Gate driver circuits, motor drive devices using them, and electronic devices.

Abstract

This solves the problem that arises when turning off high-side or low-side transistors. [Solution] The first output sensor 280 controls the output voltage V of the output stage 110. OUT The first threshold voltage V TH1 When the value drops to a certain level, the first output detection signal VOUTDET1 is asserted. When the output stage 110 is in current source mode, the control circuit 210 responds to the instruction to turn off the high-side transistor MH by causing the high-side driver 220 to sink the high-side gate current I from the gate of the high-side transistor MH. HG_OFF The first current I1 is set. The control circuit 210 responds to the assertion of the first output detection signal VOUTDET1 by setting the high-side gate current I HG_OFF Set the current to a second current I2, which is less than the first current I1.

Description

[Technical Field]

[0001] This disclosure relates to a gate driver circuit. [Background technology]

[0002] Half-bridge circuits, H-bridge circuits, and three-phase bridge circuits (hereinafter collectively referred to as switching circuits) using power transistors are used in motor driver circuits, DC / DC converters, power conversion devices, and the like. [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] International Publication No. WO2022 / 259780

[0004] [overview] This disclosure is made in the present circumstances, and one exemplary objective of a certain aspect thereof is to provide a gate driver circuit that can solve problems that arise when turning off a high-side transistor or a low-side transistor in a switching circuit.

[0005] A gate driver circuit in one aspect of the present disclosure drives a high-side transistor and a low-side transistor constituting an output stage. The gate driver circuit comprises a high-side driver for driving the high-side transistor, a low-side driver for driving the low-side transistor, a first output sensor that asserts a first output detection signal when the output voltage of the output stage drops to a first threshold voltage, and a control circuit for controlling the high-side driver and the low-side driver. When the output stage is in current source mode, the control circuit, in response to an instruction to turn off the high-side transistor, sets the high-side gate current that the high-side driver sinks from the gate of the high-side transistor to a first current, and in response to the assertion of the first output detection signal, sets the high-side gate current to a second current that is less than the first current.

[0006] Another aspect of the present disclosure is a gate driver circuit. This gate driver circuit comprises a high-side driver for driving a high-side transistor, a low-side driver for driving a low-side transistor, a third output sensor that asserts a third output detection signal when the output voltage of the output stage rises to a third threshold voltage, and a control circuit for controlling the high-side driver and the low-side driver. When the output stage is in current sink mode, the control circuit sets the low-side gate current that the low-side driver sinks from the gate of the low-side transistor to a fourth current quantity in response to an instruction to turn off the low-side transistor, and sets the low-side gate current to a fifth current quantity that is less than the fourth current quantity in response to the assertion of the third output detection signal.

[0007] Furthermore, any combination of the above components, and any substitution of the components or expressions of this disclosure between methods, apparatus, systems, etc., are also valid embodiments of the present invention. [Brief explanation of the drawing]

[0008] [Figure 1] Figure 1 is a circuit diagram illustrating the switching of a switching circuit. [Figure 2] Figure 2 shows the operating waveform of the switching circuit in Figure 1. [Figure 3] Figure 3 is a circuit diagram of a switching circuit according to an embodiment. [Figure 4] Figure 4 is a waveform diagram illustrating the operation of the switching circuit shown in Figure 3. [Figure 5] Figure 5 is a circuit diagram of a switching circuit according to Modification Example 1. [Figure 6] Figure 6 is a waveform diagram illustrating the operation of the switching circuit shown in Figure 5. [Figure 7] Figure 7 is a circuit diagram of a switching circuit according to modified example 2. [Figure 8] Figure 8 is a waveform diagram illustrating the operation of the switching circuit shown in Figure 7. [Figure 9]Figure 9 is a circuit diagram of a switching circuit according to modified example 3. [Figure 10] Figure 10 is a circuit diagram of a switching circuit according to modified example 4. [Figure 11] Figure 11 is a circuit diagram of a switching circuit according to modified example 5. [Figure 12] Figure 12 is a circuit diagram of a motor drive device according to an embodiment.

[0009] [Detailed explanation] (Summary of the embodiment) This section outlines some exemplary embodiments of the present disclosure. This outline is intended to provide a basic understanding of the embodiments and to simplify some concepts of one or more embodiments, serving as a prelude to the more detailed descriptions that follow later, and is not intended to limit the scope of the invention or disclosure. For convenience, “one embodiment” may be used to refer to one embodiment (example or variation) or more embodiments (example or variation) disclosed herein.

[0010] This summary is not intended to be a comprehensive overview of all possible embodiments, nor is it intended to identify key elements of all embodiments or to define the scope of some or all aspects. Its sole purpose is to present some concepts of one or more embodiments in a simplified form as a prelude to the more detailed descriptions that will follow.

[0011] A gate driver circuit according to one embodiment drives a high-side transistor and a low-side transistor that constitute an output stage. The gate driver circuit includes a high-side driver that drives the high-side transistor, a low-side driver that drives the low-side transistor, a first output sensor that asserts a first output detection signal when the output voltage of the output stage drops to a first threshold voltage, and a control circuit that controls the high-side driver and the low-side driver. When the output stage is in current source mode, the control circuit responds to an instruction to turn off the high-side transistor by setting the high-side gate current that the high-side driver sinks from the gate of the high-side transistor to a first current amount, and responds to the assertion of the first output detection signal by setting the high-side gate current to a second current amount that is less than the first current amount.

[0012] During the transition from a high output state to a low output state (or high impedance state), the drain current flowing through the high-side transistor (hereinafter referred to as the high-side current) changes while the output voltage is transitioning from a high voltage to a low voltage. After the output voltage transition is complete, the high-side current becomes substantially constant. In the above configuration, the assertion of the first output detection signal indicates the completion of the output voltage transition. When the output stage operates in current source mode, the turn-off time can be shortened and power consumption reduced by increasing the high-side gate current during the period when the high-side current is substantially constant after the output voltage transition is complete. Furthermore, during the period when the high-side current changes during the output voltage transition, reducing the high-side gate current can decrease the rate of change of the high-side current and suppress EMI. Negative voltages generated at the output can also be suppressed.

[0013] In one embodiment, the gate driver circuit may further include a second output sensor that asserts a second output detection signal when the output voltage drops to a second threshold voltage that is predetermined to be lower than the input voltage of the output stage. In response to the assertion of the second output detection signal, the control circuit may set the high-side gate current to a third current amount that is less than the first current amount.

[0014] In a section where the high-side current is substantially constant, the amount of high-side gate current can be switched in two stages to increase the first current, further shortening the turn-off time and reducing power consumption.

[0015] In one embodiment, the gate driver circuit may further include a first delay circuit that delays the second output detection signal. The control circuit may set the high-side gate current to a third current quantity in response to the assertion of the delayed second output detection signal.

[0016] This allows the period in which the high-side gate current is the first current to be extended by the amount of the delay, thus further shortening the turn-off time.

[0017] In one embodiment, the gate driver circuit may further include a high-side-off sensor that asserts a high-side-off detection signal when the gate-source voltage of the high-side transistor falls below a predetermined threshold level, and a high-side-off locking switch connected between the gate and source of the high-side transistor. The control circuit may turn on the high-side-off locking switch in response to the assertion of the high-side-off detection signal when the output stage is in current-source mode. This prevents the high-side transistor from self-turning on.

