Improved gate clamping

Abstract

Circuit that includes: a switch (30); a switchable clamping element (28) coupled to the switch (30); and a driver (40) configured to control the switch (30) at least partially based on a driver control signal, the driver (40) further configured to enable or disable the switchable clamping element (28), and wherein the switchable clamping element (28) is configured to clamp a voltage across the switch (30) when the switchable clamping element (28) is enabled by the driver (40) and when the voltage across the switch (30) or a current across the switch (30) meets a threshold value for activating the switchable clamping element (28), wherein the driver (40) is further configured to enable or disable the switchable clamping element (28) based at least in part on a voltage across the switch (30) or a current at the switch (30), to detect a fault condition at the switch (30) based on the voltage across the switch (30) or the current at the switch (30), and to release the switchable clamping element (28) in response to the detection of the impending or actual fault condition at the switch (30).

Description

Technical area

[0001] The disclosure relates to techniques for gate clamping a switch. background

[0002] Some circuits may use power converters to convert (e.g., boost or buck) an input voltage or current from a power source into a regulated output voltage or current for powering a component, circuit, or other electrical device. Switch-based power converters may use one or more switches and signal modulation techniques to regulate an output. Leakage flux inductance is a parasitic effect associated with a power converter. Leakage flux inductance can be caused by power converter wiring, power converter interconnections, the geometric arrangement of power converter electrical components, the length of a power converter current path, the location of power converter capacitor decoupling, etc.A change in the current level in a power converter's current path can result in a noise pulse across the noise or stray flux inductance. The amplitude of the noise pulse can be defined by the magnitude of the stray flux inductance and the current gradient over time (di / dt). This noise pulse is added to the normal operating voltage, and the sum of both can exceed the tolerated voltage (e.g., operating voltage) of a switch and can lead to the destruction of the switch. Furthermore, the noise pulse can introduce electromagnetic interference (EMI)-based noise into the rest of the power converter and the associated system and / or corrupt measurements or the overall behavior of the power converter and / or the system.For example, parasitic effects and stray flux inductance can cause overcurrent, overvoltage, or other types of faults at the one or more switches of a power converter, particularly when a switch transitions between operation in an on-state and a switch-off state (e.g., when a switch turns on or off).

[0003] Some power converters may incorporate features or characteristics to limit noise and stray flux inductance. Although noise and stray flux inductance can be limited and reduced, some noise and stray flux inductance will inevitably remain. Additionally, some power converters may employ fixed clamping elements across one or more components of a power converter to protect the components from damage caused by potential or actual overcurrent, overvoltage, or other fault conditions that may occur or occur during a fault operating condition of the power converter induced by noise and stray flux inductance. However, the use of fixed clamping elements may reduce the operating voltage of the power converter and / or degrade the overall efficiency of the power conversion system.

[0004] From the document DE 103 39 689 B4 a circuit arrangement with a load transistor and a voltage limiting circuit is known, which can be deactivated depending on a load current through the load transistor and / or a control voltage of the load transistor.

[0005] It is therefore an object of the present invention to provide improved approaches to clamping in which these disadvantages are wholly or partially avoided. Short summary

[0006] A circuit according to claim 1 or 18 and a method according to claim 16 are provided. The subclaims define further embodiments.

[0007] In general, techniques and circuits are described for selectively clamping the voltage and / or current at a switch of a power converter to prevent impending or actual fault conditions (e.g., overvoltages and / or overcurrents) from damaging the switch. A power converter (e.g., a buck or boost converter, an inverter, etc.) may include at least one switch and may use signal modulation techniques to turn the switch on and / or off to convert an input voltage into a regulated output voltage and / or current.

[0008] The power converter may further include a switchable clamping element for clamping a voltage and / or current across the switch to prevent the voltage and / or current from reaching a level that could damage the switch. When the power converter detects a voltage across the switch that indicates a risk of an actual or potential fault condition, the power converter "releases" the switchable clamping element (e.g., turns on the switchable clamping element and causes the switchable clamping element to operate in an on state).By enabling the switchable clamp, the power converter configures the switchable clamp to create an additional current path through the switchable clamp to divert excess current caused by the fault condition away from the switch when a threshold or other activation criteria of the switchable clamp are met. If the voltage across the switch indicates no risk of an actual or potential fault condition, the power converter "locks" the switchable clamp (e.g., turns off the switchable clamp). By locking the switchable clamp, the power converter configures the switchable clamp to prevent an additional current path from being created through the switchable clamp even when the threshold or other activation criteria of the switchable clamp are met.

[0009] In one example, the disclosure is directed to a circuit including a switch, a switchable clamping element coupled to the switch, and a driver configured to control the switch based at least in part on a driver control signal. "Based at least in part on" means that, in addition to the explicitly stated elements (here: driver control signal), further elements may also serve as a basis. The driver is further configured to enable or disable the switchable clamping element. The switchable clamping element is configured to clamp a voltage across the switch when the switchable clamping element is enabled by the driver and when the voltage across the switch or a current across the switch meets a threshold for activating the switchable clamping element.

[0010] In another example, the disclosure is directed to a method including controlling, by a driver configured to control a switch, a switchable clamping element coupled to the switch based at least in part on a voltage across the switch or a current at the switch, wherein the switchable clamping element is configured to clamp the voltage across the switch when the switchable clamping element is enabled by the driver and when the voltage across the switch or the voltage at the switch meets a threshold for enabling the switchable clamping element.

[0011] In another example, the disclosure is directed to a circuit including means for controlling a switchable clamping element coupled to a switch based at least in part on a voltage across the switch or a current at the switch, wherein the switchable clamping element is configured to clamp the voltage across the switch when the switchable clamping element is enabled by the driver and when the voltage across the switch or the voltage at the switch meets a threshold for activating the switchable clamping element.

[0012] The details of one or more examples are set forth in the accompanying drawings and the following description. Other features, objects, and advantages of the disclosure will be apparent from the description and drawings, and from the claims. Brief description of the drawings Fig. 1 is a block diagram illustrating an example system for converting power from a power source in accordance with one or more aspects of the present disclosure. Fig. 2 is a block diagram showing an example of a power converter of the Fig. 1 shown example system. Fig. 3 is a circuit diagram illustrating an example converter unit incorporating improved gate clamping in accordance with one or more aspects of the present disclosure. Fig. 4 is a circuit diagram illustrating an additional example converter unit including a voltage booster for providing improved gate clamping in accordance with one or more aspects of the present disclosure. Fig. 5 is a block diagram showing an example driver of the Fig. 3 shown example converter unit and the one in Fig. 4 shows the additional example converter unit. Fig. 6 is a flowchart illustrating example operation of an example power converter in accordance with one or more aspects of the present disclosure. Fig. 7 is a timing diagram illustrating various timing characteristics of one or more aspects of the present disclosure. Detailed description

[0013] In some applications, a power converter (hereinafter referred to as a "converter") can convert (e.g., by stepping up or stepping down) an input voltage or current from a power source into a regulated output voltage or current for a device (e.g., a load). The converter may comprise a half-bridge containing one or more switches (e.g., MOS power switching transistors, gallium nitride (GaN-based) switches, or other types of switching devices). For example, a half-bridge may include a high-side switch coupled to a low-side switch at a switching node. By controlling the switches of the half-bridge using modulation techniques, the converter can regulate the magnitude of current or voltage at the half-bridge switching node.

[0014] Such modulation of the half-bridge switches can operate according to pulse width modulation (PWM), pulse density modulation (PDM) or any other suitable modulation technique.

[0015] Fault conditions (e.g., voltage or current spikes that exceed the operating voltage or current of the half-bridge components) can occur at a switch during a switching cycle due to stray flux inductance levels at the switch when a switch turns on or off. For example, the power converter may be susceptible to a magnitude of electrical noise or radiation that causes an overcurrent and / or overvoltage spike across a switch. The overcurrent, overvoltage, or other type of fault condition can cause a current and / or voltage level at the switch that exceeds the operating ratings of the switch and could cause damage to the switch. In some cases, switches with higher operating tolerances are used in a power converter to account for possible overcurrent, overvoltage, or other fault conditions.Switches with higher operating tolerances may impose higher circuit costs.

