Power transistor drive circuit and power transistor drive method

Abstract

This disclosure relates to a power transistor driving circuit and a power transistor driving method. The power transistor driving circuit includes an input module, an output module, and a transformer. The input module and the output module are connected through the transformer. The input module controls the primary end of the transformer to generate an alternating current based on the acquired input signal. The output module receives the voltage signal from the secondary end of the transformer and controls the switching on and off of the power transistor based on the received voltage signal. The input module includes: a control module for outputting a control signal based on the power supply voltage; and a current-limiting resistor module for adjusting the value of the current-limiting resistor in the input module according to the control signal, so that the current-limiting resistor value increases as the power supply voltage increases. When the power supply voltage is low, the current-limiting resistor value is small to ensure that the driving current is large enough to achieve effective signal transmission and reception. As the power supply voltage increases, the current-limiting resistor also increases, reducing the driving current and thus reducing the power consumption of the chip.

Description

Technical Field

[0001] This disclosure relates to the field of electronic circuits, and more specifically, to a power transistor driving circuit and a power transistor driving method. Background Technology

[0002] In ultra-high voltage power transistor drive circuits, there is a problem of different power supply domains at the input and output terminals. Generally, the input ground is connected to the system ground and is 0V; while the output ground is a floating ground, connected to the source of the power transistor (e.g., IGBT), with a minimum of 0V and a maximum of several hundred volts or even over a thousand volts. Therefore, it is necessary to isolate the input and output, such as by using a transformer for input-output isolation.

[0003] In highly integrated applications, the input chip, output chip, and transformer used for isolation are packaged together. To meet the requirements of small size, the chip-level transformer used is implemented by coupling coils on a silicon chip. The inductance of the transformer is very small, typically on the order of tens of nanofarads. To enable signal transmission between the input and output stages, an alternating current signal is usually generated on the transmitting coil of the transformer. Through signal coupling between the coils, the receiving end can receive the corresponding signal and process and respond accordingly.

[0004] To ensure that the secondary chip can correctly receive and identify the corresponding signal, the current supplied to the transformer needs to be large enough. If the current is too small, the resonance amplitude on the transformer will decrease, and the secondary chip may not be able to identify the corresponding signal. Summary of the Invention

[0005] The purpose of this disclosure is to provide a reliable and low-power power transistor drive circuit and a power transistor drive method.

[0006] To achieve the above objectives, this disclosure provides a power transistor driving circuit, which includes an input module, an output module, and a transformer. The input module and the output module are connected through the transformer. The input module is used to control the primary end of the transformer to generate an alternating current according to the acquired input signal. The output module is used to receive the voltage signal from the secondary end of the transformer and control the switching on and off of the power transistor according to the received voltage signal.

[0007] The input module includes:

[0008] The control module is used to output control signals according to the magnitude of the power supply voltage;

[0009] A current-limiting resistor module is used to adjust the value of the current-limiting resistor in the input module according to the control signal, so that the value of the current-limiting resistor increases as the power supply voltage increases.

[0010] Optionally, the current-limiting resistor module includes a first preset resistor, n parallel resistors, and n parallel switching transistors. The n parallel resistors and the n parallel switching transistors correspond one-to-one. Each parallel resistor and its corresponding parallel switching transistor are connected in series and then in parallel with the first preset resistor. The parallel resistor is the current-limiting resistor in the input module.

[0011] The control signal includes n sub-signals, and the n parallel switching transistors receive the n sub-signals in a one-to-one correspondence. Each parallel switching transistor is used to control the on / off state of the source and drain according to the sub-signal received by the gate.

[0012] Optionally, the current-limiting resistor module includes a first preset resistor, n series resistors and n series switching transistors, wherein the n series resistors and the n series switching transistors correspond one-to-one, and each series resistor is connected in parallel with its corresponding series switching transistor. The first preset resistor and the n series resistors are connected in series, and the series resistor is the current-limiting resistor in the input module.

[0013] The control signal includes n sub-signals, and the n series-connected switches receive the n sub-signals in a one-to-one correspondence. Each series-connected switch is used to control the on / off state of the source and drain according to the sub-signal received at its gate.

[0014] Optionally, the current-limiting resistor module includes a parallel part and a series part. The parallel part includes a first preset resistor, m mixed parallel resistors and m mixed parallel switching transistors. The m mixed parallel resistors and the m mixed parallel switching transistors correspond one-to-one. Each mixed parallel resistor and its corresponding mixed parallel switching transistor are connected in series and then in parallel with the first preset resistor.

[0015] The series section includes (nm) hybrid series switching transistors and (nm) hybrid series resistors connected in series. The (nm) hybrid series resistors and the (nm) hybrid series switching transistors correspond one-to-one, and each hybrid series resistor and its corresponding hybrid series switching transistor are connected in parallel.

