Gate driver circuits, three-phase gate drivers, and switching circuits

Abstract

This provides a gate driver circuit that can more reliably and appropriately drive high-side transistors. [Solution] The gate driver circuit 100 includes a high-side driver 122 for driving the high-side transistor MH, a charge pump line 162 to which a charge pump voltage generated by charge pump circuits 160, 260, 360 that is higher than the input voltage of the high-side transistor MH is supplied, current source circuits 170, 270U~270W, 370U~370W configured to supply a constant current from the charge pump line 162 to a bootstrap capacitor for driving the high-side transistor MH, and a current control circuit 128 that controls the on / off switching of the constant current supply to the bootstrap capacitor by the current source circuits 170, 270U~270W, 370U~370W. The charge pump circuit 360 does not need to have an output capacitor.

Description

[Technical Field]

[0001] This disclosure relates to gate driver circuits, three-phase gate drivers, and switching circuits. [Background technology]

[0002] Conventionally, transistors and gate driver circuits for driving those transistors have been used in various applications such as DC / DC converters and motor drive devices.

[0003] When driving a high-side transistor composed of an N-channel MOS (Metal Oxide Semiconductor) transistor, a bootstrap circuit may be used (see, for example, Patent Document 1). The bootstrap circuit generates a bootstrap voltage that is higher than the input voltage of the high-side transistor. This bootstrap voltage is used to drive the high-side transistor. [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2024-160804

[0005] [overview] However, the inventors have come to recognize the following problem: A bootstrap circuit generates a bootstrap voltage by charging a bootstrap capacitor when the low-side switching element is on. When PWM (Pulse Width Modulation) control is performed with a high duty cycle, the on period of the low-side switching element becomes shorter. As a result, the bootstrap capacitor may not be sufficiently charged, and the high-side transistor may not be driven properly.

[0006] This disclosure is made in view of these circumstances, and one of its exemplary objectives is to provide gate driver circuits, three-phase gate drivers, and switching circuits that can more reliably and properly drive high-side transistors.

[0007] One aspect of the present disclosure is a gate driver circuit for a high-side transistor. The gate driver circuit comprises a high-side driver for driving a high-side transistor; a charge pump line to which a charge pump voltage generated by a charge pump circuit higher than the input voltage of the high-side transistor is supplied; a current source circuit configured to supply a constant current from the charge pump line to a bootstrap capacitor for driving the high-side transistor; and a current control circuit for controlling the on / off switching of the supply of constant current to the bootstrap capacitor by the current source circuit.

[0008] Furthermore, any combination of the above components, as well as any conversion of the expressions of this disclosure between methods, apparatus, systems, etc., are also valid as aspects of this disclosure. [Brief explanation of the drawing]

[0009] [Figure 1] Figure 1 is a block diagram of the electronic device according to the first embodiment. [Figure 2] Figure 2 is a circuit diagram of a charge pump circuit according to the same embodiment. [Figure 3] Figure 3 is a circuit diagram of the current source circuit according to the same embodiment. [Figure 4] Figure 4 is a block diagram of the high-side control circuit according to the same embodiment. [Figure 5] Figure 5 is a timing chart showing an example of the operation of the gate driver circuit according to the same embodiment. [Figure 6] Figure 6 is a block diagram of the electronic device according to the second embodiment. [Figure 7] Figure 7 is a circuit diagram of the charge pump circuit and current source circuit according to the third embodiment. [Figure 8]Figure 8 is a timing chart illustrating an example of the operation of the charge pump circuit and current source circuit according to the same embodiment. [Figure 9] Figure 9 is a circuit diagram illustrating examples of operation of a charge pump circuit and a current source circuit related to the comparative technology. [Figure 10] Figure 10 is a circuit diagram of the charge pump circuit and current source circuit according to the fourth embodiment. [Figure 11] Figure 11 is a timing chart illustrating an example of the operation of the charge pump circuit and current source circuit according to the same embodiment.

[0010] [Detailed explanation] (overview) 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. It is not intended to limit the scope of the invention or disclosure. This outline is not a comprehensive overview of all possible embodiments, nor is it intended to identify essential elements of all embodiments or to delineate the scope of some or all aspects. For convenience, “one embodiment” may be used to refer to one or more embodiments (examples or variations) disclosed herein.

[0011] A gate driver circuit according to one embodiment includes a high-side driver for driving a high-side transistor, a charge pump line to which a charge pump voltage generated by a charge pump circuit, which is higher than the input voltage of the high-side transistor, is supplied, a current source circuit configured to supply a constant current from the charge pump line to a bootstrap capacitor for driving the high-side transistor, and a current control circuit for controlling the on / off switching of the constant current supply to the bootstrap capacitor by the current source circuit.

[0012] This configuration allows for the charging of the bootstrap capacitor by supplying a constant current to it, ensuring that the capacitor voltage reaches the desired level more reliably. As a result, the high-side transistor can be driven more reliably and appropriately.

[0013] In one embodiment, the gate driver circuit may further include a voltage sensor for detecting the capacitor voltage of the bootstrap capacitor. The current control circuit may control the on / off switching of the constant current supply to the bootstrap capacitor by the current source circuit according to the comparison result between the capacitor voltage detected by the voltage sensor and a comparison voltage.

[0014] In one embodiment, the current control circuit may keep the current source circuit supplying a constant current to the bootstrap capacitor on until the voltage sensor detects that the capacitor voltage has reached a threshold voltage. The current control circuit may switch the current source circuit's supply of a constant current to the bootstrap capacitor from on to off in response to the voltage sensor detecting that the capacitor voltage has reached a threshold voltage.

[0015] In one embodiment, the current control circuit may, with the threshold voltage set as the upper threshold voltage, switch the supply of a constant current to the bootstrap capacitor by the current source circuit from off to on when the voltage sensor detects that the capacitor voltage has dropped to a lower threshold voltage, which is lower than the upper threshold voltage, after the capacitor voltage has reached the upper threshold voltage.

[0016] In one embodiment, the current control circuit may switch the supply of a constant current to the bootstrap capacitor by the current source circuit from off to on in response to the voltage sensor detecting that the capacitor voltage is below a predetermined low-voltage threshold voltage.

[0017] In one embodiment, the current source circuit may be configured to allow switching of the magnitude of the constant current.

[0018] In one embodiment, the current source circuit may include a current mirror circuit and a switching circuit. The current mirror circuit may include two transistors forming a current mirror pair. The current mirror circuit may be configured such that the current flowing through one of the two transistors is copied by the other transistor. The switching circuit may be configured to switch the state of the current mirror circuit between a first state in which the current flowing through one transistor is zero and a second state in which a constant current flows through the other transistor. The other transistor may be located between the charge pump line and the bootstrap capacitor.

[0019] In one embodiment, the charge pump circuit may include a charge pump capacitor. The charge pump circuit may alternately repeat a charging phase, which charges the charge pump capacitor to generate a charge pump voltage, and a boosting phase, which boosts the voltage at one end of the output side of the charge pump capacitor. The switching circuit may operate in synchronization with the charge pump circuit, setting the current mirror circuit to a first state during the charging phase and to a second state during the boosting phase.

[0020] In one embodiment, the current source circuit may further include a rectifier element. The rectifier element may be provided between the other transistor and the bootstrap capacitor, such that the direction from the other transistor to the bootstrap capacitor is forward.

[0021] A switching circuit according to one embodiment may include the gate driver circuit, a bootstrap capacitor, a high-side transistor, and a charge pump circuit.

