Adjustable negative voltage clamping circuit and electronic equipment

Abstract

The technical scheme of the invention provides an adjustable negative voltage clamping circuit and electronic equipment, one end of the circuit is coupled to a first end of a switch tube, the other end of the circuit is coupled to a control end of the switch tube, the circuit comprises an adjustable clamping voltage module and a fixed clamping voltage module which are connected in series, the size of the internal current of the adjustable clamping voltage module is controlled by a threshold control signal, and the adjustable clamping voltage module provides an adjustable part of clamping voltage for the circuit; the fixed clamping voltage module is configured to detect the voltage difference between the first end and the second end of the fixed clamping voltage module, and is in a conducting state when the voltage difference is greater than or equal to a threshold voltage, so that the circuit can clamp the switch tube; when the voltage difference is smaller than the threshold voltage, the circuit is in a blocking state, and normal work of a switching tube in the circuit is ensured; therefore, by adjusting the current flowing through the adjustable clamping voltage module, the clamping voltage of the negative voltage clamping circuit is adjustable.

Description

Technical Field

[0001] The invention relates to the field of power electronics, and in particular to an adjustable negative voltage clamping circuit and electronic equipment. Background Art

[0002] With the rapid development of modern electronic technology, high-side switch chips are widely used in automotive electronics, industrial control and other fields. With its advantages of simple driving, high reliability and small size, high-side switch chips are in line with the current development trend of intelligent, miniaturized and highly integrated electronic control systems.

[0003] In the application scenario where the high-side switch drives an inductive load, due to the freewheeling effect of the inductive load, negative pressure may appear at the end of the power tube connected to the inductive load during the shutdown process. If the negative pressure is too large, the power tube will be broken down, or even the chip latch will burn out. Therefore, the high-side switch chip needs to have the function of quickly dissipating the magnetic energy on the inductive load after shutdown to ensure the safe operation of the entire system.

[0004] In existing design schemes, a negative voltage clamp circuit is often added to the circuit to ensure the rapid demagnetization of the inductive load. Specifically, the inductive load can be demagnetized directly by using a voltage-stabilizing TVS tube, or the power tube can be turned on by using a Zener diode to achieve rapid demagnetization of the inductive load. However, in these two methods, the threshold of the negative voltage clamp circuit is determined by the total conduction threshold of the voltage-stabilizing TVS tube or the Zener diode. It can be understood that the threshold of the negative voltage clamp circuit is a fixed value, which is difficult to apply in situations where the switching frequency and thermal management need to be managed.

[0005] Therefore, how to control the demagnetization speed of the inductive load has become a technical problem that urgently needs to be solved in the industry. Summary of the invention

[0006] The invention provides an adjustable negative voltage clamping circuit and electronic equipment, which solve the technical problem of how to control the demagnetization speed of an inductive load.

[0007] According to a first aspect of the present invention, an embodiment of the present invention provides an adjustable negative voltage clamp circuit, wherein a first end of the circuit is coupled to a first end of a switch tube, and a second end of the circuit is coupled to a control end of the switch tube; wherein:

[0008] The first end of the switch tube receives the power supply voltage, the second end is grounded through the inductive load, the control end receives the switch control signal, and the control end of the switch tube is also coupled to the second end through the pull-down module, and the pull-down module is used to provide a pull-down current;

[0009] The circuit comprises an adjustable clamping voltage module and a fixed clamping voltage module connected in series;

[0010] The control end of the adjustable clamping voltage module receives a threshold control signal, and the adjustable clamping voltage module is used to adjust the current flowing through the adjustable clamping voltage module based on the threshold control signal to control the clamping voltage of the adjustable negative voltage clamping circuit;

[0011] The fixed clamp voltage module is configured as follows:

[0012] Detecting a voltage difference between a first terminal and a second terminal of the fixed clamping voltage module, and being in a conducting state when the voltage difference is greater than or equal to a threshold voltage, so that the adjustable negative voltage clamping circuit can clamp the switch tube;

[0013] When the voltage difference is less than the threshold voltage, the switch is in a blocking state, so that the adjustable negative voltage clamp circuit can ensure the normal operation of the switch tube.

[0014] Optionally, the adjustable clamping voltage module includes a first resistor, a second resistor and a current control unit;

[0015] The first end of the first resistor and the first end of the current control unit both receive the supply voltage, the second end of the first resistor and the first end of the second resistor are coupled through a first node, the second end of the second resistor is coupled to the first end of the fixed clamping voltage module, and the first node receives the threshold control signal;

[0016] A control terminal of the current control unit is coupled to the first node and receives the threshold control signal. A second terminal of the current control unit is coupled to a first terminal of the fixed clamping voltage module.

