Switching device overcurrent protection circuit and transistor

Abstract

The invention provides a switching device overcurrent protection circuit and a transistor. The switching device overcurrent protection circuit comprises a target switching device and a resistance value self-adjusting circuit, the resistance value self-adjusting circuit is connected with a potential sampling point, and the potential sampling point comprises a source electrode of a target switching device or a drain electrode of the target switching device; the resistance value self-adjusting circuit is used for collecting the potential at the potential sampling point and adjusting the resistance value of the resistance value self-adjusting circuit according to the collected potential, so that the overcurrent on the target switching device is reduced, and the overcurrent tolerance time of the target switching device is prolonged. The circuit can quickly respond to the current change of a target switching device, adjusts the current of the target switching device by adjusting the resistance value of a target loop where the target switching device is located, prolongs the large current tolerance time of the target switching device while reducing the peak current of the switching device, and improves the switching efficiency. And enough time is reserved for an external control circuit to trigger a gate turn-off signal of a target switching device.

Description

Technical Field

[0001] The present invention belongs to the technical field of electronic circuits, and in particular relates to an overcurrent protection circuit for a switching device and a transistor. Background Art

[0002] Switching devices, such as GaN high electron mobility transistor (GaN HEMT) devices, can generally be divided into two types: normally-on devices and normally-off devices. Among them, the high electron mobility transistor (HEMT) device is a naturally normally-on conduction channel due to its unique two-dimensional carrier gas channel, namely two-dimensional electron gas (2DEG) or two-dimensional hole gas (2DHG), so the normally-on GaN HEMT device directly uses the two-dimensional carrier gas channel as a conductive channel. However, in general circuits, normally-off devices are more likely to be used. The current mainstream direction is to use P-type gallium nitride GaN as the gate electrode, or to use the groove etching method to make a metal electrode near the channel layer to form a gate electrode, which can reduce the two-dimensional carrier gas concentration in the gate coverage area to form a depletion region, thereby forming a normally-off device. Another mainstream method is to use an enhancement mode silicon metal-oxide-semiconductor field-effect transistor (MOSFET) and a normally-on GaN HEMT device to obtain an equivalent normally-off device by cascading.

[0003] In order to avoid the occurrence of large currents burning circuit components in the event of a short circuit, an overcurrent protection device is usually added to the circuit. A general overcurrent protection device can be a fuse, that is, when the current is too large, the current path is cut off by fusing its own material to protect the circuit. Another mainstream method is to connect a sampling resistor in series in the circuit loop, feed back the voltage on the sampling resistor to the operational amplifier, and then control the gate drive signal of the switching device through the signal output of the operational amplifier. When the current exceeds the preset value, the gate drive signal of the switching device is triggered to turn off the switching device and cut off the current in the circuit. There are also other methods that use complex circuit combinations to detect overcurrents, and send a gate drive signal to the switching device after a series of feedback to turn off the switching device.

[0004] Whether it is a fuse or an overcurrent protection device composed of a sampling resistor plus an operational amplifier or other overcurrent protection devices formed by a complex circuit combination, they all need a certain amount of time to work. Before these overcurrent protection devices work, the switch device will be subjected to a large current. When the large current passes for a time that exceeds the tolerance time of the switch device itself, it will cause irreversible damage to the switch device. In addition, although the fuse-based protection device is simple in design, it is a one-time device. After it blows, a new fuse must be manually replaced before the protection device can be reactivated, which leads to problems such as complex circuit maintenance and low efficiency. Summary of the invention

[0005] In order to solve the above problems existing in the prior art, the present invention provides a switch device overcurrent protection circuit and a transistor. The specific technical solution includes:

[0006] In a first aspect, the present invention provides a switching device overcurrent protection circuit, comprising:

[0007] Target switching device and resistance value self-adjusting circuit;

[0008] The resistance value self-adjusting circuit is connected to a potential sampling point, and the potential sampling point includes a source electrode of a target switching device or a drain electrode of a target switching device;

[0009] The resistance self-adjusting circuit is used to collect the potential at the potential sampling point and adjust its own resistance according to the collected potential to reduce the overcurrent on the target switching device and extend the overcurrent tolerance time of the target switching device.