[0022] A three-phase gate driver according to one embodiment may control a three-phase bridge circuit having a first leg including a first high-side transistor and a first low-side transistor, a second leg including a second high-side transistor and a second low-side transistor, and a third leg including a third high-side transistor and a third low-side transistor. This three-phase gate driver may include a first gate driver circuit which is the gate driver circuit that controls the first high-side transistor as a high-side transistor, a second gate driver circuit which is the gate driver circuit that controls the second high-side transistor as a high-side transistor, and a third gate driver circuit which is the gate driver circuit that controls the third high-side transistor as a high-side transistor.

[0023] (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, the embodiments are illustrative and not limiting to the disclosure and invention, and not all features or combinations thereof described in the embodiments are necessarily essential to the disclosure and invention.

[0024] In this specification, "member A is 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.

[0025] Similarly, "member C is positioned (placed) 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 or impair the functions or effects produced by their combination.

[0026] In this specification, the symbols attached to electrical signals such as voltage signals and current signals, or to circuit elements such as resistors, capacitors, and inductors, shall represent the respective voltage values, current values, or circuit constants (resistance values, capacitance values, and inductance) as needed.

[0027] Furthermore, in this specification, "integrated" includes cases where all components of a circuit are formed on a semiconductor substrate, or where the main components of a circuit are integrated, and some resistors, capacitors, etc., may be provided outside the semiconductor substrate for adjusting circuit constants.

[0028] (First Embodiment) Figure 1 is a block diagram of the electronic device 1 according to the first embodiment. The electronic device 1 according to this embodiment includes a switching circuit 10 and a load 19. The load 19 is the output voltage V of the switching circuit 10. OUT It operates accordingly.

[0029] The switching circuit 10 according to this embodiment comprises a gate driver circuit 100 and peripheral circuits 180. The gate driver circuit 100 and peripheral circuits 180 are connected to each other via various pins provided on the gate driver circuit 100 (for example, bootstrap pin BST, high-side gate pin HG, switching pin SW, low-side gate pin LG, and low-side source pin LS).

[0030] The peripheral circuit 180 consists of a half-bridge circuit 182 and a bootstrap capacitor C. BST It is equipped with.

[0031] The half-bridge circuit 182 has an input voltage V CC Output voltage V corresponding to the corresponding value OUT It is configured to generate [the specified value]. The half-bridge circuit 182 according to this embodiment has a high-side transistor MH, a low-side transistor ML, and a resistor R2.

[0032] The high-side transistor MH and the low-side transistor ML are each configured by an N-channel MOS transistor. The drain of the high-side transistor MH is connected to the input voltage V CC is supplied power line 184 (input line), and the source of the high-side transistor MH is connected to the output voltage V OUT is supplied output line 186, and the gate of the high-side transistor MH is connected to the high-side gate pin HG.

[0033] The output line 186 connects the switching pin SW and the load 19. The drain of the low-side transistor ML is connected to the output line 186, the source of the low-side transistor ML is connected to the low-side source pin LS, and the gate of the low-side transistor ML is connected to the low-side gate pin LG. One end of the resistor R2 is connected to the low-side source pin LS, and the other end of the resistor R2 is connected to the ground line 188.

[0034] Bootstrap capacitor C BST is provided to drive the high-side transistor MH. Bootstrap capacitor C BST has one end connected to the bootstrap pin BST, and bootstrap capacitor C BST has the other end connected to the output line 186. Bootstrap capacitor C BST has a capacitor voltage V C which, when the voltage of the bootstrap pin BST is defined as V BST , is expressed as V C =V BST -V OUT .

[0035] The gate driver circuit 100 drives the high-side transistor MH and the low-side transistor ML. The gate driver circuit 100 according to this embodiment mainly comprises a logic circuit 110, a high-side control circuit 120, a bootstrap line 130, a switching line 132, a power supply line 134, a low-side control circuit 140, a charge pump circuit 160, a charge pump line 162, a current source circuit 170, a resistor R1, and a rectifier element D1. The gate driver circuit 100 may be an integrated circuit (IC) integrated onto a single semiconductor chip.

[0036] Bootstrap line 130 is a line (or node) connected to bootstrap pin BST. Switching line 132 is a line (or node) connected to switching pin SW. Power line 134 is connected to bootstrap capacitor C. BST Power supply voltage V REG This is the line (or node) to which the charge pump voltage V is supplied. The charge pump line 162 is supplied with the charge pump voltage V generated by the charge pump circuit 160. CP1 This is the line (or node) that supplies it.

[0037] The logic circuit 110 controls the control signal S CTR Accordingly, a PWM signal is generated to control the high-side control circuit 120 and the low-side control circuit 140. Control signal S CTR For example, the output voltage V OUT The logic circuit 110 may include, for example, a high-side control signal S transmitted to the high-side control circuit 120. HCTR and the low-side control signal S transmitted to the low-side control circuit 140 LCTR It generates things like this.

[0038] The high-side control circuit 120 performs control related to the driving of the high-side transistor MH. In this embodiment, the high-side control circuit 120 receives the high-side control signal S from the logic circuit 110. HCTR High-side gate signal S corresponding to the signal SGH Generates a high-side gate signal S. GH This is supplied to the gate of the high-side transistor MH via the high-side gate pin HG. In addition, the high-side control circuit 120 according to this embodiment controls the operation of the current source circuit 170 with a control signal S SW Generates.

[0039] The low-side control circuit 140 performs control over the driving of the low-side transistor ML. For example, the low-side control circuit 140 receives the low-side control signal S from the logic circuit 110. LCTR Low-side gate signal S corresponding to the signal S GL Generates a low-side gate signal S. GL This power is supplied to the gate of the low-side transistor ML via the low-side gate pin LG.

[0040] The charge pump circuit 160 receives the input voltage V of the half-bridge circuit 182 (or high-side transistor MH). CC A higher charge pump voltage V CP1 The charge pump circuit 160 according to this embodiment generates the input voltage V CC Power supply voltage V REG The superimposed charge pump voltage V CP1 Generates.

[0041] The current source circuit 170 receives power from the charge pump line 162 to the bootstrap capacitor C BST It is configured to supply a constant current I1 to the bootstrap capacitor C via the bootstrap line 130 and bootstrap pin BST. BST This supplies power to the bootstrap capacitor C. BST The capacitor is charged, and the capacitor voltage V C It will rise.

[0042] The resistor R1 and the rectifier element D1 are connected to the bootstrap capacitor C. BSTTogether, these constitute a bootstrap circuit. One end of resistor R1 is connected to power line 134. The rectifier element D1 is composed of a diode. The anode of rectifier element D1 is connected to the other end of resistor R1, and the cathode of rectifier element D1 is connected to bootstrap line 130.

[0043] Figure 2 is a circuit diagram of the charge pump circuit 160 according to this embodiment. The charge pump circuit 160 according to this embodiment includes a buffer 164, rectifier elements D2, D3 and a charge pump capacitor C chg and output capacitor C OUT It has a charge pump capacitor C. chg and output capacitor C OUT These capacitors may be externally attached to the semiconductor chip constituting the gate driver circuit 100. By externalizing these capacitors, capacitances of several nF, which are difficult to achieve with IC chips, can be realized. As a result, a current capability of several tens of mA can be achieved, for example.

[0044] The rectifier elements D2 and D3 are each composed of diodes. The anode of rectifier element D2 receives the input voltage V CC A charge is supplied, and the cathode of rectifier element D2 is connected to the anode of rectifier element D3. The cathode of rectifier element D3 is connected to the charge pump line 162. Charge pump capacitor C chg One end is connected to the cathode of rectifier element D2. Output capacitor C OUT One end is connected to the charge pump line 162, and the output capacitor C OUT The other end has an input voltage V CC A clock signal S from an oscillator (not shown) is supplied to buffer 164. CLK The input is, and buffer 164 receives the clock signal S CLK It generates an output voltage V1 corresponding to the charge pump capacitor C. chg It is supplied to the other end.