[0018] In one embodiment, when the output stage is in current sink mode, the control circuit may, in response to an instruction to turn off the high-side transistor, set the high-side gate current that the high-side driver sinks from the gate of the high-side transistor to a first current quantity, and in response to the assertion of the high-side off detection signal, turn on the high-side off fixed switch.

[0019] During the transition from a high-output state to a low-output state (or high-impedance state), in current-sink mode, the output voltage remains near the input voltage, resulting in minimal fluctuations in the drain current of the high-side transistor. Therefore, by sinking the high-side gate current of the first current until the turn-off of the high-side transistor is complete, the high-side transistor can be turned off in a short time.

[0020] In one embodiment, the gate driver circuit may further include a third output sensor that asserts a third output detection signal when the output voltage of the output stage rises to a third threshold voltage. The control circuit may, when the output stage is in current sink mode, set the low-side gate current that the low-side driver sinks from the gate of the low-side transistor to a fourth current quantity in response to an instruction to turn off the low-side transistor, and set the low-side gate current to a fifth current quantity that is less than the fourth current quantity in response to the assertion of the third output detection signal.

[0021] During the transition from a low output state to a high output state (or high impedance state), the drain current flowing through the low-side transistor (hereinafter referred to as the low-side current) changes while the output voltage is transitioning from a low voltage to a high voltage. After the output voltage transition is complete, the low-side current becomes substantially constant. In the above configuration, the assertion of the third output detection signal indicates the completion of the output voltage transition. When the output stage operates in current sink mode, the low-side gate current can be increased during the period when the low-side current is substantially constant after the output voltage transition is complete, thereby shortening the turn-off time and reducing power consumption. Furthermore, during the period when the low-side current changes during the output voltage transition, the rate of change of the low-side current can be reduced by decreasing the low-side gate current, thereby suppressing EMI.

[0022] In one embodiment, the gate driver circuit may further include a fourth output sensor that asserts a fourth output detection signal when the output voltage rises to a fourth threshold voltage that is predetermined to be lower than the input voltage of the output stage. When the output stage is in current sink mode, the control circuit may, in response to the assertion of the fourth output detection signal, set the low-side gate current to a fifth current amount that is less than the fourth current amount.

[0023] In a section where the low-side current is substantially constant, the amount of low-side gate current can be switched in two stages to increase the fourth current, further shortening the turn-off time and reducing power consumption.

[0024] In one embodiment, the gate driver circuit may further include a second delay circuit that delays the fourth output detection signal. The control circuit may set the low-side gate current to a fifth current quantity in response to the assertion of the delayed fourth output detection signal when the output stage is in current sink mode.

[0025] This allows the period in which the low-side gate current is the fourth current to be extended by the amount of the delay time, thus further shortening the turn-off time.

[0026] In one embodiment, the gate driver circuit may further include a low-side off sensor that asserts a low-side off detection signal when the gate-source voltage of the low-side transistor falls below a predetermined threshold level, and a low-side off lock switch connected between the gate and source of the low-side transistor. The control circuit may turn on the low-side off lock switch in response to the assertion of the low-side off detection signal when the output stage is in current-source mode. This prevents the low-side transistor from self-turning on.

[0027] In one embodiment, when the output stage is in current sink mode, the control circuit may, in response to an instruction to turn off the low-side transistor, set the high-side gate current that the low-side driver sinks from the gate of the low-side transistor to a fourth current quantity, and in response to the assertion of the low-side off detection signal, turn on the low-side off fixed switch.

[0028] During the transition from a low-output state to a high-output state (or high-impedance state), when in current-source mode, the output voltage remains near the ground voltage, resulting in minimal fluctuations in the drain current of the low-side transistor. Therefore, by sinking the low-side gate current of the fourth current until the low-side transistor's turn-off is complete, the low-side transistor can be turned off in a short time.

[0029] A gate driver circuit according to one embodiment drives a high-side transistor and a low-side transistor that constitute an output stage. The gate driver circuit includes a high-side driver that drives the high-side transistor, a low-side driver that drives the low-side transistor, a third output sensor that asserts a third output detection signal when the output voltage of the output stage rises to a third threshold voltage, and a control circuit that controls the high-side driver and the low-side driver. When the output stage is in current sink mode, the control circuit responds to an instruction to turn off the low-side transistor by setting the low-side gate current that the low-side driver sinks from the gate of the low-side transistor to a fourth current quantity, and responds to the assertion of the third output detection signal by setting the low-side gate current to a fifth current quantity that is less than the fourth current quantity.

[0030] In one embodiment, the gate driver circuit may further include a fourth output sensor that asserts a fourth output detection signal when the output voltage rises to a fourth threshold voltage that is predetermined to be lower than the input voltage of the output stage. In response to the assertion of the fourth output detection signal, the control circuit may set the low-side gate current to a fifth current amount that is less than the fourth current amount.

[0031] In one embodiment, the gate driver circuit may further include a second delay circuit that delays the fourth output detection signal. The control circuit may set the low-side gate current to a fifth current quantity in response to the assertion of the delayed fourth output detection signal.

[0032] In one embodiment, the gate driver circuit may further include a low-side off sensor that asserts a low-side off detection signal when the gate-source voltage of the low-side transistor falls below a predetermined threshold level, and a low-side off lock switch connected between the gate and source of the low-side transistor. The control circuit may turn on the low-side off lock switch in response to the assertion of the low-side off detection signal when the output stage is in current-source mode. This prevents the low-side transistor from self-turning on.

[0033] In one embodiment, when the output stage is in current sink mode, the control circuit may, in response to an instruction to turn off the low-side transistor, set the low-side gate current that the low-side driver sinks from the gate of the low-side transistor to a fourth current quantity, and in response to the assertion of the low-side off detection signal, turn on the low-side off fixed switch.

[0034] During the transition from a low-output state to a high-output state (or high-impedance state), when in current-source mode, the output voltage remains near the ground voltage, resulting in minimal fluctuations in the drain current of the low-side transistor. Therefore, by sinking the low-side gate current of the fourth current until the low-side transistor's turn-off is complete, the low-side transistor can be turned off in a short time.

[0035] In one embodiment, the gate driver circuit may be integrated onto a single semiconductor substrate. "Integrated integration" includes cases where all the circuit components are formed on the semiconductor substrate, or where the main components of the circuit are integrated, and some resistors, capacitors, etc., may be provided outside the semiconductor substrate for adjusting circuit constants. Integrating the circuit onto a single chip can reduce the circuit area and maintain uniformity of the characteristics of the circuit elements.

[0036] In one embodiment, the motor drive circuit may include an output stage including a high-side transistor and a low-side transistor, and one of the above-described gate driver circuits for driving the output stage.

[0037] In one embodiment, the electronic device may include a motor and the motor drive device described above for driving the motor.

[0038] (Embodiment) Preferred embodiments will be described below with reference to the drawings. The same or equivalent components, members, and processes shown in each drawing will be denoted by the same reference numerals, and redundant descriptions will be omitted as appropriate. Furthermore, these embodiments are illustrative and not limiting to the invention, and not all features or combinations thereof described in the embodiments are necessarily essential to the invention.