[0010] In a second aspect, the present invention provides a method for overcurrent protection of a switching device, comprising:

[0011] Collecting the target potential corresponding to the source or drain of the target switching device;

[0012] According to the target potential, the resistance value of the loop where the source or drain of the target switching device is located is adjusted to reduce the overcurrent on the target switching device and extend the overcurrent tolerance time of the target switching device.

[0013] In a third aspect, the present invention further provides a transistor, comprising any switching device overcurrent protection circuit provided in the first aspect and its optional aspects.

[0014] In a fourth aspect, the present invention further provides an electronic device, comprising any switching device overcurrent protection circuit provided in the first aspect and its optional aspects.

[0015] Beneficial effects of the present invention:

[0016] The switching device overcurrent protection circuit and transistor provided by the present invention include a target switching device and a resistance value self-adjusting circuit; the resistance value self-adjusting circuit is connected to a potential sampling point in the target switching device overcurrent protection circuit, and the potential sampling point includes a source electrode of the target switching device or a drain electrode of the target switching device; the resistance value self-adjusting circuit is used to collect the potential at the potential sampling point, and adjust its own resistance according to the collected potential, so as to reduce the overcurrent on the target switching device and prolong the overcurrent tolerance time of the target switching device.

[0017] By sampling the potential at relevant positions in the circuit and adjusting the resistance in the circuit according to the sampling results, thereby changing the current flowing through the target switching device, the peak current of the circuit can be controlled, and the high current tolerance time of the target switching device can be extended while reducing the peak current of the switching device, leaving enough time for the external control circuit to trigger the gate shutdown signal of the target switching device. The target switching device can continue to be used and the overcurrent protection function can continue to function after it is reopened, with a high degree of automation.

[0018] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 A schematic diagram of the structure of an overcurrent protection circuit for a switching device provided by the present invention;

[0020] Figure 2 A schematic structural diagram of another switching device overcurrent protection circuit provided by the present invention;

[0021] Figure 3 A schematic structural diagram of another switching device overcurrent protection circuit provided by the present invention;

[0022] Figure 4 A schematic structural diagram of another switching device overcurrent protection circuit provided by the present invention;

[0023] Figure 5 A schematic structural diagram of another switching device overcurrent protection circuit provided by the present invention;

[0024] Figure 6 A schematic structural diagram of another switching device overcurrent protection circuit provided by the present invention;

[0025] Figure 7 A schematic structural diagram of another switching device overcurrent protection circuit provided by the present invention;

[0026] Figure 8 A structural schematic diagram of a trigger circuit provided by the present invention;

[0027] Fig. 9A schematic diagram of the structure of another trigger circuit provided by the present invention;

[0028] Fig.10 A structural schematic diagram of another trigger circuit provided by the present invention;

[0029] Fig.11 The present invention provides a schematic structural diagram of a resistance self-adjusting circuit. DETAILED DESCRIPTION

[0030] The present invention is further described in detail below with reference to specific embodiments, but the embodiments of the present invention are not limited thereto.

[0031] Since the critical breakdown field strength of GaN devices is much higher than that of Si devices, the chip area of ​​GaN HEMT with the same withstand voltage specification will be much smaller than that of Si MOSFET. Correspondingly, when a short circuit occurs, the junction temperature of the GaN HEMT device caused by the large current will rise faster, eventually causing the HEMT device itself to burn out.

[0032] Therefore, when using HEMT devices or other switching devices, such as SiC MOSFET switching devices, on the one hand, it is necessary to improve the device's own tolerance time to large currents from the perspective of device design, and on the other hand, it is necessary to adopt an overcurrent protection circuit with faster response speed and higher regulation efficiency.

[0033] The present invention provides an overcurrent protection circuit for a switching device. When a short circuit or the like occurs in the circuit and a large current is generated, the potential at a relevant position in the circuit is sampled, and the resistance in the circuit is adjusted according to the sampling result, thereby changing the current flowing through the switching device. This can control the peak current of the circuit, and can extend the large current tolerance time of the switching device while reducing the peak current of the switching device, leaving sufficient time for an external control circuit to trigger a gate shutdown signal of the switching device. The switching device can continue to be used and its overcurrent protection function can continue to be performed after it is reopened.

[0034] Figure 1 A schematic diagram of a switch device overcurrent protection circuit provided by the present invention is shown in FIG. Figure 1 As shown, including:

[0035] Target switching device and resistance value self-adjusting circuit.

[0036] The resistance value self-adjusting circuit is connected to a potential sampling point in an overcurrent protection circuit of a target switching device.