[0016] Some power converters may include features to minimize EMI and noise from flux leakage inductance at a switch, thus limiting the frequency and / or magnitude of an overcurrent, overvoltage, or other fault condition to prevent a voltage or current at a switch from exceeding the operating ratings of the switch. For example, some power converters may include additional shielding to minimize the amount of external electrical radiation and noise at a switch. Although some power converters may be designed and / or operated to minimize EMI and noise, EMI and noise at a power converter switch can almost never be completely eliminated or limited to a zero level.

[0017] Some power converters may include what is referred to as a "fixed clamp" or "fixed clamp" (e.g., a Zener diode, a TVS diode, an avalanche diode, or other electrical circuits and / or components that can be used as a "clamp" to suppress a voltage and / or current) disposed across a switch and configured to suppress voltage and / or current spikes at the switch and protect against potential damage that may be caused by a fault condition at the switch. For example, some power converters may include a Zener diode disposed across a switch and configured to operate as a fixed clamp. When the voltage across the switch and across the fixed clamp meets a threshold or other activation criteria of the fixed clamp (e.g.,When the voltage across the switch exceeds a breakdown voltage of the Zener diode, a current path is created through the fixed clamp element. The current path drains excess current through the fixed clamp element and protects the switch against overvoltage. As a result of the additional current path created by the fixed clamp element, the voltage across the switch is limited, or clamped, at a level that remains at or below the threshold of the fixed clamp element (e.g., the breakdown voltage of the Zener diode). In other words, the fixed clamp element limits the voltage across the switch from exceeding the threshold of the fixed clamp element and the maximum voltage for the switch.

[0018] The terms "clamping element" and "clamp" are used throughout this disclosure to describe any electrical device, component, or circuit used to suppress or clamp a voltage and / or current. The use of the terms "fixed clamp" and "fixed clamping element" is used to refer to clamps and clamping elements that cannot be "locked" or "turned off." For example, by being fixed, a fixed clamp or fixed clamping element cannot be locked and prevented from forming a current path through the fixed clamp or fixed clamping element if the voltage across the fixed clamp or fixed clamp meets the threshold or other activation criteria of the fixed clamping element.In other words, with a fixed clamp or clamping element, a current path is always formed through the fixed clamp or clamping element if the threshold or other activation criteria are met.

[0019] Various types of switchable clamps are described below, and the circuits and techniques described generally apply to each of these types of switchable clamps. For example, one type of switchable clamp is a "normally released" (e.g., "normally on") type switchable clamp. A normally released or normally on type switchable clamp refers to a switchable clamp that can clamp a voltage across a switch even when a driver is not controlling the switchable clamp and / or the driver is not energized. If the driver is connected, the driver can control the switchable clamp to lock the switchable clamp; otherwise, the normally released or normally on type switchable clamp is enabled.In some examples, a normally-on type switchable clamp element may be modeled as a normally-on transistor (e.g., a depletion MOS transistor) in series with a clamp.

[0020] A second type of switchable clamp is a "normally locked" (e.g., "normally off") type switchable clamp. A normally locked or normally off type switchable clamp refers to a switchable clamp that cannot clamp voltage across a switch unless a driver is not controlling the switchable clamp and / or the driver is energized to release the switchable clamp. If the driver is connected, the driver can control the switchable clamp to release the switchable clamp; otherwise, the normally locked or normally off type switchable clamp is locked. In some examples, a normally off type switchable clamp may be modeled as a normally off transistor (e.g., an enhancement MOS transistor) in series with a clamp.

[0021] By using fixed clamping elements that rely solely on thresholds (e.g., breakdown voltage) or other activation criteria to protect switches from fault conditions, power converters may be limited by the fixed clamping elements from operating at higher working voltages that exceed the thresholds or other activation criteria of the fixed clamping elements. In other words, the maximum working voltage of some power converters that use fixed clamping elements may be based on the thresholds or other activation criteria of the fixed clamping elements rather than on the actual operating voltage of the power converter's switches.For this reason, fixed clamping elements may prevent some power converters from operating outside a tolerance window of the fixed clamping elements, even though the switches protected by the fixed clamping elements may have operating voltages indicating that the switches can be operated at a higher working voltage that exceeds this tolerance window.

[0022] The risk of an overvoltage at the switch due to a noise pulse introduced by stray flux inductance can be reduced by either slowing the switching speed (lower di / dt) or reducing the normal operating voltage. Both slowing the switching speed and reducing the normal operating voltage can have a negative impact on the overall efficiency of a power converter. A slower switching speed can lead to more switching losses because it increases the duration of the transition time between the on and off states (and vice versa) of a switch. Reducing the normal operating voltage can result in increased current requirements to achieve the same power rating. This can lead to more conduction losses and potentially more expensive components to support the higher current requirements.

[0023] In some power converters, the disadvantages described above with using fixed clamping elements (e.g., causing a reduced operating voltage, etc.) can be overcome by using higher-voltage-class fixed clamping elements (e.g., fixed clamping elements that inherently have higher thresholds, a higher breakdown voltage, or other improved activation criteria). For example, some power converters may use higher-voltage-class fixed clamping elements that have breakdown voltages at the same voltage level as the operating voltage of the switches that the fixed clamping elements protect. However, like higher-voltage-class switches, higher-voltage-class fixed clamping elements can steadily increase the cost and size of the power converter.

[0024] In general, circuits and techniques of this disclosure may enable a power converter to selectively enable or enable a "switchable clamp" to protect a switch of the power converter from fault conditions at the switch if the power converter determines that a fault condition may occur or is occurring at the switch. Once enabled, the switchable clamp is configured to create a current path through the switchable clamp if a threshold or other activation criteria of the switchable clamp is met.

[0025] The current path created by an enabled or enabled switchable clamping element can divert current away from a switch during a fault condition (e.g., overvoltage or overcurrent across the switch) and protect the switch from being damaged by the fault condition. However, the current path created by an enabled or enabled switchable clamping element can also prevent the switch from operating at a working voltage level that exceeds the threshold or other activation criteria of the switchable clamping element.

[0026] To enable the switch to operate at higher working voltages (e.g., voltage levels that exceed the threshold or other activation criteria of the switchable clamping element), the power converter can selectively disable or de-energize the switchable clamping element if the power converter determines that a fault condition is not likely to occur on the switch. By disabling or de-energizing the switchable clamping element, even if a threshold or other activation criteria of the switchable clamping element are met, the switchable clamping element is prevented from creating the excess current path through the switchable clamping element. By disabling the switchable clamping element and preventing an excess current path from being created through the switchable clamping element, the power converter can enable the switch to operate at a higher working voltage level (e.g.,a voltage level that exceeds the threshold or activation criteria of the switchable clamping element) than the working voltage at which the switch is restricted to operate when the switchable clamping element is enabled.

[0027] Instead of using one or more fixed clamping elements like some other power converters, the power converter according to the circuits and techniques described herein uses one or more switchable clamping elements that can be selectively enabled or enabled to protect a switch from a fault condition in the event that a fault condition occurs at the switch, and that can further be selectively disabled or disabled when the voltage at the switch indicates that a fault condition is not likely to occur. Because the selectable clamping element is not permanently enabled or enabled, a fault condition at a switch of the power converter is not necessarily tied to the breakdown voltage of a clamping element. The power converter can operate at an elevated working voltage (e.g.a voltage exceeding the breakdown voltage of the switchable clamping element) and can operate with greater efficiency and lower switching losses than some other power converters that use fixed clamping elements. Additionally, the power converter can accommodate potential overcurrent and / or overvoltage conditions using lower-rated (e.g., operating voltage and / or operating current) switches and / or switches with lower tolerance (relative to some conventional techniques), thereby helping to reduce the implementation cost of the power converter.

[0028] The term "fault conditions" is used throughout the disclosure to describe both actual voltage and / or current spikes that could damage a switch of a power converter, as well as voltage and / or current levels that indicate an impending fault condition, or a voltage or current level that a level of an actual fault condition could reach. A fault condition may correspond to a voltage or current spike that exceeds the operating voltage or current of a switch and is not necessarily tied to the threshold or other activation criteria (e.g., breakdown voltage) of a clamping element.

