High-side driver circuit for bridge circuit, low-side driver circuit, driving method for bridge circuit, driver circuit, motor drive device using the same, and electronic device

Abstract

To provide a driver circuit capable of detecting output voltage transitions.SOLUTION: A low-side driver circuit 400 drives a low-side transistor ML. A source rise detection circuit 440 generates a source rise detection signal SRC_RISE, which indicates a transition of an output VOUT of a bridge circuit 100 to a high voltage VIN, when a bridge circuit 110 operates in a source mode, a first switch 430 is in an ON state, and a gate-to-source voltage VLGS of the low-side transistor ML crosses a positive first threshold voltage VTH1.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to a driver circuit for a bridge circuit. [Background technology]

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

[0003] The bridge circuit has an upper arm provided between the input line IN and the output line OUT, and a lower arm provided between the output line OUT and a ground line. The upper arm includes a high-side transistor and a flywheel diode connected in parallel. The lower arm includes a low-side transistor and a flywheel diode connected in parallel.

[0004] The bridge circuit can switch between a high output state, where the high-side transistor is on and the low-side transistor is off, and a low output state, where the high-side transistor is off and the low-side transistor is on. In the high output state, the output line OUT carries the voltage V of the input line. IN The output voltage V is at substantially the same voltage level as OUT In the low output state, the output line OUT has an output voltage V that is substantially the same voltage level as the voltage on the ground line. OUT occurs. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] International Publication No. WO2022 / 259780

[0006] The output voltage V is used to control the high-side driver that drives the high-side transistor and the low-side driver that drives the low-side transistor. OUTThe input voltage V IN and the output voltage V OUT By monitoring the potential difference between the high-side and low-side transistors, the output voltage V OUT Conversely, the output voltage V OUT The output voltage may be detected to have transitioned to low by monitoring the potential difference between the low-side transistor and the ground voltage of 0V, i.e., the voltage across the low-side transistor.

[0007] However, the input voltage V IN In high voltage applications where the output voltage V OUT It is difficult to monitor directly.

[0008] [overview] The present disclosure has been made in view of the above-mentioned problems, and one exemplary purpose of an embodiment thereof is to provide a driver circuit capable of detecting a transition in an output voltage.

[0009] An aspect of the present disclosure relates to a low-side driver circuit that drives a low-side transistor that forms a bridge circuit together with a high-side transistor. The low-side driver circuit includes a low-side gate driver that controls a gate voltage of the low-side transistor, a first switch connected between the gate and source of the low-side transistor, a low-side control circuit that generates a first low-side control signal that controls the low-side gate driver and a second low-side control signal that controls the first switch, and a source rise detection circuit that generates a source rise detection signal regarding a transition of an output of the bridge circuit to a high voltage when the gate-source voltage of the low-side transistor crosses a positive first threshold voltage with the first switch on when the bridge circuit operates in a source mode.

[0010] Another aspect of the present disclosure relates to a high-side driver circuit that drives a high-side transistor that forms a bridge circuit together with a low-side transistor, the high-side driver circuit including: a high-side gate driver that controls a gate voltage of the high-side transistor, a second switch connected between the gate and source of the high-side transistor, a high-side control circuit that generates a first high-side control signal that controls the high-side gate driver and a second high-side control signal that controls the second switch, and a sync-rise detection circuit that generates a sync-rise detection signal regarding a transition of an output of the bridge circuit to a high voltage when the gate-source voltage of the high-side transistor crosses a negative third threshold voltage with the second switch on when the bridge circuit operates in a sink mode.

[0011] Another aspect of the present disclosure relates to a driver circuit for driving high-side and low-side transistors that constitute a bridge circuit. The driver circuit includes: a low-side gate driver that controls a gate voltage of the low-side transistor; a first switch connected between the gate and source of the low-side transistor; a low-side control circuit that generates a first low-side control signal that controls the low-side gate driver and a second low-side control signal that controls the first switch; a source-rise detection circuit that generates a source-rise detection signal related to a transition of an output of the bridge circuit to a high voltage when the gate-source voltage of the low-side transistor crosses a positive first threshold voltage with the first switch on when the bridge circuit operates in a source mode; a high-side gate driver that controls the gate voltage of the high-side transistor; a second switch connected between the gate and source of the high-side transistor; a high-side control circuit that generates a first high-side control signal that controls the high-side gate driver and a second high-side control signal that controls the second switch; and a sink-rise detection circuit that generates a sink-rise detection signal related to a transition of an output of the bridge circuit to a high voltage when the gate-source voltage of the high-side transistor crosses a negative third threshold voltage with the second switch on when the bridge circuit operates in a sink mode.

[0012] Another aspect of the present disclosure relates to a method for driving a bridge circuit including a high-side transistor and a low-side transistor, the method comprising: a source-rise transition step of increasing an output voltage of the bridge circuit when the bridge circuit operates in a source mode, the source-rise transition step comprising: a low-side gate driver reducing a gate-source voltage of the low-side transistor to turn off the low-side transistor; a first switch connected between the gate and source of the low-side transistor; a high-side gate driver sourcing a drive current to the gate of the high-side transistor; a source-rise detection signal changing when the gate-source voltage of the low-side transistor crosses a first positive threshold voltage; and a high-side gate driver changing the drive current in response to the change in the source-rise detection signal.

[0013] Another aspect of the present disclosure relates to a method for driving a bridge circuit including a high-side transistor and a low-side transistor. The method includes a source fall transition step for reducing an output voltage of the bridge circuit when the bridge circuit operates in a source mode. In an initial state, a first switch provided between the gate and source of the low-side transistor is in an on state. The source fall transition step includes a high-side gate driver sinking a drive current from the gate of the high-side transistor, changing a source fall detection signal when the gate-source voltage of the low-side transistor crosses a negative second threshold voltage, changing the drive current in response to the change in the source fall detection signal, and turning off the first switch. The low-side gate driver increases the gate-source voltage of the low-side transistor to turn on the low-side transistor.

[0014] Another aspect of the present disclosure is also a method for driving a bridge circuit including a high-side transistor and a low-side transistor. The driving method includes a sync-rise transition step of increasing the output voltage of the bridge circuit when the bridge circuit operates in sink mode. In an initial state, a second switch provided between the gate and source of the high-side transistor is in an on state. The sync-rise transition step includes a step of a low-side gate driver sourcing a drive current to the gate of the low-side transistor, a step of changing a sync-rise detection signal when the gate-source voltage of the high-side transistor crosses a fourth positive threshold voltage, a step of the low-side gate driver changing the drive current in response to the change in the sync-rise detection signal, a step of turning off the second switch, and a step of a high-side gate driver increasing the gate-source voltage of the high-side transistor to turn on the high-side transistor.

[0015] Another aspect of the present disclosure also relates to a method for driving a bridge circuit including a high-side transistor and a low-side transistor. The method includes a sink fall transition step for reducing an output voltage of the bridge circuit when the bridge circuit operates in a sink mode. The sink fall transition step includes a step of a high-side gate driver reducing a gate-source voltage of the high-side transistor to turn off the high-side transistor, a step of turning on a second switch provided between the gate and source of the high-side transistor, a step of a low-side gate driver sourcing a drive current to the gate of the low-side transistor, a step of changing a sink fall detection signal when the gate-source voltage of the high-side transistor crosses a positive third threshold voltage, and a step of the low-side gate driver changing the drive current in response to the change in the sink fall detection signal.