[0037] The potential sampling point includes a source of the target switching device or a drain of the target switching device.

[0038] The resistance value self-adjusting circuit is used to collect the potential at the potential sampling point, and adjust its own resistance value according to the collected potential to adjust the current on the target switching device.

[0039] Wherein, the gate of the target switching device is connected to an external driving signal.

[0040] The target switch device can be a normally-on device or a normally-off device, that is, an enhancement-mode device or a depletion-mode device. Exemplarily, the target switch device is a GaN HEMT device.

[0041] Exemplarily, it can be a transistor based on silicon Si, silicon carbide SiC, gallium nitride GaN, and can be any three-terminal device with a source (emitter), a gate and a drain (collector), such as MOSFET, HEMT, COOLMOS, insulated-gate bipolar transistor (IGBT).

[0042] The gate of a three-terminal device is usually connected to an external drive signal, the drain (collector) is usually connected to a high potential point in the circuit loop, and the source (emitter) is usually connected to a low potential point in the circuit loop. The conduction and shutoff of the current from the drain (collector) to the source (emitter) is controlled by whether the voltage difference between the gate and the source (emitter) reaches the threshold voltage.

[0043] The potential sampling point may be the source of the target switching device or the drain of the target switching device, or may be a corresponding position on the loop where the source of the target switching device or the drain of the target switching device is located.

[0044] For example, see Figure 2 , the resistance value self-adjusting circuit is connected in series with the target switching device, the drain of the target switching device is connected to the third terminal of the resistance value self-adjusting circuit, and the source is connected to the second terminal of the resistance value self-adjusting circuit. The potential sampling point is the source of the target switching device. The resistance value self-adjusting circuit adjusts its own resistance value according to the voltage difference between the potential of the source of the target switching device and the potential of the drain of the resistance value self-adjusting circuit to reduce the overcurrent on the target switching device.

[0045] Optionally, it also includes: a trigger circuit.

[0046] The trigger circuit is connected to the source or drain of the target switch device and the resistance self-adjusting circuit, and the lowest potential in the trigger circuit is lower than the lowest potential in the resistance self-adjusting circuit.

[0047] The potential sampling point includes one of a source of the target switching device, a drain of the target switching device, and a lowest potential point in the trigger circuit.

[0048] The lowest potential in the trigger circuit is lower than the lowest potential in the resistance self-adjusting circuit, that is, the resistance self-adjusting circuit always maintains a higher potential than the trigger circuit.

[0049] See also Figure 3 , Figure 4 When the trigger circuit is connected in series between the resistance value self-adjusting circuit and the target switching device, the potential sampling point can be the source of the target switching device to collect the voltage on the trigger circuit and the target switching device, that is, to feed back the voltage carried by the trigger circuit and the target switching device to the resistance value adjusting circuit; it can also be the drain of the target switching device (the lowest potential point in the trigger circuit) to collect the voltage on the trigger circuit, that is, to feed back the voltage carried by the trigger circuit to the resistance value adjusting circuit.

[0050] exist Figure 3 In the embodiment, the first end of the resistance self-adjusting circuit is connected to the second end of the trigger circuit to ensure that the trigger circuit can be in the on state when the circuit is turned on. The second end of the resistance self-adjusting circuit is connected to the source of the target switching device, the third end of the resistance self-adjusting circuit is connected to the first end of the trigger circuit, and the third end of the trigger circuit is connected to the drain of the target switching device. The potential sampling point is the source of the target switching device, and the voltage difference between the potential of the source of the target switching device and the potential of the drain of the resistance self-adjusting circuit is the voltage carried by the trigger circuit and the target switching device.

[0051] exist Figure 4 In the embodiment, the first end of the resistance self-adjusting circuit is connected to the second end of the trigger circuit to ensure that the trigger circuit can be in the on state when the circuit is turned on. The second end of the resistance self-adjusting circuit is connected to the drain of the target switching device, and the third end is connected to the first end of the trigger circuit. The third end of the trigger circuit is connected to the drain of the target switching device. The potential sampling point is the drain of the target switching device (the lowest potential point in the trigger circuit), and the voltage difference between the potential of the drain of the target switching device (the lowest potential point in the trigger circuit) and the potential of the drain of the resistance self-adjusting circuit is the voltage carried on the trigger circuit.