[0039] In this specification, "member A connected to member B" includes not only cases where member A and member B are directly connected physically, but also cases where member A and member B are indirectly connected via other members that do not substantially affect their electrical connection or impair the functions or effects produced by their combination.

[0040] Similarly, "the state in which member C is provided between member A and member B" includes not only cases where member A and member C, or member B and member C, are directly connected, but also cases where they are indirectly connected via other members that do not substantially affect their electrical connection state or impair the functions or effects produced by their combination.

[0041] First, we will explain the problems that occur when turning off a power transistor in a switching circuit.

[0042] Figure 1 is a circuit diagram illustrating the switching of the switching circuit 10. Here, the turn-off operation of the high-side transistor will be explained. The switching circuit 10 includes a high-side transistor MH and a low-side transistor ML connected in series between the power supply terminal and the ground terminal.

[0043] The switching circuit 10 in Figure 1 operates in current source mode, and current I flows from the switching circuit 10 to the load (not shown). OUT It will be supplied.

[0044] state φ H This indicates a high-output state where the high-side transistor MH is ON and the low-side transistor ML is OFF. The high-side current I flows from the power line through the high-side transistor MH. HO Output current I OUT It is supplied to the load as such.

[0045] States φ1 and φ2 indicate the turn-off period of the high-side transistor MH. The high-side driver 20 draws a constant gate current I from the gate of the high-side transistor MH. HG By pulling out the power, the gate-source voltage of the high-side transistor MH decreases over time. In state φ1, the load current is mainly the high-side current I flowing through the high-side transistor MH. HO In state φ2, the load current is the high-side current I flowing through the high-side transistor MH. HOand the current I flowing through the body diode of the low-side transistor ML LO is the total of these.

[0046] State φ DT indicates a dead time state in which both the high-side transistor MH and the low-side transistor ML are off. At this time, the load is supplied from the body diode of the low-side transistor ML.

[0047] FIG. 2 is an operation waveform diagram of the switching circuit 10 in FIG. 1. In states φ1 and φ2, it is assumed that the high-side driver 20 sinks a certain amount of gate current I HG from the gate of the high-side transistor MH. The gate current I HG is defined such that the direction flowing into the gate of the high-side transistor MH is positive and the direction pulled out from the gate is negative.

[0048] In control where the gate current I HG is set to a certain amount, if the gate current I HG is small, the power consumption of the high-side transistor MH increases and the amount of heat generation increases.

[0049] Conversely, if the gate current I HG is increased, the power consumption of the high-side transistor MH decreases, but the slope of the high-side current I HO flowing through the high-side transistor MH in state φ2 becomes larger, and the EMI becomes larger. Also, if the slope of the high-side current I HO in state φ2 is large, the output voltage V OUT becomes a large negative voltage until the body diode of the low-side transistor ML conducts.

[0050] Thus, in control where the gate current I HG is set to a certain amount, there is a trade-off relationship between the power consumption of the high-side transistor MH, the EMI, and the negative voltage of the output.

[0051] The following describes a gate driver circuit that can suppress EMI and negative voltage while reducing power consumption.

[0052] Figure 3 is a circuit diagram of a switching circuit 100 according to an embodiment. The switching circuit 100 includes an output stage 110 and a gate driver circuit 200. Here, only the configuration of one phase of the switching circuit 100 is shown, but the switching circuit 100 may be a three-phase circuit or an H-bridge circuit.

[0053] The output stage 110 includes a high-side transistor MH located between the power line (input line) 102 and the output terminal (output line) 104, and a low-side transistor ML located between the output line 104 and the ground line 106. The input line 102 has an input voltage V M In this embodiment, the high-side transistor MH and the low-side transistor ML are N-channel MOSFETs, and their respective body diodes also function as flywheel diodes.

[0054] The gate driver circuit 200 drives the high-side transistor MH and the low-side transistor ML of the output stage 110.

[0055] Between the bootstrap pin BST and output line 104 is the bootstrap capacitor C. BST The following connections are made. The high-side gate pin HG is connected to the gate of the high-side transistor MH. The switching pin SW is connected to the source of the high-side transistor MH and the drain of the low-side transistor ML. The low-side gate pin LG is connected to the gate of the low-side transistor ML.

[0056] Bootstrap line 202 is connected to bootstrap pin BST. A constant voltage V is supplied to bootstrap line 202 via rectifier element 203. REG A voltage is applied. Rectifier element 203 and bootstrap capacitor C BSTThis forms a bootstrap circuit, and the voltage V of the bootstrap line 202 BST V OUT +V REG Maintain the forward voltage at -Vf. Vf is the forward voltage of the rectifier element 203.

[0057] The gate driver circuit 200 is a functional IC integrated on a single semiconductor substrate, comprising a control circuit 210, a high-side driver 220, a low-side driver 250, a first output sensor 280, a high-side off sensor 290, and a low-side off sensor 292. The control circuit 210 controls the high-side driver 220 and the low-side driver 250 according to the load state of the output stage 110.

[0058] The high-side driver 220 includes a turn-on circuit 230 and a turn-off circuit 240. The turn-on circuit 230 becomes active when the high-side transistor MH is turned on, and a gate current I is supplied to the gate of the high-side transistor MH. HG_ON Source it. Gate current I HG_ON This charges the gate capacitance of the high-side transistor MH, causing the gate-source voltage of the high-side transistor MH to rise.

[0059] The turn-off circuit 240 becomes active when the high-side transistor MH is turned off, and a gate current I is released from the gate of the high-side transistor MH. HG_OFF Sink the gate current I HG_OFF This discharges the gate capacitance of the high-side transistor MH, causing the gate-source voltage of the high-side transistor MH to decrease.

[0060] The low-side driver 250 includes a turn-on circuit 260 and a turn-off circuit 270. The turn-on circuit 260 becomes active when the low-side transistor ML is turned on, and a gate current I is supplied to the gate of the low-side transistor ML. LG_ON Source it. Gate current I LG_ONThis charges the gate capacitance of the low-side transistor ML, increasing the gate-source voltage of the low-side transistor ML.

[0061] The turn-off circuit 270 becomes active when the low-side transistor ML is turned off, and the gate current I from the gate of the low-side transistor ML is released. LG_OFF Sink the gate current I LG_OFF This discharges the gate capacitance of the low-side transistor ML, causing the gate-source voltage of the low-side transistor ML to decrease.

[0062] The first output sensor 280 is connected to the switching line 206, and the output voltage V OUT It monitors the output voltage V. The first output sensor 280 monitors the output voltage V. OUT However, the first threshold voltage V TH1 When it falls below this value, the first output detection signal VOUTDET1 is asserted (e.g., high). First threshold voltage V TH1 This can be set to around 0V, for example, around 1V.

[0063] The high-side-off sensor 290 asserts (e.g., high) the high-side-off detection signal HS_OFF when it detects the turn-off of the high-side transistor MH. For example, the high-side-off sensor 290 detects the gate-source voltage V of the high-side transistor MH. HGS A predetermined threshold voltage V OFF Compared with V HGS <V OFF Therefore, the high-side off detection signal HS_OFF is asserted.