[0016] The resistance formed by connecting the parallel part and the series part in series is the current-limiting resistor in the input module.

[0017] The control signal includes n sub-signals. The m hybrid parallel switches and the (nm) hybrid series switches receive the n sub-signals in a one-to-one correspondence. Each hybrid parallel switch and each hybrid series switch is used to control the on / off state of the source and drain according to the sub-signal received by the gate.

[0018] Optionally, the control module includes n voltage divider resistors and n voltage divider comparators. The n voltage divider resistors are connected in series between the power supply and the ground. The n voltage divider resistors and the n voltage divider comparators correspond one-to-one. The first input terminal of each voltage divider comparator is input with a predetermined reference voltage, and the second input terminal of each voltage divider comparator is connected to the same side of the corresponding voltage divider resistor.

[0019] The n voltage divider comparators each output one of the n sub-signals.

[0020] Optionally, the control module includes a first voltage divider resistor, a second voltage divider resistor, and n common voltage comparators. The first voltage divider resistor and the second voltage divider resistor are connected in series between the power supply and the ground. The first input terminal of each common voltage comparator receives n different reference voltages, and the second input terminal of each common voltage comparator is connected between the first voltage divider resistor and the second voltage divider resistor.

[0021] The n common-voltage comparators each output the n sub-signals.

[0022] Optionally, the control module includes a current source, a preset switching transistor, and n signal generation sub-modules. The n signal generation sub-modules output the n sub-signals respectively. Each signal generation sub-module includes a first switching transistor, a second switching transistor, a voltage drop generation module, a second preset resistor, and a capacitor.

[0023] In this configuration, the source of the preset switch, the source of the first switch, and the source of the second switch are connected to a power supply. The drain and gate of the preset switch are grounded through the current source. The gate of the first switch is connected to the gate of the preset switch, and the drain of the first switch is connected to the gate of the second switch. The drain of the first switch is grounded through the voltage drop generation module. The drain of the second switch is connected to one end of the second preset resistor and one end of the capacitor. The other end of the second preset resistor and the other end of the capacitor are grounded. The drain of the second switch outputs the sub-signal.

[0024] Optionally, the voltage drop generation module includes a third switch and a fourth switch, the drain of the third switch is connected to the drain of the first switch, the third switch and the fourth switch are connected in a diode configuration, and the source of the fourth switch is grounded.

[0025] Optionally, the third and fourth switching transistors are MOSFETs or bipolar transistors.

[0026] Optionally, the voltage drop generation module is a resistor or a diode.

[0027] This disclosure also provides a power transistor driving method applied to a power transistor driving circuit, the power transistor driving circuit including an input module, an output module, and a transformer, the input module and the output module being connected through the transformer, the method including:

[0028] The input module controls the primary terminal of the transformer to generate an alternating current based on the acquired input signal, wherein a control signal is output according to the magnitude of the power supply voltage; and the value of the current-limiting resistor in the input module is adjusted according to the control signal so that the value of the current-limiting resistor increases as the power supply voltage increases.

[0029] The output module receives the voltage signal from the secondary side of the transformer and controls the switching on and off of the power transistor according to the received voltage signal.

[0030] Through the above technical solution, the current-limiting resistor value in the input module of the power transistor driver circuit increases with the increase of the power supply voltage. Thus, when the power supply voltage is low, the current-limiting resistor value is small, ensuring that the drive current is large enough to achieve effective signal transmission and reception. As the power supply voltage increases, the current-limiting resistor also increases, reducing the drive current and thereby reducing the chip's power consumption.

[0031] Other features and advantages of this disclosure will be described in detail in the following detailed description section. Attached Figure Description

[0032] The accompanying drawings are provided to further illustrate the present disclosure and form part of the specification. They are used together with the following detailed description to explain the present disclosure, but do not constitute a limitation thereof. In the drawings:

[0033] Figure 1 This is a schematic diagram illustrating the basic principle of power transistor drive circuits in related technologies;

[0034] Figure 2 This is a schematic diagram of the input section of a power transistor drive circuit in related technologies;

[0035] Figure 3 This is a schematic diagram of the power transistor drive circuit of an exemplary embodiment;

[0036] Figure 4 This is a schematic diagram of the input module of a power transistor drive circuit in an exemplary embodiment;

[0037] Figure 5a This is a schematic diagram of the structure of a current-limiting resistor module in an exemplary embodiment;

[0038] Figure 5b This is a schematic diagram of the structure of a current-limiting resistor module according to another exemplary embodiment;

[0039] Figure 5c This is a schematic diagram of the structure of a current-limiting resistor module, which is yet another exemplary embodiment.