[0017] Optionally, the current control unit includes a first transistor;

[0018] The first end of the first transistor receives the supply voltage, the control end thereof is coupled to the first node and receives the threshold control signal, and the second end thereof is coupled to the first end of the fixed clamping voltage module.

[0019] Optionally, types of the first transistor include: PMOS transistor, PNP transistor, NMOS transistor and NPN transistor.

[0020] Optionally, the threshold control signal is a current signal or a voltage signal.

[0021] Optionally, the fixed clamping voltage module includes N Zener diodes connected in series in sequence, where N is an integer greater than or equal to 1;

[0022] The negative electrode of the fixed clamping voltage module is coupled to the second end of the adjustable clamping voltage module, and the positive electrode thereof is coupled to the control end of the switch tube.

[0023] Optionally, the fixed clamping voltage module includes N diodes connected in series in sequence, where N is an integer greater than or equal to 1;

[0024] The negative electrode of the fixed clamping voltage module is coupled to the control end of the switch tube, and the positive electrode of the fixed clamping voltage module is coupled to the second end of the adjustable clamping voltage module.

[0025] Optionally, the pull-down module includes a pull-down resistor;

[0026] The first end of the pull-down resistor is coupled to the second end of the fixed clamping voltage module, and the second end of the pull-down resistor is coupled to the second end of the switch tube.

[0027] Optionally, the pull-down module includes a pull-down current source;

[0028] The first end of the pull-down current source is coupled to the second end of the fixed clamp voltage module, and the second end of the pull-down current source is coupled to the second end of the switch tube.

[0029] Optionally, the adjustable negative voltage clamp circuit further includes a threshold adjustment module, and the threshold adjustment module is used to output the threshold control signal based on the first information.

[0030] Optionally, the first information includes one or more of sampling temperature information, clamping voltage information, zero-crossing detection information, and interface instruction information.

[0031] Optionally, the switch tube is an NMOS tube.

[0032] According to a second aspect of the present invention, an embodiment of the present invention provides an electronic device, comprising the adjustable negative voltage clamping circuit as described in any one of the first aspect of the present invention.

[0033] Compared with the prior art, the technical solution of the embodiment of the present invention has the following beneficial effects:

[0034] In the adjustable negative voltage clamping circuit and electronic device of the technical solution of the present invention, the circuit includes an adjustable clamping voltage module and a fixed clamping voltage module connected in series, one end of the circuit is coupled to the first end of the switch tube, and the other end is coupled to the control end of the switch tube. The internal current size of the adjustable clamping voltage module is controlled by a threshold control signal to provide an adjustable clamping voltage for the circuit; the fixed clamping voltage module is configured to detect the voltage difference between the first end and the second end of the fixed clamping voltage module, and is in a conducting state when the voltage difference is greater than or equal to the threshold voltage, so that the circuit can clamp the switch tube; when the voltage difference is less than the threshold voltage, it is in a blocking state, so that the adjustable negative voltage clamping circuit is in a blocking state, ensuring the normal operation of the switch tube in the circuit; thus, the present invention makes the clamping voltage of the negative voltage clamping circuit adjustable by adjusting the current flowing through the adjustable clamping voltage module. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0036] Figure 1 It is a schematic diagram of the internal structure of a high-side switch chip in the prior art;

[0037] Figure 2 is corresponding to Figure 1 Working waveform diagram;

[0038] Figure 3 It is a structural schematic diagram of the first inductive load freewheeling circuit in the prior art;

[0039] Figure 4 It is a structural schematic diagram of a second inductive load freewheeling circuit in the prior art;

[0040] Figure 5 is a structural schematic diagram of a first adjustable negative voltage clamping circuit provided by an embodiment of the present invention;

[0041] Figure 6 is a structural schematic diagram of a second adjustable negative voltage clamping circuit provided by an embodiment of the present invention;

[0042] Figure 7 is a structural schematic diagram of a third adjustable negative voltage clamping circuit provided by an embodiment of the present invention;

[0043] Figure 8 is a structural schematic diagram of a fourth adjustable negative voltage clamping circuit provided by an embodiment of the present invention;

[0044] Fig. 9 is a structural schematic diagram of a fifth adjustable negative voltage clamping circuit provided by an embodiment of the present invention;

[0045] Fig.10 It is a structural schematic diagram of a sixth adjustable negative voltage clamping circuit provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0046] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0047] The terms "first", "second", "third", "fourth", etc. (if any) in the specification and claims of the present invention and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the data used in this way can be interchanged where appropriate, so that the embodiments of the present invention described herein can be implemented in an order other than those illustrated or described herein. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions, for example, a process, method, system, product or device that includes a series of steps or units is not necessarily limited to those steps or units that are clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0048] The technical solution of the present invention is described in detail with specific embodiments below. The following specific embodiments can be combined with each other, and the same or similar concepts or processes may not be described in detail in some embodiments.