[0016] Any combination of the above components, or mutual substitution of components or expressions between methods, devices, systems, etc. are also valid aspects of the present invention. [Brief explanation of the drawings]

[0017] [Figure 1] FIG. 1 is a circuit diagram of a switching circuit according to an embodiment. [Figure 2] FIG. 2 is an equivalent circuit diagram of a MOSFET. [Figure 3] FIG. 3 is a waveform diagram illustrating the detection of the source-rise transition by the source-rise detection circuit. [Figure 4] FIG. 4 is a waveform diagram illustrating the detection of a source fall transition by the source fall detection circuit. [Figure 5] FIG. 5 is a waveform diagram illustrating the detection of the sync-rise transition by the sync-rise detection circuit. [Figure 6] FIG. 6 is a waveform diagram illustrating the detection of a synchro fall transition by the synchro fall detection circuit. [Figure 7] FIG. 7 is a circuit diagram of a driving circuit according to an embodiment. [Figure 8] FIG. 8 is a diagram illustrating an example of current control of the high-side gate driver in the source-rise transition. [Figure 9] FIG. 9 is a diagram illustrating an example of current control during source-fall transition. [Figure 10] FIG. 10 is a diagram illustrating an example of current control in a sync-rise transition. [Figure 11] FIG. 11 is a diagram illustrating an example of current control during sinkfall transition. [Figure 12] FIG. 12 is a circuit diagram of a motor drive device including a switching circuit according to an embodiment.

[0018] [Detailed explanation] (Outline of the embodiment) A summary of some exemplary embodiments of the present disclosure is provided. This summary is intended to provide a simplified overview of some concepts of one or more embodiments in order to provide a basic understanding of the embodiments as a prelude to the more detailed description that follows. It is not intended to limit the scope of the invention or disclosure. This summary is not an exhaustive overview of all possible embodiments, and is not intended to identify key elements of all embodiments or to delineate the scope of some or all aspects. For convenience, the term "one embodiment" may refer to one embodiment (example or variant) or multiple embodiments (examples or variants) disclosed herein.

[0019] A low-side driver circuit according to one embodiment drives a low-side transistor that constitutes a bridge circuit together with a high-side transistor. The low-side driver circuit includes a low-side gate driver that controls a gate voltage of the low-side transistor, a first switch connected between the gate and source of the low-side transistor, a low-side control circuit that generates a first low-side control signal that controls the low-side gate driver and a second low-side control signal that controls the first switch, and a source rise detection circuit that generates a source rise detection signal regarding a transition of an output of the bridge circuit to a high voltage when the gate-source voltage of the low-side transistor crosses a positive first threshold voltage with the first switch on when the bridge circuit operates in a source mode.

[0020] A first switch is provided between the gate and source of the low-side transistor to prevent self-turn-on. In source mode, a rise transition of the output voltage occurs when the first switch is on. When the output voltage rises, current flows through the first switch via the parasitic capacitance of the low-side transistor, causing a voltage drop. By detecting this voltage drop, the rise transition of the output voltage can be detected without directly monitoring the voltage across the low-side transistor or the high-side transistor. The source-rise detection signal may indicate the start or end of the rise transition, or another point during the rise transition.

[0021] In one embodiment, the low-side driver circuit may further include a source fall detection circuit that generates a source fall detection signal regarding a transition of the output of the bridge circuit to a low voltage when the gate-source voltage of the low-side transistor crosses a negative second threshold voltage with the first switch on when the bridge circuit operates in source mode.

[0022] In source mode, a fall transition of the output voltage occurs when the first switch is on. When the output voltage drops, current flows in the reverse direction through the parasitic capacitance of the low-side transistor, causing a negative voltage drop across the first switch. By detecting this negative voltage drop, the output voltage fall transition can be detected without directly monitoring the voltage across the low-side or high-side transistor. The source fall detection signal may indicate the start or end of the fall transition, or another point during the fall transition.

[0023] In one embodiment, the low-side driver circuit may provide a source rise detection signal and a source fall detection signal to a high-side driver circuit that drives a high-side transistor. The source rise detection signal and the source fall detection signal may be used for sequence control in the high-side driver circuit.

[0024] A high-side driver circuit according to one embodiment drives a high-side transistor that constitutes a bridge circuit together with a low-side transistor. The high-side driver circuit includes a high-side gate driver that controls a gate voltage of the high-side transistor, a second switch connected between the gate and source of the high-side transistor, a high-side control circuit that generates a first high-side control signal that controls the high-side gate driver and a second high-side control signal that controls the second switch, and a sync-rise detection circuit that generates a sync-rise detection signal regarding a transition of an output of the bridge circuit to a high voltage when the gate-source voltage of the high-level transistor crosses a negative third threshold voltage with the second switch on when the bridge circuit operates in a sink mode.

[0025] In sink mode, a rise transition of the output voltage occurs when the second switch is on. When the output voltage rises, current flows in the reverse direction through the parasitic capacitance of the high-side transistor in the second switch, causing a negative voltage drop. By detecting this negative voltage drop, the rise transition of the output voltage can be detected without directly monitoring the voltage across the low-side or high-side transistor. The sink rise detection signal may indicate the start or end of the rise transition, or another point during the rise transition.

[0026] In one embodiment, the high-side driver circuit may further include a sink fall detection circuit that generates a sink fall detection signal regarding a transition of the output of the bridge circuit to a low voltage when the gate-source voltage of the high-side transistor crosses a positive fourth threshold voltage with the second switch on when the bridge circuit operates in sink mode.

[0027] In sink mode, a fall transition of the output voltage occurs when the second switch is on. When the output voltage drops, current flows through the second switch via the parasitic capacitance of the high-side transistor, causing a voltage drop. By detecting this voltage drop, a fall transition of the output voltage can be detected without directly monitoring the voltage across the low-side or high-side transistor. The sink fall detection signal may indicate the start or end of the fall transition, or another point during the fall transition.

[0028] In one embodiment, the sync rise detection signal and the sync fall detection signal may be supplied to a low-side driver circuit that drives a low-side transistor, and the sync rise detection signal and the sync fall detection signal can be used for sequence control in the low-side driver circuit.

[0029] A driver circuit according to one embodiment drives high-side and low-side transistors constituting a bridge circuit and includes: a low-side gate driver that controls the gate voltage of the low-side transistor; a first switch connected between the gate and source of the low-side transistor; a low-side control circuit that generates a first low-side control signal that controls the low-side gate driver and a second low-side control signal that controls the first switch; a source-rise detection circuit that generates a source-rise detection signal related to a transition of an output of the bridge circuit to a high voltage when the gate-source voltage of the low-side transistor crosses a first positive threshold voltage with the first switch on when the bridge circuit operates in a source mode; a high-side gate driver that controls the gate voltage of the high-side transistor; a second switch connected between the gate and source of the high-side transistor; a high-side control circuit that generates a first high-side control signal that controls the high-side gate driver and a second high-side control signal that controls the second switch; and a sink-rise detection circuit that generates a sink-rise detection signal related to a transition of an output of the bridge circuit to a high voltage when the gate-source voltage of the high-side transistor crosses a third negative threshold voltage with the second switch on when the bridge circuit operates in a sink mode.

[0030] In one embodiment, the high-side gate driver and the low-side gate driver may be current-driven, and the high-side control circuit may vary the output current of the high-side gate driver in response to a change in the source rise detection signal when the bridge circuit operates in a source mode, and the low-side control circuit may vary the output current of the low-side gate driver in response to a change in the sink rise detection signal when the bridge circuit operates in a sink mode.

[0031] In one embodiment, the driver circuit may further include a source fall detection circuit that generates a source fall detection signal regarding a transition of the output of the bridge circuit to a low voltage when the gate-source voltage of the low-side transistor crosses a negative second threshold voltage with the first switch on when the bridge circuit operates in source mode, and a sink fall detection circuit that generates a sink fall detection signal regarding a transition of the output of the bridge circuit to a low voltage when the gate-source voltage of the high-side transistor crosses the negative second threshold voltage with the second switch on when the bridge circuit operates in sink mode.

[0032] The high-side gate driver and the low-side gate driver may be current-driven. The high-side control circuit may change the output current of the high-side gate driver in response to a change in the source fall detection signal when the bridge circuit operates in a source mode, and the low-side control circuit may change the output current of the low-side gate driver in response to a change in the sink fall detection signal when the bridge circuit operates in a sink mode.