[0029] Fig. 1 is a block diagram illustrating an example system for converting power from a power source in accordance with one or more aspects of the present disclosure. Fig. 1 shows system 1 comprising three separate and distinguishable components, shown as power source 2, power converter 6, and device 4. However, system 1 may include additional or fewer components. For example, power source 2, power converter 6, and device 4 may be three individual components or may represent a combination of one or more components that provide the functionality of system 1 as described herein.

[0030] System 1 includes power source 2, which provides electrical energy (i.e., power) to System 1. Numerous examples of power source 2 exist, and they may include, but are not limited to, power grids, generators, power transformers, batteries, solar power modules, wind turbines, regenerative braking systems, hydroelectric generators, or any other form of electrical power device capable of providing electrical energy in the form of voltage to System 1.

[0031] System 1 includes power converter 6, which operates as a switch-based power converter that converts electrical energy provided by power source 2 into a usable form of electrical energy for device 4. Examples of power converter 6 may include various types of power supplies, battery chargers, power supplies for microprocessors or other integrated circuits, and the like.

[0032] System 1 includes device 4, which receives the electrical power (e.g., voltage, current, etc.) converted by power converter 6 and, in some examples, uses the electrical power to perform a function. Numerous examples of device 4 exist, and they may include, but are not limited to, computing devices and related components such as microprocessors, electrical components, circuits, laptop computers, desktop computers, tablet computers, mobile phones, batteries, speakers, lighting units, automotive / marine / aviation / train-related components, motors, transformers, or any other type of electrical device and / or circuitry that receives electrical power in the form of voltage or current from a power converter.

[0033] Power source 2 can provide a first voltage via interconnect 8, and device 4 can receive a second voltage, converted by power converter 6, via interconnect 10. Interconnects 8 and 10 represent any medium capable of conducting electrical energy from one location to another. Examples of interconnects 8 and 10 include, but are not limited to, physical and / or wireless electrical transmission media such as electrical wires, electrical traces, conductive gas tubes, twisted pairs, and the like. Interconnect 10 provides electrical coupling between power converter 6 and device 4, and interconnect 8 provides electrical coupling between power source 2 and power converter 6. Device 4 is electrically coupled to power converter 6, which is coupled to power source 2.

[0034] In the example of system 1, a voltage generated by power source 2 may be regulated and / or converted into a form suitable for use by device 4. For example, power source 2 may output power at a first voltage level at link 8, and power converter 6 may accept this power. The power at the first voltage level may not be suitable for powering device 4. For example, device 4 may require power at a second voltage level that is different (e.g., higher or lower) than the first voltage level associated with the power provided by power source 2. Power converter 6 may convert the power at the first voltage level into power at a second voltage level necessary and suitable for powering device 4.The power converter 6 can output the power at the second voltage level, and the device 4 can receive this power at the connection link 10. The device 4 can use the power at the second voltage level to perform a function (e.g., powering a microprocessor).

[0035] Fig. 2 is a block diagram showing an example of a power converter of the Fig. 1. In particular, Fig. 2 a more detailed exemplary view of the power converter 6 of system 1 Fig. 1 and the electrical connections to the power source 2 and the device 4, which are provided by the connecting lines 8 and 10 respectively.

[0036] The power converter 6 is shown as having two electrical components, the control unit 12 and the converter unit 14, which the power converter 6 uses to convert power received via the connection path 8 into a different form and / or magnitude of power that the power converter 6 outputs to the connection path 10. The power converter 6 may have additional or fewer electrical components than those shown in Fig. 2. For example, in some examples, the control unit 12 and the converter unit 14 are a single semiconductor chip, electrical component, or circuit, while in other examples, more than two chips, components, and / or circuits provide the power converter 6 with the functionality of the control unit 12 and converter unit 14.

[0037] The converter unit 14 represents a switch-based power conversion element of the power converter 6 that converts power received at an input terminal coupled to the interconnect 8 into a different form of power and provides the converted and different form of power at an output terminal coupled to the interconnect 10. The converter unit 14 is described in more detail below, but in general, the converter unit 14 may receive power at a first voltage level at a connection (e.g., an input terminal) coupled to the interconnect 8. The converter unit 14 may transfer power at a second voltage level based at least in part on the power at the first voltage level at a different connection (e.g., an output terminal) coupled to the interconnect 10.The converter unit 14 may receive a driver control signal or driver command, such as a pulse width modulation (PWM) signal, a pulse density modulation (PDM) signal, or another signal for controlling the converter unit 4 according to another suitable modulation technique, from the control unit 12 over the interconnection link 16. The converter unit 14 may use the driver control signal or driver command signal to control the shape and magnitude of the power that the converter unit 14 outputs at the interconnection link 10. The converter unit 14 includes a driver circuit or unit for adjusting the voltage and current levels of the driver control signal at the interconnection link 16 to the voltage and current levels required to set the switch to its on state or off state.

[0038] The converter unit 14 may include one or more switches, gate drivers, half-bridge circuits, H-bridge circuits, input filters, output filters, or combinations thereof to provide output power at the interconnect 10 based on an input power received at interconnect 8 and a driver control signal received at interconnect 16. The converter unit 14 may include one or more switching devices, capacitors, resistors, transistors, transformers, inductors, clamping elements, and / or other electrical components or circuits disposed within the converter unit 14 for providing output power at the interconnect 10.

[0039] For example, the converter unit 14 may include a half-bridge arranged in parallel with an input terminal of the power converter 6 and including a first switch (e.g., a high-side switch) coupled at a switching node to a second switch (e.g., a low-side switch). A driver may be coupled to the first switch of the half-bridge and may be configured to control the first switch based on a driver control signal (e.g., PWM, PDM, or the like). Additionally, the converter unit 14 may include one or more switchable clamping elements coupled to the first switch for clamping a voltage across the first switch when both the switchable clamping element is enabled or caused by the driver to operate in an on-state of the switchable clamping element, and a threshold or other activation criteria of the switchable clamping element are met.The switchable clamping element is described in more detail below with reference to the other figures. In some examples, the driver of a converter unit 14 may control (e.g., enable / disable or turn on / off) the switchable clamping element based on a voltage level and / or current level detected at the first switch that indicates to the driver that a fault condition will occur or is occurring at the first switch. In other examples, the control unit 12 or other circuitry of the converter unit 14 may control (e.g., enable / disable or turn on / off) the switchable clamping element in the event that an impending or actual fault condition is detected at the first switch.

[0040] The control unit 12 of the power converter 6 can provide a driver control signal or a driver command to the converter unit 14 via the connection link 16 to control the shape and magnitude of the power that the converter unit 14 outputs at the connection link 10. For example, the control unit 12 can generate a PWM signal or another signal associated with another suitable modulation technique based on the voltage level of an input power at the connection link 8 and / or the connection link 10. In other examples, the control unit 12 can generate a PWM signal or another signal associated with another suitable modulation technique based on the voltage level of an input power detected at the connection link 8 and / or the connection link 10. In other words, the control unit 12 can provide a power converter 6 with a driver control signal for modulating (e.g.,Controlling) the circuit pattern of the switches of the half-bridge of the converter unit 14 to cause the converter unit 14 to output power at the link 10 having a modulated voltage level based at least on the voltage level of the input power at link 8 and / or link 10.

[0041] For example, control unit 12 may provide a PWM signal that causes a driver of converter unit 14 to transition a switch between operating in an on state and an off state (e.g., to turn a switch on or turn a switch off) over interconnect 16. In response to the voltage level of the input power at interconnect 8, control unit 12 may vary the duty cycle of the PWM signal to adjust the times at which the driver causes the state of the switches to change. By varying the duty cycle of the driver control signal, control unit 12 may change the shape or magnitude of the output power provided by converter unit 14 at interconnect 10 (e.g., change the voltage level of the output power).

[0042] In other examples, converter unit 12 may provide a PDM signal over interconnect 16 that causes a driver of converter unit 14 to cause a switch of a half-bridge to transition between an on state and an off state. In response to the voltage level of the input power at interconnect 8, control unit 12 may vary the average value of the PDM signal to adjust the frequency with which the driver causes the state of the switches to change. By varying an average value of the PDM signal, control unit 12 may change the shape or magnitude of the output power provided by converter unit 14 at interconnect 10 (e.g., change the voltage level of the output power).