[0064] When the low-side off sensor 292 detects the turn-off of the low-side transistor ML, it asserts (e.g., high) the low-side off detection signal LS_OFF. For example, the low-side off sensor 292 detects the gate-source voltage V of the low-side transistor ML. LGS A predetermined threshold voltage V OFF Compared with V LGS <V OFFTherefore, the low-side off detection signal LS_OFF is asserted.

[0065] In this embodiment, the turn-off circuit 240 of the high-side driver 220 draws a gate current I from the gate of the high-side transistor MH. HG_OFF It is configured to be switchable in multiple stages.

[0066] In addition to turning the turn-off circuit 240 on and off, the control circuit 210 also controls the gate current I generated by the turn-off circuit 240. HG_OFF It controls the amount of current.

[0067] Specifically, the control circuit 210 controls the output current I of the output stage 110. OUT In the operating mode (current source mode) where current flows out toward the load (not shown), the turn-off circuit 240 is controlled as follows.

[0068] The control circuit 210 responds to the instruction to turn off the high-side transistor MH by controlling the gate current I of the turn-off circuit 240. HG_OFF Set the first current quantity I1. Then, in response to the assertion of the first output detection signal VOUTDET1, the gate current I HG_OFF Set the current to a second current I2, which is less than the first current I1.

[0069] In response to the assertion of the high-side off detection signal HS_OFF, the control circuit 210 activates the low-side driver 250 and starts the turn-on operation of the low-side transistor ML.

[0070] Furthermore, the control circuit 210 controls the turn-off circuit 240 in response to the assertion of the high-side off detection signal HS_OFF, thereby controlling the gate-source voltage V of the high-side transistor MH. HGSThe voltage is fixed to 0V. For example, the high-side driver 220 may include a high-side off lock switch 222, which is an NMOS transistor connected between the gate and source of the high-side transistor MH, and by fully turning on the high-side off lock switch 222 in response to the assertion of the high-side off detection signal HS_OFF, the high-side transistor MH may be fixed in the off state. This prevents the high-side transistor MH from self-turning on during the turn-on operation of the low-side transistor ML after the high-side transistor MH has turned off.

[0071] If the turn-off circuit 240 includes an NMOS transistor connected between the gate and source of the high-side transistor MH, this NMOS transistor may be used as a high-side off fixed switch 222.

[0072] The above describes the configuration of the switching circuit 100. Next, its operation will be explained.

[0073] Figure 4 is a waveform diagram illustrating the operation of the switching circuit 100 shown in Figure 3. The switching circuit 100 is operating in current source mode. The method for determining the current sink mode and current source mode is not particularly limited and can be performed using publicly available technology (for example, Japanese Patent Application Publication No. 10-341588). Specifically, in current source mode, the first output detection signal VOUTDET1 and the second output detection signal VOUTDET2 are asserted before the high-side off detection signal HS_OFF. Conversely, in current sink mode, the high-side off detection signal HS_OFF is asserted before the first output detection signal VOUTDET1 and the second output detection signal VOUTDET2. Therefore, the control circuit 210 may determine the current sink mode and current source mode based on the order in which several detection signals change.

[0074] When a command to turn off the high-side transistor MH is issued at time t0, the control circuit 210 controls the gate current I HGSet the current to the first current I1 and activate the turn-off circuit 240 of the high-side driver 220.

[0075] At time t1, the output voltage V OUT The first threshold voltage V TH1 When the value falls below a certain level, the first output detection signal VOUTDET1 is asserted. In response to the assertion of the first output detection signal VOUTDET1, the control circuit 210 sets the gate current I HG Set this to the second current quantity I2.

[0076] At time t2, the gate-source voltage V of the high-side transistor MH is HGS The threshold voltage V OFF When the voltage drops to a certain level, the high-side off detection signal HS_OFF is asserted.

[0077] When the high-side off detection signal HS_OFF is asserted, the gate-source voltage V of the high-side transistor MH is activated. HGS The voltage is fixed at 0V.

[0078] Furthermore, in response to the assertion of the high-side off detection signal HS_OFF, the low-side driver 250 becomes active and starts the turn-on operation of the low-side transistor ML.

[0079] The above describes the operation of the switching circuit 100.

[0080] In the time chart of Figure 4, the period t0 to t1 corresponds to state φ1 in Figure 1, and the period t1 to t2 corresponds to state φ2 in Figure 1. According to the gate driver circuit 200 of the embodiment, the first output sensor 280 detects the transition from state φ1 to φ2, and in state φ1, the gate current I HG_OFF By increasing the current, the turn-off time can be shortened, and the power consumption of the high-side transistor MH can be reduced. Also, in state φ2, the gate current I HG_OFF By reducing the amount of current, the high-side current I HO The slope can be reduced, and EMI can be suppressed. Also, the output voltage VOUT This can suppress the generation of negative voltage.

[0081] Then, after the turn-off of the high-side transistor MH is complete, fixing the high-side transistor MH in the off position prevents it from self-turning on during the subsequent turn-on operation of the low-side transistor ML.

[0082] Next, we will explain a modified version of the switching circuit 100.

[0083] In the embodiment shown in Figure 3, the gate current I HG_OFF The switching was done in two stages, but it would also be possible to switch in three or more stages.

[0084] (Variation 1) Figure 5 is a circuit diagram of the switching circuit 100A according to Modification 1. In Modification 1, the turn-off circuit 240A of the high-side driver 220A has a gate current I HG_OFF This is configured to be switchable in three stages. The high-side driver 220A may include a high-side off fixed switch 222, but this is omitted in Figure 5 and subsequent figures.

[0085] The gate driver circuit 200A further includes a second output sensor 282. The second output sensor 282 is connected to the switching line 206 and outputs voltage V OUT The second output sensor 282 monitors the output voltage V. OUT However, the first threshold voltage V TH1 A higher second threshold voltage V TH2 When it falls below this level, the second output detection signal VOUTDET2 is asserted (e.g., high). Second threshold voltage V TH2 The input voltage V M It can be set in the vicinity. Asserting the second output detection signal VOUTDET2 is done when the output voltage V OUT This indicates the start of the transition.

[0086] For example, V TH1 =V TH ,V TH2=VM-V TH It may also be defined as follows: V TH This can be set to approximately 1V.

[0087] The control circuit 210A responds to the instruction to turn off the high-side transistor MH by adjusting the gate current I of the turn-off circuit 240A. HG_OFF Set this to the first current quantity I1.

[0088] Then, in response to the assertion of the second output detection signal VOUTDET2, the control circuit 210A controls the gate current I of the turn-off circuit 240A. HG_OFF Set this to the third current I3. The third current I3 is I1 > I3 > I2 It satisfies the relationship.

[0089] Then, in response to the assertion of the first output detection signal VOUTDET1, the control circuit 210A controls the gate current I of the turn-off circuit 240A. HG_OFF Set this to the second current quantity I2.

[0090] In response to the assertion of the high-side off detection signal HS_OFF, the control circuit 210A activates the low-side driver 250 and starts the turn-on operation of the low-side transistor ML.

[0091] The above describes the configuration of the gate driver circuit 200A. Next, we will explain its operation.