[0045] The operation of the charge pump circuit 160 will be explained. The charge pump circuit 160 operates under an input voltage V CCA higher charge pump voltage V CP1 The charging phase and boosting phase are alternately repeated to generate the voltage. In the charging phase, the charge pump circuit 160 controls the charge pump capacitor C chg This is the charging phase. In the boost phase, the charge pump circuit 160 charges the charge pump capacitor C. chg This is the phase in which the voltage at one end of the output side is boosted. Here, the charge pump capacitor C chg The voltage at one end of the output side is the voltage V at node N1 between rectifier element D2 and rectifier element D3. N1 In this embodiment, the phase of the charge pump circuit 160 is determined by the clock signal S CLK When the signal is low, it enters the charging phase, and the clock signal S CLK The boost phase occurs when the voltage level is high.

[0046] During the charging phase (i.e., the clock signal S) CLK When the voltage is low, the output voltage V1 of buffer 164 becomes 0V. The voltage drop across rectifier element D2 is V f Expressed as such, the voltage V at node N1 N1 V N1 =V CC -V f This results in the charge pump capacitor C chg V CC -V f It is charged by the boost phase (i.e., the clock signal S CLK When the voltage is high, the output voltage V1 of buffer 164 is equal to the power supply voltage V REG This is the result. At this time, the charge pump capacitor C chg The voltage across both ends is V CC -V f Because it is maintained, the voltage V of node N1 N1 V N1 =V CC -V f +V REG The voltage at this time is V. N1 (=V CC -V f +V REG ) by output capacitor C OUTis charged. By repeating the charging phase and the boosting phase, the charge pump voltage V CP1 becomes V CP1 =V CC -2V f +V REG .

[0047] FIG. 3 is a circuit diagram of the current source circuit 170 according to the present embodiment. The current source circuit 170 according to the present embodiment includes a current mirror circuit 172 and a switching circuit 174.

[0048] The current mirror circuit 172 includes two transistors MP1 and MP2 forming a current mirror pair, and is configured such that the current flowing through one transistor MP1 is copied by the other transistor MP2. The transistors MP1 and MP2 are each configured by a P-channel MOS transistor. The gate of the transistor MP1 is connected to the drain of the transistor MP1 in common with the gate of the transistor MP2. The source of the transistor MP1 is connected to the charge pump line 162 in common with the source of the transistor MP2. Therefore, the charge pump voltage V is applied to the respective sources of the transistors MP1 and MP2 CP1 is supplied. The drain of the transistor MP2 is connected to the bootstrap line 130.

[0049] The switching circuit 174 is configured to be capable of switching the state of the current mirror circuit 172 between a first state in which the current amount of the transistor MP1 is zero and a second state in which a constant current flows through the transistor MP1. The switching circuit 174 according to the present embodiment includes a switch SW1 and a current source 176. The switch SW1 may be configured by various switch elements, and is provided between the drain of the transistor MP1 and the current source 176. ON and OFF of the switch SW1 are controlled by the control signal S SW . The current source 176 is configured to be capable of generating a constant current I V .

[0050] When the switch SW1 is ON, the current I generated by the current source 176 Vflows through transistor MP1. Transistor MP2 copies the current I flowing through transistor MP1 V to generate a constant current I1. When switch SW1 is off, no current flows through transistor MP2, and the current amount of transistor MP1 becomes zero. As a result, no current flows through transistor MP2 either (I1=0).

[0051] The current source circuit 170 according to the present embodiment is configured to be capable of switching the magnitude of the constant current I1. Specifically, the current source 176 is configured to be capable of switching the current I V magnitude. By switching the magnitude of the current I V , the magnitude of the constant current I1 can be switched. The switching of the magnitude of the current I V may be performed by, for example, the high-side control circuit 120.

[0052] Figure 4 is a block diagram of the high-side control circuit 120 according to the present embodiment. The high-side control circuit 120 according to the present embodiment includes a high-side driver 122, a voltage sensor 124, and a current control circuit 128.

[0053] The high-side driver 122 drives the high-side transistor MH. The high-side driver 122 according to the present embodiment uses the bootstrap voltage V of the bootstrap line 130 BST to generate the high-side gate signal S corresponding to the high-side control signal S HCTR GH .

[0054] The voltage sensor 124 detects the voltage between the bootstrap line 130 and the switching line 132, that is, the capacitor voltage V of the bootstrap capacitor C BST C . The voltage sensor 124 includes a threshold voltage sensor 125 and a low voltage sensor 126.

[0055] The threshold voltage sensor 125 outputs a sensor signal S indicating the comparison result between the threshold voltage and the capacitor voltage V C ​​​SNS1 Generates sensor signal S. SNS1 This is the lower threshold voltage and the capacitor voltage V C The signal shows the comparison result with the upper threshold voltage, which is higher than the lower threshold voltage, and the capacitor voltage V. C It may include signals that show the comparison result with the sensor signal S. SNS1 This is transmitted to the current control circuit 128. The threshold voltage sensor 125 may include a comparator for comparing voltages, if necessary.

[0056] The low-voltage sensor 126 has a predetermined low-voltage threshold voltage and a capacitor voltage V C Sensor signal S showing the comparison result SNS2 This generates a threshold voltage, which is lower than the lower threshold voltage, and this voltage is used to generate the capacitor voltage V. C The sensor signal S may be set to a level that, if it falls below a certain point, could potentially cause unintended effects on the drive of the high-side transistor MH. SNS2 This is transmitted to the current control circuit 128. The low-voltage sensor 126 may include a comparator for comparing voltages, if necessary.

[0057] The current control circuit 128 uses a bootstrap capacitor C provided by the current source circuit 170. BST The current control circuit 128 according to this embodiment controls the on / off supply of constant current I1 to the signal. SW This generates a constant current I1 to control the on / off state of switch SW1 of the current source circuit 170. When switch SW1 is on, the constant current I1 is supplied (I1>0), and when switch SW1 is off, the constant current I1 is supplied off (I1=0).

[0058] In this embodiment, the current control circuit 128 controls the capacitor voltage V detected by the voltage sensor 124. C And, according to the comparison result with the comparison voltage, the bootstrap capacitor C of the current source circuit 170 BST Controls the on / off switching of the constant current I1 supply to the capacitor. The comparison voltage is the capacitor voltage V. CThis is the voltage used for comparison, and includes, for example, the lower threshold voltage, the upper threshold voltage, and a predetermined low-voltage threshold voltage.

[0059] The current control circuit 128 controls the capacitor voltage V C The bootstrap capacitor C of the current source circuit 170 continues until the threshold voltage sensor 125 detects that the voltage has reached the upper threshold voltage. BST The constant current I1 supply to the bootstrap capacitor C may be kept on. This ensures that even when the load 19 is heavy and has a high duty cycle, the constant current I1 is kept on. BST By supplying it to, the capacitor voltage V can be more reliably supplied. C It becomes possible to raise it sufficiently.

[0060] The current control circuit 128 controls the capacitor voltage V C When the threshold voltage sensor 125 detects that the voltage has reached the upper threshold voltage, the bootstrap capacitor C of the current source circuit 170 is activated. BST The supply of constant current I1 to the capacitor can be switched from on to off. This will change the capacitor voltage V C This prevents an excessive rise in [the substance].

[0061] The current control circuit 128 controls the capacitor voltage V C After the upper threshold voltage is reached, the capacitor voltage V C When the threshold voltage sensor 125 detects that the voltage has dropped to the lower threshold voltage, the bootstrap capacitor C of the current source circuit 170 activates. BST The supply of constant current I1 to V can be switched from off to on. This allows for a more reliable capacitor voltage V as described above. C It becomes possible to raise it sufficiently.