[0049] It should be understood that the high-side switch chip described in the present invention is an intelligent power switch chip that integrates a high-voltage power tube and a driving, control, and protection circuit.

[0050] As an example, the high-side switch chip can be used as a power switch chip for high-current and low-frequency applications.

[0051] As described in the background art, it is currently difficult to achieve controlled demagnetization speed of an inductive load. This will be described in detail below with reference to the accompanying drawings.

[0052] Please refer to Figure 1 , Figure 1 FIG. 2 shows the internal structure of a high-side switch chip. P The first end receives the supply voltage V CC , the second end is grounded through an inductive load, and its control end receives a switch control signal.

[0053] Among them, Figure 1 In the example, the load inductance I LOAD With load resistance R LOAD constitutes the inductive load.

[0054] Please refer to Figure 2 , Figure 2 is corresponding to Figure 1 Circuit waveform diagram, where:

[0055] V GATE , which can be understood as the waveform of the switch control signal;

[0056] i L, which can be understood as the current waveform flowing through the inductive load;

[0057] V OUT , which can be understood as the high-side switch M P The voltage waveform at the second terminal.

[0058] It can be seen that in the high-side switch M P When driving an inductive load, if the switch control signal changes from high level to low level, the high-side switch M P To maintain the inductor current, V OUT The polarity of the voltage will change from positive to negative. If this negative voltage is not limited, the absolute value of the negative voltage will increase to a level sufficient to break down the devices in the circuit to maintain the inductor current.

[0059] To resolve this issue, refer to Figure 3 , Figure 3 FIG. 2 shows an inductive load freewheeling circuit. It can be seen that the circuit includes an external freewheeling diode D1 connected in parallel with the inductive load, and the high-side switch M is realized by the external freewheeling diode D1. P Inductive load follow current.

[0060] Although the circuit of this method is simple, it requires an external circuit that consumes area, and the attenuation rate of the discharge current is limited, which may still cause damage to the circuit or chip.

[0061] For another solution, see Figure 4 , Figure 4 Another inductive load freewheeling circuit is shown. It can be seen that the circuit includes a high-side switch M P Parallel voltage stabilizing TVS tube TVS.

[0062] exist Figure 4 In the example V CC is the supply voltage, V OUT is the voltage at the output terminal. When the voltage V CC -V OUT When the voltage is greater than the breakdown voltage of the voltage stabilizing TVS tube, the voltage stabilizing TVS tube will provide a V CC To V OUT A low-resistance path is created to maintain the inductor current and eliminate the magnetic energy on the inductor.

[0063] This method has a faster current decay rate, but it also requires external circuits that consume area and has requirements for the voltage regulation value of the Zener diode.

[0064] In other implementations, an inductive load shutdown protection circuit may also be added to the chip so that when the high-side switch M P When the source has a negative voltage, the high-side switch M is clamped P Source-drain voltage VDS Avoid power tube breakdown and briefly open the power tube to maintain the inductor current until the magnetic energy on the inductor is completely discharged.

[0065] As an example, the inductive load shutdown protection circuit is arranged on the high side switch M P Between the gate and drain, the circuit can be similar to a Zener circuit.

[0066] However, in the above solution, the threshold of the negative voltage clamping circuit (i.e., the clamping voltage) is determined by the total conduction threshold of the voltage-stabilizing TVS tube or the Zener diode. It can be understood that the threshold of the negative voltage clamping circuit is a fixed value, and it is difficult to dynamically or accurately control the demagnetization power consumption, and thus it is difficult to apply it in situations where there are different requirements for demagnetization speed and demagnetization peak power.