[0040] Figure 6a This is a schematic diagram of the structure of a control module in an exemplary embodiment;

[0041] Figure 6b This is a schematic diagram of the control module in another exemplary embodiment;

[0042] Figure 6c This is a schematic diagram of the control module of yet another exemplary embodiment;

[0043] Figures 7a-7c yes Figure 6c A waveform diagram of the control module during operation;

[0044] Figure 8 This is a flowchart of a power transistor driving method provided in an exemplary embodiment. Detailed Implementation

[0045] The specific embodiments of this disclosure will be described in detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are for illustration and explanation only and are not intended to limit this disclosure.

[0046] Figure 1 This is a schematic diagram illustrating the basic principle of a power transistor drive circuit in related technologies. Figure 1 In the power transistor drive circuit 100, there is a problem that the power supply domains of the input section 101 and the output section 102 are different. The ground VSS1 of the input section 101 is connected to the system ground and is 0V; while the ground VSS2 of the output section 102 is a floating ground, connected to the source S of the power transistor IGBT, with a minimum of 0V and a maximum of several hundred volts or even more than one thousand volts. The signal output from the output section 102 is connected to the gate G of the IGBT, and the drain D of the IGBT can be connected to the power supply. An isolator 103 is used between the input section 101 and the output section 102 for isolation. The isolator 103 can be a transformer.

[0047] In highly integrated applications, the input section 101, output section 102, and the transformer used as an isolator 103 are packaged together. To meet the requirements of small size, the chip-level transformer used is implemented by coupling coils on a silicon chip. The transformer's inductance is very small. To achieve signal transmission between the input section 101 and the output section 102, the input section 101 typically transmits an alternating current signal to the transmitting coil of the transformer, which is then transmitted to the output section 102 through signal coupling between the coils. To ensure that the output section 102 can correctly receive and recognize the signal, the current supplied to the transformer needs to be large enough. If the current is too small, the resonant amplitude on the transformer will decrease, and the output section 102 may not be able to recognize the signal.

[0048] Figure 2 This is a schematic diagram of the input section of a power transistor drive circuit in related technologies. The input section 101 receives the input signal, which passes through an inverter Q1 and then into a NAND gate Q2. The signal generated by the frequency generation module is also input into the NAND gate Q2. The output of the NAND gate Q2 passes through a buffer Q3 and is then input to the gate of the first switching transistor Q4. The drain of the first switching transistor Q4 is connected to the power supply (VDD) through a fixed resistor Rg. The source of the first switching transistor Q4 is connected to the drain of the second switching transistor Q5 and to one end of an isolator. The gate of the second switching transistor Q5 receives the aforementioned input signal, and its source is connected to the other end of the isolator and grounded. The fixed resistor Rg is used for current limiting to prevent excessive current through the first switching transistor Q4, which could lead to excessive chip wear or even localized overheating and burnout.

[0049] exist Figure 2 In the proposed solution, the current-limiting resistor for the input section 101 of the power transistor driver circuit is of a fixed value, and the setting of the current-limiting resistor value needs to consider the entire operating voltage range. When the power supply voltage is relatively low, the current-limiting resistor must be small enough to ensure that the drive current is large enough for effective signal transmission and reception. However, when the power supply voltage is high, the corresponding drive current will be very large, leading to a significant increase in chip power consumption. The inventors envisioned controlling the current-limiting resistor value to increase with the increase of the power supply voltage to reduce the chip's power consumption.

[0050] Figure 3 This is a schematic diagram of the power transistor drive circuit of an exemplary embodiment. For example... Figure 3 As shown, the power transistor drive circuit may include an input module 10, an output module 20, and a transformer 30, with the input module 10 and output module 20 connected via the transformer 30. The input module 10 controls the primary side of the transformer 30 to generate an alternating current based on an acquired input signal (e.g., a PWM signal). The output module 20 receives a voltage signal from the secondary side of the transformer 30 and controls the switching of the power transistor based on the received voltage signal.

[0051] The input module 10 may include a control module 11 and a current-limiting resistor module 12.

[0052] The control module 11 is used to output control signals according to the magnitude of the power supply voltage.

[0053] The current-limiting resistor module 12 is used to adjust the value of the current-limiting resistor in the input module 10 according to the control signal, so that the value of the current-limiting resistor increases as the power supply voltage increases.

[0054] In this way, when the power supply voltage is low, the current-limiting resistor value is small to ensure that the drive current is large enough to achieve effective signal transmission and reception. As the power supply voltage increases, the current-limiting resistor also increases, reducing the drive current and thus reducing the chip's power consumption.