[0062] The current control circuit 128 controls the capacitor voltage V C When the low-voltage sensor 126 detects that the voltage is below a predetermined low-voltage threshold voltage, the bootstrap capacitor C of the current source circuit 170 activates. BSTThe supply of constant current I1 to the capacitor can be switched from off to on. This will change the capacitor voltage V C The decrease in this value suppresses situations in which the operation of the high-side transistor MH stops.

[0063] Figure 5 is a timing chart showing an example of the operation of the gate driver circuit 100 according to this embodiment. Here, the high-side transistor MH and low-side transistor ML of the half-bridge circuit 182 are assumed to be switched in accordance with the control by the gate driver circuit 100.

[0064] Figure 5 shows the control signal S of switch SW1 of the current source circuit 170. SW , capacitor voltage V C And it shows the state of load 19. Switch SW1 controls the control signal S SW It is on when it is at a high level (H), and the control signal S SW Assume that it is off when it is at a low level (L). thL This is the lower threshold voltage, V thH This is the upper threshold voltage, V LV This is a predetermined low-voltage threshold voltage.

[0065] Before time t1, there is no load 19 and switch SW1 is ON. At this time, the capacitor voltage V is increased due to the operation of the bootstrap circuit and the supply of constant current I1 by the current source circuit 170. C The voltage increases. At time t1, the capacitor voltage V C The upper threshold voltage V thH When this value is reached, switch SW1 switches from on to off. While switch SW1 is off, the constant current I1 is not supplied by the current source circuit 170, and the capacitor voltage V is reduced by the operation of the bootstrap circuit. C It will rise.

[0066] At time t2, when load 19 (normal level) is connected to the switching circuit 10, the capacitor voltage V CThe rise stops (or slows down). At time t3, when load 19 becomes overloaded, the bootstrap circuit alone is insufficient, and the capacitor voltage V C It begins to decline.

[0067] At time t4, the capacitor voltage V C The lower threshold voltage V thL When this happens, switch SW1 switches from off to on. As a result, the constant current I1 supplied by the current source circuit 170 causes the capacitor voltage V C It begins to rise.

[0068] Subsequently, at times t5, t6, and t7, the capacitor voltage V C The upper threshold voltage V thH or lower threshold voltage V thL Each time this happens, switch SW1 switches between on and off. This ensures that even under overload conditions, the capacitor voltage V C The appropriate voltage range (specifically, the upper threshold voltage V thH and the lower threshold voltage V thL It becomes possible to fit it in between (and).

[0069] Note that the capacitor voltage V C The threshold voltage V LV If the following occurs, intentionally set the capacitor voltage V C Switch SW1 may always be left ON, except when lowering the value. This more reliably prevents the high-side driver 122 from ceasing to operate.

[0070] The configuration of the gate driver circuit 100 and the switching circuit 10 using the same according to this embodiment, as well as an example of the operation of the gate driver circuit 100, have been described above. The gate driver circuit 100 according to this embodiment comprises a high-side driver 122, a current control circuit 128, a charge pump line 162, and a current source circuit 170. The high-side driver 122 drives the high-side transistor MH. The charge pump line 162 controls the input voltage V of the high-side transistor MH. CCThe charge pump voltage V generated by the charge pump circuit 160 is higher than the charge pump voltage V. CP1 The current is supplied. The current source circuit 170 has a bootstrap capacitor C to drive the high-side transistor MH. BST The current control circuit 128 is configured to supply a constant current I1 from the charge pump line 162. The current control circuit 128 is configured to supply a bootstrap capacitor C from the current source circuit 170. BST Controls the on / off switching of the constant current I1 supply to the device.

[0071] According to this configuration, the bootstrap capacitor C BST By supplying a constant current I1 to the bootstrap capacitor C BST It assists in charging and more reliably increases the capacitor voltage V C This allows the size to be adjusted to the desired level. As a result, it becomes possible to drive the high-side transistor MH more reliably and appropriately.

[0072] Here, without the charge pump circuit 160 and the current source circuit 170, only the bootstrap circuit is used to create the bootstrap capacitor C. BST Charge the capacitor and the capacitor voltage V C Let's consider driving the high-side transistor MH using this. In this case, if PWM control is performed with a high duty cycle under overload conditions, the time during which the low-side transistor ML is ON (i.e., the bootstrap capacitor C) BST The charging time of the bootstrap capacitor C is shortened. BST It may not be fully charged.

[0073] According to the gate driver circuit 100 of this embodiment, even under overload conditions with a high duty cycle, the current source circuit 170 supplies current from the charge pump line 162 to the bootstrap capacitor C BST A constant current I1 can be supplied to it. As a result, the bootstrap capacitor C BST It will be possible to fully charge it.

[0074] In addition, instead of the bootstrap circuit, the charge pump voltage V of the charge pump circuit 160 is used. CP1 Let's consider driving the high-side transistor MH. In this case, the high-side transistor MH can be operated at a higher voltage compared to when it is driven only by the bootstrap circuit as described above. Therefore, it becomes possible to drive the high-side transistor MH properly even at high duty cycles.

[0075] However, the charge pump voltage V CP1 When driving the high-side transistor MH, a high voltage is always applied to the high-side driver 122, so it is necessary to use a component with a high voltage rating for the high-side driver 122. Generally, the higher the voltage rating, the larger the area of ​​the component, which results in the disadvantage of a larger area for the high-side driver 122. Also, the charge pump voltage V CP1 Because it constantly utilizes high voltage, the efficiency of power consumption also decreases (for example, to less than 50%).

[0076] In contrast, according to the gate driver circuit 100 of this embodiment, the bootstrap capacitor C is accessed from the charge pump line 162. BST The constant current I1 supply to the capacitor can be switched on or off. Therefore, the capacitor voltage V C This prevents the charge pump voltage from becoming too high. CP1 This eliminates the need to use high-voltage components, such as those required when driving the high-side transistor MH with only the driver, thus suppressing the need to increase the area of ​​the high-side driver 122. Furthermore, since the constant current I1 is supplied only supplementarily (partially), power consumption efficiency is also improved.

[0077] (Second Embodiment) Figure 6 is a block diagram of the electronic device 2 according to the second embodiment. The electronic device 2 according to the second embodiment includes a switching circuit 20 and a load 29. The switching circuit 20 according to the second embodiment includes a three-phase gate driver 200 and peripheral circuits 280. In addition, one or more elements described for the electronic device 1 according to the above embodiment may be applied to the electronic device 2 according to the second embodiment as needed.

[0078] Load 29 operates in response to the output signal from the switching circuit 20 (more specifically, the output signal from the three-phase bridge circuit 282, which will be described later). Load 29 may be, for example, a three-phase motor.

[0079] The peripheral circuit 280 consists of a three-phase bridge circuit 282 and three bootstrap capacitors (first bootstrap capacitor C). BST_U , second bootstrap capacitor C BST_V , the third bootstrap capacitor C BST_W ) is equipped with.

[0080] The three-phase bridge circuit 282 has a first leg 284, a second leg 286, and a third leg 288. The first leg 284 consists of a first high-side transistor MHU, a first low-side transistor MLU, and a resistor R 14 This includes the second leg 286, which consists of the second high-side transistor MHV, the second low-side transistor MLV, and resistor R 15 This includes the third leg 288, which consists of the third high-side transistor MHW, the third low-side transistor MLW, and resistor R 16 These include the following. These legs may be configured similarly to the half-bridge circuit 182 according to the first embodiment.