[0033] In one embodiment, the driver circuit may further include a low-side sensor that generates a low-side sense signal indicating a comparison result between the gate-source voltage of the low-side transistor and the fifth threshold voltage when the first switch is in an off state, and a high-side sensor that generates a high-side sense signal indicating a comparison result between the gate-source voltage of the high-side transistor and the sixth threshold voltage when the second switch is in an off state.

[0034] (Embodiment) Preferred embodiments will be described below with reference to the drawings. The same or equivalent components, parts, and processes shown in each drawing will be designated by the same reference numerals, and redundant descriptions will be omitted where appropriate. Furthermore, the embodiments are merely examples and do not limit the invention, and all features and combinations thereof described in the embodiments are not necessarily essential to the invention.

[0035] In this specification, "a state in which component A is connected to component B" includes not only a case in which component A and component B are directly physically connected to each other, but also a case in which component A and component B are indirectly connected to each other via other components that do not substantially affect the electrical connection between them or that do not impair the function or effect achieved by their connection.

[0036] Similarly, "a state in which component C is provided between component A and component B" includes not only cases in which components A and C, or components B and C, are directly connected, but also cases in which they are indirectly connected via other components that do not substantially affect the electrical connection state between them or impair the functions or effects achieved by their combination.

[0037] The vertical and horizontal axes of the waveform diagrams and time charts referred to in this specification have been appropriately enlarged or reduced to facilitate understanding, and the waveforms shown have been simplified, exaggerated, or emphasized to facilitate understanding.

[0038] 1 is a circuit diagram of a switching circuit 100 according to an embodiment. The switching circuit 100 includes a bridge circuit 110 and a driver circuit 200. Although only the configuration of one phase of the switching circuit 100 is shown here, the switching circuit 100 may be a three-phase circuit or an H-bridge circuit.

[0039] The input line 102 is connected to the input voltage V IN The technology according to the present disclosure is provided by IN This is particularly useful in applications where the input voltage V IN It can also be used in applications with voltages of several tens of volts.

[0040] The bridge circuit 110 includes a high-side transistor MH connected between an input line (input terminal) 102 and an output line (output terminal) 104, and a low-side transistor ML connected between the output line 104 and a ground line 106. The high-side transistor MH and the low-side transistor ML are N-channel transistors.

[0041] The driver circuit 200 controls the high-side transistor MH and the low-side transistor ML of the bridge circuit 110. The driver circuit 200 controls a high output state φ in which the high-side transistor MH is on and the low-side transistor ML is off. H , the high-side transistor MH is off and the low-side transistor ML is on in the low output state φ L The bridge circuit 110 switches between two states: a high-impedance state φ in which both the high-side transistor MH and the low-side transistor ML are off; HZ In some cases, the high output state φ H The output voltage V OUT is the input voltage V IN The low output state φ L At this point, the output voltage V OUT takes on a voltage level substantially equal to the ground voltage (0V).

[0042] The driver circuit 200 includes a high-side driver circuit 300 and a low-side driver circuit 400. The high-side driver circuit 300 and the low-side driver circuit 400 may be separate integrated circuits (ICs), or may be integrated into a single IC.

[0043] (2) Configuration of the low-side driver circuit 400 First, we will explain the configuration of the low-side driver circuit 400. The low-side driver circuit 400 includes a low-side control circuit 410, a low-side gate driver 420, a first switch 430, a source rise detection circuit 440, and a source fall detection circuit 450.

[0044] The low-side gate driver 420 controls the gate voltage V of the low-side transistor ML in response to the low-side control signal LCTRL1 generated by the low-side control circuit 410. LG The low-side gate driver 420 may be a voltage-driven type or a current-driven type. When the low-side gate driver 420 turns on the low-side transistor ML based on the low-side control signal LCTRL1, the low-side gate driver 420 controls the gate-source voltage V LGS From 0V to the gate high voltage V H Gate high voltage V H is the gate-source voltage of the NMOS transistor, V GS(th) On the other hand, when the low-side gate driver 420 turns off the low-side transistor ML, the gate-source voltage V LGS The gate high voltage V H to 0V.

[0045] The first switch 430 is an NMOS transistor connected between the gate and source of the low-side transistor ML, and is controlled in response to a low-side control signal LCTRL2 generated by the low-side control circuit 410. The first switch 430 is turned on during the off period of the low-side transistor ML, and controls the gate-source voltage V LGS is fixed to around 0 V. The first switch 430 prevents the low-side transistor ML from self-turning on.

[0046] The low-side control circuit 410 generates a first low-side control signal LCTRL 1 that controls the low-side gate driver 420 and a second low-side control signal LCTRL 2 that controls the first switch 430 .

[0047] The source rise detection circuit 440 detects whether the bridge circuit 110 is in source mode, i.e., the output current I OUT The source rise detection circuit 440 is active in the low output state φ Lto high output state φ H When the output voltage V OUT is the input voltage V IN When it rises to the vicinity of the high output state φ H When this happens, the output, the source rise detection signal SRC_RISE, is changed.

[0048] When the first switch 430 is in an on state, the source-rise detection circuit 440 detects the voltage across the first switch 430, that is, the gate-source voltage V of the low-side transistor ML. LGS the positive first threshold voltage V TH1 The gate-source voltage V of the low-side transistor ML is compared with LGS is positive when the gate voltage is higher than the source voltage, and negative when the gate voltage is lower than the source voltage. LGS is the first threshold voltage V TH1 When the source rise detection signal SRC_RISE crosses the positive edge, the signal level of the source rise detection signal SRC_RISE is changed. Either the positive edge or the negative edge of the source rise detection signal SRC_RISE may be used as a significant signal, or both may be used.

[0049] The source fault detection circuit 450 is active when the bridge circuit 110 is in source mode. The source fault detection circuit 450 is in a high output state φ H to low output state φ L When the output voltage V OUT When the voltage drops to near 0V, that is, the low output state φ H When this happens, the output, the source fall detection signal SRC_FALL, is changed.

[0050] When the first switch 430 is in an on state, the source fall detection circuit 450 detects the voltage across the first switch 430, that is, the gate-source voltage V of the low-side transistor ML. LGS the negative second threshold voltage V TH2Then, the source fall detection circuit 450 compares the gate-source voltage V LGS is the second threshold voltage V TH2 When the signal crosses the positive edge, the signal level of the source fall detection signal SRC_FALL is changed. Either the positive edge or the negative edge of the source fall detection signal SRC_FALL may be used as a significant signal, or both may be used.

[0051] The above is the configuration of the low-side driver circuit 400. Next, the operations of the source rise detection circuit 440 and the source fall detection circuit 450 will be described.

[0052] Before describing the operations of the source rise detection circuit 440 and the source fall detection circuit 450, the parasitic capacitance of a MOSFET (Metal Oxide Semiconductor Field Effect Transistor) used as the low-side transistor ML will be described.

[0053] Figure 2 is an equivalent circuit diagram of a MOSFET. A MOSFET has gate-source capacitance Cgs, gate-drain capacitance Cgd, and drain-source capacitance Cds. The sum of the gate-source capacitance Cgs and gate-drain capacitance Cgd is called input capacitance Ciss, and the sum of the gate-drain capacitance Cgd and drain-source capacitance Cds is called output capacitance Coss. Ciss=Cgs+Cgd Coss=Cds+Cgd The input capacitance Ciss does not depend on the drain-source voltage Vds of the MOSFET, but the output capacitance Coss depends on the drain-source voltage Vds of the MOSFET, and decreases as the drain-source voltage Vds increases.

[0054] 3 is a waveform diagram illustrating the detection of a source rise transition by the source rise detection circuit 440. The bridge circuit 110 is operating in the source mode.

[0055] The initial state (i) is a low output state, in which the low-side transistor ML is on and the high-side transistor MH is off.

