High voltage, bidirectional protection circuit and method

Abstract

The systems and methods herein use a sense circuit to detect an overvoltage at a voltage node as a drain current. A current mode comparator converts the detected current into a control signal, which is provided to a control circuit. The control circuit uses the control signal cut-off of a bias current to turn off a switch in a protection circuit to create a high impedance electrical path between the voltage node and the voltage node to be protected.

Description

[0001] Cross-reference to related applications

[0002] This application claims priority to U.S. Provisional Patent Application No. 63 / 197,449, filed June 6, 2021, entitled "High-Voltage, Bidirectional Protection Circuits and Methods," by Gabriel Eugen Tanase, filed May 13, 2022, entitled "High-Voltage, Bidirectional Protection Circuits and Methods," which is incorporated herein by reference in its entirety. Each reference mentioned in this patent document is incorporated herein by reference in its entirety. Technical Field

[0003] This disclosure generally relates to systems and methods for protecting circuit components from failures or physical damage caused by overvoltage conditions. More specifically, this disclosure relates to active circuits and methods for detecting, monitoring, and protecting against overvoltage conditions. Background Technology

[0004] It is often necessary to protect low-voltage electronic circuit components from excessive voltage, which can cause component failure and, in some cases, even physical damage. While some existing designs limit the maximum usable voltage to acceptable levels, this is not always practical or even feasible depending on the specific application. Therefore, there is a need for systems and methods that allow low-voltage circuit components to operate safely when unintendedly exposed to high voltage. Summary of the Invention

[0005] According to a first aspect of the present invention, an overvoltage protection method is provided, comprising: using a high-voltage resistor coupled to a voltage node to generate a drain current of a switch; using a current sensing circuit to detect the drain current indicating an overvoltage condition at the voltage node; using a current-mode comparator to convert the current into a control signal; and using a control circuit that, in response to receiving the control signal, turns off a set of switching devices coupled to the voltage node to be protected to create a high-impedance electrical path between the voltage node and the voltage node to be protected.

[0006] According to a second aspect of the present invention, a bipolar high-voltage protection circuit is provided, comprising: a protection circuit coupled to a voltage node to be protected and an output voltage node, wherein the protection circuit is a switching network presenting a high impedance and thereby protecting the voltage node to be protected from the effects of a high voltage that may exist at the output voltage node; a voltage sensing circuit that detects the voltage at the output voltage node and generates an output signal indicating the overvoltage condition in response to sensing an overvoltage condition at the output voltage node; and a control circuit coupled to the voltage sensing circuit, wherein the control circuit, in response to receiving the output signal, causes the protection circuit to present a high impedance to isolate the voltage node to be protected from the overvoltage condition.

[0007] According to a third aspect of the invention, a switching network for bidirectional high-voltage protection of a voltage node is provided, the switching network comprising: two sets of switches, each set of switches being coupled to a voltage node to be protected and an output voltage node, the output voltage node presenting a voltage within a certain voltage range during normal operation; a set of comparators, each comparator being coupled to a switch in a third set of switches and generating a low-level signal, the low-level signal being used to control bias current to turn on the two sets of switches, such that the voltage drop between the voltage node to be protected and the output voltage node is determined by the on-resistance of the two sets of switches and the load current flowing through the output voltage node; and in response to the voltage at the output voltage node falling outside the voltage range, a drain current exceeding a current value causes the corresponding comparator in the set of comparators to generate a high-level signal, the high-level signal causing these bias currents and thus turning off the two sets of switches, thereby creating a high-impedance path between the voltage node to be protected and the output voltage node, the voltage at the voltage node to be protected being controlled within the voltage range by the output stage state of an operational amplifier, the voltage at the output voltage node presenting a value between a negative high voltage and a positive high voltage. Attached Figure Description

[0008] Reference will be made to embodiments of the invention, examples of which may be illustrated in the accompanying drawings. These drawings are intended to be illustrative and not restrictive. While the invention has been described in general within the context of these embodiments, it should be understood that it is not intended to limit the scope of the invention to these specific embodiments. Items in the drawings are not drawn to scale.

[0009] Figure 1 This is a simplified block diagram of a protection circuit according to various embodiments of this disclosure.

[0010] Figure 2 This is a simplified block diagram of exemplary symmetrical protection circuit block diagrams according to various embodiments of this disclosure.

[0011] Figure 3This is a flowchart illustrating various embodiments of the present disclosure for protecting circuit components from overvoltage conditions.

[0012] Figure 4 This is a schematic diagram of an exemplary bidirectional high-voltage protection circuit according to various embodiments of this disclosure.

[0013] Figure 5 This is a flowchart of a process for protecting a circuit from positive and negative overvoltages according to various embodiments of this disclosure. Detailed Implementation

[0014] In the following description, specific details are set forth for purposes of explanation in order to provide an understanding of the invention. However, it will be apparent to those skilled in the art that the invention can be practiced without these details. Furthermore, those skilled in the art will recognize that the embodiments of the invention described below can be implemented in various ways, such as processes, apparatuses, systems, devices, or methods, on tangible computer-readable media.

[0015] The components or modules shown in the figures illustrate exemplary embodiments of the invention and are intended to avoid obscuring the invention. It should also be understood that throughout this discussion, a component can be described as a separate functional unit that may include subunits; however, those skilled in the art will recognize that various components or portions thereof may be divided into separate components or may be integrated together, including within a single system or component. It should be noted that the functions or operations discussed herein can be implemented as components. Components can be implemented in software, hardware, or a combination thereof.