[0067] In view of this, the present invention provides an adjustable negative voltage clamping circuit, one end of the circuit is coupled to the first end of the switch tube, and the other end is coupled to the control end of the switch tube. The circuit includes an adjustable clamping voltage module and a fixed clamping voltage module connected in series. The internal current size of the adjustable clamping voltage module is controlled by a threshold control signal to provide an adjustable clamping voltage for the circuit; the fixed clamping voltage module is configured to detect the voltage difference between the first end and the second end of the fixed clamping voltage module, and is in a conducting state when the voltage difference is greater than or equal to the threshold voltage, so that the circuit can clamp the switch tube; when the voltage difference is less than the threshold voltage, it is in a blocking state, so that the adjustable negative voltage clamping circuit is in a blocking state, ensuring that the switch tube in the circuit works normally; thus, the present invention makes the clamping voltage of the negative voltage clamping circuit adjustable by adjusting the current flowing through the adjustable clamping voltage module.

[0068] In order to make the above-mentioned objects, features and beneficial effects of the present invention more obvious and easy to understand, specific embodiments of the present invention are described in detail below with reference to the accompanying drawings.

[0069] Figure 5 is an adjustable negative voltage clamping circuit according to an embodiment of the present invention. Figure 5 In the example, the load inductance I LOAD With load resistance R LOAD The inductive load 10 is formed.

[0070] Please refer to Figure 5 The first end of the circuit is coupled to the switch tube M P The first end of the switch tube M P The control end; wherein:

[0071] The switch tube M P The first end receives the supply voltage V CC The second end is grounded through an inductive load, and the control end receives a switch control signal.P The control end is also coupled to the second end thereof through a pull-down module 40, and the pull-down module 40 is used to provide a pull-down current;

[0072] The circuit includes an adjustable clamping voltage module 20 and a fixed clamping voltage module 30 connected in series;

[0073] The control end of the adjustable clamping voltage module 20 receives a threshold control signal, and the adjustable clamping voltage module 20 is used to adjust the current flowing through the adjustable clamping voltage module 20 based on the threshold control signal to control the clamping voltage of the adjustable negative voltage clamping circuit;

[0074] The fixed clamping voltage module 30 is configured as follows:

[0075] The voltage difference between the first terminal and the second terminal of the fixed clamping voltage module 30 is detected, and when the voltage difference is greater than or equal to the threshold voltage, the switch tube M is in the on state, and the fixed clamping voltage module 30 ... P ;

[0076] When the voltage difference is less than the threshold voltage, the switch tube M is in a blocking state. P Works fine.

[0077] Among them, the switch tube M P Of course, the present invention is not limited to this. P It can also be used for other switch tubes that need negative pressure management P .

[0078] In the embodiment of the present invention, the fixed clamping voltage module 30 is used to ensure that the circuit is within the switch tube M P The adjustable clamping voltage module 20 is used to adjust the switch tube M P The magnitude of the voltage that needs to be clamped.

[0079] Each module of the present invention is now further described.

[0080] In one implementation, please refer to Figure 6 The adjustable clamping voltage module 20 includes a first resistor R 1 , the second resistor R 2 and a current control unit 201;

[0081] The first resistor R 1 The first end of the current control unit 201 and the first end of the current control unit 201 both receive the supply voltage V CC , the first resistor R 1 The second end of the second resistor R 2The first end of the second resistor R is coupled through the first node. 2 The second end of is coupled to the first end of the fixed clamp voltage module 30, and the first node receives the threshold control signal;

[0082] A control terminal of the current control unit 201 is coupled to the first node and receives the threshold control signal. A second terminal of the current control unit 201 is coupled to a first terminal of the fixed clamping voltage module 30 .

[0083] It should be understood that the present invention does not limit the first resistor R 1 With the second resistor R 2 The resistance value can be set by technicians in this field as needed.

[0084] In addition, the present invention does not limit the internal circuit of the current control unit 201. As long as the current flowing through the adjustable clamping voltage module 20 can be adjusted based on the threshold control signal, the transistor that controls the threshold voltage (i.e., the clamping voltage) of the adjustable clamping voltage module 20 is within the protection scope of the present invention.

[0085] For a specific implementation, please refer to Figure 7 The current control unit 201 includes a first transistor M 1 ;

[0086] The first transistor M 1 The first end receives the supply voltage V CC , a control end of which is coupled to the first node and receives the threshold control signal, and a second end of which is coupled to the first end of the fixed clamping voltage module 30 .

[0087] exist Figure 7 In the example, the first transistor M 1 It is a PMOS transistor.

[0088] Of course, the present invention is not limited thereto. For example, the first transistor M 1 Types include: PMOS transistors, PNP transistors (such as Figure 8 As shown in Q1), NMOS transistor and NPN transistor. As long as the transistor can meet the corresponding working principle and regulation principle, it is within the protection scope of the present invention.