[0043] The control unit 12 may include any suitable arrangement of analog and / or digital hardware, software, firmware, or any combination thereof to perform the techniques associated with the control unit 12 herein. For example, the control unit 12 may include any one or more microprocessors, signal processors, application-specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), or any equivalent integrated, digital, analog, or discrete logic circuitry, as well as any combinations of such components. If the control unit 12 includes software or firmware, the control unit 12 further includes digital and / or analog hardware for storing and executing the software or firmware, such as one or more processors or processing units.In general, a processing unit may include one or more microprocessors, signal processors, ASICs, FPGAs, or any other equivalent integrated, digital, analog, or discrete logic circuitry, as well as any combination of such components. Although . Fig. 2, the control unit 12 may include a memory configured to store data. The memory may include any volatile or non-volatile media, such as random access memory (RAM), read-only memory (ROM), non-volatile RAM (NVRAM), electrically erasable programmable ROM (EEPROM), flash memory, and the like. In some examples, the memory may be external to the control unit 12 and / or the power converter 6, e.g., it may be external to a package in which the control unit 12 and / or the power converter 6 are housed.

[0044] Fig. 3 is a circuit diagram illustrating an example converter unit incorporating improved gate clamping in accordance with one or more aspects of this disclosure. For example, Fig. 3 the converter unit 14A, which is a more detailed exemplary view of the converter unit 14 of the power converter 6 from Fig. 2 represents. Fig. 3 is shown below in the context of System 1 from Fig. 1 and the power converter 6 of Fig. 2 described.

[0045] The converter unit 14A includes terminal 18, terminal 20, half-bridge 26, switchable clamp element 28, and driver 40. The half-bridge 26 includes switch 30, which is coupled to switch 32 at switching node 52. The half-bridge 26 is arranged in parallel with the terminal 18, with a first terminal point of switch 30 coupled to node 50 and a second terminal point of switch 32 coupled to node 54. Fig. 3 illustrates half-bridge 26 as including stray flux inductors 22 and 24 to model stray flux inductance based on electrical noise or other radiation received at half-bridge 26. The stray flux inductance at half-bridge 26 may cause an overcurrent, overvoltage, or other type of fault condition at half-bridge 26, particularly when (as described below) converter unit 14A causes switches 30 and 32 to transition between operation in an on-state and an off-state (e.g., turning on or off). In some examples, a filter (e.g., an output filter) may be placed at terminal 20, and another filter (e.g., an input filter) may be placed at terminal 18 to reduce stray flux inductance. To simplify the description, Fig. 3 these input and / or output filters are not shown.

[0046] Fig. 3 is described below in the context of converter unit 14A, which operates as a buck converter for converting input power to an output power having a voltage level lower than the input power voltage level. In some examples, converter unit 14A may be a boost converter for converting input power to an output power having a voltage level higher than the input power voltage level.

[0047] For example, when operating as a buck converter or step-down converter, the converter unit 14A may accept input power at an input voltage level transmitted over connection path 8 to terminal 18 (e.g., an input terminal) and provide output power at an output voltage level lower than the input voltage level via connection path 10 to terminal 20 (e.g., an output terminal). In some examples, when operating as a boost converter or step-up converter, the terminal 18 may be coupled to connection path 10, and the terminal 20 may be coupled to connection path 8, and the converter unit 14A may accept input power at an input voltage level at terminal 20 (e.g., an input terminal) and provide output power at an output voltage level higher than the input voltage level at terminal 18 (e.g.,an output port).

[0048] Terminal 18 includes two connection points corresponding to nodes 50 and 54 of converter unit 14A. Terminal 20 includes two connection points corresponding to switching node 52 of half-bridge 26 and node 54. Although not shown, terminals 18 and 20 may include one or more filters for filtering the input power and / or output power received and transmitted by converter unit 14A. For example, an output filter (e.g., an inductor and a capacitor) may be disposed between switching node 52 and a connection point of terminal 20 when converter unit 14A operates as a buck converter, and an output filter may be disposed between node 50 and a connection point of terminal 18 when converter unit 14A operates as a boost converter. Converter unit 14A may employ modulation techniques (e.g.,PWM, PDM, or other suitable modulation techniques) to provide an output power having an output voltage level and / or an output current level at the switching node 52 that is based on an input voltage level of input power received across the half-bridge 26 at terminal 18 and at terminal 20.

[0049] Switch 30 may comprise a high-side switch of half-bridge 26, and switch 32 may comprise a low-side switch of half-bridge 26. Many examples of switches 30 and 32 exist, and these switches may be any type of switching device suitable for stepping down (e.g., bucking or boosting) an input power voltage level to an output power voltage level at switching node 52.For example, some examples of switch 30 and switch 32 may include silicon-based (Si-based) switching devices, gallium nitride-based (GaN-based) switching devices, and / or silicon carbide-based (SiC-based) switching devices, GaN high electron mobility transistor (GaN HEMT-based) switching devices, metal oxide semiconductor (MOS-based) switching devices, field effect transistor (FET-based) switching devices, N-type MOSFET-based switching devices, P-type MOSFET-based switching devices, diodes, HEMT-FET (GaN), JFET (SiC, normally on), IGBT switching devices, or any other type of power switching transistors, switching elements, or switching devices.

[0050] The driver 40 includes a gate driver for controlling the switch 30 and the switchable clamping element 28. In other examples not shown, the control unit 12 may send a signal enabling the control unit 12 to directly control the switchable clamping element 28 over the connection path 16. In some examples, for example, when the switch 32 is a controllable switching device and not a diode, the converter unit 14A includes an additional driver for controlling switch 32. The driver 40 may include additional connections to the Fig. 3. For example, the driver 40 may include a connection to a potential or current source and a connection to a local reference potential.

[0051] In the example of Fig. 3, the driver 40 is coupled to the switch 30 such that an output produced by the driver 40 over the interconnect 60 can cause the switch 30 to transition from operation between an on state and an off state. In other words, by outputting a signal over the interconnect 60, the driver 40 can cause the switch 30 to "turn on" or "turn off." The driver 40 is configured to control the switch 30 (e.g., turn on or turn off) based at least in part on a driver control signal received over the interconnect 16. For example, the control unit 12 of the power converter 6 can send a driver control signal over the interconnect 16 to cause the converter unit 14A to modulate the switches 30 and / or 32.Based on the driver control signal received over link 16, driver 40 may produce an output on link 60 that causes switch 30 to transition between operation in an on state of switch 30 and an off state of switch 30 to modulate the voltage level of an output power at switching node 52.

[0052] As in Fig. 3, the driver 40 is coupled to the switchable clamping element 28 such that an output produced by the driver 40 over the connecting path 64 can enable the switchable clamping element 28 via the connecting path 64, thereby causing the switchable clamping element 28 to transition from operation between an on state and a off state (e.g., turning on or off). In other words, the driver 40 can enable the switchable clamping element 28 by outputting one signal over the connecting path 64 and cause the switchable clamping element 28 to "turn on." Similarly, the driver 40 can disable the switchable clamping element 28 and cause the switchable clamping element 28 to "turn off" by outputting another signal over the connecting path 64.

[0053] Driver 40 is configured to control switchable clamping element 28 (e.g., enable or disable switchable clamping element 28) based at least in part on a voltage level and / or a current level detected by driver 40 at switch 30. For example, driver 40 may receive information over link 62 indicative of a voltage level across switch 30 and / or a current at switch 30. Based at least in part on the voltage level detected across switch 30 and / or the current at switch 30, driver 40 may enable switchable clamping element 28 and cause switchable clamping element 28 to transition from operation in a disabled state to an enabled state, or disable switchable clamping element 28 and cause switchable clamping element 28 to transition from operation in an enabled state to a disabled state.

[0054] The switchable clamping element 28 is coupled to the switch 30 for clamping a voltage across the switch 30 when the switchable clamping element 28 is enabled by the driver 40 and when a threshold or other activation criteria of the switchable clamping element 28 are met. When the switchable clamping element 28 is disabled by the driver 40, the switchable clamping element 28 is prevented from clamping a voltage across the switch 30 even when the threshold or other activation criteria of the switchable clamping element 28 are met.