[0055] Figure 4 This is a schematic diagram of the input module of a power transistor drive circuit in an exemplary embodiment. (See diagram below.) Figure 4 As shown, in Figure 2 Based on this, the fixed resistor Rg in the input module is replaced with a control module 11 and a current-limiting resistor module 12. The control module 11 is connected between the power supply and ground, and the current-limiting resistor module 12 is connected between the power supply and the drain of the first switching transistor Q4. The resistance between R+ and R- at both ends of the current-limiting resistor module 12 is the adjustable current-limiting resistor, and its value is controlled by the control module 11. The control module 11 controls the resistance value of the current-limiting resistor module 12 according to the power supply voltage, so that its resistance (current-limiting resistor value) increases as the power supply voltage increases.

[0056] The current-limiting resistor module 12 can be composed of resistors connected in series and / or in parallel, wherein the parallel connection method is described in detail below. Figure 5a For series connection methods, see Figure 5b For a hybrid series and parallel connection method, see Figure 5c .

[0057] Figure 5a This is a schematic diagram of the structure of a current-limiting resistor module 12 in an exemplary embodiment. Figure 5a As shown, the current limiting resistor module 12 may include a first preset resistor R0, n parallel resistors R11 to R1n and n parallel switching transistors PM11 to PM1n. The n parallel resistors and n parallel switching transistors correspond one-to-one. Each parallel resistor and its corresponding parallel switching transistor are connected in series and then in parallel with the first preset resistor R0. The parallel resistor is the current limiting resistor in the input module 10.

[0058] That is, the first parallel resistor R11 and the corresponding parallel switch PM11 are connected in series and then in parallel with the first preset resistor R0; the second parallel resistor R12 and the corresponding parallel switch PM12 are connected in series and then in parallel with the first preset resistor R0; ..., the nth parallel resistor R1n and the corresponding parallel switch PM1n are connected in series and then in parallel with the first preset resistor R0.

[0059] In this context, connecting the parallel resistor and the corresponding parallel switch in series means connecting the drain and source of the parallel switch in series with the parallel resistor, such as... Figure 5a As shown in the diagram, the source of the parallel switching transistor is connected to one end of the first preset resistor R0, and the drain of the parallel switching transistor is connected to the other end of the first preset resistor R0 through a corresponding parallel resistor.

[0060] In this embodiment, the control signal includes n sub-signals, where n is an integer greater than or equal to 1. Each of the n parallel switching transistors receives one of the n sub-signals, and each parallel switching transistor controls the on / off state of its source and drain based on the sub-signal received at its gate. The sub-signals received by the n parallel switching transistors PM11 to PM1n are Ct1 to Ctn, respectively.

[0061] exist Figure 5a In the circuit, the first preset resistor R0 is directly connected to the transformer drive circuit, and the n parallel resistors R11 to R1n are controlled by the n parallel switching transistors PM11 to PM1n respectively. Figure 5a The PMOS device is used as the switching transistor. When the sub-signal is "0", the corresponding parallel resistor is connected to the circuit, thereby reducing the resistance value of the current limiting resistor module 12. When the sub-signal is "1", the corresponding parallel resistor is disconnected from the circuit, thereby increasing the resistance value of the current limiting resistor module 12.

[0062] Figure 5b This is a schematic diagram of the structure of a current-limiting resistor module 12 in another exemplary embodiment. (See diagram below.) Figure 5b As shown, the current-limiting resistor module 12 may include a first preset resistor R0, n series resistors R21 to R2n, and n series switching transistors PM21 to PM2n. The n series resistors and n series switching transistors correspond one-to-one. Each series resistor is connected in parallel with its corresponding series switching transistor. The first preset resistor R0 and the n series resistors are connected in series, and the resulting resistance is the current-limiting resistor in the input module 10.

[0063] That is, the first series resistor R21 is connected in parallel with the corresponding series switch PM21, the second series resistor R22 is connected in parallel with the corresponding series switch PM22, ..., the nth series resistor R2n is connected in parallel with the corresponding series switch PM2n.

[0064] The control signal includes n sub-signals, and n series-connected switches receive the n sub-signals in a one-to-one correspondence. Each series-connected switch is used to control the on / off state of the source and drain according to the sub-signal received by the gate.

[0065] exist Figure 5b In the circuit, the first preset resistor R0 is directly connected to the transformer drive circuit, and the n series resistors R21 to R2n are controlled by the n series switching transistors PM21 to PM2n respectively. Figure 5b The PMOS device is used as the switching transistor. When the sub-signal is "1", the corresponding series resistor is connected to the circuit, thereby increasing the resistance value of the current limiting resistor module 12. When the sub-signal is "0", the corresponding series resistor is disconnected from the circuit, thereby decreasing the resistance value of the current limiting resistor module 12.

