other embodiments) The technology disclosed herein is not limited to the above-described embodiments, and can be substituted within the scope of the claims.

[0072] For example, in the above-described first and second embodiments, the current supplied to the gate of the high-side driver element 11 is adjusted to adjust the charging and discharging periods of the gate, thereby controlling the slope of the current flowing between the drain and source of the high-side driver element 11 and the slope of the output voltage. However, the present invention is not limited to this, and the current slope and the voltage slope may be controlled by adjusting the voltage supplied to the gate of the high-side driver element 11.

[0073] In the first and second embodiments, the current supplied to the gate of the high-side driver element 11 is adjusted to adjust the charging and discharging periods of the gate, thereby controlling the slope of the current flowing between the drain and source of the high-side driver element 11 and the slope of the output voltage. However, the current slope and the voltage slope may be controlled by adjusting the current supplied to the gate of the low-side driver element 12. In this case, the low-side pre-driver circuit 22 needs to be configured as shown in FIG. 4.

[0074] In the first and second embodiments, the solenoid 100, which is the load, is connected to the ground. However, the present invention is not limited to this, and the solenoid 100 may be connected to a power source.

[0075] In the first embodiment described above, the second switch 21f is turned off except when controlling the voltage slope. However, the second switch 21f may be turned on when the third switch 21g is turned on, i.e., when the boost circuit 21c is used. This allows the gate to be charged and discharged as quickly as possible while minimizing the effect on voltage slope control.

[0076] The above-described embodiments are merely examples and should not be construed as limiting the scope of the present disclosure. The scope of the present disclosure is defined by the claims, and all modifications and variations that fall within the scope of the claims equivalents are within the scope of the present disclosure. [Industrial Applicability]

[0077] The technology disclosed herein is useful for achieving both a reduction in EMI noise and a reduction in switching loss in a load drive control device while standardizing the IC configuration. [Explanation of symbols]

[0078] 1 Driver IC (load drive control device) 10 Driver circuit 11 High-side driver element 12 Low-side driver element 20 Pre-driver circuit 21 High-side pre-driver circuit 21b Current slope control circuit 21c Voltage slope control circuit 22 Low-side pre-driver circuit 30 Controllers 100 Solenoid valve (load) 201 Driver IC (load drive control device) 240 Storage device

Claims

1. A load drive control device that controls driving of a load mounted on a vehicle, a driver circuit for driving a load; a pre-driver circuit for driving the driver circuit; a controller that controls a driving state of the driver circuit by outputting a current control signal and a voltage control signal to the pre-driver circuit; the driver circuit has a high-side transistor provided between a first terminal to which a wire harness is connected and an output terminal, and a low-side driver element provided between a second terminal to which a wire harness is connected and the output terminal, The pre-driver circuit a current slope control circuit that controls a gate current or a gate voltage of the high-side transistor based on the current control signal received from the controller, thereby controlling the gradient of a current slope, which is the rise and fall of an output current output from the output terminal; a voltage slope control circuit that controls a gate current or a gate voltage of the high-side transistor based on the voltage control signal received from the controller, thereby controlling a gradient of a voltage slope that is a rise and fall of an output voltage output from the output terminal; The controller a current control signal selected from a plurality of current control signals set for each current slope pattern, and a voltage control signal selected from a plurality of voltage control signals set for each voltage slope pattern, are output to the pre-driver circuit as the current control signal, thereby controlling the gradient of the current slope and the gradient of the voltage slope, When turning on the high-side transistor, the current control signal is output to control the gradient of the current slope, and then the voltage control signal is output to control the gradient of the voltage slope; When turning off the high-side transistor, the voltage control signal is output to control the gradient of the voltage slope, and then the current control signal is output to control the gradient of the current slope; the pre-driver circuit further includes a current supply circuit that inputs and outputs the first control current generated by the current slope control circuit and the second control current generated by the voltage slope control circuit to and from the gate of the high-side transistor; the current slope control circuit generates the first control current that increases or decreases in response to the current control signal, and supplies the first control current to the gate of the high-side transistor via the current supply circuit, thereby controlling the gradient of the current slope; the voltage slope control circuit generates the second control current that increases or decreases in response to the voltage control signal, and supplies the second control current to the gate of the high-side transistor via the current supply circuit, thereby controlling the gradient of the voltage slope. A load drive control device characterized by:

2. 2. The load drive control device according to claim 1, a memory device electrically connected to the controller and configured to store a plurality of the current control signals and a plurality of the voltage control signals; The controller reads a desired current control signal from the plurality of current control signals stored in the storage device and outputs it to the current slope control circuit, and reads a desired voltage control signal from the plurality of voltage control signals stored in the storage device and outputs it to the voltage slope control circuit.

3. 3. The load drive control device according to claim 2, the storage device pre-stores combinations of the plurality of current control signals and the plurality of voltage control signals; The controller reads a combination of the current control signal and the voltage control signal from the storage device, outputs the current control signal according to the combination to the current slope control circuit, and outputs the voltage control signal according to the combination to the voltage slope control circuit.

4. 2. The load drive control device according to claim 1, The controller controls the gradient of the current slope when turning on and off the high-side transistor, and the period of time is: When the high-side transistor is turned on, a period is set from when the high-side transistor is turned on until a current output from the high-side transistor reaches a predetermined current, a voltage control signal for controlling a voltage slope gradient when the high-side transistor is turned off, and a time period from when the high-side transistor is turned off to when the high-side transistor is turned off is set.

5. 2. The load drive control device according to claim 1, a period during which the controller controls the gradient of the voltage slope when the high-side transistor is turned on and off, the period being set to a period including a mirror period when the high-side transistor is turned on and off.

6. 2. The load drive control device according to claim 1, the load is provided between the output terminal and ground, 10. A load drive control device, wherein the low-side driver element is a transistor or a diode.

7. 4. The load drive control device according to claim 3, The load drive control device is characterized in that the controller receives a setting signal from an external device and changes the combination of the current control signal and the voltage control signal read from the storage device based on the setting signal.

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