[0055] For example, the switchable clamping element 28 may include the switch 34 and the terminal 36. The terminal 36 is shown as a Zener diode, however, the terminal 36 may include a snubber diode, an avalanche diode, or other electrical circuits and / or components that can be used as a clamp to suppress a voltage and / or current across the switch 30. The terminal 36 may have properties or characteristics that depend on a threshold or other activation criteria of the terminal 36 that, if met, cause a current path to form through the terminal 36. For example, if the voltage level across the terminal 36 is greater than or equal to a breakdown voltage associated with the terminal 36, a current path may form through the terminal 36, which may otherwise not exist if the voltage level across the terminal 36 is less than the breakdown voltage.

[0056] To control the switchable clamping element 28, the driver 40 may output one or more signals or commands over the interconnect 64 to cause the switch 34 of the switchable clamping element 28 to transition between operation in an on state and an off state. When the driver 40 causes the switch 34 to operate in the on state, the driver 40 enables the switchable clamping element 28. Once enabled, and if and when a voltage level at the switch 30 reaches the breakdown voltage of the terminal 36, a current path may form across the interconnect 66 and through the terminal 36 and the switch 34 to prevent the voltage at the switch 30 from exceeding the breakdown voltage of the terminal 36. When the driver 40 causes the switch 34 to operate in the off state, the driver 40 disables the switchable clamping element 28.Once disabled, even if the voltage level across switch 30 reaches or exceeds the breakdown voltage of terminal 36, a current path is prevented from forming across interconnect 66 and through terminal 36 and switch 34. In other words, by disabling switchable clamping element 28, driver 40 causes an open circuit to form through switchable clamping element 28, thus configuring switch 30 to operate at operating voltages that may exceed the breakdown voltage of terminal 36.

[0057] The power converter 6 can accept input power at the input terminal 18 when the source 2 applies power over the interconnect 8. The driver 40 can receive a driver control signal over the interconnect 16 from the control unit 12 for controlling the switch 30 (e.g., in accordance with one or more modulation techniques). The control unit 12 can provide the driver control signal to the cycle switch 30 of the driver 40 and / or the switch 32 and cause the switch 30 and / or the switch 32 of the half-bridge 26 to transition between operation in an on-state and an off-state in accordance with a modulation technique used by the power converter 6 to produce an output power at the output terminal 20 having a voltage and / or current level based on the voltage level of the input power at the input terminal 18.Driver 40 may control switch 30 of half-bridge 26 based at least in part on the driver control signal. Driver 40 may cause switch 30 to transition between operation in an on-state of switch 30 and an off-state of switch 30 (e.g., turning on and off) to produce an output power at switching node 52 having a voltage level based on the voltage level of the input power at input terminal 18.

[0058] Driver 40 may periodically and / or continuously determine whether a fault condition exists or will occur at switch 30 (e.g., based on the voltage level and / or current level detected at switch 30) and control switchable clamping element 28 accordingly. In other words, switch 40 may enable or "turn on" switchable clamping element 28 upon detecting a voltage across switch 30 and / or a current at switch 30 that indicates to driver 40 that a fault condition (e.g., overcurrent, overvoltage, etc.) is occurring or will occur at switch 30. By enabling or turning on switchable clamping element 28, driver 40 configures switchable clamping element 28 to provide a current path to protect switch 30 in the event that the threshold or other activation criteria of switchable clamping element 28 are met.Driver 40 may similarly disable switchable clamp 28 upon detecting a voltage across switch 30 and / or a current at switch 30 that indicates to driver 40 that no fault condition (e.g., overcurrent, overvoltage, etc.) is occurring or likely to occur at switch 30. By disabling or disabling switchable clamp 28, driver 40 configures switchable clamp 28 to prevent a current path through switchable clamp 28 even if the threshold or other activation criteria of switchable clamp 28 are met.

[0059] Driver 40 can control (e.g., enable or disable) switchable clamping element 28 by sending control commands over link 64. If driver 40 detects a fault condition that is occurring or about to occur at switch 30 based on the voltage across switch 30 or the current at switch 30, driver 40 can enable or enable switchable clamping element 28 by sending a command or signal over link 64 that causes switchable clamping element 28 to remain in an on state during operation or to transition from operation in an off state and begin operation in the on state.Otherwise, if the driver 40 does not detect a fault condition that is occurring or will occur at the switch 30 based on the voltage at the switch 30 or the current at the switch 30, the driver 40 may disable or de-energize the switchable clamping element 28 by sending a command or signal over the link 64 to cause the switchable clamping element 28 to remain in an off-state during operation or to transition from operation to an on-state and begin operation in the off-state.

[0060] Driver 40 may detect a fault condition at switch 30 based on whether or not a voltage or current level at switch 30 meets a threshold. If the voltage or current level meets the particular threshold, driver 40 may determine that a fault condition is occurring at switch 30, a fault condition is likely to occur at switch 30, or a fault condition is not likely to occur at switch 30. In other words, driver 40 may determine whether the voltage or current at switch 30 is at, or may reach, a level that could damage switch 30, or whether the voltage or current at switch 30 is at a level that indicates tolerable noise or intentional voltage or current spikes in the system.

[0061] For example, driver 40 may detect a voltage / current level at link 62. Driver 40 may compare the voltage / current level to a threshold. The threshold may correspond to a voltage level that fits within a voltage / current operating window or the tolerance of switch 30. Comparing the voltage / current level to the threshold may indicate to driver 40 that an impending fault condition exists at a switch if the voltage / current level is within an illegal value of the maximum or upper limit of the voltage / current operating window or the tolerance of the switch. In some examples, comparing the voltage / current level to the threshold may indicate to driver 40 that an actual fault condition is occurring if, for example, the voltage / current level at the switch exceeds the maximum or upper limit of the voltage / current operating window or the tolerance of the switch.In some examples, comparing the voltage / current level to the threshold may indicate to driver 40 that a fault condition is not likely to occur if, for example, the voltage / current level at the switch is at or near a zero level or is near the minimum or lower limit of the voltage / current operating window or tolerance of the switch.

[0062] In some examples, the driver 40 (or the control unit 12) may determine, based on the voltage across the switch 30 or the current at the switch 30, that a probability associated with a fault condition at the switch 30 does not meet a probability threshold, and the driver 40 (or the driver 40 in response to a command from the control unit 12) may disable the switchable clamping element 28 in response to determining that the probability associated with the fault condition at the switch 30 does not meet the probability threshold. In other words, the driver 40 or the control unit 12 may determine (e.g., via a lookup table or calculation) a probability associated with the voltage / current at the switch 30 based on the comparisons described above between the voltage / current level at the link 62 and the threshold.The driver 40 or the control unit 12 can determine a quantified probability that a fault condition is occurring, will occur, or is less likely to occur at the switch 30. The driver 40 or the control unit 12 can control the switchable clamping element 28 in response to and based on the determined probability of a fault condition at the switch 30.

[0063] In some examples, driver 40 may determine whether a fault condition is occurring, likely to occur, or less likely to occur at switch 30 in other ways without relying solely on the voltage / current at switch 30. For example, driver 40 may check for potential fault conditions using modulation timing analysis techniques (e.g., PWM, PDM timing analysis techniques, etc.) or response time analysis techniques related to feedback signals.

[0064] In some examples, driver 40 may determine the modulation time applied to switch 30 (e.g., based on operating characteristics of switch 30 measured over link 62 or characteristics of the driver control signal received over link 16). Based on the modulation time, driver 40 may determine whether a fault condition may or may not exist at switch 30 to determine whether to enable or disable switchable clamp element 28.

[0065] In some examples, driver 40 may determine the response time associated with switch 30 (e.g., how quickly switch 30 turns on or off) in response to a specific driver control signal (modulation driver control signal) received over link 16. Based on the response time associated with switch 30, driver 40 may determine whether a fault condition may or may not exist at switch 30 to determine whether to enable or disable switchable clamp element 28.

[0066] In some examples, driver 40 may further detect a transition of a modulation pattern from the driver control signal received over link 16 and, based on the modulation pattern, determine whether or not to enable or disable switchable clamping element 28 to protect switch 30. For example, driver 40 may enable or disable switchable clamping element 28 in response to detecting a change from one PWM switching pattern to another. The PWM pattern transition may not necessarily indicate that a PWM pattern associated with switch 30 is transitioning, but may instead indicate that a PWM pattern of another switch is transitioning and could cause a fault condition at switch 30.