[0066] In the control module 11, the magnitude of the power supply voltage can be determined by a comparator, and then sub-signals Ct1 to Ctn can be generated.

[0067] Figure 5c This is a schematic diagram of the current-limiting resistor module 12, which is another exemplary embodiment. (See diagram below.) Figure 5c As shown, the current-limiting resistor module 12 may include a parallel section and a series section. The parallel section may include a first preset resistor R0, m mixed parallel resistors R31 to R3m, and m mixed parallel switching transistors PM31 to PM3m. The m mixed parallel resistors and the m mixed parallel switching transistors correspond one-to-one. Each mixed parallel resistor and its corresponding mixed parallel switching transistor are connected in series and then in parallel with the first preset resistor R0.

[0068] The series section may include (nm) hybrid series switching transistors PM3(m+1) to PM3n and (nm) hybrid series resistors R3(m+1) to R3n connected in series. The (nm) hybrid series resistors and (nm) hybrid series switching transistors correspond one-to-one, and each hybrid series resistor is connected in parallel with its corresponding hybrid series switching transistor.

[0069] The resistance of the parallel and series components connected in series is the current-limiting resistor in input module 10.

[0070] The control signals include n sub-signals. m hybrid parallel switches and (nm) hybrid series switches receive the n sub-signals in a one-to-one correspondence. Each hybrid parallel switch and each hybrid series switch is used to control the on / off state of the source and drain based on the sub-signal received at the gate. m is an integer less than n.

[0071] exist Figure 5cIn this circuit, the first preset resistor R0 is directly connected to the transformer drive circuit, and the m hybrid parallel resistors R31 to R3m are respectively controlled by the m hybrid parallel switching transistors PM31 to PM3m. The (n - m) hybrid series resistors R3(m + 1) to R3n are respectively controlled by the (n - m) hybrid series switching transistors PM3(m + 1) to PM3n.

[0072] Figure 5c In this circuit, PMOS devices are also used as switching transistors. When the sub - signal is "0", the corresponding hybrid parallel resistor or hybrid series resistor is connected to the circuit, thereby changing the resistance value of the current - limiting resistor module 12; when the sub - signal is "1", the corresponding hybrid parallel resistor or hybrid series resistor disconnects the circuit, thereby changing the resistance value of the current - limiting resistor module 12.

[0073] Figure 6a is a schematic structural diagram of the control module 11 of an exemplary embodiment. As Figure 6a shown, the control module 11 includes n voltage - dividing resistors RA1 to RAn and n voltage - dividing comparators P11 to P1n. The n voltage - dividing resistors are connected in series between the power supply and the ground wire, and the n voltage - dividing resistors and the n voltage - dividing comparators correspond one by one. The first input terminal (-) of each voltage - dividing comparator inputs a predetermined reference voltage VREF, and the second input terminal (+) of each voltage - dividing comparator is respectively connected to the same side of the corresponding voltage - dividing resistor. Among them, the n voltage - dividing comparators respectively output n sub - signals Ct1 to Ctn.

[0074] Among them, the voltage - dividing resistor has two sides, one side close to the power supply and the other side close to the ground wire. The second input terminal (+) of each voltage - dividing comparator is connected to the side of the corresponding voltage - dividing resistor close to the power supply, or is connected to the side of the corresponding voltage - dividing resistor close to the ground wire.

[0075] Figure 6a In this circuit, the first input terminal (-) of each voltage - dividing comparator is connected to the reference voltage VREF, and the second input terminal (+) is connected to the resistor voltage - dividing sampling terminal of the power supply. The n voltage - dividing resistors are connected in series to form a voltage - dividing circuit. Taking Figure 6a the generation process of the control signal Ct1 in this circuit as an example, when the power supply voltage VDD is high enough and VREF < VF1, the generated sub - signal Ct1 is "1" at this time and is output to the current - limiting resistor module 12, Figure 5a and the parallel resistor corresponding to the sub - signal Ct1 in this circuit is in the off state;

[0076] As the power supply voltage VDD drops, when VF1 < VREF, the generated sub - signal Ct1 is "0" and is output to the current - limiting resistor module 12, Figure 5aThe parallel resistor corresponding to the neutron signal Ct1 is in the connected state, which reduces the equivalent impedance on the drive circuit, that is, reduces the resistance value of the current limiting resistor module 12, thereby increasing the transformer drive current that can be provided under the corresponding power supply voltage.

[0077] The generation principle of sub-signals Ct2~Ctn is similar to that of Ct1. The flip point of voltage divider comparators P11~P1n can be achieved by adjusting the input reference or adjusting the voltage divider resistor ratio of the power supply. Figure 6a In this system, multiple comparators correspond to the same reference voltage and different sampling inputs.