[0092] Figure 6 is a waveform diagram illustrating the operation of the switching circuit 100A shown in Figure 5. The switching circuit 100A is operating in current source mode.

[0093] When a command to turn off the high-side transistor MH is issued at time t0, the control circuit 210A controls the gate current I HG Set this to the first current I1 and activate the turn-off circuit 240A of the high-side driver 220.

[0094] At time t1, the output voltage V OUTfalls below the second threshold voltage V TH2 , the second output detection signal VOUTDET2 is asserted. In response to the assertion of the second output detection signal VOUTDET2, the control circuit 210A sets the gate current I HG to the third current amount I3.

[0095] At time t2, when the output voltage V OUT falls below the first threshold voltage V TH1 , the first output detection signal VOUTDET1 is asserted. In response to the assertion of the first output detection signal VOUTDET1, the control circuit 210A sets the gate current I HG to the second current amount I2.

[0096] At time t3, when the voltage V HGS between the gate and source of the high-side transistor MH drops to the threshold voltage V OFF , the high-side off detection signal HS_OFF is asserted. When the high-side off detection signal HS_OFF is asserted, the voltage V HGS between the gate and source of the high-side transistor MH is fixed to 0V.

[0097] Also, in response to the assertion of the high-side off detection signal HS_OFF, the low-side driver 250 becomes active and starts the turn-on operation of the low-side transistor ML.

[0098] The above is the operation of the switching circuit 100A.

[0099] According to the first modification, by adding the second output sensor 282, in the section corresponding to the state φ1 in FIG. 1, the gate current I HG_OFF can be switched in two steps between the first current amount I1 and the third current amount I3. Thereby, the first current amount I1 in the first modification can be made larger than the first current amount I1 in the embodiment, and thereby, the turn-off time can be made shorter, and the power consumption of the high-side transistor MH can be further reduced.

[0100] (First modification) FIG. 7 is a circuit diagram of a switching circuit 100B according to Modification 2.

[0101] The gate driver circuit 200B further includes a first delay circuit 284. The first delay circuit 284 delays the second output detection signal VOUTDET2 by a certain delay time τd. The control circuit 280B, in response to the assertion of the delayed second output detection signal VOUTDET2, changes the gate current I HG_OFF from the first current amount I1 to the third current amount I3.

[0102] FIG. 8 is a waveform diagram for explaining the operation of the switching circuit 100B of FIG. 7. The switching circuit 100B is operating in the current source mode. In FIG. 8, the operation waveforms of the switching circuit 100A according to Modification 1 are shown by dashed lines.

[0103] At time t0, when a command to turn off the high-side transistor MH is generated, the control circuit 210B sets the gate current I HG to the first current amount I1 and activates the turn-off circuit 240B of the high-side driver 220.

[0104] At time t1, when the output voltage V OUT falls below the second threshold voltage V TH2 , the second output detection signal VOUTDET2 is asserted, and at time t2 after the elapse of the delay time τd, the output VOUTDET2' of the first delay circuit 284 is asserted. In response to the assertion of the delayed second output detection signal VOUTDET2, the control circuit 210B sets the gate current I HG to the third current amount I3.

[0105] At time t3, when the output voltage V OUT falls below the first threshold voltage V TH1 , the first output detection signal VOUTDET1 is asserted. In response to the assertion of the first output detection signal VOUTDET1, the control circuit 210B sets the gate current I HG to the second current amount I2.

[0106] At time t4, the gate-source voltage V of the high-side transistor MH is HGS The threshold voltage V OFF When the voltage drops to this level, the high-side off detection signal HS_OFF is asserted. When the high-side off detection signal HS_OFF is asserted, the gate-source voltage V of the high-side transistor MH is activated. HGS The voltage is fixed at 0V.

[0107] Furthermore, in response to the assertion of the high-side off detection signal HS_OFF, the low-side driver 250 becomes active and starts the turn-on operation of the low-side transistor ML.

[0108] The above describes the operation of the switching circuit 100B.

[0109] According to this modified example 2, the gate current I is different from that in modified example 1. HG_OFF The time during which the first current I1 is set becomes longer by the delay time τd. As a result, compared to Modification 1, The turn-off time of the high-side transistor MH can be further shortened, improving efficiency.

[0110] The previous explanation described the turn-off of the high-side transistor MH when operating in current-source mode. In the following modification, similar control is applied to the turn-off of the low-side transistor ML when operating in current-sink mode.

[0111] Figure 9 is a circuit diagram of the switching circuit 100C according to the modified example 3. The gate driver circuit 200C applies the control of the gate driver circuit 200 in Figure 3 to the low-side transistor ML as well.

[0112] In the gate driver circuit 200C, the turn-off circuit 270C of the low-side driver 250C turns off the low-side transistor ML, sinking current I from the gate of the low-side transistor ML. LG_OFF It is configured to be switchable in two stages.

[0113] Furthermore, the gate driver circuit 200C includes a third output sensor 286 in addition to the gate driver circuit 200 shown in Figure 3. The third output sensor 286 controls the output voltage V OUT It monitors the output voltage V. The third output sensor 286 monitors the output voltage V. OUT However, the third threshold voltage V TH3 When it exceeds this value, the third output detection signal VOUTDET3 is asserted (e.g., high). Third threshold voltage V TH3 The input voltage V M It can be set in the vicinity. For example, V TH1 =V TH , V TH3 =V M -V TH That is also acceptable.

[0114] In addition to turning the turn-off circuit 270C on and off, the control circuit 210C controls the gate current I generated by the turn-off circuit 270C. LG_OFF It controls the amount of current.

[0115] Specifically, the control circuit 210C controls the output current I of the output stage 110. OUT In the operating mode (current sink mode) in which current flows in from the load (not shown), the turn-off circuit 270C is controlled as follows.

[0116] The control circuit 210C responds to the instruction to turn off the low-side transistor ML by controlling the gate current I of the turn-off circuit 270C. LG_OFF Set the fourth current quantity I4. Then, in response to the assertion of the third output detection signal VOUTDET3, the gate current I LG_OFF Set the current to the fifth current I5, which is less than the fourth current I4.

[0117] In response to the assertion of the low-side off detection signal LS_OFF, the control circuit 210C activates the high-side driver 220 and starts the turn-on operation of the high-side transistor MH.

[0118] Furthermore, the control circuit 210C, in response to the assertion of the low-side off detection signal LS_OFF, controls the turn-off circuit 270C, thereby controlling the gate-source voltage V of the low-side transistor ML. LGS The voltage is fixed to 0V. For example, the low-side driver 250C may include a low-side off lock switch 252, which is an NMOS transistor connected between the gate and source of the low-side transistor ML, and by fully turning on the low-side off lock switch 252 in response to the assertion of the low-side off detection signal HS_OFF, the low-side transistor ML can be fixed in the off state. This prevents the low-side transistor ML from self-turning on during the turn-on operation of the high-side transistor MH after the low-side transistor ML has turned off.

[0119] If the turn-off circuit 270C includes an NMOS transistor connected between the gate and source of the low-side transistor ML, this NMOS transistor may be used as the low-side off fixed switch 252.

[0120] The above describes the configuration of the gate driver circuit 200C. This modified example 3 allows for reduced power consumption of the low-side transistor ML while suppressing EMI.