[0067] In some examples, the control unit 12 may send a command or signal over the link 16 to the driver 40 to cause the driver 40 to enable or disable the switchable clamping element 28 based on various operating and / or configuration parameters of the power converter 6 maintained by the control unit 12. In other words, the control unit 12 may enable or disable the switchable clamping element 28 based on various operating states or specifications of the power converter 6. For example, the control unit 12 may cause the driver 40 to enable or disable the switchable clamping element 28 by transmitting configuration data over a configuration means for configuring the driver 40 (e.g., the link 16 or other logic of the driver 40).

[0068] In some examples, the maximum operating voltage / current of switch 30 may exceed the breakdown voltage of clamp 36. Unlike some power converters that use fixed clamping elements to prevent the voltage across a switch from exceeding the breakdown voltage of the fixed clamping element, driver 40 may determine whether the voltage across switch 30 and / or the current at switch 30 meets a threshold indicating that an actual fault condition (e.g., a valid fault condition) may or may not exist, or even a threshold indicating whether or not a fault condition is likely to occur in the near future.If the voltage merely exceeds the breakdown voltage of terminal 36 but does not meet the threshold to indicate a fault condition, driver 40 may disable switchable clamping element 28 to allow switch 30 to operate at a working voltage that exceeds the breakdown voltage of terminal 36, but cannot exceed the operating voltage of switch 30. In other words, driver 40 may enable or disable switchable clamping element 28 to allow switch 30 to operate at a working voltage that fits within the working voltage of switch 30, which may exceed the breakdown voltage of terminal 36 of switchable clamping element 28.

[0069] In some examples, a load (e.g., device 4) may be coupled to terminal 20 (e.g., the output terminal) for receiving output power at switching node 52. In some examples, converter 14A may include an H-bridge including half-bridge 26 coupled to a second half-bridge at output terminal 20. The second half-bridge may include a high-side switch coupled to a low-side switch at a switching node of the second half-bridge. A first connection point of terminal 20 (e.g., an output terminal) may be coupled to switching node 52 of half-bridge 26, and a second connection point of terminal 20 may be coupled to the switching node of the second half-bridge. In other words, converter unit 14A may drive an H-bridge made up of two half-bridges: half-bridge 26 of converter unit 14A and an additional half-bridge.

[0070] In some examples, the switchable clamping element is controlled by each driver of the power converter. For example, in a half-bridge, a power converter may have a respective driver that controls the high-side switch of the half-bridge and the low-side switch of the half-bridge. The power converter may further include a respective switchable clamping element at each of the switches of the half-bridge, with each respective driver of the power converter controlling one of the respective switchable clamping elements. In other words, a high-side driver may control the high-side switch and also a switchable high-side clamping element for protecting the high-side switch. Similarly, a low-side driver may control the low-side switch and also a switchable low-side clamping element for protecting the high-side switch.

[0071] Instead of using one or more fixed clamping elements like some power converters, the power converter 6 includes one or more switchable clamping elements that a driver can selectively enable or enable to protect a half-bridge from an impending or actual fault condition on the half-bridge, and can selectively disable or lock the one or more switchable clamping elements when a fault condition on the half-bridge is less likely to occur. Unlike some other power converters that use one or more fixed clamping elements, the one or more selectable clamping elements are not permanently enabled or enabled, and therefore, a fault condition on a half-bridge is not necessarily tied to the breakdown voltage of a terminal.The power converter can disable the switchable clamping elements if the power converter determines that fault conditions are less likely to occur, and when the switchable clamping elements are disabled, it can operate the half-bridge switches at an increased working voltage (e.g., a voltage that exceeds the breakdown voltage of the switchable clamping element) with increased efficiency and with fewer switching losses than other power converters that use fixed clamping elements.

[0072] Fig. 4 is a circuit diagram illustrating an additional example converter unit including a voltage booster for providing improved gate clamping, in accordance with one or more aspects of the present disclosure. For example, Fig. 4 the converter unit 14B, which is a more detailed exemplary view of the converter unit 14 of the power converter 6 from Fig. 2 represents. Fig. 4 is shown below in the context of System 1 from Fig. 1 and the power converter 6 of Fig. 2 described.

[0073] In addition to the components used in the converter unit 14A of Fig. 3 and described above with reference to the converter unit 14A of Fig. 3, the converter unit 14B includes the driver 80, the voltage booster 82, and the connecting links 70 and 72. The voltage booster 82 may be required, for example, if the driver 80 is divided into two sections, a low-current section and a high-current section. Dividing the driver 80 into two or more sections may be necessary, in particular, for controlling switches with a high gate current demand and to improve the heat dissipation of the driver 80. In one implementation, a low-current section 40 and a high-current section (or voltage booster) 82 may be two different units. In another implementation, the driver 80 may include the voltage booster stage and optionally also the switchable clamping element.

[0074] The voltage booster 82 is arranged between the driver 40 and the switch 30 for stepping down or driving one or more outputs from the driver 40, which the voltage booster 82 can receive via the connecting link 64 and / or the connecting link 60, with sufficient current to control the switchable clamping element 28 and the switch 30. As shown in Fig. 4 is shown surrounding terminal 36 and a portion of booster 82, portions of switchable clamping element 28 may be located within (e.g., inside) booster 82. Although shown as an external component of booster 82, terminal 36 may also be located within booster 82, so that the entire switchable clamping element 28 may be located within booster 82.

[0075] The voltage booster 82 is configured to enable or disable the switchable clamping element 28 to cause the switchable clamping element 28 to transition (e.g., turn on or turn off) between operation in a turned-off state of the switchable clamping element 28 and an turned-on state of the switchable clamping element 28 based on at least one of the one or more outputs from the driver 40. The at least one of the one or more outputs from the driver 40 may be based on the voltage across the switch 30 or the current across the switch 30. For example, the voltage booster 82 may receive an output from the driver 40 via the interconnect 64 when the driver 40 detects an actual fault condition at the switch 30 based on a voltage measurement taken via the interconnect 62.The output from the driver 40 via the connection path 64 can cause the voltage booster 82 to enable or disable the switchable clamping element 28 based on the voltage across the switch 30 or the current at the switch 30.

[0076] The voltage booster 82 may include an internal switch as a portion of the switchable clamping element 28 for enabling or disabling the switchable clamping element 28. The voltage booster 82 may be configured to cause the internal switch to transition between operation in an internal switch off state and an internal switch on state (e.g., turning on or off) based on the voltage detected by the driver 40 across the switch 30 or the current at the switch 30.For example, based on one or more commands or signals received over link 64 from driver 40 to enable or disable switchable clamp 28, voltage booster 82 may cause the internal switch of voltage booster 82 to turn on, thus enabling switchable clamp 28 to provide a current path across link 66, through terminal 36, and across link 68 in the event that a threshold or activation criteria of terminal 36 is met.Conversely, the voltage booster 82 may receive an output from the driver 40 to disable the switchable clamp element 28, causing the voltage booster 82 to cause the internal switch of the voltage booster 82 to operate in a cut-off state of the internal switch to prevent a current path from forming across the interconnect 66, through the terminal 36, and across the interconnect 68, even if a threshold or activation criteria of the terminal 36 are met.

[0077] Driver 80 may receive a driver control signal over link 16 from control unit 12 to cause switch 32 to transition between operation in an on state and an off state to modulate an output at switching node 52. For example, driver 80 may output a voltage or current over link 72 that causes switch 32 to turn on or off based on the driver control signal received over link 16.

[0078] In some examples, the converter unit 14B may include a second switchable clamping element (e.g., in addition to the switchable clamping element 28) coupled to the switch 32 to clamp a voltage across the switch 32 when both the second switchable clamping element is enabled and when a threshold or activation criteria of the second switchable clamping element is met. The driver 80 may control the switch 32 (e.g., turn on or off) and control the second switchable clamping element (e.g., enable or disable). The driver 80 may be configured to control the switch 32 based at least in part on the driver control signal received over the link 16. The driver 80 may be further configured to control the second switchable clamping element based at least in part on the voltage across the switch 32 or the current at the switch 32 (e.g.,based on information received by the driver 80 on the link 63).