[0078] Figure 6b This is a schematic diagram of the structure of the control module 11 in another exemplary embodiment. Figure 6b In this example, multiple comparators correspond to the same sampling input and different reference voltages. For example... Figure 6b As shown, the control module 11 includes a first voltage divider resistor RB1, a second voltage divider resistor RB2, and n common-voltage comparators P21 to P2n. The first and second voltage divider resistors are connected in series between the power supply and ground, forming a voltage divider circuit. Each common-voltage comparator's first input terminal (-) receives n different reference voltages VREF1 to VREFn, and each common-voltage comparator's second input terminal (+) is connected between the first and second voltage divider resistors. The voltage divider resistance between the first and second voltage divider resistors is VF. The n common-voltage comparators each output n sub-signals Ct1 to Ctn.

[0079] Figure 6c This is a schematic diagram of the control module in yet another exemplary embodiment. (See diagram below.) Figure 6c As shown, the control module 11 includes a current source I0, a preset switch PM0, and n signal generation sub-modules 111 to 11n. The n signal generation sub-modules output n sub-signals Ct1 to Ctn respectively. Each signal generation sub-module includes a first switch PMa, a second switch PMb, a voltage drop generation module, a second preset resistor RC, and a capacitor C0.

[0080] In this configuration, the source of the preset switch PM0, the source of the first switch PMa, and the source of the second switch PMb are connected to the power supply. The drain and gate of the preset switch PM0 are grounded through a current source. The gate of the first switch PMa is connected to the gate of the preset switch PM0. The drain of the first switch PMa is connected to the gate of the second switch PMb. The drain of the first switch PMa is grounded through a voltage drop generation module. The drain of the second switch PMb is connected to one end of the second preset resistor RC and one end of the capacitor C0. The other end of the second preset resistor RC and the other end of the capacitor C0 are grounded. The drain of the second switch PMb outputs a sub-signal.

[0081] Figure 6cThe voltage drop generation module includes a third switch NM1 and a fourth switch NM2. The drain of the third switch NM1 is connected to the drain of the first switch, and the third switch NM1 and the fourth switch NM2 are connected in a diode configuration. The source of the fourth switch NM2 is grounded.

[0082] The third switch NM1 and the fourth switch NM2 can be MOSFETs or transistors. Figure 6c The third switch NM1 and the fourth switch NM2 are N-type MOSFETs.

[0083] Figures 7a-7c yes Figure 6c The waveform diagram of the control module 11 during operation is shown. Current source I0 generates a voltage drop of VNET0 across the third switch NM1 and the fourth switch NM2. When the power supply voltage VDD is high enough to keep I0 constant, VNET0 will also be fixed. As the power supply voltage VDD decreases, when it approaches VNET0, the current I1 will not be able to maintain its current and will decrease. Correspondingly, VNET0 will also decrease, essentially following the power supply voltage VDD. Figure 7a As shown.

[0084] The difference between the power supply voltage VDD and VNET0, V1 = VDD - VNET0, controls the conduction of the second switching transistor PMb, and thus the output current I2. The magnitude of current I2 is primarily determined by the device size (current) of the second switching transistor PMb and the value of V1, and they are directly proportional. Given the dimensions of the second switching transistor PMb, we have I2 = K * V1, where K is a relevant current generation coefficient related to the device's operating state. The maximum value of I2 is limited by the power supply voltage VDD / R1, where R1 is the resistance value of the second preset resistor RC.

[0085] That is, when K*V1>VDD / R1, I2=VDD / R1; when K*V1<=VDD / R1, I2=K*V1. The output signal Ct1 of the control module 11 is the voltage drop I2*R1 generated by I2 across the second preset resistor RC, as shown below. Figure 7b and Figure 7c As shown.

[0086] When the power supply voltage is high enough, the output Ct1 signal will approach the power supply voltage VDD, and the corresponding switch in the current limiting resistor module 12 will turn off. Figure 5a The corresponding parallel resistor is disconnected from the drive circuit.

[0087] As the power supply voltage VDD gradually decreases, V1 will decrease. When K*V1≤VDD / R1, the current I2 will gradually decrease from VDD / R1. Furthermore, the voltage Ct1 will also decrease from the power supply voltage VDD, gradually turning on the corresponding switch in the current limiting resistor module 12 until it is fully turned on. Figure 5a The resistors in the circuit are gradually connected into the drive circuit, improving the power supply capability of the drive circuit under the current power supply voltage. When the power supply voltage VDD drops to the point where the second switching transistor PMb is turned off, I2 = 0, and the output of Ct1 will be pulled down to the "0" potential by R1, as shown below. Figure 7c As shown.