[0121] (Modification 4) Figure 10 is a circuit diagram of the switching circuit 100D according to modified example 4. The gate driver circuit 200D applies the control of the gate driver circuit 200A in Figure 5 to the low-side transistor ML as well.

[0122] The gate driver circuit 200D includes a third output sensor 286 and a fourth output sensor 288, in addition to the gate driver circuit 200A shown in Figure 5.

[0123] The fourth output sensor 288 outputs an output voltage V OUT However, the fourth threshold voltage V TH4 When it exceeds this value, the fourth output detection signal VOUTDET4 is asserted. The fourth threshold voltage V TH4This can be set to around 0V. For example, each threshold voltage may be defined as follows: V TH1 =V TH V TH2 =V M -V TH V TH3 =V M -V TH V TH4 =V TH In this case, the first output sensor 280 and the fourth output sensor 288 can be used interchangeably, and the second output sensor 282 and the third output sensor 286 can be used interchangeably. By using interchangeable output sensors with the same threshold voltage, the increase in circuit area can be suppressed.

[0124] The control circuit 210D responds to the instruction to turn off the low-side transistor ML by controlling the gate current I of the turn-off circuit 270D. HG_OFF Set this to the fourth current quantity I4.

[0125] Then, in response to the assertion of the fourth output detection signal VOUTDET4, the control circuit 210D controls the gate current I of the turn-off circuit 270D. LG_OFF Set this to the sixth current quantity I6. The sixth current quantity I6 is I4>I6>I5 It satisfies the relationship.

[0126] Then, in response to the assertion of the third output detection signal VOUTDET3, the control circuit 210D controls the gate current I of the turn-off circuit 270D. LG_OFF Set this to the 5th current quantity I5.

[0127] In response to the assertion of the low-side off detection signal LS_OFF, the control circuit 210D activates the high-side driver 220A and starts the turn-on operation of the high-side transistor MH.

[0128] Furthermore, the control circuit 210D controls the turn-off circuit 270D in response to the assertion of the low-side off detection signal LS_OFF, thereby controlling the gate-source voltage V of the low-side transistor ML. LGS Set it to 0V.

[0129] (Variation 5) Figure 11 is a circuit diagram of the switching circuit 100E according to modified example 5. The gate driver circuit 200E applies the control of the gate driver circuit 200B in Figure 7 to the low-side transistor ML as well.

[0130] The gate driver circuit 200E includes, in addition to the gate driver circuit 200B shown in Figure 7, a third output sensor 286, a fourth output sensor 288, and a second delay circuit 289.

[0131] The second delay circuit 289 delays the fourth output detection signal VOUTDET4. The control circuit 210E responds to the delayed fourth output detection signal VOUTDET4 by adjusting the gate current I of the turn-off circuit 270E. LG_OFF Set this to the sixth current quantity I6.

[0132] Next, the high output state φ of the switching circuit 100 when the output stage 110 is in current sink mode. H Low output state φ L This section describes the transition process to (or to a high-impedance state).

[0133] When the output stage 110 is in current sink mode, the output voltage V OUT This is high voltage (input voltage) V IN Maintain the vicinity, output voltage V OUT Because there is almost no change, the drain current of the high-side transistor MH is practically constant, and EMI is unlikely to occur.

[0134] When the output stage 110 is in current sink mode, the control circuit 210 responds to the instruction to turn off the high-side transistor MH by controlling the high-side gate current I HG_OFFSet the first current quantity I1. Then, in response to the assertion of the high-side-off detection signal HS_OFF, turn on the high-side-off fixed switch 222.

[0135] The above describes the turn-off operation of the high-side transistor MH in current sink mode. In current sink mode, during the turn-off of the high-side transistor MH, the output voltage V OUT Because there is no transition, the high-side gate current I of the first current I1 remains constant until the high-side transistor MH turns off. HG_OFF By syncing, the high-side transistor MH can be turned off in a short time.

[0136] Next, the low output state φ of the switching circuit 100 when the output stage 110 is in current source mode. L From high output state φ H This section describes the transition process to (or to a high-impedance state).

[0137] When the output stage 110 is in current source mode, the output voltage V OUT It maintains a low voltage (ground voltage) of around 0V, and the output voltage V OUT Because there is almost no change, the drain current of the low-side transistor ML is practically constant, and EMI is unlikely to occur.

[0138] When the output stage 110 is in current source mode, the control circuit 210 responds to the instruction to turn off the low-side transistor ML by controlling the low-side gate current I LG_OFF Set this to the fourth current quantity I4. Then, in response to the assertion of the low-side off detection signal LS_OFF, turn on the off-fixed switch 252.

[0139] The above describes the turn-off operation of the low-side transistor ML in current source mode. In current source mode, during the turn-off of the low-side transistor ML, the output voltage V OUT Because there is no transition, the low-side gate current I of the fourth current I4 remains unchanged until the low-side transistor ML turns off. LG_OFFBy syncing, the low-side transistor ML can be turned off in a short time.

[0140] (Application) Next, the applications of the switching circuit 100 will be explained. The switching circuit 100 can be suitably used in a motor drive circuit.

[0141] Figure 12 is a circuit diagram of a motor drive device 300 according to an embodiment. The motor drive device 300 drives a three-phase motor 302, which is the load, and controls its rotational state.

[0142] The motor drive unit 300 comprises an output stage 310 and a gate driver circuit 400. The output stage 310 is a three-phase inverter having U-phase, V-phase, and W-phase legs, and each phase leg has a high-side transistor MH and a low-side transistor ML.

[0143] The gate driver circuit 400 includes a control circuit 410 and high-side drivers 420U~420W and low-side drivers 450U~450W. The control circuit 410 generates control signals that indicate the state of the six arms constituting the output stage 310 based on the state of the load, which is a three-phase motor 302.

[0144] The high-side drivers 420U to 420W are constructed using the same architecture as the high-side driver 220 described above. The low-side drivers 450U to 450W are constructed using the same architecture as the low-side driver 250 described above.

[0145] Here, a three-phase motor is used as an example, but a single-phase motor can also be used. In this case, the output stage 310 will be an H-bridge circuit.

[0146] Next, the applications of the motor drive unit 300 will be explained. The motor drive unit 300 can be used to control the spindle motor of a hard disk, or to control the lens drive motor of an imaging device. Alternatively, it can be used to drive the drive motor of a printer head, or the paper feed motor. Alternatively, the motor drive unit 300 can be used to drive motors in electric vehicles, hybrid vehicles, and the like.

[0147] The embodiments are illustrative, and it will be understood by those skilled in the art that various modifications are possible in combinations of their components and processing steps, and that such modifications also fall within the scope of this disclosure or the present invention. Such modifications will be described below.

[0148] (Variation 1) In this embodiment, the output stage 110 is composed of discrete components, but it is not limited to that, and the output stage 110 may be integrated into the gate driver circuit 200.

[0149] (Modification 2) The upper arm 112 and the lower arm 114 may be composed of IGBTs (Insulated Gate Bipolar Transistors).