[0089] exist Figure 7 In the example, to control the first transistor M 1 , the threshold control signal is the current signal I ADJ Of course, it can also be other electrical signals, such as voltage signals, etc. Those skilled in the art can select a suitable control signal method as needed.

[0090] Regarding the fixed clamping voltage module 30, in one implementation, please continue to refer to Figure 7 The fixed clamping voltage module 30 includes N Zener diodes (D Z1 ~D Zn ), N is an integer greater than or equal to 1;

[0091] The cathode of the fixed clamping voltage module 30 is coupled to the second end of the adjustable clamping voltage module 20, and the anode of the fixed clamping voltage module 30 is coupled to the switch tube M. P control terminal.

[0092] exist Figure 7 In the example, the adjustable clamping voltage module 20 and the fixed clamping voltage module 30 form a power supply voltage V CC The switch tube M P The source voltage detection circuit, when the drive circuit controls the switch tube M P When the gate voltage drops, it goes through the following three processes in sequence:

[0093] The switch tube M P The source of the voltage drops in the positive voltage range, which means that the supply voltage V CC The voltage difference between the first end Vout of the inductive load and the first end Vout of the inductive load is not large enough to turn on the N Zener diodes, and the switch tube M P Gate V GATE If it is only controlled by the external switch control signal, the voltage Vout of the first end of the inductive load will keep decreasing;

[0094] If the switch tube M P When the source of the switch tube M drops to the negative voltage range, but the negative voltage is not low enough to turn on the N Zener diodes, the situation is the same as that of the switch tube M described above. P The source is the same as the case of positive pressure;

[0095] Once the switch tube M P The negative voltage of the source makes the N Zener diodes conduct, and the voltage between Vcc and Vgate will be clamped at the clamping voltage set by the present invention, that is, the Vgate voltage will no longer decrease as the voltage of Vout becomes negative (assuming that the Vcc voltage is constant), which will cause the voltage difference between Vgate and Vout to tend to increase, thereby making the switch tube M P Can continue to provide inductance L LOAD demagnetization current path.

[0096] It should be understood that due to the existence of a negative feedback loop, the voltage between Vgate and Vout does not actually increase.

[0097] Specifically, if the voltage difference between Vgate and Vout increases, the switch tube M P The current provided will exceed the inductor demagnetization current, causing the Vout voltage to rise, which in turn causes the voltage difference between Vgate and Vout to decrease, forming negative feedback.

[0098] Furthermore, in actual operation, when the Vout voltage is a relatively large negative voltage, it will only be clamped to the clamping voltage of the N Zener diodes and the switching voltage of the switch tube M. P The gate-source voltage required for the demagnetization current to flow (approximately P Miller platform voltage) and the first transistor M 1 The sum of the drain-source voltage.

[0099] The sum of the fixed clamping voltages that the fixed clamping voltage module 30 can provide is N×V z , where V z is the Zener voltage of the Zener diode. Only when the voltage difference between the first end and the second end of the fixed clamping voltage module 30 is greater than or equal to the threshold voltage, the N Zener diodes connected in series will enter Zener breakdown and conduct, thereby clamping the switch tube M. P .

[0100] In another specific embodiment, please refer to Figure 8 The fixed clamping voltage module 30 includes N diodes (D 1 ~D m ), N is an integer greater than or equal to 1;

[0101] The negative electrode of the fixed clamping voltage module 30 is coupled to the switch tube M. P The control end of the adjustable clamping voltage module 20 has a positive electrode coupled to the second end of the adjustable clamping voltage module 20.

[0102] Figure 8 The working principle of the fixed clamp voltage module 30 in the example is similar to Figure 7 The working principle of the fixed clamping voltage module 30 in the example is similar, and the present invention will not be repeated here.

[0103] Of course, the present invention does not limit the specific internal structure of the fixed clamping voltage module 30.

[0104] Regarding the pull-down module 40, in a specific implementation, please refer to Figure 7 , the pull-down module 40 includes a pull-down resistor R0;

[0105] The first end of the pull-down resistor R0 is coupled to the second end of the fixed clamp voltage module 30, and the second end thereof is coupled to the switch tube M.P The second end.

[0106] In another specific embodiment, please refer to Figure 8 The pull-down module 40 includes a pull-down current source I 0 ;

[0107] The pull-down current source I 0 The first end of the fixed clamp voltage module 30 is coupled to the second end of the fixed clamp voltage module 30, and the second end of the fixed clamp voltage module 30 is coupled to the switch tube M P The second end.

[0108] Of course, the present invention does not limit the specific structure of the pull-down module 40 , and it may also be other circuits or components capable of implementing pull-down.