[0088] The threshold of the resistor access control signal (sub-signal Ct1~Ctn) in the current limiting resistor module 12 is mainly determined by the dimensions of the current source I0 and the third switch NM1 and the fourth switch NM2. Among them, the current source I0 is controlled by the dimensions of the first switch PMa.

[0089] In addition to MOSFETs, the voltage drop generation module can also be a resistor or a diode.

[0090] This disclosure also provides a power transistor driving method applied to a power transistor driving circuit. The power transistor driving circuit includes an input module 10, an output module 20, and a transformer 30, wherein the input module 10 and the output module 20 are connected through the transformer 30. Figure 8 This is a flowchart of a power transistor driving method provided in an exemplary embodiment. For example... Figure 8 As shown, the method may include:

[0091] In step S101, the input module 10 controls the primary terminal of the transformer 30 to generate an alternating current based on the acquired input signal. Specifically, a control signal is output based on the power supply voltage, and the value of the current-limiting resistor in the input module 10 is adjusted according to the control signal so that the current-limiting resistor value increases as the power supply voltage increases.

[0092] In step S102, the output module 20 receives the voltage signal from the secondary side of the transformer 30 and controls the opening and closing of the power transistor according to the received voltage signal.

[0093] Through the above technical solution, the current-limiting resistor value in the input module of the power transistor driver circuit increases with the increase of the power supply voltage. Thus, when the power supply voltage is low, the current-limiting resistor value is small, ensuring that the drive current is large enough to achieve effective signal transmission and reception. As the power supply voltage increases, the current-limiting resistor also increases, reducing the drive current and thereby reducing the chip's power consumption.

[0094] The preferred embodiments of this disclosure have been described in detail above with reference to the accompanying drawings. However, this disclosure is not limited to the specific details of the above embodiments. Within the scope of the technical concept of this disclosure, various simple modifications can be made to the technical solutions of this disclosure, and these simple modifications all fall within the protection scope of this disclosure.

[0095] It should also be noted that the various specific technical features described in the above embodiments can be combined in any suitable manner without contradiction. To avoid unnecessary repetition, this disclosure will not describe the various possible combinations separately.

[0096] Furthermore, various different embodiments of this disclosure can be combined in any way, as long as they do not violate the spirit of this disclosure, they should also be regarded as the content disclosed in this disclosure.

Claims

1. A power transistor drive circuit, characterized in that, The power transistor drive circuit includes an input module (10), an output module (20), and a transformer (30). The input module (10) and the output module (20) are connected through the transformer (30). The input module (10) is used to control the primary end of the transformer (30) to generate alternating current according to the acquired input signal. The output module (20) is used to receive the voltage signal from the secondary end of the transformer (30) and control the opening and closing of the power transistor according to the received voltage signal. The input module (10) includes: The control module (11) is used to output control signals according to the magnitude of the power supply voltage; The current limiting resistor module (12) is used to adjust the value of the current limiting resistor in the input module (10) according to the control signal so that the value of the current limiting resistor increases as the power supply voltage increases; After receiving the input signal, the input section (101) passes through an inverter (Q1) and then inputs to a NAND gate (Q2). The signal generated by the frequency generation module is also input to the NAND gate (Q2). The output of the NAND gate (Q2) passes through a buffer (Q3) and then inputs to the gate of the first switch (Q4). The source of the first switch (Q4) is connected to the drain of the second switch (Q5) and to one end of the isolator (103). The gate of the second switch (Q5) receives the input signal, and the source of the second switch (Q5) is connected to the other end of the isolator (103) and grounded. The control module (11) is connected between the power supply and the ground, and the current limiting resistor module (12) is connected between the power supply and the drain of the first switching transistor (Q4).

2. The power transistor drive circuit according to claim 1, characterized in that, The current-limiting resistor module (12) includes a first preset resistor (R0), n parallel resistors (R11~R1n) and n parallel switching transistors (PM11~PM1n). The n parallel resistors and the n parallel switching transistors correspond one-to-one. Each parallel resistor and its corresponding parallel switching transistor are connected in series and then in parallel with the first preset resistor (R0). The resulting parallel resistor is the current-limiting resistor in the input module (10). The control signal includes n sub-signals, and the n parallel switching transistors receive the n sub-signals in a one-to-one correspondence. Each parallel switching transistor is used to control the on / off state of the source and drain according to the sub-signal received by the gate.

3. The power transistor drive circuit according to claim 1, characterized in that, The current-limiting resistor module (12) includes a first preset resistor (R0), n series resistors (R21~R2n) and n series switching transistors (PM21~PM2n). The n series resistors and the n series switching transistors correspond one-to-one. Each series resistor is connected in parallel with its corresponding series switching transistor. The first preset resistor and the n series resistors are connected in series. The resistor after series connection is the current-limiting resistor in the input module (10). The control signal includes n sub-signals, and the n series-connected switches receive the n sub-signals in a one-to-one correspondence. Each series-connected switch is used to control the on / off state of the source and drain according to the sub-signal received at its gate.