[0052] See also Figure 5 , Figure 6 The target switch device is connected in series between the resistance self-adjusting circuit and the trigger circuit. The potential sampling point can be the lowest potential point in the trigger circuit to collect the voltage on the trigger circuit and the target switch device, that is, to feed back the voltage carried by the trigger circuit and the target switch device to the resistance adjustment circuit.

[0053] exist Figure 5In the embodiment, the first end of the resistance self-adjusting circuit is connected to the second end of the trigger circuit to ensure that the trigger circuit can be in the on state when the circuit is turned on. The second end is connected to the third end of the trigger circuit, and the third end is connected to the drain of the target switch device. The source of the target switch device is connected to the first end of the trigger circuit. The potential sampling point is the third end of the trigger circuit, that is, the lowest potential point in the trigger circuit. The voltage difference between the potential of the lowest potential point in the trigger circuit and the potential of the drain of the resistance self-adjusting circuit is the voltage carried by the trigger circuit and the target switch device.

[0054] exist Figure 6 In the embodiment, the second end of the resistance self-adjusting circuit is connected to the third end of the trigger circuit, and the third end is connected to the drain of the target switch device. The source of the target switch device is connected to the first end of the trigger circuit. The source of the target switch device is also connected to the second end of the trigger circuit to ensure that the trigger circuit can be in a conducting state when the circuit is turned on. The potential sampling point is the third end of the trigger circuit, that is, the lowest potential point in the trigger circuit. The voltage difference between the potential of the lowest potential point in the trigger circuit and the potential of the drain of the resistance self-adjusting circuit is the voltage carried by the trigger circuit and the target switch device.

[0055] See also Figure 7 The resistance self-adjusting circuit is connected in series between the target switch device and the trigger circuit. The potential sampling point can be the lowest potential point in the trigger circuit to collect the voltage on the trigger circuit, that is, to feed back the voltage carried by the trigger circuit to the resistance self-adjusting circuit.

[0056] exist Figure 7 In the embodiment, the source of the target switch device is connected to the first end of the resistance self-adjusting circuit and the second end of the trigger circuit respectively. The second end of the resistance self-adjusting circuit is connected to the third end of the trigger circuit, and the third end is connected to the first end of the trigger circuit. The potential sampling point is the third end of the trigger circuit, that is, the lowest potential point in the trigger circuit. The voltage difference between the potential of the lowest potential point in the trigger circuit and the potential of the drain of the resistance self-adjusting circuit is the voltage carried by the trigger circuit.

[0057] It should be noted that the target switch device can be a normally open switch device or a normally closed switch device. Accordingly, when the target switch device is a normally open switch device, any circuit composed of the target switch device, the resistance value self-adjusting circuit, and the trigger circuit, and when the target switch device is a normally closed switch device, any circuit composed of the target switch device, the resistance value self-adjusting circuit, and the trigger circuit, all belong to the protection scope of the present invention. Figure 2-Figure 7 These are just some of the circuit examples and do not represent all of them.

[0058] Optionally, after a resistor is connected in series with the source of the target switching device or the drain of the target switching device or the lowest potential point in the trigger circuit, the end of the resistor that is not connected to the source of the target switching device or the drain of the target switching device or the lowest potential point in the trigger circuit is used as a potential sampling point.

[0059] This method can increase the potential of the potential sampling point and increase the voltage difference between the resistance value self-adjusting circuit and the potential sampling point.

[0060] The resistor can be a normal resistor or a thermistor.

[0061] When the resistor adopts a thermistor, when the circuit device has an electrothermal effect, the resistance value self-adjusting circuit can more sensitively and quickly sense the temperature change of the switching device, the change of the potential of the potential sampling point, etc.

[0062] Optionally, the trigger circuit includes a first switching device.

[0063] The source of the first switching device is connected to the resistance self-adjusting circuit, or the source of the first switching device is connected to the drain of the target switching device, or the source of the first switching device is connected to the drain of the target switching device and the resistance self-adjusting circuit respectively.

[0064] The drain of the first switching device is connected to the lowest potential point in the resistance self-adjusting circuit, or the source of the target switching device.

[0065] The gate of the first switching device is connected to the highest potential point in the resistance self-adjusting circuit, or the source of the target switching device.

[0066] It should be noted that the lowest potential point and the highest potential point are relative concepts.