[0109] Now Figure 7 Based on this, the working principle of the circuit provided by the present invention is explained.

[0110] exist Figure 7 In the example, the total clamping voltage V of the adjustable negative voltage clamp circuit is CLAMP The following relationship exists:

[0111] V CLAMP =V DSP =V DS1 +N×V Z +V GS0 (1)

[0112] Among them, V DS1 The first transistor M 1 The drain-source voltage, V DSP The first transistor M 1 The drain-source voltage difference, N×V Z is the total Zener voltage of N Zener diodes, V GS0 The switch tube M P The corresponding gate-source voltage when the demagnetization current flows.

[0113] exist Figure 7 In the example, the current flowing through the Zener diode is I DZ , the current I flowing through the M1 channel D1 The current I flowing through R0 R0 Here, the current I flowing through R1 and R2 is R1 and I R2 Much smaller than I D1 , which can be ignored in engineering.

[0114] exist Figure 7 In the example, the switch tube M P The voltage between the gate and source also has the following relationship:

[0115] V GS0 =V GATE -V OUT =R 0 *I R0 (2)

[0116] Then we can get

[0117] I R0 =V GS0 / / R 0 (3)

[0118] For the demagnetization process of the inductive load, it is actually the current flowing through the switch tube M P The current I DP The current I in the inductor of the inductive load L The balance is reached automatically, and the following relationship exists:

[0119]

[0120] Wherein, gf is the switch tube M P The forward transconductance, V TH The switch tube M P The threshold voltage.

[0121] Combining equation (2) and equation (4), we can get

[0122]

[0123] As can be seen from the above analysis, I R0 =I D1 , then the first transistor M 1 The gate-source voltage satisfies the following relationship

[0124]

[0125] Wherein, gm is the first transistor M 1 The transconductance, V TH0 The first transistor M 1 The threshold voltage.

[0126] Since the first transistor M 1 The drain-source voltage also has the following relationship

[0127]

[0128] Where R1 is the first resistor R 1 The resistance value of R2 is the second resistor R 2 resistance value.

[0129] Flowing through the first resistor R 1and the second resistor R 2 The current is I R1 and I R2 Therefore, without introducing the threshold control signal ( Figure 7 The current signal I ADJ ), because there is no current at the gate of MOS, so I R1 =I R2 , the equilibrium state (7) can also be expressed as follows:

[0130] V DS1 =I R1 ×(R 1 +R 2 ) (8)

[0131] When the threshold control signal ( Figure 7 The current signal I ADJ ) after the first transistor M 1 The drain-source voltage has the following relationship:

[0132] If current flows into

[0133] V DS1 =I R1 ×R 1 +(I R1 +I ADJ )×R 2 (9)

[0134] If current flows out,

[0135] V DS1 =I R1 ×R 1 +(I R1 -I ADJ )×R 2 (10)

[0136] It can be seen that by introducing the threshold control signal, the first transistor M can be controlled 1 The drain-source voltage value is determined, and the threshold voltage is then adjusted.

[0137] exist Figure 7 In the example, the first transistor M 1 For a BJT transistor, in the embodiment of the present invention, a BJT transistor with a large current gain β is selected. In the equilibrium state, it can be approximately considered that there is no current in the base stage in equation (7), so I R1 =I R2 . Figure 7 Other working principles and adjustment principles in the examples are similar to Figure 7 Similar, no further elaboration is required here.

[0138] In actual operation, the chip or system will sample the temperature, clamping voltage, the switch tube M P The threshold control signal is adjusted based on the voltage value and other data.

[0139] Furthermore, in a specific implementation, please refer to Figure 8 The adjustable negative voltage clamping circuit further includes a threshold adjustment module 50, and the threshold adjustment module 50 is used to output the threshold control signal based on the first information.

[0140] As an example, the first information includes one or more of sampling temperature information, clamping voltage information, zero-crossing detection information, and interface instruction information.

[0141] The interface instruction information may be an instruction of a digital interface, and the digital interface may be a common interface signal such as SPI, I2C, etc. The corresponding threshold value is adjusted through the instruction of the digital interface;

[0142] In other implementations, the interface instruction information may also be an instruction from an analog setting port, such as setting I ADJ , and temperature compensation is performed on the clamping threshold of the present invention.

[0143] To control Figure 7 Taking the adjustable negative voltage clamp circuit shown as an example, if the chip or system detects a temperature rise, the threshold adjustment module 50 can reduce the current of the threshold control signal flowing in, or keep the current of the threshold control signal in an outflow state, so as to reduce the clamping voltage, reduce the demagnetization power, and limit the temperature rise.