4. The power transistor drive circuit according to claim 1, characterized in that, The current-limiting resistor module (12) includes a parallel section and a series section. The parallel section includes a first preset resistor (R0), m mixed parallel resistors (R31~R3m), and m mixed parallel switching transistors (PM31~PM3m). The m mixed parallel resistors and the m mixed parallel switching transistors correspond one-to-one. Each mixed parallel resistor and its corresponding mixed parallel switching transistor are connected in series and then in parallel with the first preset resistor (R0). The series section includes (nm) hybrid series switching transistors (PM3(m+1)~PM3n) and (nm) hybrid series resistors (R3(m+1)~R3n) connected in series. Each (nm) hybrid series resistor corresponds one-to-one with each (nm) hybrid series switching transistor, and each hybrid series resistor is connected in parallel with its corresponding hybrid series switching transistor. The resistance formed by connecting the parallel part and the series part in series is the current-limiting resistor in the input module (10). The control signal includes n sub-signals. The m hybrid parallel switches and the (nm) hybrid series switches receive the n sub-signals in a one-to-one correspondence. Each hybrid parallel switch and each hybrid series switch is used to control the on / off state of the source and drain according to the sub-signal received by the gate.

5. The power transistor drive circuit according to any one of claims 2-4, characterized in that, The control module (11) includes n voltage divider resistors (RA1~RAn) and n voltage divider comparators (P11~P1n). The n voltage divider resistors are connected in series between the power supply and the ground. The n voltage divider resistors and the n voltage divider comparators correspond one-to-one. The first input terminal of each voltage divider comparator is input with a predetermined reference voltage (VREF). The second input terminal of each voltage divider comparator is connected to the same side of the corresponding voltage divider resistor. The n voltage divider comparators each output one of the n sub-signals.

6. The power transistor drive circuit according to any one of claims 2-4, characterized in that, The control module (11) includes a first voltage divider resistor (RB1), a second voltage divider resistor (RB2), and n common voltage comparators (P21~P2n). The first voltage divider resistor and the second voltage divider resistor are connected in series between the power supply and the ground. The first input terminal of each common voltage comparator receives n different reference voltages (VREF1~VREFn), and the second input terminal of each common voltage comparator is connected between the first voltage divider resistor and the second voltage divider resistor. The n common-voltage comparators each output the n sub-signals.

7. The power transistor drive circuit according to any one of claims 2-4, characterized in that, The control module (11) includes a current source (I0), a preset switch (PM0), and n signal generation sub-modules (111~11n). The n signal generation sub-modules output the n sub-signals respectively. Each signal generation sub-module includes a first switch (PMa), a second switch (PMb), a voltage drop generation module, a second preset resistor (RC), and a capacitor (C0). In this configuration, the source of the preset switch, the source of the first switch, and the source of the second switch are connected to a power supply. The drain and gate of the preset switch are grounded through the current source. The gate of the first switch is connected to the gate of the preset switch, and the drain of the first switch is connected to the gate of the second switch. The drain of the first switch is grounded through the voltage drop generation module. The drain of the second switch is connected to one end of the second preset resistor and one end of the capacitor. The other end of the second preset resistor and the other end of the capacitor are grounded. The drain of the second switch outputs the sub-signal.

8. The power transistor drive circuit according to claim 7, characterized in that, The voltage drop generation module includes a third switch (NM1) and a fourth switch (NM2). The drain of the third switch is connected to the drain of the first switch. The third switch and the fourth switch are connected in a diode configuration. The source of the fourth switch is grounded.

9. The power transistor drive circuit according to claim 8, characterized in that, The third and fourth switching transistors are MOSFETs or bipolar transistors.

10. The power transistor drive circuit according to claim 7, characterized in that, The voltage drop generation module is a resistor or a diode.

11. A power transistor driving method, applied to the power transistor driving circuit as described in any one of claims 1-10, characterized in that, The power transistor drive circuit includes an input module (10), an output module (20), and a transformer (30). The input module (10) and the output module (20) are connected through the transformer (30). The method includes: The input module (10) controls the primary end of the transformer (30) to generate alternating current according to the acquired input signal. The input module (10) outputs a control signal according to the power supply voltage and adjusts the value of the current limiting resistor in the input module (10) according to the control signal so that the value of the current limiting resistor increases as the power supply voltage increases. The output module (20) receives the voltage signal from the secondary side of the transformer (30) and controls the opening and closing of the power transistor according to the received voltage signal.

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