[0081] The three-phase gate driver 200 mainly consists of a logic circuit 210, a first high-side control circuit 220U, a second high-side control circuit 220V, a third high-side control circuit 220W, a first low-side control circuit 240U, a second low-side control circuit 240V, a third low-side control circuit 240W, a charge pump circuit 260, a first current source circuit 270U, ​​a second current source circuit 270V, a third current source circuit 270W, and a resistor R 11 ~R 13 It also includes rectifier elements D11 to D13.

[0082] The three-phase gate driver 200 includes three gate driver circuits (first to third gate driver circuits). In the second embodiment, the logic circuit 210 and the charge pump circuit 260 are shared by the three gate driver circuits. Specifically, the logic circuit 210, the first high-side control circuit 220U, the first low-side control circuit 240U, the charge pump circuit 260, the first current source circuit 270U, ​​and the resistor R 11 The rectifier element D11 constitutes the first gate driver circuit. Also included are the logic circuit 210, the second high-side control circuit 220V, the second low-side control circuit 240V, the charge pump circuit 260, the second current source circuit 270V, and the resistor R 12 The rectifier element D12 constitutes the second gate driver circuit. Furthermore, the logic circuit 210, the third high-side control circuit 220W, the third low-side control circuit 240W, the charge pump circuit 260, the third current source circuit 270W, and the resistor R 13 The rectifier element D13 constitutes the third gate driver circuit.

[0083] Hereafter, when the first high-side control circuit 220U, the second high-side control circuit 220V, and the third high-side control circuit 220W are not specifically distinguished, they will be collectively referred to as "high-side control circuit 220". Similarly, when the first low-side control circuit 240U, the second low-side control circuit 240V, and the third low-side control circuit 240W are not specifically distinguished, they will be collectively referred to as "low-side control circuit 240". Furthermore, when the first current source circuit 270U, ​​the second current source circuit 270V, and the third current source circuit 270W are not specifically distinguished, they will be collectively referred to as "current source circuit 270".

[0084] The high-side control circuit 220 according to the second embodiment may have substantially the same configuration as the high-side control circuit 120 according to the first embodiment. Similarly, the low-side control circuit 240 according to the second embodiment may have substantially the same configuration as the low-side control circuit 140 according to the first embodiment. Furthermore, the charge pump circuit 260 according to the second embodiment may have substantially the same configuration as the charge pump circuit 160 according to the first embodiment, and the charge pump voltage V CP2 This generates the current. Furthermore, the current source circuit 270 according to the second embodiment may have substantially the same configuration as the current source circuit 170 according to the first embodiment.

[0085] Resistance R 11 And the rectifier element D11 is the first bootstrap capacitor C BST_U Together, it forms the bootstrap circuit of the first gate driver circuit. Resistor R 12 And the rectifier element D12 is the second bootstrap capacitor C BST_V Together, it forms the bootstrap circuit for the second gate driver circuit. Resistor R 13 And the rectifier element D13 is the third bootstrap capacitor C BST_W Together, this constitutes the bootstrap circuit for the third gate driver circuit.

[0086] The logic circuit 210 controls the high-side control circuit 220 and the low-side control circuit 240, similar to the logic circuit 110 in the above embodiment. The high-side control circuit 220 drives the corresponding high-side transistors of the three-phase bridge circuit 282, utilizing the charge pump circuit 260 and the current control circuit 128 as needed. The low-side control circuit 240 drives the corresponding low-side transistors of the three-phase bridge circuit 282.

[0087] (Third embodiment) In the third embodiment, the configuration of the charge pump circuit and the operation of the current source circuit of the three-phase gate driver differ from those of the second embodiment. The electronic device according to the third embodiment has substantially the same configuration as the electronic device 2 according to the second embodiment, except for the charge pump circuit.

[0088] Figure 7 is a circuit diagram of the charge pump circuit 360, first current source circuit 270U, ​​second current source circuit 270V, and third current source circuit 270W according to the third embodiment. As shown in Figure 7, the charge pump circuit 360 according to the third embodiment has an output capacitor C OUT This differs from the charge pump circuits 160 and 260 according to the above embodiment in that it does not have [a certain feature].

[0089] The current source circuit 270 has substantially the same configuration as the current source circuit 170 according to the first embodiment. Specifically, the first current source circuit 270U has a current mirror circuit 172U and a switching circuit 174U, the second current source circuit 270V has a current mirror circuit 172V and a switching circuit 174V, and the third current source circuit 270W has a current mirror circuit 172W and a switching circuit 174W.

[0090] The switching circuit 174U of the first current source circuit 270U switches the state of the current mirror circuit 172U between a first state in which the current flowing through transistor MP1 is zero and a second state in which a constant current flows through transistor MP1, similar to the switching circuit 174 in the first embodiment. Similarly, the switching circuit 174V switches the state of the current mirror circuit 172V between a first state and a second state, and the switching circuit 174W switches the state of the current mirror circuit 172W between a first state and a second state. The switching circuits 174U, 174V, and 174W each have a first switch SW_U, a second switch SW_V, and a third switch SW_W, in addition to the current source 176.

[0091] The on / off state of the first switch SW_U is controlled by the control signal S SW_U It is controlled by the second switch SW_V. Also, the on / off state of the second switch SW_V is controlled by the control signal S SW_V It is controlled by the control signal S. Furthermore, the on / off state of the third switch SW_W is controlled by the control signal S. SW_W These control signals S are controlled by: SW_U ,S SW_V ,S SW_W This may be generated by the corresponding high-side control circuit.

[0092] The charge pump circuit 360 according to this embodiment alternately repeats a charging phase and a boosting phase, similar to the charge pump circuits 160 and 260 according to the above embodiment. However, the charge pump circuit 360 according to this embodiment does not have an output capacitor. Therefore, the charge pump voltage V according to this embodiment CP2 This changes rapidly each time the phase switches, compared to the charge pump voltage according to the above embodiment.

[0093] The switching circuits 176U to 176W according to this embodiment each operate in synchronization with the charge pump circuit 360. Specifically, during the charging phase, the switching circuits 176U to 176W each set the corresponding current mirror circuit among the current mirror circuits 172U to 172W to the first state. Furthermore, during the boosting phase, the switching circuits 176U to 176W each set the corresponding current mirror circuit among the current mirror circuits 172U to 172W to the second state.

[0094] From the current source circuit 270 having the current mirror circuit 172U~172W in the second state, current I U ~I W The following is output. Current I output from the first current source circuit 270U U This is the first bootstrap capacitor C BST_U The current I supplied to and output from the second current source circuit 270V is supplied to the power source. V This is the second bootstrap capacitor C BST_V The current I supplied to and output from the third current source circuit 270W is supplied to the power source. W This is the third bootstrap capacitor C BST_W It is supplied to.

[0095] Here, the voltage V BST_U This is the first bootstrap capacitor C BST_U This is the voltage at one end of the first current source circuit 270U. Also, voltage V BST_V This is the second bootstrap capacitor C BST_V This is the voltage at one end of the 270V side of the second current source circuit. Also, voltage V BST_W This is the third bootstrap capacitor C BST_W This is the voltage at one end of the 270W side of the third current source circuit. Furthermore, the voltage V OUT_U This is the output voltage of the first leg 284, and the voltage V OUT_V This is the output voltage of the second leg 286, and the voltage V OUT_W This is the output voltage of the third leg, 288.

[0096] Figure 8 is a timing chart illustrating an example of the operation of the charge pump circuit 360 and the current source circuit 270 according to the third embodiment.

[0097] The labels "LLL," "HLL," and "HHL" at the top of Figure 8 indicate the logic of the three-phase bridge circuit 282. Each label, from left to right, indicates the logic of the first leg 284, the second leg 286, and the third leg 288. The "H" (high) in the label indicates that the corresponding high-side transistor is on and the corresponding low-side transistor is off. The "L" (low) in the label indicates that the corresponding high-side transistor is off and the corresponding low-side transistor is on. For example, the label "HLL" indicates that the logic of the first leg 284 is high, and the logic of the second leg 286 and the third leg 288 are both low.