[0067] The trigger circuit includes only one first switch device, which can reduce the series resistance in the circuit and reduce the power consumption of the circuit.

[0068] The first switch device may be a normally open switch device or a normally closed switch device. Figure 2-Figure 7 The trigger circuit in the embodiment includes a first switch device, which is a normally-off switch device. To ensure that the trigger circuit can be in an on state when the circuit is turned on, the gate of the first switch device needs to be connected to a higher potential than the source thereof, such as Figure 2-Figure 7 The connection method shown. It should be noted that Figure 2-Figure 7 This is just an example and is not a specific limitation.

[0069] When the first switch device is a normally open switch device, in order to ensure that the trigger circuit can be in the on state when the circuit is turned on, the gate of the first switch device needs to be connected to a lower potential than its source. To save space, the specific circuit is not shown, and any connection method that can be achieved according to the content recorded in this article belongs to the protection scope of the present invention.

[0070] Figure 8 A structural schematic diagram of a trigger circuit provided by the present invention, optionally, when the trigger circuit includes multiple first switching devices.

[0071] The gate electrodes of the plurality of first switching devices are connected to the highest potential point in the resistance self-adjusting circuit, or to the source electrode of the target switching device.

[0072] Each first switch device is connected in series via a source and a drain, and the drain with the highest potential in the circuit formed by the series connection is connected to the lowest potential point in the resistance value self-adjusting circuit, or the source of the target switch device.

[0073] The source with the lowest potential is connected to the resistance self-adjusting circuit, or the source with the lowest potential is connected to the drain of the target switching device, or the source with the lowest potential is connected to the drain of the target switching device and the resistance self-adjusting circuit respectively.

[0074] Optional, see Fig. 9 , Fig.10 In the trigger circuit, the drain of the first switching device with the highest potential is connected to a resistor and then to the source of the target switching device, or to the lowest potential point of the resistance value self-adjusting circuit.

[0075] Exemplarily, the resistor may be a general resistor or a thermistor.

[0076] When the temperature rises, the resistance of the thermistor will increase accordingly. Therefore, when the current increases or the temperature increases caused by the current increase, the voltage difference fed back by the trigger circuit can be further increased, thereby improving the feedback capability of the trigger circuit.

[0077] It can be understood that when the trigger circuit includes only one first switch device, the drain of the first switch device with the highest potential is the drain of the first switch device. Fig. 9 When the trigger circuit includes multiple first switch devices, in the circuit formed by connecting the multiple first switch devices in series, the drain of the first switch device with the highest potential is connected to a resistor and then to the gate of the resistance self-adjusting circuit, see Fig.10 .

[0078] Optionally, the first switch device is a normally open switch or a normally closed switch device, that is, it can be a depletion switch device or an enhancement switch device. Exemplarily, the first switch device is a GaN HEMT device.

[0079] The more the number of first switch devices connected in series in the trigger circuit is, the greater the voltage fed back by the trigger circuit when the circuit current is close to the set protection value, that is, the more sensitive the protection response is.

[0080] Commonly used GaN HEMT enhancement devices are usually PGaN gate devices, whose internal resistance will increase significantly with the increase of temperature. In other words, when the current in the circuit increases, the current flowing through the internal resistance will generate heat, causing the temperature of the device to rise. This will cause the internal resistance of the device to increase, forming a positive feedback, that is, the greater the current, the more heat, the greater the internal resistance, and the further increase in heat, which is very beneficial to amplify the voltage fed back to the resistance value self-regulating circuit, so that the self-regulating circuit can respond to the increase in current in the circuit more quickly and better protect the target switching device.

[0081] Optionally, the resistance self-regulating circuit includes a first depletion-type switching device.

[0082] The gate of the first depletion-type switch device is connected to the potential sampling point, the drain corresponds to the highest potential in the resistance value self-adjusting circuit, and the source corresponds to the lowest potential in the resistance value self-adjusting circuit.

[0083] The resistance self-regulating circuit includes only one first depletion-type switch device, which can reduce the series resistance in the circuit and reduce the power consumption of the circuit.

[0084] Fig.11 This is a schematic structural diagram of a resistance self-adjusting circuit provided by the present invention. Optionally, the resistance self-adjusting circuit includes a plurality of first depletion-type switching devices.