[0056] To prevent a shoot-through current, the low-side transistor ML is turned off first (ii). The low-side gate driver 420 turns off the gate-source voltage V of the low-side transistor ML. LGS to turn off the low-side transistor ML.

[0057] After the low-side transistor ML is turned off, the first switch 430 is fully turned on (iii).

[0058] Next, the high-side gate driver 320 controls the gate-source voltage V of the high-side transistor MH. HGS (iv) The gate-source voltage V of the high-side transistor MH is increased. HGS When increases, the output voltage V OUT is 0V to the input voltage V IN rises towards

[0059] Output voltage V OUT is the input voltage V IN When the voltage rises to around 100V, the gate-drain capacitance C gd , the current I gd flows (v). This current I gd flows through the first switch 430, which is in a fully on state, causing a voltage drop. The on-resistance of the first switch 430 is R ON When this is done, the voltage drop is I gd ×R ON This voltage drop is the gate-source voltage V of the low-side transistor ML. LGS Increases.

[0060] The source-rise detection circuit 440 includes a voltage comparator or a voltage comparison means instead thereof, and detects the gate-source voltage of the low-side transistor ML (i.e., the voltage drop I gd ×R ON ) and the first threshold voltage VTH1 A source rise detection signal SRC_RISE is generated based on the comparison result. For example, I gd =0.3A, R ON =3Ω, a voltage of about 0.3×3=0.9V is generated across the first switch 430 (that is, across the gate and source of the low-side transistor ML).

[0061] Therefore, the first threshold voltage V TH1 If we set the range of V to 0.1V to 0.5V, for example 0.2V, the output voltage V OUT High voltage V IN It is possible to detect a transition to

[0062] 4 is a waveform diagram illustrating the detection of a source fall transition by the source fall detection circuit 450. The bridge circuit 110 is operating in source mode.

[0063] The initial state (i) is a high output state, in which the low-side transistor ML is off and the high-side transistor MH is on. At this time, the first switch 430 is in the on state.

[0064] To prevent a shoot-through current, the high-side transistor MH is turned off first (ii). The high-side gate driver 320 turns off the gate-source voltage V of the high-side transistor MH. HGS Decreases.

[0065] Gate-source voltage V of high-side transistor MH HGS As the impedance of the high-side transistor MH decreases, the output voltage V OUT is decreasing.

[0066] Output voltage V OUT When the voltage drops to around 0V, the capacitance C gd Current I gd This current I gdflows through the first switch 430, which is in a fully on state, causing a voltage drop. The on-resistance of the first switch 430 is R ON When this is done, the voltage drop is I gd ×R ON This voltage drop generates a negative voltage between the gate and source of the low-side transistor ML.

[0067] The source fall detection circuit 450 includes a voltage comparator or a voltage comparison means instead thereof, and detects the gate-source voltage of the low-side transistor ML (i.e., the voltage drop I gd ×R ON ) and the negative second threshold voltage V TH2 A source fall detection signal SRC_FALL is generated based on the comparison result of I gd =0.4A, R ON = 3 Ω, a voltage of about 0.4 × 3 = 1.2 V is generated across the first switch 430 (i.e., between the gate and source of the low-side transistor ML). However, because the current flows to the substrate via the body diode, the voltage drop is clamped to about the forward voltage of the body diode (0.7 V).

[0068] Therefore, the second threshold voltage V TH2 If we set the range of V to -0.1 to -0.5V, for example -0.2V, the output voltage V OUT The transition of the signal to a low voltage of 0V can be detected.

[0069] When the fall transition is complete, the first switch 430 is turned off. Then, the low-side gate driver 420 increases the gate-source voltage VLGS of the low-side transistor ML to turn on the low-side transistor ML (v).

[0070] (1) Configuration of the High-Side Driver Circuit 300 Next, the configuration of the high-side driver circuit 300 will be described.

[0071] The configuration of the high-side driver circuit 300 is similar to that of the low-side driver circuit 400. The high-side driver circuit 300 includes a high-side control circuit 310, a high-side gate driver 320, a second switch 330, a synch rise detection circuit 340, and a synch fall detection circuit 350.

[0072] The high-side gate driver 320 controls the gate voltage V of the high-side transistor MH in response to the high-side control signal HCTRL1 generated by the high-side control circuit 310. HG The high-side gate driver 320 may be a voltage-driven type or a current-driven type.

[0073] When the high-side gate driver 320 turns on the high-side transistor MH, the gate-source voltage V HGS From 0V to the gate high voltage V H Gate high voltage V H is the gate-source voltage of the NMOS transistor, V GS(th) On the other hand, when the high-side gate driver 320 turns off the high-side transistor MH, the gate-source voltage V LGS The gate high voltage V H to 0V.

[0074] The second switch 330 is an NMOS transistor connected between the gate and source of the high-side transistor MH, and is controlled in response to a high-side control signal HCTRL2 generated by the high-side control circuit 310. The second switch 330 is turned on during the off period of the high-side transistor MH, and the gate-source voltage V HGS is fixed to around 0 V. The second switch 330 prevents the high-side transistor MH from self-turning on.

[0075] The high-side control circuit 310 generates a first high-side control signal HCTRL1 that controls the high-side gate driver 320 and a second high-side control signal HCTRL2 that controls the second switch 330 .

[0076] The sink rise detection circuit 340 detects whether the bridge circuit 110 is in sink mode, i.e., whether the output current I OUT is active in an operating mode in which the load flows toward the bridge circuit 110. The sync rise detection circuit 340 is in the low output state φ L to high output state φ H When the output voltage V OUT is the input voltage V IN When it rises to the vicinity of the high output state φ H When this happens, the output, the sink rise detection signal SNK_RISE, is changed.

[0077] When the second switch 330 is in an on state, the synchronism rise detection circuit 340 detects the voltage across the second switch 330, that is, the gate-source voltage V of the high-side transistor MH. HGS the negative third threshold voltage V TH3 The sync rise detection circuit 340 compares the gate-source voltage V HGS is the third threshold voltage V TH3 When the signal level of the sync rise detection signal SNK_RISE is changed, the signal level of the sync rise detection signal SNK_RISE is changed.

[0078] The sink fall detection circuit 350 is active when the bridge circuit 110 is in the sink mode. H to low output state φ L When the output voltage V OUT When the voltage drops to near 0V, that is, the low output state φ H In this case, the output, the source rise detection signal SNK_FALL, is changed.

[0079] When the second switch 330 is in an on state, the sink fall detection circuit 350 detects the voltage across the second switch 330, that is, the gate-source voltage V of the high-side transistor MH. HGS The positive fourth threshold voltage V TH4 The sink fall detection circuit 350 compares the gate-source voltage V HGS is the fourth threshold voltage V TH4 When the signal level of the sink fall detection signal SNK_FALL is changed, the signal level of the sink fall detection signal SNK_FALL is changed.

[0080] The above is the configuration of the high-side driver circuit 300. Next, the operations of the synch rise detection circuit 340 and the synch fall detection circuit 350 will be described.

[0081] 5 is a waveform diagram illustrating the detection of the sync-rise transition by the sync-rise detection circuit 340. The bridge circuit 110 is operating in the sync mode.

[0082] The initial state (i) is a low output state, in which the low-side transistor ML is on, the high-side transistor MH is off, and the second switch 330 is on.

[0083] To prevent a shoot-through current, the low-side transistor ML is turned off first (ii). The low-side gate driver 420 turns off the gate-source voltage V of the low-side transistor ML. LGS The gate-source voltage V of the low-side transistor ML is reduced. LGS As the impedance of the low-side transistor ML decreases, the impedance of the output voltage V OUT is rising.

[0084] Output voltage V OUT is the input voltage V IN When the voltage drops to around 100V, a capacitance C gd Current I gd This current I gdflows through the second switch 330, which is in a fully on state, causing a voltage drop. The on-resistance of the second switch 330 is R ON When this is done, the voltage drop is I gd ×R ON This voltage drop generates a negative voltage between the gate and source of the low-side transistor ML.