[0098] Below the logic label of the three-phase bridge circuit 282, from top to bottom, is the voltage V at node N1 of the charge pump circuit 360. N1 , the control signal S of the first switch SW_U SW_U , the current I output by the first current source circuit 270U U , the control signal S of the second switch SW_V SW_V , the current I output by the second current source circuit 270V V , the first bootstrap capacitor C BST_U Voltage V at one end BST_U and the second bootstrap capacitor C BST_V Voltage V at one end BST_V This indicates.

[0099] Voltage V N1 This changes periodically in accordance with the switching between the charging phase φ1 and the boosting phase φ2 of the charge pump circuit 360. Specifically, the voltage V N1 In the charging phase φ1, V N1 =V CC -V f Therefore, in the boost phase φ2, V N1 =V CC -V f +VREG This is the result.

[0100] Control signal S SW_U ,S SW_V It takes high (H) or low (L), and the control signal S SW_U ,S SW_V When it is high, the corresponding switch (first switch SW_U or second switch SW_V) is turned on, and the control signal S SW_U ,S SW_V When it is low, the corresponding switch (first switch SW_U or second switch SW_V) is turned off. Figure 8 shows the control signal S of the third switch SW_W. SW_W Although not shown, in the time range shown in Figure 8, the logic of the third leg 288 is always low, and the control signal S SW_W It is always low.

[0101] Before time t1, the logic of the three-phase bridge circuit 282 is "LLL". Therefore, the control signal S SW_U ,S SW_V Both are low, and the current I U ,I V It is not output (I U =0, I V (=0). Also, the first bootstrap capacitor C BST_U The voltage across both ends (i.e., V BST_U -V OUT_U ) and the second bootstrap capacitor C BST_V The voltage across both ends (i.e., V BST_V -V OUT_V ) are, respectively, the lower threshold voltage V thL V BST_U =V L_U , V BST_V =V L_V That is the case.

[0102] At time t1, the logic of the three-phase bridge circuit 282 changes to "HLL". Therefore, the logic of the first leg 284 goes high, the first high-side transistor MHU turns on, and the first low-side transistor MLU turns off. As a result, voltage V BST_U This is essentially the input voltage VCC V L_U From there, it rises to V H_U This is the result.

[0103] The first current source circuit 270U is the first bootstrap capacitor C BST_U The voltage across both ends is the lower threshold voltage V thL Therefore, in response to the logic of the first leg 284 going high, the first bootstrap capacitor C BST_U It operates to supply a constant current to the control signal S. SW_U This will change in sync with the charge pump circuit 360. More specifically, the control signal S SW_U It goes low during the charging phase φ1 and high during the boost phase φ2.

[0104] For example, at time t2, the phase of the charge pump circuit 360 switches from the charging phase φ1 to the boosting phase φ2. Control signal S SW_U This changes from low to high in accordance with the phase switch. Also, at time t3, the phase of the charge pump circuit 360 switches from the boost phase φ2 to the charging phase φ1. Control signal S SW_U This changes from high to low in accordance with the transition between phases.

[0105] Control signal S SW_U During the period when is low (for example, at times t1~t2, t3~t4), the first switch SW_U is off, so the current I U It is not output (I U =0). Control signal S SW_U During the period when it is high (for example, from time t2 to t3), the first switch SW_U is on, so the current I U The output is (I U >0). Output current I U Therefore, the first bootstrap capacitor C BST_U It will be charged.

[0106] At time t4, the logic of the three-phase bridge circuit 282 changes to "HHL". Therefore, the logic of the second leg 286 goes high, the second high-side transistor MHV turns on, and the second low-side transistor MLV turns off. As a result, voltage V BST_V This is essentially the input voltage V CC V L_V From there, it rises to V H_V This is the result.

[0107] The second current source circuit 270V is connected to the second bootstrap capacitor C. BST_V The voltage across both ends is the lower threshold voltage V thL Therefore, in response to the logic of the second leg 286 going high, the second bootstrap capacitor C BST_V It operates to supply a constant current to the control signal S. SW_V This will change in sync with the charge pump circuit 360. More specifically, the control signal S SW_V is the control signal S SW_U Similarly, it goes low during the charging phase φ1 and high during the boosting phase φ2.

[0108] For example, control signal S SW_U ,S SW_V During the period when is low (for example, from time t4 to t5), the first switch SW_U and the second switch SW_V are off, respectively. Therefore, current I U ,I V It is not output (I U =0,I V =0). Control signal S SW_U ,S SW_V During the period when it is high (for example, from time t5 to t6), the first switch SW_U and the second switch SW_V are both on. Therefore, current I U ,I V The output is (I U >0, I V >0). Output current I U ,I V Therefore, the first bootstrap capacitor C BST_U and the second bootstrap capacitor CBST_V It will be charged.

[0109] The operation examples of the charge pump circuit 360 and current source circuit 270 according to this embodiment have been described above. In this operation example, an example in which the logic of each leg is high or low was described, but the logic of each leg may be Z logic. The current source circuit corresponding to the leg that takes Z logic may operate in synchronization with the charge pump circuit 360, similar to the current source circuit corresponding to the leg that takes high logic.

[0110] According to the three-phase gate driver of this embodiment, the current source circuit 270 operates in synchronization with the charge pump circuit 360 as described above. This suppresses the reverse flow of current through the body diode of transistor MP2 in the current mirror circuits 172U to 172W.

[0111] Furthermore, according to the three-phase gate driver of this embodiment, reverse current flow through the body diode of transistor MP2 is suppressed, making it possible to appropriately assist each bootstrap circuit without providing an output capacitor in the charge pump circuit 360.

[0112] The advantages of the three-phase gate driver according to this embodiment become even clearer when compared with the comparative technology. Figure 9 is a circuit diagram illustrating an example of operation of the charge pump circuit 360 and current source circuit 270 according to the comparative technology. Here, the logic of the three-phase bridge circuit 282 is "HLZ", and the phase of the charge pump circuit 360 is assumed to be the charging phase φ1. Also, the first bootstrap capacitor C BST_U The voltage across both ends and the third bootstrap capacitor C BST_W The voltages across the two ends are, respectively, the lower threshold voltage V thL Let it be so.

[0113] In the comparative technique, the current source circuit 270 operates independently of the charge pump circuit 360. Specifically, in the first current source circuit 270U, ​​which corresponds to a leg where the logic is high, and the third current source circuit 270W, which corresponds to a leg where the logic is Z logic, the first switch SW_U and the third switch SW_W remain on regardless of the phase change in the charge pump circuit 360.

[0114] When the charge pump circuit 360 is in the charging phase, the voltage V at node N1 of the charge pump circuit 360 N1 is the voltage V N1 =V CC -V f This is the result. At this point, the first bootstrap capacitor C BST_U Voltage V at one end BST_U However, the voltage V at node N1 of charge pump circuit 360 N1 Higher than V BST_U >V CC -V f Let's assume that the voltage drop across the body diode of transistor MP2 is V. f Therefore, the charge pump voltage V CP2 V CP2 =V BST_U -V f This is the result.

[0115] Third bootstrap capacitor C BST_W Voltage V at one end BST_W The charge pump voltage V CP2 If it is lower than that, a reverse current I is supplied to transistor MP2 of the first current source circuit 270U via the body diode. U This current flows through the transistor MP2 of the third current source circuit (270W), creating a forward current I. W It flows as a current I in the reverse direction. U When the current flows, the first bootstrap capacitor C BST_U It is discharged.