[0085] After the gates of the first depletion-type switching devices are connected, they are connected to the potential sampling point, and multiple first depletion-type switches are connected in series through the source and the drain. The drain with the highest potential in the circuit formed by the series connection corresponds to the highest potential in the resistance value self-regulating circuit, and the source with the lowest potential corresponds to the lowest potential in the resistance value self-regulating circuit.

[0086] The more first depletion-type switch devices are connected in series in the resistance self-adjusting circuit, the faster the resistance value of the resistance self-adjusting circuit increases when the circuit current approaches the set protection value, that is, the faster the protection response speed is.

[0087] Exemplarily, the first depletion-mode switch device is a GaN HEMT device.

[0088] Figure 2-Figure 7The resistance value self-regulating circuit includes two first depletion-type switching devices connected in series.

[0089] When the resistance self-regulating circuit includes multiple depletion-type devices, by setting the threshold voltages of different depletion-type devices, a faster shutdown response speed can be achieved, and the resistance value in the circuit can be quickly increased or even the circuit path can be shut down when the circuit current increases sharply, thereby reducing the time when the peak current flows through the switching device and extending the tolerance time of the switching device under extreme current conditions.

[0090] When the temperature of the switching device increases, its internal resistance will also increase accordingly, and then its internal resistance voltage will also increase. Therefore, based on the circuit provided by the present invention, when the switching device has poor heat dissipation due to some reason, and the heat accumulates in the device to cause the device temperature to rise, the change in the internal resistance voltage will also be fed back to the resistance value self-adjusting circuit. After exceeding a certain limit, the resistance value self-adjusting circuit will be triggered to adjust the resistance value to limit the current, or shut down the circuit to protect the target switching device. Therefore, the circuit can not only monitor the change of the current in the circuit, but also monitor the temperature change of the switching device.

[0091] Any first depletion-mode device may be a single chip, or a combined depletion-mode device formed by combining multiple chips in a manner of connecting gates in parallel, sources in parallel, and drains in parallel.

[0092] Due to space limitations, the present invention does not show all possible implementations of the circuit, but circuit structures that can be obtained or inferred from the contents of the present invention all fall within the protection scope of the present invention.

[0093] Combine the following Figure 2 , for further detailed explanation.

[0094] Figure 2 In the embodiment, the resistance value self-adjusting circuit is connected in series with the target switch device, and the resistance value self-adjusting circuit includes two depletion-type switch devices U1 and U2 connected in series, and the target switch device includes a normally-off switch device U3 (enhancement switch device). The gates of U1 and U2 are both connected to the source of U3, the potential of the drain of U1 is higher than the source of U2, and the source of U1 is connected to the drain of U2.

[0095] When current flows through the series circuit composed of the resistance self-regulating circuit and the switching device, a voltage difference will be generated between the drain of U1 and the source of U3. The source of this voltage difference is the voltage division of the on-state internal resistance of each device in the series circuit. Since the source of U3 is connected to the gates of U1 and U2, a feedback loop is formed, so that the voltage difference between the drain of U2 and the source of U3 provides a negative gate voltage for the depletion-type switching device U1 in the resistance self-regulating circuit, and the voltage difference between the drain of U3 and the source of U3 provides a negative gate voltage for the depletion-type switching device U2 in the resistance self-regulating circuit. When the on-current in the circuit increases, the voltage division on the device will also increase. When this voltage difference increases to the vicinity of the turn-off threshold of U1 and / or U2 in the resistance value self-regulating circuit, U1 and / or U2 begin to enter the high resistance range, and the resistance of U2 close to the switch device increases sharply, which will further sharply amplify the negative voltage on the gate of U1 far from the switch device, and accelerate the turn-off of U1 far from the switch device, that is, through a depletion-type device as a voltage difference amplifier to accelerate the amplification of the gate negative voltage of another depletion-type switch device, thereby achieving the speed of turning off the circuit current. When the depletion-type switch device is in the off state at a certain moment, since the switch device U3 is still in the on state, the remaining charge in the resistance value self-regulating circuit and the switch device U3 will be quickly discharged, and the current in the series circuit composed of the resistance value self-regulating circuit and the switch device U3 will decrease sharply, that is, the voltage division of the device will also decrease sharply, and the corresponding negative gate voltage bias acting on U1 and U2 of the resistance value self-regulating circuit will also decrease sharply, and finally the entire resistance value self-regulating circuit will resume conduction. If the peak current still acts on the entire circuit loop at this time, it is obvious that the above process will be repeated continuously until the current in the circuit loop returns to a normal level or the external drive control signal turns off the switch device.