[0085] The synchronism detection circuit 340 includes a voltage comparator or a voltage comparison means instead thereof, and detects the gate-source voltage of the high-side transistor MH (i.e., the voltage drop I gd ×R ON ) and the negative third threshold voltage V TH3 A sync rise detection signal SNK_RISK is generated based on the comparison result of I gd =0.4A, R ON = 3 Ω, a voltage of about 0.4 × 3 = 1.2 V is generated across the second switch 330 (i.e., between the gate and source of the high-side transistor MH). However, because the current flows to the substrate via the body diode, the voltage drop is clamped to about the forward voltage of the body diode (0.7 V).

[0086] Therefore, the second threshold voltage V TH2 If we set the range of V to -0.1 to -0.5V, for example -0.2V, the output voltage V OUT High voltage V IN It is possible to detect a transition to

[0087] 6 is a waveform diagram illustrating the detection of a synchro fall transition by the synchro fall detection circuit 350. The bridge circuit 110 is operating in the synchro fall mode.

[0088] The initial state (i) is a high output state, in which the high-side transistor MH is on and the low-side transistor ML is off.

[0089] To prevent a shoot-through current, the high-side transistor MH is turned off first (ii). The high-side gate driver 320 turns off the gate-source voltage V of the high-side transistor MH. HGS , turning off the high-side transistor MH.

[0090] After the high-side transistor MH is turned off, the second switch 330 is fully turned on (iii).

[0091] Subsequently, the low-side gate driver 420 controls the gate-source voltage V of the low-side transistor ML. LGS (iv) The gate-source voltage V of the low-side transistor ML is increased. LGS When increases, the output voltage V OUT is the input voltage V IN decreases from 0V to 1V.

[0092] Output voltage V OUT When the voltage drops to around 0V, the gate-drain capacitance C gd , the current I gd flows (v). This current I gd flows through the second switch 330, which is in a fully on state, causing a voltage drop. The on-resistance of the second switch 330 is R ON When this is done, the voltage drop is I gd ×R ON This voltage drop is the gate-source voltage V of the high-side transistor MH. HGS Increases.

[0093] The sinkfall detection circuit 350 includes a voltage comparator or a voltage comparison means that is an alternative to the voltage comparator, and detects the gate-source voltage of the high-side transistor MH (i.e., the voltage drop I gd ×R ON ) and the fourth threshold voltage V TH4 A sink fall detection signal SNK_FALL is generated based on the comparison result. For example, I gd =0.3A, R ON=3Ω, a voltage of about 0.3×3=0.9V is generated across the second switch 330 (that is, across the gate and source of the high-side transistor MH).

[0094] Therefore, the fourth threshold voltage V TH4 If we set the range of V to 0.1V to 0.5V, for example 0.2V, the output voltage V OUT The transition of the signal to a low voltage of 0V can be detected.

[0095] According to the driver circuit 200 of this embodiment, it is possible to indirectly detect an output transition by detecting a minute change in voltage occurring between the gate and source of the low-side transistor ML without monitoring the voltage across the high-side transistor MH. Similarly, it is possible to indirectly detect an output transition by detecting a minute change in voltage occurring between the gate and source of the high-side transistor MH without monitoring the voltage across the low-side transistor ML.

[0096] Next, a specific configuration example of the driver circuit 200 will be described.

[0097] 7 is a circuit diagram of a driver circuit 200C according to an embodiment. The driver circuit 200C includes a high-side driver circuit 300C and a low-side driver circuit 400C. In this embodiment, the high-side driver circuit 300C and the low-side driver circuit 400C are integrated on separate semiconductor chips. The detection signals SRC_RISE and SRC_FALL generated by the low-side driver circuit 400C are supplied to the high-side driver circuit 300C. The detection signals SNK_RISE and SNK_FALL generated by the high-side driver circuit 300C are supplied to the low-side driver circuit 400C.

[0098] The low-side driver circuit 400C further includes a low-side sensor 460 and a third switch 432. The low-side sensor 460 detects the gate-source voltage V of the low-side transistor ML when the first switch 430 is in an off state. LGS and the fifth threshold voltage V TH5The fifth threshold voltage V TH5 is the threshold voltage V of the MOS transistor GS(th) The low-side sense signal LS can be used as a signal indicating that the low-side transistor ML has been turned on during a turn-on operation of the low-side transistor ML, and as a signal indicating that the low-side transistor ML has been turned off during a turn-off operation of the low-side transistor ML.

[0099] The third switch 432 is connected to the gate of the low-side transistor ML. The third switch 432 is controlled in response to a control signal LCTRL3 generated by the low-side control circuit 410. When the third switch 432 is turned on, the low-side transistor ML is fixed to the on state.

[0100] Similarly, the high-side driver circuit 300C further includes a high-side sensor 360 and a fourth switch 332. The high-side sensor 360 detects the gate-source voltage V of the high-side transistor MH when the second switch 330 is in an off state. HGS and the sixth threshold voltage V TH6 The high-side sense signal HS can be used as a signal indicating that the high-side transistor MH has been turned on during a turn-on operation of the high-side transistor MH, and as a signal indicating that the high-side transistor MH has been turned off during a turn-off operation of the high-side transistor MH.

[0101] The fourth switch 332 is connected to the gate of the high-side transistor MH. The fourth switch 332 is controlled in response to a control signal HCTRL3 generated by the high-side control circuit 310. When the fourth switch 332 is turned on, the high-side transistor MH is fixed to the on state.

[0102] The high-side gate driver 320 and the low-side gate driver 420 are current-driven. Specifically, the high-side gate driver 320 includes a source current source 322 and a sink current source 324. The source current source 322 becomes active when the high-side transistor MH is turned on, and sources a drive current to the gate of the high-side transistor MH. The sink current source 324 becomes active when the high-side transistor MH is turned off, and sinks a drive current from the gate of the high-side transistor MH.

[0103] The source current source 322 and the sink current source 324 are variable current sources that can control the drive current in multiple stages. In a sequence for turning on the high-side transistor MH, the high-side control circuit 310 switches the current generated by the source current source 322 in multiple stages over time. In a sequence for turning off the high-side transistor MH, the high-side control circuit 310 also switches the current generated by the sink current source 324 in multiple stages over time.

[0104] Similarly, the low-side gate driver 420 includes a source current source 422 and a sink current source 424. The source current source 422 is active when the low-side transistor ML is turned on and sources drive current to the gate of the low-side transistor ML. The sink current source 424 is active when the low-side transistor ML is turned off and sinks drive current from the gate of the low-side transistor ML.

[0105] The source current source 422 and the sink current source 424 are variable current sources that can control the drive current in multiple stages. The low-side control circuit 410 switches the current generated by the source current source 422 in multiple stages over time in a sequence for turning on the low-side transistor ML. The low-side control circuit 410 also switches the current generated by the sink current source 424 in multiple stages over time in a sequence for turning off the low-side transistor ML.

[0106] The above transition detection signals SRC_RISE, SRC_FALL, SNK_RIS, and SNK_FALL can be used for dynamic current control of the drive current.

[0107] FIG. 8 is a diagram for explaining an example of current control of the high-side gate driver 320 in a source rise transition.

[0108] At time t0, the high-side gate driver 320 starts sourcing a current I of the first current amount I1 to the gate of the high-side transistor MH. ON

[0109] At time t1, when the voltage V between the gate and source of the high-side transistor MH exceeds the sixth threshold voltage V HGS the output HS of the high-side sensor 360 is asserted. In response to the assertion of the high-side sense signal HS, the high-side control circuit 310 switches the control signal HCTRL1 so that the current I TH6 becomes the second current amount I2 (I2 < I1). ON

[0110] When the output voltage V OUT rises, at time t2, the source rise detection signal SRC_RISE, which is the output of the source rise detection circuit 440 of the low-side driver circuit 400C, changes to high. In response to this change, the high-side control circuit 310 switches the control signal HCTRL1 so that the current I ON becomes the third current amount I3 (I3 > I2).