[0144] As an example, the zero-crossing detection information can be understood as the detection of the demagnetization time. Specifically, after the demagnetization of the inductive load is completed, the switch tube M P The voltage value of the second terminal will return to 0, by switching the switch tube M P By detecting the voltage value of the second terminal of the demagnetization device, the total demagnetization time can be obtained.

[0145] To control Figure 7 Taking the adjustable negative voltage clamp circuit shown as an example, the zero-crossing detection information can be understood as the duration of the detection of the source voltage Vout as a negative voltage. If the detected time is short, it indirectly indicates that the power is high. In this case, the current of the threshold control signal flowing in can be reduced, or the current of the threshold control signal can be kept in an outflow state to reduce the clamping voltage and extend the duration of the zero-crossing detection, thereby achieving the purpose of reducing the demagnetization power.

[0146] It should be understood that the first information has multiple implementation modes and multiple combination methods in practical applications, which are not limited in the present invention.

[0147] It can be seen that the present invention designs the adjustable clamping voltage module 20 and the fixed clamping voltage module 30 so that the present invention can adjust the current flowing through the adjustable clamping voltage module 20, so that the negative voltage clamping circuit can not only meet the normal operation of the circuit, but also ensure the safety of the circuit under a negative voltage state, and the clamping voltage value is adjustable and has good compatibility.

[0148] At the same time, the circuit provided by the present invention can adapt to occasions with different requirements for demagnetization speed and demagnetization peak power. When the temperature, load current, and even the system switching frequency change dynamically, the clamping voltage can be dynamically adjusted by adjusting the threshold control signal, thereby achieving real-time thermal management and efficiency management.

[0149] In the above embodiment, the first end of the adjustable clamping voltage module 20 is coupled to the switch tube M P The first end of the fixed clamping voltage module 30 is coupled to the first end of the fixed clamping voltage module 30, and the second end of the fixed clamping voltage module 30 is coupled to the switch tube M P control terminal.

[0150] It should be understood that the present invention does not limit the positions of the adjustable clamping voltage module 20 and the fixed clamping voltage module 30 in the circuit. Fig.10 , or the first end of the fixed clamping voltage module 30 is coupled to the switch tube M P The first end of the adjustable clamping voltage module 20 is coupled to the first end of the adjustable clamping voltage module 20, and the second end of the adjustable clamping voltage module 20 is coupled to the switch tube M P Those skilled in the art can select a suitable circuit connection method as required.

[0151] In addition, an embodiment of the present invention further provides an electronic device, including any of the above-mentioned adjustable negative voltage clamping circuits. As an example, it can be a power device. For example, a switching power supply (SMPS), an inverter, a high-frequency drive device, a drive motor, a charging pile, etc., and the present invention is not limited to this.

[0152] In a specific implementation, if the power device is an application with an inductive load and requires a higher switching frequency, the adjustable negative voltage clamping circuit provided by the present invention can be used to adjust the clamping voltage according to the switching frequency in the application to shorten or extend the demagnetization time.

[0153] In other embodiments, if the power device is an application with an inductive load and has high requirements for thermal management, the adjustable negative voltage clamping circuit provided by the present invention can be used to lower the clamping voltage according to the thermal management requirements in the application to reduce the demagnetization peak power.

[0154] In other embodiments, if the power device is an application with an inductive load and has requirements for switching frequency and thermal management, the adjustable negative voltage clamping circuit provided by the present invention can be used to adjust the appropriate clamping voltage, thereby achieving a balance between demagnetization time and peak power in the application.

[0155] In summary, the embodiment of the present invention is designed to couple one end of the adjustable negative voltage clamping circuit to the first end of the switch tube, and the other end to the control end of the switch tube. The circuit includes an adjustable clamping voltage module and a fixed clamping voltage module connected in series. The internal current size of the adjustable clamping voltage module is controlled by a threshold control signal to provide an adjustable clamping voltage for the circuit; the fixed clamping voltage module is configured to detect the voltage difference between the first end and the second end of the fixed clamping voltage module, and is in a conducting state when the voltage difference is greater than or equal to the threshold voltage, so that the circuit can clamp the switch tube; when the voltage difference is less than the threshold voltage, it is in a blocking state, so that the adjustable negative voltage clamping circuit is in a blocking state, ensuring that the switch tube in the circuit works normally; thus, the present invention makes the clamping voltage of the negative voltage clamping circuit adjustable by adjusting the current flowing through the adjustable clamping voltage module.