[0079] Fig. 5 is a block diagram showing the driver 40 of the Fig. 3 shown converter unit 14A and the one in Fig. 4 represents the converter unit 14B shown. Fig. 5 is shown below in the context of System 1 from Fig. 1 and the power converter 6 of Fig. 2 described. Fig. 5 is further described below in the context of the converter unit 14A of Fig. 3 and, as indicated, in the context of the converter unit 14B of Fig. 4 described.

[0080] The driver 40 of Fig. 5 includes a driver output signal unit 90, a sensor unit 92, and within the sensor unit 92, the driver 40 includes an overcurrent protection unit 94 (hereinafter "OCP unit" 94) and an overvoltage protection unit 98 (hereinafter "OVP unit" 98). The driver 40 may include additional or fewer components than those shown in the example of Fig. 5. For example, driver 40 may include additional components, circuits, or elements for controlling switch 30 based on a driver control signal and for controlling switchable clamping element 28 based on a voltage across switch 30 or the current at switch 30.

[0081] The driver 40 is coupled to the interconnect 16 for receiving a driver control signal from the control unit 12 at the driver output signal unit 90. The driver 40 can drive a current or voltage across the interconnect 60 to cause the switch 30 to turn on or off (e.g., transition between operation in an on state of switch 30 and an off state of switch 30) based on the driver control signal received across the interconnect 16. In some examples, such as the example of the converter unit 14A of Fig. 3, the link 60 may couple the driver 40 directly to the switch 30 to effect a change in the operating state of the switch 30. In some examples, such as the example of the converter unit 14B of Fig. 4, the interconnect 60 may couple the driver 40 to the voltage booster 82 of the converter unit 14B to cause the voltage booster 82 to effect a change in the operating state of the switch 30 via a current or voltage at the interconnect 70.

[0082] In some examples, in addition to receiving a driver control signal over link 16, driver 40 may receive a command or signal from control unit 12 indicating either whether or not control unit 12 detects an actual or impending fault condition at half-bridge 26 (e.g., based on the voltage or current detected by control unit 12 at link 8 and / or link 10), or in some cases, the command or signal may indicate a determination made by control unit 12 to enable or disable switchable clamp element 28.The driver output signal unit 90 can drive a command or signal over the interconnection link 64 based on the command or signal received over the interconnection link 16 indicating a fault condition to enable or disable the switchable clamping element 28 and cause the switchable clamping element 28 to operate in either an on state or a off state. In other words, the driver 40 can receive information over the interconnection link 16 directly from the control unit 12 (e.g., an instruction to enable or disable the switchable clamping element 28, information about the current or voltage at the switch 30, etc.), and based on the information received directly from the control unit 12, the driver output signal unit 90 of the driver 40 can send a command or signal over the interconnection link 64 to enable or disable the switchable clamping element 28.

[0083] The sensor unit 92 of the driver 40 can detect whether a fault condition exists, or is likely or less likely to exist, at a half-bridge 26 based on a voltage and / or current detected by the driver 40 at the switch 30 via the connection path 62. The sensor unit 92 can provide an indication of a fault condition, or its absence, to the driver output signal unit 90 to cause the driver output signal unit 90 to enable the switchable clamping element 28 by issuing a command via the connection path 64 to cause the switchable clamping element 28 to turn on, or to disable the switchable clamping element 28 by issuing a command via the connection path 64 to cause the switchable clamping element 28 to turn off.

[0084] The sensor unit 92 includes the OCP unit 94 and the OVP unit 98. The OCP unit 94 provides the overcurrent detection functionality for the driver 40. The OCP unit 94 may detect an overcurrent condition at the switch 30 based on information received over the interconnect 62. For example, the OCP unit 94 may receive information about a current at the switch 30 and determine that the current meets (e.g., exceeds) a current threshold equal to or within a tolerance of the maximum operating current that the switch 30 can handle. The OCP unit 94 may send information to the driver output signal unit 90 in response to detecting an overcurrent condition at the switch 30 to cause the driver 40 to release (e.g., turn on) the switchable clamping element 28 to protect the switch 30 from the overcurrent condition.

[0085] The OVP unit 98 provides overvoltage detection functionality for the driver 40. The OVP unit 98 may receive information about a voltage across the switch 30 and determine that the voltage meets (e.g., exceeds) a voltage threshold corresponding to (or near the maximum) of the operating voltage that the switch 30 can handle. For example, the OVP unit 98 may determine the voltage of the switch 30 and determine whether the voltage exceeds the operating voltage of the switch 30 or is within its tolerance. The OVP unit 98 may send information to the driver output signal unit 90 in response to detecting an overvoltage condition at the switch 30 to cause the driver 40 to release (e.g., turn on) the switchable clamping element 28 to protect the switch 30 from the overvoltage condition.

[0086] The driver output signal unit 90 of the driver 40 can control the switchable clamping element 28 by sending commands or signals over the connection link 64 based on information provided by the OCP unit 94 and the OVP unit 98 indicating a fault condition, or lack thereof, at the switch 30 of the half-bridge 26. The driver 40 can control the switchable clamping element 28 based on a voltage across the switch 30 or whether the OVP unit 98 detects an overvoltage condition. The driver 40 can control the switchable clamping element 28 based on a current at the switch 30 and whether the OCP unit 94 detects an overcurrent condition.

[0087] Fig. 6 is a flowchart illustrating example operation of an example power converter in accordance with one or more aspects of the present disclosure. Fig. 6 is shown below in the context of System 1 of Fig. 1, of the power converter 6 of Fig. 2 and the converter unit 14A of Fig. 3 described.

[0088] A driver may receive a driver control signal for controlling a switch (100). For example, driver 40 may receive a driver control signal from control unit 12 over link 16 for modulating switch 30 according to PWM, PDM, or other suitable modulation technique to produce an output power having a specific voltage or current level at switch node 52 based on the voltage level of an input power at terminal 18.

[0089] The driver may control the switch based at least in part on the driver control signal (110). For example, the driver 40 may send one or more commands over the link 60 that directly cause (or indirectly cause by passing through a voltage booster) the switch 30 to transition between operation in an on state and an off state according to the driver control signal.

[0090] The driver may detect a voltage across the switch or a current at the switch (120). For example, the driver 40 may receive information over the interconnect 62 indicating the current at the switch 30 or the voltage across the switch 30. The driver 40 may compare the information received over the interconnect 62 to a threshold to determine whether a fault condition (e.g., overcurrent, overvoltage, etc.) exists at the half-bridge 26 or whether a fault condition is likely or less likely to occur at the half-bridge 26.

[0091] The driver may control a switchable clamping element coupled to the switch based at least in part on the voltage across the switch or the current at the switch (130). For example, the driver 40 may determine that either the voltage or the current meets the threshold to indicate that a fault condition is occurring or likely to occur at the half-bridge 26. The driver 40 may send a command over the link 64 to enable the switchable clamping element 28 and configure the switchable clamping element 28 to protect the switch 30 against the fault condition by creating a current path through the switchable clamping element 28 if a threshold or other activation criteria of the switchable clamping element 28 is met.Otherwise, driver 40 may determine that neither the voltage nor the current meets the threshold indicating that a fault condition is occurring or likely to occur at half-bridge 26. Driver 40 may send a command over link 64 that disables switchable clamp 28 and configures switchable clamp 28 to prevent a current path from forming through switchable clamp 28 even if a threshold or activation criteria of switchable clamp 28 are met. By disabling switchable clamp 28, power converter 6 can operate switch 30 at a higher operating voltage. (e.g. a voltage may exceed the breakdown voltage of terminal 36 of the switchable clamping element 28).

[0092] Fig. 7 is a flowchart illustrating example timing diagrams of one or more aspects of the present disclosure. Fig. 7 is shown below in the context of System 1 of Fig. 1, of the power converter 6 of Fig. 2 and the converter unit 14A of Fig. 3. The graph 260 of Fig. Figure 7 shows the signal (e.g., a PWM signal) generated by driver 40 over link 60 to control switch 30 in accordance with a modulation technique. Graphic 264 of Fig. Figure 7 shows the signal generated by the driver 40 over the connecting path 64 for controlling (e.g., enabling or disabling) the switchable clamping element 28 (e.g., switch 34).