[0111] Subsequently, at time t3, the source rise detection signal SRC_RISE changes to low. In response to this change, at time t4, the high-side control circuit 310 switches the control signal HCTRL3 so that the fourth switch 332 is turned on.

[0112] The above is an example of current control in a source rise transition.

[0113] ​​FIG. 9 is a diagram for explaining an example of current control in a source fall transition. At time t0, the high-side gate driver 320 starts sinking the current I of the first current amount I1 from the gate of the high-side transistor MH. ON As a result, the voltage V between the gate and source of the high-side transistor MH HGS decreases.

[0114] At time t1, when the voltage V between the gate and source of the high-side transistor MH HGS falls below the sixth threshold voltage V TH6 , the output HS of the high-side sensor 360 is negated. In response to the negation of the high-side sense signal HS, the high-side control circuit 310 switches the control signal HCTRL1 so that the current I OFF becomes the second current amount I2 (I2 < I1).

[0115] When the output voltage V OUT further decreases, at time t2, the source fall detection signal SRC_FALL, which is the output of the source fall detection circuit 450 of the low-side driver circuit 400C, changes to high. In response to this change, the high-side control circuit 310 switches the control signal HCTRL1 so that the current I OFF becomes the third current amount I3 (I3 > I2).

[0116] Subsequently, at time t3, the source fall detection signal SRC_FALL changes to low. In response to this change, at time t4, the high-side control circuit 310 switches the control signal HCTRL2 so that the second switch 330 is turned on.

[0117] The above is an example of current control in a source fall transition.

[0118] FIG. 10 is a diagram for explaining an example of current control in a sink rise transition. At time t0, the low-side gate driver 420 starts sinking the current I of the first current amount I1 from the gate of the low-side transistor ML. OFF As a result, the voltage V between the gate and source of the low-side transistor MLLGS decreases. As the impedance of the low-side transistor ML increases, the output voltage V OUT increases.

[0119] At time t1, when the voltage V LGS between the gate and source of the low-side transistor ML falls below the fifth threshold voltage V TH5 , the output LS of the low-side sensor 460 is negated. In response to the negation of the low-side sense signal LS, the low-side control circuit 410 switches the control signal LCTRL1 so that the current I OFF becomes the second current amount I2 (I2 < I1).

[0120] When the output voltage V OUT further increases, at time t2, the sink rise detection signal SNK_RISE, which is the output of the sink rise detection circuit 340 of the high-side driver circuit 300C, changes to high. In response to this change, the low-side control circuit 410 switches the control signal LCTRL1 so that the current I OFF becomes the third current amount I3 (I3 > I2).

[0121] Subsequently, at time t3, the sink rise detection signal SNK_RISE changes to low. In response to this change, at time t4, the low-side control circuit 410 switches the control signal LCTRL2 so that the first switch 430 turns on.

[0122] The above is an example of current control in the sink transition.

[0123] FIG. 11 is a diagram for explaining an example of current control in the sink fall transition.

[0124] At time t0, the low-side gate driver 420 starts sourcing a current I ON of the first current amount I1 to the gate of the low-side transistor ML.

[0125] At time t1, when the voltage V LGS between the gate and source of the low-side transistor ML is the fifth threshold voltage VTH5 When it exceeds, the output LS of the side sensor 460 is asserted. In response to the assertion of the side sense signal LS, the side control circuit 410 sets the current I ON so that it becomes the second current amount I2 (I2 < I1) by switching the control signal LCTRL1.

[0126] In response to the decrease in the impedance of the side transistor ML, the output voltage V OUT decreases. At time t2, the sink fall detection signal SNK_FALL, which is the output of the sink rise detection circuit 340 of the high side driver circuit 300C, changes to high. In response to this change, the side control circuit 410 sets the current I ON so that it becomes the third current amount I3 (I3 > I2) by switching the control signal LCTRL1.

[0127] Subsequently, at time t3, the sink fall detection signal SNK_FALL changes to low. In response to this change, at time t4, the side control circuit 410 switches the control signal LCTRL3 so that the third switch 432 is turned on.

[0128] The above is an example of current control in the sink fall transition.

[0129] Subsequently, the use of the switching circuit 100 will be described. The switching circuit 100 can be suitably used for a driver circuit of a motor.

[0130] FIG. 12 is a circuit diagram of a motor drive device 500 including the switching circuit 100 according to the embodiment. The motor drive device 500 drives a three-phase motor 502 as a load and controls its rotational state.

[0131] The motor drive device 500 includes a bridge circuit 110 and a driver circuit 600. The bridge circuit 110 is a three-phase inverter and has legs for the U phase, V phase, and W phase. Each phase leg has an upper arm and a lower arm.

[0132] The driver circuit 600 includes high-side driver circuits 300U to 300W, low-side driver circuits 400U to 400W, and a control circuit 610. The control circuit 610 includes a feedback circuit that performs feedback control so that the state of the three-phase motor 502 approaches a target state, and generates control signals that indicate the states of the six arms that make up the bridge circuit 110.

[0133] Although a three-phase motor is used as an example here, a single-phase motor may also be used, in which case the bridge circuit 110 becomes an H-bridge circuit.

[0134] Next, applications of the motor drive device 500 will be described. The motor drive device 500 can be used to control the spindle motor of a hard disk or the lens drive motor of an imaging device. Alternatively, it can be used to drive a printer head drive motor or a paper feed motor. Alternatively, the motor drive device 500 can be used to drive motors in electric vehicles, hybrid vehicles, etc.

[0135] The embodiments are merely examples, and it will be understood by those skilled in the art that various modifications are possible in the combination of the respective components and the respective treatment processes, and that such modifications are also within the scope of the present disclosure and the present invention. Such modifications will be described below.

[0136] (Variation 1) In the embodiment, the bridge circuit 110 is configured with discrete components, but this is not limiting, and the bridge circuit 110 may be integrated into the driver circuit 200.

[0137] (Variation 2) The high-side transistor MH and the low-side transistor ML may be configured by an IGBT (Insulated Gate Bipolar Transistor).

[0138] (Variation 3) The application of the switching circuit 100 is not limited to the motor drive device 500. 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, etc. Therefore, the switching circuit 100 can be used in consumer devices including electronic devices and home appliances, automobiles and on-board components, industrial vehicles and industrial machinery.

[0139] The embodiments merely illustrate the principles and applications of the present invention, and many modifications and changes in arrangement are possible to the embodiments without departing from the spirit of the present invention as defined in the claims.

[0140] (Addendum) The present specification discloses the following techniques.

[0141] (Item 1) A low-side driver circuit that drives a low-side transistor that configures a bridge circuit together with a high-side transistor, a low-side gate driver that controls a gate voltage of the low-side transistor; a first switch connected between the gate and source of the low-side transistor; a low-side control circuit that generates a first low-side control signal for controlling the low-side gate driver and a second low-side control signal for controlling the first switch; a source rise detection circuit configured to generate a source rise detection signal regarding a transition of an output of the bridge circuit to a high voltage when a gate-source voltage of the low-side transistor crosses a positive first threshold voltage with the first switch in an on state when the bridge circuit operates in a source mode; 1. A low-side driver circuit comprising:

[0142] (Item 2) 2. The low-side driver circuit of claim 1, further comprising a source fall detection circuit that generates a source fall detection signal regarding a transition of the output of the bridge circuit to a low voltage when the gate-source voltage of the low-side transistor crosses a negative second threshold voltage with the first switch on when the bridge circuit operates in a source mode.

[0143] (Item 3) 3. The low-side driver circuit according to item 2, wherein the source rise detection signal and the source fall detection signal are supplied to a high-side driver circuit that drives the high-side transistor.