[0096] Specifically, when the current is too large or the temperature is too high, the resistance value of the resistance self-adjusting circuit increases to the point where the internal depletion-type device U1 and / or U2 is turned off. At this time, the target switch device U3 is still in the on state (the external drive circuit has not yet sent a shutdown signal). A typical situation at this time is that the charge cannot flow between the drain and source of the depletion-type device U1 and / or U2, but there is still a normal current path between the source of U1 or U2 and the source of the target switch device U3 (that is, the target switch device U3 is still turned on). Therefore, the voltage of the source of U2 will be the same as that of the target switch device U3. The voltage of the source becomes consistent, that is, the voltage difference between the source of U2 and the gate of U2 will decrease, and U2 will resume the low internal resistance conduction state. Then, the voltage difference between the source of U1, that is, the drain of U2, and the source of U2 will decrease, and the voltage of the source of U2 and the drain of U3 are consistent, so the negative gate voltage of the source of U1 and the gate of U1 is also reduced, and U1 also resumes the low internal resistance conduction state. At this time, the circuit between the drain of U1 and the drain of U3 is restored to conduction. At this time, if the gate of U3 still does not receive the shutdown signal, then the drain of U1 and the source of U3 will become a current path. The above process will be repeated in the circuit at a very high frequency. It can be understood that when the current is too large or the temperature of the switching device is too high, the overcurrent protection circuit proposed by the present invention will limit the current to a certain value or a certain interval, and will maintain the output of this limit current before the external drive circuit sends a signal to close the target switching device.

[0097] The switch device overcurrent protection circuit provided by the present invention feeds back the voltage carried by the target switch device alone, or feeds back the voltage carried by the trigger circuit connected in series with the target switch device alone, or feeds back the voltage carried by the target switch device and the voltage carried by the trigger circuit connected in series with the target switch device together after superposition to the resistance value self-adjusting circuit connected in series with the target switch device. The resistance value of the resistance value self-adjusting circuit will self-adjust according to the feedback voltage. Specifically, the larger the feedback voltage difference is, the higher the resistance of the resistance self-regulating circuit is, and the speed at which its resistance increases with the increase of the voltage difference is nonlinear, that is, when the feedback voltage difference is lower than a certain value, the resistance of the resistance self-regulating circuit increases slowly, so that it will not bring too much extra power consumption to the circuit in normal working state, and when the feedback voltage difference is close to or exceeds a certain value, the resistance of the resistance self-regulating circuit will increase rapidly, and the circuit can be completely shut down in a transient state. By using such a method to protect the target switching device from overcurrent, a very fast response speed can be achieved, and the target switching device can be protected in the first place, and at the same time, sufficient time can be gained for the external control circuit to trigger the gate shut-off signal of the target switching device. Furthermore, this overcurrent protection method can also control the current in the circuit within an appropriate range, extending the overcurrent tolerance time of the switching device.

[0098] The present invention also provides a method for overcurrent protection of a switching device, comprising: collecting a target potential corresponding to a source or drain of a target switching device; and adjusting the resistance value of a loop where the source or drain of the target switching device is located according to the target potential to reduce the overcurrent on the target switching device and extend the overcurrent tolerance time of the target switching device.

[0099] The present invention also provides a transistor, comprising any one of the above-mentioned switch device overcurrent protection circuits.

[0100] Exemplarily, the switch devices involved in the switch device overcurrent protection circuit all use GaN HEMT devices, and they are packaged as a transistor as a whole, which can be equivalent to an independent GaN HEMT transistor discrete device, which has better overcurrent tolerance.

[0101] Furthermore, the transistor can also be made into a monolithic on-chip integrated GaN HEMT device.

[0102] It should be understood that the structure of a HEMT device generally includes a substrate, a buffer layer, a channel layer, a barrier layer, and a cap layer. The device electrodes include a gate, a source, and a drain. In a monolithic on-chip integrated GaN HEMT device, the specific layout of the gate, source, and drain and the interconnections are generally adjusted based on the structure of the HEMT device. Such layer structures and layouts are well known to technicians in the industry and will not be described in detail here.

[0103] The above structure is only a general semiconductor device structure. In practical applications, any device whose internal circuit or its equivalent circuit is any switch device overcurrent protection circuit disclosed in the present invention belongs to the protection scope of the present invention.