[0116] Thus, if the current source circuit 270 operates without synchronization with the charge pump circuit 360, a reverse current may flow in some of the current source circuits 270 during the charging phase, causing some of the bootstrap capacitors to discharge.

[0117] In contrast, as in the third embodiment, when the current source circuit 270 operates in synchronization with the charge pump circuit 360, the current mirror circuit of the current source circuit 270 corresponding to the leg where the logic is high or Z logic enters a first state (i.e., the amount of current is zero) during the charging phase. Therefore, reverse current flow in the current source circuit 270 is suppressed during the charging phase.

[0118] (Fourth Embodiment) In the electronic device according to the fourth embodiment, the configuration and operation of the current source circuit differ from those of the third embodiment. Figure 10 is a circuit diagram of the charge pump circuit 360, the first current source circuit 370U, the second current source circuit 370V, and the third current source circuit 370W according to the fourth embodiment. Hereinafter, when the first current source circuit 370U, the second current source circuit 370V, and the third current source circuit 370W are not specifically distinguished, they will be collectively referred to as the "current source circuit 370".

[0119] The first current source circuit 370U according to the fourth embodiment has a configuration in which a rectifier element D4 is added to the first current source circuit 270U according to the third embodiment. The rectifier element D4 according to this embodiment is a diode. The rectifier element D4 consists of a transistor MP2 and a first bootstrap capacitor C BST_U Between these two points, transistor MP2 is connected to the first bootstrap capacitor C. BST_U It is provided so that the direction toward is forward. Specifically, the anode of rectifier element D4 is connected to the drain of transistor MP2, and the cathode of rectifier element D4 is connected to the first bootstrap capacitor C BST_U It is connected to one end of the first current source circuit 370U.

[0120] The second current source circuit 370V, like the first current source circuit 370U, has a configuration in which a rectifier element D4 is added to the second current source circuit 270V according to the third embodiment. Similarly, the third current source circuit 370W has a configuration in which a rectifier element D4 is added to the third current source circuit 270W according to the third embodiment.

[0121] Figure 11 is a timing chart illustrating an example of the operation of the charge pump circuit 360 and current source circuit 370 according to the fourth embodiment. Figure 11 shows, from top to bottom, the voltage V at node N1 of the charge pump circuit 360. N1 , the control signal S of the first switch SW_U SW_U , the current I output by the first current source circuit 370U U , the control signal S of the second switch SW_V SW_V , the current I output by the second current source circuit 370V V , the first bootstrap capacitor C BST_U Voltage V at one end BST_U and the second bootstrap capacitor C BST_V Voltage V at one end BST_V This indicates.

[0122] The logic of the three-phase bridge circuit 282 is based on time t 11 It is "LLL" before time t. 11 In this case, the first bootstrap capacitor C BST_U The voltage across both ends and the second bootstrap capacitor C BST_V The voltages across the two ends are, respectively, the lower threshold voltage V thL Let V be the case. BST_U and V BST_V These are, respectively, V L_U and V L_V This is the case. Time t 11 In this configuration, the logic of the three-phase bridge circuit 282 changes to "HLL". As a result, the voltage V BST_U V L_U From V H_U It will rise.

[0123] The first current source circuit 270U is the first bootstrap capacitor C BST_UIt operates to supply a constant current, specifically during the boost phase φ2 (time t 12 ~t 13 ), current I U (>0) 1st Bootstrap C BST_U It supplies power to the following: At this time, the control signal S SW_U This is maintained high regardless of the phase of the charge pump circuit 360.

[0124] time t 14 In this state, the logic of the three-phase bridge circuit 282 changes to "HHL". As a result, the voltage V BST_V V L_V From V H_V It rises to 270V. The second current source circuit is connected to the second bootstrap capacitor C. BST_V It operates to supply a constant current, specifically during the boost phase φ2 (time t 15 ~t 16 ), current I V (>0) Second Bootstrap C BST_V It supplies power to the following: At this time, the control signal S SW_V This is maintained high regardless of the phase of the charge pump circuit 360.

[0125] The configuration and operation examples of the charge pump circuit 360 and current source circuit 370 according to this embodiment have been described above. The current source circuit 370 according to this embodiment has a rectifier element D4. This rectifier element D4 is provided between the transistor MP2 and the bootstrap capacitor so that the direction from transistor MP to bootstrap capacitor is forward. Therefore, in the current source circuit 370, reverse current flow through the body diode of transistor MP2 is suppressed.

[0126] While the embodiments described herein have been explained using specific terminology, this explanation is merely illustrative to aid understanding and does not limit the scope of this disclosure or the claims. The scope of the present invention is defined by the claims. Furthermore, not only the embodiments described herein, but also embodiments, examples, and modifications not described herein are included in the scope of the present invention.

[0127] (First variation) In the above embodiment, an example was described in which the rectifier element of the bootstrap circuit is a diode. However, the rectifier element is not limited to this, and may be composed of, for example, a MOS transistor (e.g., a P-channel type). By composing the rectifier element with a MOS transistor, synchronous rectification becomes possible.

[0128] (Second variation) In the above embodiment, an example was described in which the switching circuits 10 and 20 have a half-bridge circuit 182 or a three-phase bridge circuit 282. However, the switching circuit is not limited to this and may have circuits including various high-side transistors, such as an H-bridge circuit. Furthermore, the number of gate driver circuits may be appropriately adjusted according to the number of high-side transistors.

[0129] (Third variation) In the above embodiment, an example was described in which the high-side transistor is composed of an N-channel type MOS transistor. However, the high-side transistor may be composed of, for example, an N-channel type IGBT (Insulated Gate Bipolar Transistor).

[0130] (Note) The technology disclosed herein can be understood in one respect as follows:

[0131] (Item 1) A gate driver circuit for a high-side transistor, A high-side driver that drives the aforementioned high-side transistor, A charge pump line to which a charge pump voltage generated by the charge pump circuit, which is higher than the input voltage of the high-side transistor, is supplied, A current source circuit configured to supply a constant current from the charge pump line to the bootstrap capacitor for driving the high-side transistor, The system includes a current control circuit that controls the on / off switching of the supply of the constant current to the bootstrap capacitor by the current source circuit. Gate driver circuit.

[0132] (Item 2) The system further includes a voltage sensor for detecting the capacitor voltage of the bootstrap capacitor, The current control circuit controls the on / off switching of the supply of the constant current to the bootstrap capacitor by the current source circuit according to the comparison result between the capacitor voltage detected by the voltage sensor and the comparison voltage. The gate driver circuit described in item 1.

[0133] (Item 3) The current control circuit maintains the supply of the constant current to the bootstrap capacitor by the current source circuit until the voltage sensor detects that the capacitor voltage has reached a threshold voltage, and switches the supply of the constant current to the bootstrap capacitor by the current source circuit from on to off in response to the voltage sensor detecting that the capacitor voltage has reached the threshold voltage. The gate driver circuit described in item 2.

[0134] (Item 4) The current control circuit, with the threshold voltage being the upper threshold voltage, switches the supply of the constant current to the bootstrap capacitor by the current source circuit from off to on when the voltage sensor detects that the capacitor voltage has dropped to a lower threshold voltage lower than the upper threshold voltage after the capacitor voltage has reached the upper threshold voltage. The gate driver circuit described in item 3.

[0135] (Item 5) The current control circuit switches the supply of the constant current to the bootstrap capacitor by the current source circuit from off to on when the voltage sensor detects that the capacitor voltage is below a predetermined low-voltage threshold voltage. A gate driver circuit as described in any one of items 2 through 4.

[0136] (Item 6) The current source circuit is configured to allow switching of the magnitude of the constant current. A gate driver circuit as described in any one of items 1 through 5.