[0093] Fig.7 shows that between time t0 and time t1, driver 40 outputs a signal to "disable" the switchable clamp element via link 64 after determining that no fault condition is detected at switch 30 or after determining that no fault condition is likely to occur at switch 30. When switchable clamp element 28 is disabled, a current path through terminal 36 is prevented from forming even if a threshold or activation criteria of terminal 36 is met by the voltage and / or current level at switch 30.

[0094] At time t1, driver 40 may detect that a fault condition is occurring or is likely to occur at switch 30 (e.g., based on a voltage and / or current measurement across interconnect 62 sensed by driver 40 or by controller 12). In response to detecting the fault condition or impending fault condition, driver 40 may enable switchable clamp 28 by issuing an enable signal across interconnect 64 to cause switch 34 of switchable clamp 28 to operate in the on state. When switchable clamp 28 is turned on or "enabled," a current path may form through terminal 36 of switchable clamp 28 if a threshold or other activation criteria of terminal 36 is met.For example, at time t2, the voltage across switch 30 may exceed the breakdown voltage of terminal 36, and until the voltage across switch 30 drops below the breakdown voltage of terminal 36 at time t3, terminal 36 causes a current path to form through switchable clamping element 28 to divert excess current away from switch 30. In some examples, the time period between times t2 and t3 (e.g., the "enable window") may provide sufficient time for driver 40 to safely turn off switch 30 (and, for example, prevent the fault condition from damaging switch 30). In some examples, after the fault condition is detected, the controller 12 and / or the driver 40 may stop the driver control signal in the current state (e.g., stop modulating the PWM) when the fault condition is detected to further prevent any damage to the switch 30.

[0095] The techniques of this disclosure may be implemented in a wide variety of devices or devices, including an integrated circuit (IC) or a group of ICs (e.g., a chipset). Various components, modules, or units are described in this disclosure to emphasize functional aspects of devices configured to carry out the disclosed techniques, but do not necessarily require implementation by different hardware units. Instead, as described above, various units may be combined into one hardware unit or provided by a collection of cooperating hardware units including one or more processors, as described above, in conjunction with suitable software and / or firmware.

[0096] Various examples have been described. These and other examples are within the scope of the following claims.

Claims

[1] Circuit comprising: a switch (30); a switchable clamping element (28) coupled to the switch (30); and a driver (40) configured to control the switch (30) at least partially based on a driver control signal, the driver (40) further configured to enable or disable the switchable clamping element (28), and wherein the switchable clamping element (28) is configured to clamp a voltage across the switch (30) when the switchable clamping element (28) is enabled by the driver (40) and when the voltage across the switch (30) or a current across the switch (30) meets a threshold value for activating the switchable clamping element (28), wherein the driver (40) is further configured to enable or disable the switchable clamping element (28) based at least in part on a voltage across the switch (30) or a current at the switch (30), to detect a fault condition at the switch (30) based on the voltage across the switch (30) or the current at the switch (30), and to release the switchable clamping element (28) in response to the detection of the impending or actual fault condition at the switch (30). [2] The circuit of claim 1, wherein the switchable clamping element (28) is arranged to refrain from clamping a voltage across the switch (30) when the switchable clamping element (28) is blocked. [3] A circuit according to claim 1 or 2, wherein the switchable clamping element (28) is arranged to refrain from clamping a voltage across the switch (30) when the switchable clamping element (28) is blocked and if the voltage across the switch (30) or the current at the switch (30) meets the threshold value for activating the switchable clamping element (28). [4] A circuit according to any one of claims 1-3, wherein the threshold value for activating the switchable clamping element (28) corresponds to a breakdown voltage or a breakdown current associated with the switchable clamping element (28). [5] Circuit according to one of claims 1-4, wherein the switch (30) is a first switch (30) and wherein the switchable clamping element (28) comprises a second switch (34) and a clamping device. [6] A circuit according to claim 5, wherein the clamping device comprises a Zener diode, an overvoltage protection diode and / or an avalanche diode. [7] The circuit of claim 5 or 6, wherein the driver (40) is configured to enable the switchable clamping element (28) at least by causing the second switch (34) to operate in an on state of the second switch (34), and wherein the driver (40) is configured to disable the switchable clamping element (28) at least by causing the second switch (34) to operate in an off state of the second switch (34). [8] The circuit of any of claims 1-7, wherein the driver is further configured to enable or disable the switchable clamping element based at least in part on a voltage between the source and drain of the switch (30). [9] The circuit of any of claims 1-8, wherein the driver (40) is further configured to receive a clamp control signal and to enable or disable the switchable clamp element (28) based on the clamp control signal. [10] A circuit according to any one of claims 1-9, wherein the switch (30) comprises a gallium nitride-based switching device. [11] The circuit of any one of claims 1-10, wherein the switch (30) is a first switch (30), wherein the switchable clamping element (28) is a first switchable clamping element (28), wherein the voltage across the first switch (30) is a first voltage, wherein the current at the first switch is a first current, wherein the threshold value is a first threshold value, and wherein the driver (40) is a first driver (40), the circuit further comprising: a half-bridge comprising the first switch (30) coupled to a second switch (32) at a switching node of the half-bridge; a second switchable clamping element coupled to the second switch; and a second driver configured to control the second switch (32) at least partially based on the driver control signal, the second driver further configured to enable or disable the second switchable clamping element, and wherein the second switchable clamping element is configured to clamp a second voltage across the second switch (32) when the second switchable clamping element is enabled by the second driver and when the second voltage across the switch (32) or a second current at the switch (32) satisfies a second threshold for activating the second switchable clamping element. [12] The circuit of claim 11, wherein the second driver is further configured to enable or disable the second switchable clamping element based at least in part on the second voltage across the second switch (32) or the second current at the second switch (32). [13] The circuit of claim 11 or 12, wherein the driver control signal is a first driver control signal, and wherein the second driver is further configured to control the second switch (32) based at least in part on a second driver control signal received by the second driver. [14] A circuit according to any one of claims 1-13, wherein the switchable clamping element (28) comprises a normally enabled type and is arranged to clamp the voltage across the switch (30) when the voltage across the switch (30) or the current at the switch (30) meets the threshold and the driver (40) is disabled. [15] A circuit according to any one of claims 1-13, wherein the switchable clamping element (28) comprises a normally-locked type and is arranged to refrain from clamping a voltage across the switch (30) when the driver (40) is locked. [16] Procedure comprising: Controlling a switchable clamping element by a driver (40) configured to control a switch (30), at least partially based on a voltage across the switch (30) or a current at the switch (30), wherein the switchable clamping element (28) is coupled to the switch, wherein the switchable clamping element is configured to clamp the voltage across the switch (30) when the switchable clamping element (28) is enabled by the driver (40) and when the voltage across the switch (30) or the current at the switch (30) meets a threshold for activating the switchable clamping element (28), Detecting the voltage across the switch (30) or the current at the switch (30) by the driver (40), wherein the driver (40) is configured to control the switchable clamping element (28) coupled to the switch (30) at least partially based on the detected voltage across the switch (30) or the detected current at the switch (30), Detecting a fault condition at the switch (30) by the driver (40) based on the voltage across the switch (30) or the current at the switch (30); and Releasing the switchable clamping element (28) by the driver (40) in response to detecting the impending or actual fault condition at the switch (30). [17] The method of claim 16, further comprising: Receiving information from a control unit by the driver (40), wherein the driver (40) controls the switchable clamping element (28) coupled to the switch (30) based at least in part on the information received from the control unit, wherein the information received from the control unit comprises an indication of a fault condition detected at the first switch (30) and / or an indication of an instruction from the control unit to enable or disable the switchable clamping element (28). [18] A driver circuit configured to control a switchable clamping element (28) coupled to a switch (30) based at least in part on a voltage across the switch (30) or a current across the switch (30), wherein the switchable clamping element (28) is configured to clamp the voltage across the switch (30) when the switchable clamping element (28) is enabled by the driver circuit (40) and when the voltage across the switch (30) or the current across the switch (30) satisfies a threshold value for activating the switchable clamping element (28), wherein the driver circuit (40) is further configured to enable or disable the switchable clamping element (28) at least partially based on a voltage across the switch (30) or a current at the switch (30), to detect a fault condition at the switch (30) based on the voltage across the switch (30) or the current at the switch (30), and to release the switchable clamping element (28) in response to the detection of the impending or actual fault condition at the switch (30).

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