[0150] (Variation 3) The applications of the switching circuit 100 are not limited to the motor drive device 300. For example, the switching circuit 100 can be suitably used in switching regulators (DC / DC converters), various power conversion devices (inverters and converters), inverters for lighting discharge lamps, digital audio amplifiers, and so on. Therefore, the switching circuit 100 can be used in consumer electronics including electronic devices and home appliances, automobiles and in-vehicle components, industrial vehicles and industrial machinery.

[0151] The embodiments described using specific terminology merely illustrate the principles and applications of the present invention, and many modifications and changes in arrangement are permitted in the embodiments, without departing from the spirit of the present invention as defined in the claims.

[0152] (Note) This specification discloses the following technologies:

[0153] (Item 1) A gate driver circuit that drives the high-side transistor and low-side transistor that constitute the output stage, A high-side driver that drives the aforementioned high-side transistor, A low-side driver that drives the low-side transistor, When the output voltage of the output stage drops to a first threshold voltage, the first output sensor asserts a first output detection signal. A control circuit for controlling the high-side driver and the low-side driver, Equipped with, The control circuit, when the output stage is in current source mode, In response to the instruction to turn off the high-side transistor, the high-side driver sets the high-side gate current that sinks from the gate of the high-side transistor to a first current quantity. A gate driver circuit that, in response to the assertion of the first output detection signal, sets the high-side gate current to a second current amount that is less than the first current amount.

[0154] (Item 2) The system further includes a second output sensor that asserts a second output detection signal when the output voltage drops to a second threshold voltage that is a predetermined voltage lower than the input voltage of the output stage. The control circuit, when the output stage is in current source mode, The gate driver circuit described in item 1, which, in response to the assertion of the second output detection signal, sets the high-side gate current to a third current amount that is less than the first current amount.

[0155] (Item 3) The system further includes a first delay circuit that delays the second output detection signal, The gate driver circuit according to item 2, wherein the control circuit sets the high-side gate current to the third current amount in response to the assertion of the delayed second output detection signal when the output stage is in current source mode.

[0156] (Item 4) A high-side off sensor asserts a high-side off detection signal when the gate-source voltage of the high-side transistor falls below a predetermined threshold level. A high-side off fixed switch connected between the gate and source of the aforementioned high-side transistor, Furthermore, The control circuit is a gate driver circuit according to any one of items 1 to 3, wherein the control circuit turns on the high-side-off fixed switch in response to the assertion of the high-side-off detection signal when the output stage is in current source mode.

[0157] (Item 5) The control circuit, when the output stage is in current sink mode, In response to the instruction to turn off the high-side transistor, the high-side driver sets the high-side gate current that sinks from the gate of the high-side transistor to a first current quantity. The gate driver circuit described in item 4, which turns on the high-side-off fixed switch in response to the assertion of the high-side-off detection signal.

[0158] (Item 6) The system further includes a third output sensor that asserts a third output detection signal when the output voltage of the output stage rises to a third threshold voltage. The control circuit, when the output stage is in current sink mode, In response to the instruction to turn off the low-side transistor, the low-side driver sets the low-side gate current sunk from the gate of the low-side transistor to a fourth current quantity. A gate driver circuit according to any one of items 1 to 3, which sets the low-side gate current to a fifth current less than the fourth current in response to the assertion of the third output detection signal.

[0159] (Item 7) The system further includes a fourth output sensor that asserts a fourth output detection signal when the output voltage rises to a fourth threshold voltage that is a predetermined voltage lower than the input voltage of the output stage. The gate driver circuit according to item 6, wherein the control circuit, when the output stage is in current sink mode, sets the low-side gate current to a fifth current amount that is less than the fourth current amount in response to the assertion of the fourth output detection signal.

[0160] (Item 8) The system further includes a second delay circuit that delays the fourth output detection signal, The gate driver circuit according to item 7, wherein the control circuit sets the low-side gate current to the fifth current amount in response to the assertion of the delayed fourth output detection signal when the output stage is in current sink mode.

[0161] (Item 9) A low-side off sensor asserts a low-side off detection signal when the gate-source voltage of the low-side transistor falls below a predetermined threshold level. A low-side off fixed switch connected between the gate and source of the low-side transistor, Furthermore, The gate driver circuit according to item 6, wherein the control circuit turns on the low-side off fixed switch in response to the assertion of the low-side off detection signal when the output stage is in current source mode.

[0162] (Item 10) The control circuit, when the output stage is in current sink mode, In response to the instruction to turn off the low-side transistor, the low-side driver sets the low-side gate current sunk from the gate of the low-side transistor to a fourth current quantity. The gate driver circuit described in item 9, which turns on the low-side off fixed switch in response to the assertion of the low-side off detection signal.

[0163] (Item 11) A gate driver circuit that drives the high-side transistor and low-side transistor that constitute the output stage, A high-side driver that drives the aforementioned high-side transistor, A low-side driver that drives the low-side transistor, When the output voltage of the preceding output stage rises to the third threshold voltage, the third output sensor asserts the third output detection signal. A control circuit for controlling the high-side driver and the low-side driver, Equipped with, The control circuit, when the output stage is in current sink mode, In response to the instruction to turn off the low-side transistor, the low-side driver sets the low-side gate current sunk from the gate of the low-side transistor to a fourth current quantity. A gate driver circuit that, in response to the assertion of the third output detection signal, sets the low-side gate current to a fifth current amount that is less than the fourth current amount.

[0164] (Item 12) The system further includes a fourth output sensor that asserts a fourth output detection signal when the output voltage rises to a fourth threshold voltage that is a predetermined voltage lower than the input voltage of the output stage. The aforementioned control circuit is The gate driver circuit according to item 11, which, in response to the assertion of the fourth output detection signal, sets the low-side gate current to a fifth current amount that is less than the fourth current amount.

[0165] (Item 13) The system further includes a second delay circuit that delays the fourth output detection signal, The gate driver circuit according to item 12, wherein the control circuit sets the low-side gate current to the fifth current amount in response to the assertion of the fourth output detection signal after a delay.

[0166] (Item 14) A low-side off sensor asserts a low-side off detection signal when the gate-source voltage of the low-side transistor falls below a predetermined threshold level. A low-side off fixed switch connected between the gate and source of the low-side transistor, Furthermore, The control circuit is a gate driver circuit according to any one of items 11 to 13, wherein the control circuit turns on the low-side off fixed switch in response to the assertion of the low-side off detection signal when the output stage is in current source mode.

[0167] (Item 15) The control circuit, when the output stage is in current sink mode, In response to the instruction to turn off the low-side transistor, the low-side driver sets the low-side gate current sunk from the gate of the low-side transistor to a fourth current quantity. The gate driver circuit described in item 14, which turns on the low-side off fixed switch in response to the assertion of the low-side off detection signal.

[0168] (Item 16) A gate driver circuit, as described in items 1 to 3 or 11 to 13, integrated onto a single semiconductor substrate.

[0169] (Item 17) An output stage including high-side transistors and low-side transistors, A gate driver circuit according to any one of items 1 to 3 or 11 to 13 that drives the output stage, A motor drive device equipped with the following features.