[0137] (Item 7) The current source circuit includes a current mirror circuit and a switching circuit. The current mirror circuit includes two transistors that form a current mirror pair, and is configured such that the current flowing through one of the two transistors is copied by the other transistor. The switching circuit is configured to switch the state of the current mirror circuit between a first state in which the current flowing through one of the transistors is zero and a second state in which a constant current flows through one of the transistors. The other transistor is provided between the charge pump line and the bootstrap capacitor. A gate driver circuit as described in any one of items 1 through 6.

[0138] (Item 8) The charge pump circuit includes a charge pump capacitor and alternately repeats a charging phase in which the charge pump capacitor is charged to generate the charge pump voltage, and a boosting phase in which the voltage at one end of the output side of the charge pump capacitor is increased. The switching circuit operates in synchronization with the charge pump circuit to set the current mirror circuit to the first state during the charging phase and to set the current mirror circuit to the second state during the boosting phase. The gate driver circuit described in item 7.

[0139] (Item 9) The current source circuit further includes a rectifier element, The rectifier element is provided between the other transistor and the bootstrap capacitor, such that the direction from the other transistor to the bootstrap capacitor is forward. The gate driver circuit described in item 7 or 8.

[0140] (Item 10) A gate driver circuit as described in any one of items 1 through 9, The bootstrap capacitor and, The aforementioned high-side transistor, The charge pump circuit comprises the above-mentioned charge pump circuit, Switching circuit.

[0141] (Item 11) A three-phase gate driver for controlling a three-phase bridge circuit having a first leg including a first high-side transistor and a first low-side transistor, a second leg including a second high-side transistor and a second low-side transistor, and a third leg including a third high-side transistor and a third low-side transistor, A first gate driver circuit which is a gate driver circuit described in any one of items 1 to 9 that controls the first high-side transistor as the high-side transistor, A second gate driver circuit which is a gate driver circuit according to any one of items 1 to 9 that controls the second high-side transistor as the high-side transistor, The device comprises a third gate driver circuit which is a gate driver circuit according to any one of items 1 to 9, for controlling the third high-side transistor as the high-side transistor, Three-phase gate driver. [Explanation of Symbols]

[0142] 1,2 Electronic equipment, 10,20 Switching circuits, 19,29 Loads, 100 Gate driver circuits, 110,210 Logic circuits, 120 High-side control circuits, 122 High-side drivers, 124 Voltage sensors, 125 Threshold voltage sensors, 126 Low-voltage sensors, 128 Current control circuits, 130 Bootstrap lines, 132 Switching lines, 134 Power lines, 140 Low-side control circuits, 160,260 Charge pump circuits, 162 Charge pump lines, 170 Current source circuits, 172,172U~172W Current mirror circuits, 174,174U~174W Switching circuits, 176 Current sources, 180 Peripheral circuits, 182 Half-bridge circuits, 184 Power lines, 186 Output lines, 188 Ground lines, 200 Three-phase gate drivers, 220U First high-side control circuit, 220V Second high-side control circuit, 220W Third high-side control circuit, 240U First low-side control circuit, 240V Second low-side control circuit, 240W Third low-side control circuit, 270U, ​​370U First current source circuit, 270V, 370V Second current source circuit, 270W, 370W Third current source circuit, R1~R2, R 11 ~R 16 Resistance, C BST Bootstrap capacitor, C BST_U First bootstrap capacitor, C BST_V Second bootstrap capacitor, C BST_W Third bootstrap capacitor, C chg Charge pump capacitor, C OUT Output capacitors, D1~D4, D11~D13 rectifier elements, MH high-side transistor, MHU first high-side transistor, MHV second high-side transistor, MHW third high-side transistor, ML low-side transistor, MLU first low-side transistor, MLV second low-side transistor, MLW third low-side transistor, MP1, MP2 transistors, SW1 switch, SW_U first switch, SW_V second switch, SW_W third switch.

Claims

1. A gate driver circuit for a high-side transistor, A high-side driver that drives the aforementioned high-side transistor, A charge pump line to which a charge pump voltage generated by the charge pump circuit, which is higher than the input voltage of the high-side transistor, is supplied, A current source circuit configured to supply a constant current from the charge pump line to the bootstrap capacitor for driving the high-side transistor, The system includes a current control circuit that controls the on / off switching of the supply of the constant current to the bootstrap capacitor by the current source circuit. Gate driver circuit.

2. The system further includes a voltage sensor for detecting the capacitor voltage of the bootstrap capacitor, The current control circuit controls the on / off switching of the supply of the constant current to the bootstrap capacitor by the current source circuit according to the comparison result between the capacitor voltage detected by the voltage sensor and the comparison voltage. The gate driver circuit according to claim 1.

3. The current control circuit maintains the supply of the constant current to the bootstrap capacitor by the current source circuit until the voltage sensor detects that the capacitor voltage has reached a threshold voltage, and switches the supply of the constant current to the bootstrap capacitor by the current source circuit from on to off in response to the voltage sensor detecting that the capacitor voltage has reached the threshold voltage. The gate driver circuit according to claim 2.

4. The current control circuit, with the threshold voltage being the upper threshold voltage, switches the supply of the constant current to the bootstrap capacitor by the current source circuit from off to on when the voltage sensor detects that the capacitor voltage has dropped to a lower threshold voltage lower than the upper threshold voltage after the capacitor voltage has reached the upper threshold voltage. The gate driver circuit according to claim 3.

5. The current control circuit switches the supply of the constant current to the bootstrap capacitor by the current source circuit from off to on when the voltage sensor detects that the capacitor voltage is below a predetermined low-voltage threshold voltage. The gate driver circuit according to claim 2.

6. The current source circuit is configured to allow switching of the magnitude of the constant current. The gate driver circuit according to claim 1.

7. The current source circuit includes a current mirror circuit and a switching circuit. The current mirror circuit includes two transistors that form a current mirror pair, and is configured such that the current flowing through one of the two transistors is copied by the other transistor. The switching circuit is configured to switch the state of the current mirror circuit between a first state in which the current flowing through one of the transistors is zero and a second state in which a constant current flows through one of the transistors. The other transistor is provided between the charge pump line and the bootstrap capacitor. The gate driver circuit according to claim 1.

8. The charge pump circuit includes a charge pump capacitor and alternately repeats a charging phase in which the charge pump capacitor is charged to generate the charge pump voltage, and a boosting phase in which the voltage at one end of the output side of the charge pump capacitor is increased. The switching circuit operates in synchronization with the charge pump circuit to set the current mirror circuit to the first state during the charging phase and to set the current mirror circuit to the second state during the boosting phase. The gate driver circuit according to claim 7.

9. The current source circuit further includes a rectifier element, The rectifier element is provided between the other transistor and the bootstrap capacitor, such that the direction from the other transistor to the bootstrap capacitor is forward. The gate driver circuit according to claim 7.

10. A gate driver circuit according to any one of claims 1 to 9, The bootstrap capacitor and, The aforementioned high-side transistor, The charge pump circuit comprises the above-mentioned charge pump circuit, Switching circuit.

11. A three-phase gate driver for controlling a three-phase bridge circuit having a first leg including a first high-side transistor and a first low-side transistor, a second leg including a second high-side transistor and a second low-side transistor, and a third leg including a third high-side transistor and a third low-side transistor, A first gate driver circuit which is a gate driver circuit according to any one of claims 1 to 9 for controlling the first high-side transistor as the high-side transistor, A second gate driver circuit which is a gate driver circuit according to any one of claims 1 to 9 for controlling the second high-side transistor as the high-side transistor, A third gate driver circuit, which is a gate driver circuit according to any one of claims 1 to 9, controls the third high-side transistor as the high-side transistor, Three-phase gate driver.

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