[0144] (Item 4) A high-side driver circuit that drives a high-side transistor that configures a bridge circuit together with a low-side transistor, a high-side gate driver that controls a gate voltage of the high-side transistor; a second switch connected between the gate and source of the high-side transistor; a high-side control circuit that generates a first high-side control signal for controlling the high-side gate driver and a second high-side control signal for controlling the second switch; a sink rise detection circuit that generates a sink rise detection signal regarding a transition of an output of the bridge circuit to a high voltage when a gate-source voltage of the high-side transistor crosses a negative third threshold voltage with the second switch in an on state when the bridge circuit operates in a sink mode; 1. A high-side driver circuit comprising:

[0145] (Item 5) 5. The high-side driver circuit of item 4, further comprising: a sink fall detection circuit that generates a sink fall detection signal regarding a transition of the output of the bridge circuit to a low voltage when the gate-source voltage of the high-side transistor crosses a positive fourth threshold voltage with the second switch on when the bridge circuit operates in a sink mode.

[0146] (Item 6) 6. The high-side driver circuit according to item 5, wherein the sync rise detection signal and the sync fall detection signal are supplied to a low-side driver circuit that drives the low-side transistor.

[0147] (Item 7) A driver circuit for driving a high-side transistor and a low-side transistor that constitute a bridge circuit, a low-side gate driver that controls a gate voltage of the low-side transistor; a first switch connected between the gate and source of the low-side transistor; a low-side control circuit that generates a first low-side control signal for controlling the low-side gate driver and a second low-side control signal for controlling the first switch; a source rise detection circuit configured to generate a source rise detection signal regarding a transition of an output of the bridge circuit to a high voltage when a gate-source voltage of the low-side transistor crosses a positive first threshold voltage with the first switch in an on state when the bridge circuit operates in a source mode; a high-side gate driver that controls a gate voltage of the high-side transistor; a second switch connected between the gate and source of the high-side transistor; a high-side control circuit that generates a first high-side control signal for controlling the high-side gate driver and a second high-side control signal for controlling the second switch; a sink rise detection circuit that generates a sink rise detection signal regarding a transition of an output of the bridge circuit to a high voltage when a gate-source voltage of the high-side transistor crosses a negative third threshold voltage with the second switch in an on state when the bridge circuit operates in a sink mode; A driver circuit comprising:

[0148] (Item 8) the high-side gate driver and the low-side gate driver are current-driven; the high-side control circuit changes an output current of the high-side gate driver in response to a change in the source rise detection signal when the bridge circuit operates in a source mode; 8. The driver circuit of claim 7, wherein the low-side control circuit changes the output current of the low-side gate driver in response to a change in the sink rise detection signal when the bridge circuit operates in a sink mode.

[0149] (Item 9) a source fall detection circuit configured to generate a source fall detection signal regarding a transition of an output of the bridge circuit to a low voltage when a gate-source voltage of the low-side transistor crosses a negative second threshold voltage while the first switch is on when the bridge circuit operates in a source mode; a sink fall detection circuit that generates a sink fall detection signal regarding a transition of an output of the bridge circuit to a low voltage when the gate-source voltage of the high-side transistor crosses a negative second threshold voltage while the second switch is on when the bridge circuit operates in a sink mode; Item 9. The driver circuit of item 7 or 8, further comprising:

[0150] (Item 10) the high-side gate driver and the low-side gate driver are current-driven; the high-side control circuit changes the output current of the high-side gate driver in response to a change in the source fall detection signal when the bridge circuit operates in a source mode; 10. The driver circuit of claim 9, wherein the low-side control circuit changes the output current of the low-side gate driver in response to a change in the sink fall detection signal when the bridge circuit operates in a sink mode.

[0151] (Item 11) a low-side sensor that generates a low-side sense signal indicating a result of comparison between a gate-source voltage of the low-side transistor and a fifth threshold voltage when the first switch is in an off state; a high-side sensor that generates a high-side sense signal indicating a result of comparison between a gate-source voltage of the high-side transistor and a sixth threshold voltage when the second switch is in an off state; 11. The driver circuit of any of items 7 to 10, further comprising:

[0152] (Item 12) a bridge circuit including a high-side transistor and a low-side transistor; A driver circuit according to any one of items 7 to 11 that drives the bridge circuit; A motor drive device comprising:

[0153] (Item 13) A motor; Item 13. The motor drive device according to item 12, which drives the motor; An electronic device comprising:

[0154] (Item 14) A method for driving a bridge circuit including a high-side transistor and a low-side transistor, comprising: a source rise transition step of increasing an output voltage of the bridge circuit when the bridge circuit operates in a source mode; The source rise transition step includes: a low-side gate driver reducing a gate-source voltage of the low-side transistor to turn off the low-side transistor; turning on a first switch provided between a gate and a source of the low-side transistor; a high side gate driver sourcing a drive current to a gate of the high side transistor; changing a source rise detection signal when a gate-source voltage of the low-side transistor crosses a first positive threshold voltage; the high-side gate driver varying the drive current in response to a change in the source rise detection signal; A driving method comprising:

[0155] (Item 15) A method for driving a bridge circuit including a high-side transistor and a low-side transistor, comprising: a source fall transition step of reducing an output voltage of the bridge circuit when the bridge circuit operates in a source mode, wherein in an initial state, a first switch provided between a gate and a source of the low-side transistor is in an on state; The source fall transition step includes: a high side gate driver sinking a drive current from a gate of the high side transistor; changing a source fall detection signal when the gate-source voltage of the low-side transistor crosses a negative second threshold voltage; the high-side gate driver varying the drive current in response to a change in the source fall detection signal; turning off the first switch; a low-side gate driver increasing a gate-source voltage of the low-side transistor to turn on the low-side transistor; A driving method comprising:

[0156] (Item 16) A method for driving a bridge circuit including a high-side transistor and a low-side transistor, comprising: a sink-rise transition step for increasing an output voltage of the bridge circuit when the bridge circuit operates in a sink mode, wherein in an initial state, a second switch provided between a gate and a source of the high-side transistor is in an on state; The sync rise transition step includes: a low side gate driver sourcing a drive current to a gate of the low side transistor; changing a synchronism detection signal when a gate-source voltage of the high-side transistor crosses a fourth positive threshold voltage; the low-side gate driver varying the drive current in response to a change in the sync rise detection signal; turning off the second switch; a high-side gate driver increasing a gate-source voltage of the high-side transistor to turn on the high-side transistor; A driving method comprising:

[0157] (Item 17) A method for driving a bridge circuit including a high-side transistor and a low-side transistor, comprising: a sink fall transition step of reducing an output voltage of the bridge circuit when the bridge circuit operates in a sink mode; The sinkfall transition step includes: a high-side gate driver reducing a gate-source voltage of the high-side transistor to turn off the high-side transistor; turning on a second switch provided between the gate and source of the high-side transistor; a low side gate driver sourcing a drive current to a gate of the low side transistor; changing a sink fall detection signal when the gate-source voltage of the high-side transistor crosses a third positive threshold voltage; the low-side gate driver varying the drive current in response to a change in the sink fall detection signal; A driving method comprising: [Explanation of symbols]

[0158] 100 Switching Circuit 102 input lines 104 output lines 106 Ground Line 110 Bridge Circuit MH high-side transistor ML low-side transistor 200 Driver Circuit 300 High-side driver circuit 310 High-side control circuit 320 High-Side Gate Driver 322 Source Current Source 324 Sink Current Source 330 Second Switch 340 Synchro detection circuit 350 Sinkfall detection circuit 360 High Side Sensor 400 Low-side driver circuit 410 Low-side control circuit 420 Low-Side Gate Driver 422 Source Current Source 424 Sink Current Source 430 First Switch 440 Source Rise Detection Circuit 450 Source Fall Detection Circuit 460 Low Side Sensor

Claims

1. A low-side driver circuit that drives a low-side transistor that configures a bridge circuit together with a high-side transistor, a low-side gate driver that controls a gate voltage of the low-side transistor; a first switch connected between the gate and source of the low-side transistor; a low-side control circuit that generates a first low-side control signal for controlling the low-side gate driver and a second low-side control signal for controlling the first switch; a source rise detection circuit configured to generate a source rise detection signal regarding a transition of an output of the bridge circuit to a high voltage when a gate-source voltage of the low-side transistor crosses a positive first threshold voltage with the first switch in an on state when the bridge circuit operates in a source mode; 1. A low-side driver circuit comprising:

2. 2. The low-side driver circuit of claim 1, further comprising: a source fall detection circuit that generates a source fall detection signal regarding a transition of an output of the bridge circuit to a low voltage when a gate-source voltage of the low-side transistor crosses a negative second threshold voltage with the first switch on when the bridge circuit operates in a source mode.