[0156] Although the present invention is disclosed as above, the present invention is not limited thereto. Any person skilled in the art can make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the scope defined by the claims.

Claims

1. An adjustable negative voltage clamp circuit, characterized in that: The first end of the circuit is coupled to the first end of the switch tube, and the second end of the circuit is coupled to the control end of the switch tube; wherein: The first end of the switch tube receives the power supply voltage, the second end is grounded through the inductive load, the control end receives the switch control signal, and the control end of the switch tube is also coupled to the second end through the pull-down module, and the pull-down module is used to provide a pull-down current; The circuit comprises an adjustable clamping voltage module and a fixed clamping voltage module connected in series; The control end of the adjustable clamping voltage module receives a threshold control signal, and the adjustable clamping voltage module is used to adjust the current flowing through the adjustable clamping voltage module based on the threshold control signal to control the clamping voltage of the adjustable negative voltage clamping circuit; The fixed clamp voltage module is configured as follows: Detecting a voltage difference between a first terminal and a second terminal of the fixed clamping voltage module, and being in a conducting state when the voltage difference is greater than or equal to a threshold voltage, so that the adjustable negative voltage clamping circuit can clamp the switch tube; When the voltage difference is less than the threshold voltage, the switch is in a blocking state, so that the adjustable negative voltage clamp circuit can ensure the normal operation of the switch tube.

2. The adjustable negative voltage clamping circuit according to claim 1, characterized in that: The adjustable clamping voltage module includes a first resistor, a second resistor and a current control unit; The first end of the first resistor and the first end of the current control unit both receive the supply voltage, the second end of the first resistor and the first end of the second resistor are coupled through a first node, the second end of the second resistor is coupled to the first end of the fixed clamping voltage module, and the first node receives the threshold control signal; A control terminal of the current control unit is coupled to the first node and receives the threshold control signal. A second terminal of the current control unit is coupled to a first terminal of the fixed clamping voltage module.

3. The adjustable negative voltage clamp circuit according to claim 2, characterized in that: The current control unit includes a first transistor; The first end of the first transistor receives the supply voltage, the control end thereof is coupled to the first node and receives the threshold control signal, and the second end thereof is coupled to the first end of the fixed clamping voltage module.

4. The adjustable negative voltage clamp circuit according to claim 3, wherein the type of the first transistor comprises: PMOS transistor, PNP transistor, NMOS transistor and NPN transistor.

5. The adjustable negative voltage clamping circuit according to claim 3, characterized in that: The threshold control signal is a current signal or a voltage signal.

6. The adjustable negative voltage clamp circuit according to claim 1, characterized in that: The fixed clamping voltage module includes N Zener diodes connected in series in sequence, where N is an integer greater than or equal to 1; The negative electrode of the fixed clamping voltage module is coupled to the second end of the adjustable clamping voltage module, and the positive electrode thereof is coupled to the control end of the switch tube.

7. The adjustable negative voltage clamp circuit according to claim 1, characterized in that: The fixed clamping voltage module includes N diodes connected in series in sequence, where N is an integer greater than or equal to 1; The negative electrode of the fixed clamping voltage module is coupled to the control end of the switch tube, and the positive electrode of the fixed clamping voltage module is coupled to the second end of the adjustable clamping voltage module.

8. The adjustable negative voltage clamp circuit according to claim 1, characterized in that: The pull-down module includes a pull-down resistor; The first end of the pull-down resistor is coupled to the second end of the fixed clamping voltage module, and the second end of the pull-down resistor is coupled to the second end of the switch tube.

9. The adjustable negative voltage clamp circuit according to claim 1, characterized in that: The pull-down module includes a pull-down current source; The first end of the pull-down current source is coupled to the second end of the fixed clamp voltage module, and the second end of the pull-down current source is coupled to the second end of the switch tube.

10. The adjustable negative voltage clamp circuit according to any one of claims 1 to 9, characterized in that: The adjustable negative voltage clamp circuit further includes a threshold adjustment module, and the threshold adjustment module is used to output the threshold control signal based on the first information.

11. The adjustable negative voltage clamping circuit according to claim 10, characterized in that: The first information includes one or more of sampling temperature information, clamping voltage information, zero-crossing detection information, and interface instruction information.

12. The adjustable negative voltage clamp circuit according to claim 1, characterized in that: The switch tube is an NMOS tube.

13. An electronic device, characterized in that: It comprises the adjustable negative voltage clamping circuit as claimed in any one of claims 1 to 12.

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