[0170] (Item 18) Motor and, A motor drive device as described in item 17 for driving the motor, An electronic device equipped with the following features. [Explanation of Symbols]

[0171] 100 Switching Circuits 102 Power Line 104 output lines 106 Grounding line 110 Output Stage MH High-Side Transistor ML Low-Side Transistor 200 Gate Driver Circuit 202 Bootstrap Line 203 Rectifier 204 Switching Line 206 Power Line 208 Grounding line 210 Control circuits 220 High-Side Driver 222 High-side off fixed switch 230 Turn-on Circuit 240 Turn-off Circuit 250 Low-Side Driver 252 Low-side off fixed switch 260 Turn-on Circuit 270 Turn-off circuit 280 First Output Sensor 282 Second Output Sensor 284 First Delay Circuit 286 Third Output Sensor 288 Fourth Output Sensor 289 Second Delay Circuit VOUTDET1 First output detection signal VOUTDET2 Second output detection signal VOUTDET3 Third Output Detection Signal VOUTDET4 4th output detection signal 290 High-side off-sensor 292 Low-side off-sensor 300 Motor drive unit 302 Three-phase motor 310 Bridge Circuit 400 Gate Driver Circuit

Claims

1. A gate driver circuit that drives the high-side transistor and low-side transistor that constitute the output stage, A high-side driver that drives the aforementioned high-side transistor, A low-side driver that drives the low-side transistor, When the output voltage of the output stage drops to a first threshold voltage, the first output sensor asserts a first output detection signal. A control circuit for controlling the high-side driver and the low-side driver, Equipped with, The control circuit, when the output stage is in current source mode, In response to the instruction to turn off the high-side transistor, the high-side driver sets the high-side gate current sunk from the gate of the high-side transistor to a first current amount. A gate driver circuit that, in response to the assertion of the first output detection signal, sets the high-side gate current to a second current amount that is less than the first current amount.

2. The system further includes a second output sensor that asserts a second output detection signal when the output voltage drops to a second threshold voltage that is a predetermined voltage lower than the input voltage of the output stage. The control circuit, when the output stage is in current source mode, The gate driver circuit according to claim 1, wherein in response to the assertion of the second output detection signal, the high-side gate current is set to a third current amount that is less than the first current amount.

3. The system further includes a first delay circuit that delays the second output detection signal, The gate driver circuit according to claim 2, wherein the control circuit sets the high-side gate current to the third current amount in response to the assertion of the delayed second output detection signal when the output stage is in current source mode.

4. A high-side off sensor asserts a high-side off detection signal when the gate-source voltage of the high-side transistor falls below a predetermined threshold level. A high-side off fixed switch connected between the gate and source of the aforementioned high-side transistor, Furthermore, The gate driver circuit according to any one of claims 1 to 3, wherein the control circuit turns on the high-side-off fixed switch in response to the assertion of the high-side-off detection signal when the output stage is in current source mode.

5. The control circuit, when the output stage is in current sink mode, In response to the instruction to turn off the high-side transistor, the high-side driver sets the high-side gate current sunk from the gate of the high-side transistor to a first current amount. The gate driver circuit according to claim 4, which turns on the high-side-off fixed switch in response to the assertion of the high-side-off detection signal.

6. The system further includes a third output sensor that asserts a third output detection signal when the output voltage of the output stage rises to a third threshold voltage. The control circuit, when the output stage is in current sink mode, In response to the instruction to turn off the low-side transistor, the low-side driver sets the low-side gate current sunk from the gate of the low-side transistor to a fourth current quantity. A gate driver circuit according to any one of claims 1 to 3, wherein in response to the assertion of the third output detection signal, the low-side gate current is set to a fifth current amount that is less than the fourth current amount.

7. The system further includes a fourth output sensor that asserts a fourth output detection signal when the output voltage rises to a fourth threshold voltage that is a predetermined voltage lower than the input voltage of the output stage. The gate driver circuit according to claim 6, wherein the control circuit, when the output stage is in current sink mode, sets the low-side gate current to a fifth current amount less than the fourth current amount in response to the assertion of the fourth output detection signal.

8. The system further includes a second delay circuit that delays the fourth output detection signal, The gate driver circuit according to claim 7, wherein the control circuit sets the low-side gate current to the fifth current amount in response to the assertion of the delayed fourth output detection signal when the output stage is in current sink mode.

9. A low-side off sensor asserts a low-side off detection signal when the gate-source voltage of the low-side transistor falls below a predetermined threshold level. A low-side off fixed switch connected between the gate and source of the low-side transistor, Furthermore, The gate driver circuit according to claim 6, wherein the control circuit turns on the low-side off fixed switch in response to the assertion of the low-side off detection signal when the output stage is in current source mode.

10. The control circuit, when the output stage is in current sink mode, In response to the instruction to turn off the low-side transistor, the low-side driver sets the low-side gate current sunk from the gate of the low-side transistor to a fourth current quantity. The gate driver circuit according to claim 9, which turns on the low-side off fixed switch in response to the assertion of the low-side off detection signal.

11. A gate driver circuit that drives the high-side transistor and low-side transistor that constitute the output stage, A high-side driver that drives the aforementioned high-side transistor, A low-side driver that drives the low-side transistor, When the output voltage of the preceding output stage rises to the third threshold voltage, the third output sensor asserts the third output detection signal. A control circuit for controlling the high-side driver and the low-side driver, Equipped with, The control circuit, when the output stage is in current sink mode, In response to the instruction to turn off the low-side transistor, the low-side driver sets the low-side gate current sunk from the gate of the low-side transistor to a fourth current quantity. A gate driver circuit that, in response to the assertion of the third output detection signal, sets the low-side gate current to a fifth current amount that is less than the fourth current amount.

12. The system further includes a fourth output sensor that asserts a fourth output detection signal when the output voltage rises to a fourth threshold voltage that is a predetermined voltage lower than the input voltage of the output stage. The aforementioned control circuit is The gate driver circuit according to claim 11, wherein in response to the assertion of the fourth output detection signal, the low-side gate current is set to a fifth current amount that is less than the fourth current amount.

13. The system further includes a second delay circuit that delays the fourth output detection signal, The gate driver circuit according to claim 12, wherein the control circuit sets the low-side gate current to the fifth current amount in response to the assertion of the fourth output detection signal after a delay.

14. A low-side off sensor asserts a low-side off detection signal when the gate-source voltage of the low-side transistor falls below a predetermined threshold level. A low-side off fixed switch connected between the gate and source of the low-side transistor, Furthermore, The gate driver circuit according to any one of claims 11 to 13, wherein the control circuit turns on the low-side off fixed switch in response to the assertion of the low-side off detection signal when the output stage is in current source mode.

15. The control circuit, when the output stage is in current sink mode, In response to the instruction to turn off the low-side transistor, the low-side driver sets the low-side gate current sunk from the gate of the low-side transistor to a fourth current quantity. The gate driver circuit according to claim 14, which turns on the low-side off fixed switch in response to the assertion of the low-side off detection signal.

16. A gate driver circuit according to any one of claims 1 to 3 or 11 to 13, which is integrated into a single semiconductor substrate.

17. An output stage including high-side transistors and low-side transistors, A gate driver circuit according to any one of claims 1 to 3, 11 to 13, for driving the output stage, A motor drive device equipped with the following features.

18. Motor and, A motor drive device according to claim 17 for driving the motor, An electronic device equipped with the following features.

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