3. 3. The low-side driver circuit according to claim 2, wherein the source rise detection signal and the source fall detection signal are supplied to a high-side driver circuit that drives the high-side transistor.

4. A high-side driver circuit that drives a high-side transistor that configures a bridge circuit together with a low-side transistor, a high-side gate driver that controls a gate voltage of the high-side transistor; a second switch connected between the gate and source of the high-side transistor; a high-side control circuit that generates a first high-side control signal for controlling the high-side gate driver and a second high-side control signal for controlling the second switch; a sink rise detection circuit that generates a sink rise detection signal regarding a transition of an output of the bridge circuit to a high voltage when a gate-source voltage of the high-side transistor crosses a negative third threshold voltage with the second switch in an on state when the bridge circuit operates in a sink mode; 1. A high-side driver circuit comprising:

5. 5. The high-side driver circuit of claim 4, further comprising: a sink fall detection circuit that generates a sink fall detection signal regarding a transition of an output of the bridge circuit to a low voltage when a gate-to-source voltage of the high-side transistor crosses a positive fourth threshold voltage with the second switch on when the bridge circuit operates in a sink mode.

6. 6. The high-side driver circuit according to claim 5, wherein the synchronism rise detection signal and the synchronism fall detection signal are supplied to a low-side driver circuit that drives the low-side transistor.

7. A driver circuit for driving a high-side transistor and a low-side transistor that constitute a bridge circuit, a low-side gate driver that controls a gate voltage of the low-side transistor; a first switch connected between the gate and source of the low-side transistor; a low-side control circuit that generates a first low-side control signal for controlling the low-side gate driver and a second low-side control signal for controlling the first switch; a source rise detection circuit configured to generate a source rise detection signal regarding a transition of an output of the bridge circuit to a high voltage when a gate-source voltage of the low-side transistor crosses a positive first threshold voltage with the first switch in an on state when the bridge circuit operates in a source mode; a high-side gate driver that controls a gate voltage of the high-side transistor; a second switch connected between the gate and source of the high-side transistor; a high-side control circuit that generates a first high-side control signal for controlling the high-side gate driver and a second high-side control signal for controlling the second switch; a sink rise detection circuit that generates a sink rise detection signal regarding a transition of an output of the bridge circuit to a high voltage when a gate-source voltage of the high-side transistor crosses a negative third threshold voltage with the second switch in an on state when the bridge circuit operates in a sink mode; A driver circuit comprising:

8. the high-side gate driver and the low-side gate driver are current-driven; the high-side control circuit changes an output current of the high-side gate driver in response to a change in the source rise detection signal when the bridge circuit operates in a source mode; 8. The driver circuit of claim 7, wherein the low-side control circuit changes the output current of the low-side gate driver in response to a change in the sink rise detection signal when the bridge circuit operates in a sink mode.

9. a source fall detection circuit configured to generate a source fall detection signal regarding a transition of an output of the bridge circuit to a low voltage when a gate-source voltage of the low-side transistor crosses a negative second threshold voltage with the first switch in an on state when the bridge circuit operates in a source mode; a sink fall detection circuit that generates a sink fall detection signal regarding a transition of an output of the bridge circuit to a low voltage when a gate-source voltage of the high-side transistor crosses a negative second threshold voltage with the second switch in an on state when the bridge circuit operates in a sink mode; 9. A driver circuit as claimed in claim 7 or 8, further comprising:

10. the high-side gate driver and the low-side gate driver are current-driven; the high-side control circuit changes the output current of the high-side gate driver in response to a change in the source fall detection signal when the bridge circuit operates in a source mode; 10. The driver circuit of claim 9, wherein the low-side control circuit changes the output current of the low-side gate driver in response to a change in the sink fall detection signal when the bridge circuit operates in a sink mode.

11. a low-side sensor that generates a low-side sense signal indicating a result of comparison between a gate-source voltage of the low-side transistor and a fifth threshold voltage when the first switch is in an off state; a high-side sensor that generates a high-side sense signal indicating a result of comparison between a gate-source voltage of the high-side transistor and a sixth threshold voltage when the second switch is in an off state; 9. A driver circuit as claimed in claim 7 or 8, further comprising:

12. a bridge circuit including a high-side transistor and a low-side transistor; a driver circuit according to claim 7 or 8 for driving the bridge circuit; A motor drive device comprising:

13. A motor; a motor drive device according to claim 12 that drives the motor; An electronic device comprising:

14. A method for driving a bridge circuit including a high-side transistor and a low-side transistor, comprising: a source rise transition step of increasing an output voltage of the bridge circuit when the bridge circuit operates in a source mode; The source rise transition step includes: a low-side gate driver reducing a gate-source voltage of the low-side transistor to turn off the low-side transistor; turning on a first switch provided between a gate and a source of the low-side transistor; a high side gate driver sourcing a drive current to a gate of the high side transistor; changing a source rise detection signal when a gate-source voltage of the low-side transistor crosses a first positive threshold voltage; the high-side gate driver varying the drive current in response to a change in the source rise detection signal; A driving method comprising:

15. A method for driving a bridge circuit including a high-side transistor and a low-side transistor, comprising: a source fall transition step of reducing an output voltage of the bridge circuit when the bridge circuit operates in a source mode, wherein in an initial state, a first switch provided between a gate and a source of the low-side transistor is in an on state; The source fall transition step includes: a high side gate driver sinking a drive current from a gate of the high side transistor; changing a source fall detection signal when the gate-source voltage of the low-side transistor crosses a negative second threshold voltage; the high-side gate driver varying the drive current in response to a change in the source fall detection signal; turning off the first switch; a low-side gate driver increasing a gate-source voltage of the low-side transistor to turn on the low-side transistor; A driving method comprising:

16. A method for driving a bridge circuit including a high-side transistor and a low-side transistor, comprising: a sink-rise transition step for increasing an output voltage of the bridge circuit when the bridge circuit operates in a sink mode, wherein in an initial state, a second switch provided between a gate and a source of the high-side transistor is in an on state; The sync rise transition step includes: a low side gate driver sourcing a drive current to a gate of the low side transistor; changing a synchronism detection signal when a gate-source voltage of the high-side transistor crosses a fourth positive threshold voltage; the low-side gate driver varying the drive current in response to a change in the sync rise detection signal; turning off the second switch; a high-side gate driver increasing a gate-source voltage of the high-side transistor to turn on the high-side transistor; A driving method comprising:

17. A method for driving a bridge circuit including a high-side transistor and a low-side transistor, comprising: a sink fall transition step of reducing an output voltage of the bridge circuit when the bridge circuit operates in a sink mode; The sinkfall transition step includes: a high-side gate driver reducing a gate-source voltage of the high-side transistor to turn off the high-side transistor; turning on a second switch provided between the gate and source of the high-side transistor; a low side gate driver sourcing a drive current to a gate of the low side transistor; changing a sink fall detection signal when the gate-source voltage of the high-side transistor crosses a positive third threshold voltage; the low-side gate driver varying the drive current in response to a change in the sink fall detection signal; A driving method comprising:

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