[0104] The present invention also provides an electronic device, comprising any one of the above-mentioned switch device overcurrent protection circuits.

[0105] The terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.

[0106] The above contents are further detailed descriptions of the present invention in combination with specific preferred embodiments, and it cannot be determined that the specific implementation of the present invention is limited to these descriptions. For ordinary technicians in the technical field to which the present invention belongs, several simple deductions or substitutions can be made without departing from the concept of the present invention, which should be regarded as falling within the protection scope of the present invention.

Claims

1. A switching device overcurrent protection circuit, It is characterized in that include: Target switch device and resistance value self-adjusting circuit; The resistance self-adjusting circuit is connected to a potential sampling point, and the potential sampling point includes a source of the target switching device or a drain of the target switching device; The resistance self-adjusting circuit is used to collect the potential at the potential sampling point and adjust its own resistance according to the collected potential to reduce the overcurrent on the target switching device and extend the overcurrent tolerance time of the target switching device.

2. The circuit according to claim 1, It is characterized in that Also includes: Trigger circuit; The trigger circuit is connected to the source or drain of the target switch device and the resistance self-adjusting circuit, and the lowest potential in the trigger circuit is lower than the lowest potential in the resistance self-adjusting circuit; The potential sampling point includes one of a source of the target switching device, a drain of the target switching device, and a lowest potential point in the trigger circuit.

3. The circuit according to claim 2, It is characterized in that The trigger circuit includes a first switching device; The source of the first switching device is connected to the resistance self-adjusting circuit, or the source of the first switching device is connected to the drain of the target switching device, or the source of the first switching device is connected to the drain of the target switching device and the resistance self-adjusting circuit respectively; The drain of the first switching device is connected to the lowest potential point in the resistance self-adjusting circuit, or the source of the target switching device; The gate of the first switching device is connected to the highest potential point in the resistance self-adjusting circuit, or the source of the target switching device.

4. The circuit according to claim 2, It is characterized in that When the trigger circuit includes a plurality of first switch devices; The gates of the plurality of first switching devices are connected to the highest potential point in the resistance self-adjusting circuit, or the source of the target switching device; Each of the first switching devices is connected in series via a source and a drain, and in a circuit formed by the series connection, the drain with the highest potential is connected to the lowest potential point in the resistance self-adjusting circuit, or the source of the target switching device; In the circuit formed after the series connection, the source with the lowest potential is connected to the resistance value self-adjusting circuit, or the source with the lowest potential is connected to the drain of the target switching device, or the source with the lowest potential is connected to the drain of the target switching device and the resistance value self-adjusting circuit respectively.

5. The circuit according to any one of claims 1 to 4, It is characterized in that The resistance self-regulating circuit comprises a first depletion-type switching device; The gate of the first depletion-mode switch device is connected to the potential sampling point, the drain corresponds to the highest potential point in the resistance self-adjusting circuit, and the source corresponds to the lowest potential point in the resistance self-adjusting circuit.

6. The circuit according to any one of claims 1 to 4, It is characterized in that The resistance self-adjusting circuit includes a plurality of first depletion-type switch devices; After the gates of each of the first depletion-mode switch devices are connected, they are connected to the potential sampling point, and multiple first depletion-mode switches are connected in series through the source and the drain. The drain with the highest potential in the circuit formed by the series connection corresponds to the highest potential point in the resistance self-adjusting circuit, and the source with the lowest potential corresponds to the lowest potential point in the resistance self-adjusting circuit.

7. The circuit according to claim 3 or 4, It is characterized in that include: In the trigger circuit, the drain of the first switch device with the highest potential is connected to a resistor and then to the source of the target switch device, or the lowest potential point of the resistance self-adjusting circuit is connected.

8. A method for overcurrent protection of a switching device, It is characterized in that include: Collecting the target potential corresponding to the source or drain of the target switching device; According to the target potential, the resistance value of the loop where the source or drain of the target switching device is located is adjusted to reduce the overcurrent on the target switching device and extend the overcurrent tolerance time of the target switching device.

9. A transistor, It is characterized in that It comprises a switching device overcurrent protection circuit as described in any one of claims 1-7.

10. An electronic device, It is characterized in that It comprises a switching device overcurrent protection circuit as described in any one of claims 1-7.

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