[0016] Furthermore, the connections between components or systems shown in the accompanying drawings are not intended to be limited to direct connections. Instead, data between these components can be modified, reformatted, or otherwise altered via intermediate components. Moreover, additional or fewer connections may be used. It should also be noted that the terms “coupled,” “connected,” or “communically coupled” should be understood to include direct connections, indirect connections via one or more intermediate devices, and wireless connections.

[0017] In this specification, references to "one embodiment," "preferred embodiment," "an embodiment," or "embodiments" mean that a specific feature, structure, characteristic, or function described in connection with an embodiment is included in at least one embodiment of the invention and may be included in more than one embodiment. Furthermore, the above phrases appearing in different places in this specification do not necessarily refer to the same embodiment or multiple embodiments.

[0018] The use of certain terms in different places in this specification is illustrative and should not be construed as restrictive. A service, function, or resource is not limited to a single service, function, or resource; the use of these terms may refer to a distributed or aggregated group of related services, functions, or resources.

[0019] The terms “include,” “including,” “comprise,” and “comprising” should be understood as open-ended terms, and any listed items following them are examples and not intended to limit the scope of the listed items. Any headings used herein are for organizational purposes only and should not be used to limit the scope of the specification or claims. Every reference mentioned in this patent document is incorporated herein by reference in its entirety.

[0020] Furthermore, it should be noted that although the embodiments described herein are given in the context of overvoltage protection as measures against high voltage, those skilled in the art will recognize that the teachings of this disclosure are not limited to overvoltage protection applications and can also be used in other contexts, including overcurrent protection.

[0021] In this document, the terms "circuit" and "sub-circuit" are used interchangeably. "High voltage" refers to a voltage greater than the operating voltage of the circuit to be protected (e.g., the supply voltage of the sub-circuit). An exemplary high voltage could be hundreds or thousands of volts. Further, the term "switch" refers to any type of switch known in the art, used in both analog and digital circuits, including transistors, thyristors, etc.

[0022] Figure 1 This is a simplified block diagram of a protection circuit according to various embodiments of this disclosure. Circuit 100 includes a circuit to be protected 102, a protection circuit 104, a voltage sensing circuit 106, and a control circuit 108. The circuit to be protected 102 may be the circuit to be protected from a certain node (in Figure 1 The middle is represented as V LOW The protection circuit 104 can be any low-voltage circuit that is affected by overcurrent or overvoltage conditions at a voltage node (denoted as V). The protection circuit 104 can present a high impedance and thus protect the circuit 102 from, for example, voltage conditions that may exist at a voltage node (denoted as V). OUT This refers to any network affected by high voltage at (e.g., the output voltage node of circuit 100). In an embodiment, protection circuit 104 may be implemented as a switching network, as referred to below. Figure 4 This will be discussed in more detail. The voltage sensing circuit 106 can detect node V. OUTAny circuit that senses the voltage at a given location, for example, by using a voltage sensing circuit system or a current sensing circuit system. Control circuit 108 may include a circuit system for controlling protection circuit 104.

[0023] In operation, in response to the voltage sensing circuit 106 detecting node V using any voltage sensing method or current sensing method known in the art, OUT At a relatively high voltage location, the voltage sensing circuit 106 can directly or indirectly convey the presence of the high voltage to the control circuit 108. In an embodiment, the control circuit 108 can then control the protection circuit 104, for example, by enabling protection against node V. OUT The high voltage at the point negatively affects the operating mode of the circuit to be protected 102.

[0024] For example, in normal working mode, node V OUT The voltage at the reference potential (e.g., ground potential) can be maintained at the node V. LOW Within the range of maximum voltages at that location. In an embodiment, V LOW It can be the power supply voltage driving the circuit 102 to be protected. In this normal or conventional mode, the voltage sensing circuit 106 can actively or passively instruct the control circuit 108 not to activate the protection mechanism.

[0025] Conversely, in the protected working mode, when node V OUT When the voltage at a point exceeds the normal range, that is, when V OUT Exceeding node V LOW When the voltage is at a certain level, the voltage sensing circuit 106 can control the circuit 108 to activate the protection mechanism, for example, by generating a current indicating an overvoltage condition and driving it into the control circuit 108.

[0026] In this embodiment, the voltage sensing circuit 106 can generate an indication of the output node V. OUT A low or high signal indicates an overvoltage condition. In response, control circuit 108 can activate one or more components in protection circuit 104 to protect circuit 102 from potentially damaging high voltage V. OUT This generates a high impedance. In an embodiment, the control circuit 108 can achieve this by activating a switching network that may be located within the protection circuit 104.

[0027] Note that in the embodiments, the protection circuit 100 may be implemented as a symmetrical circuit or a pseudo-symmetrical circuit, which is configured to protect the circuit to be protected 102 from possible occurrences at node V. OUT The effects of positive high voltage and immunity from negative high voltage are discussed, which will be referred to as +HV and -HV respectively in the following text.

[0028] Figure 2 This is a simplified block diagram of exemplary symmetrical protection circuit block diagrams according to various embodiments of this disclosure. Figure 1 Components shown in the diagram are labeled in the same manner. For the sake of brevity, descriptions or functions of components are not repeated here. In an embodiment, the voltage sensing circuit 206 can be used to detect voltage node V. OUT The voltage sensor 210 can detect the positive high voltage +HV at the location, while the voltage sensing circuit 210 can be used to detect the negative high voltage -HV. In this way, bidirectional high voltage protection can be achieved.

[0029] In this embodiment, control circuits 206 and 208 can be implemented as gate control circuits. For example, control circuit 206 can control the gates of a group of N-type MOSFET (Metal-Oxide-Semiconductor Field-Effect Transistor) devices, while control circuit 208 can control the gates of a group of P-type MOSFET devices.

[0030] In an embodiment, the circuit to be protected may include circuits that can have V CC As a power supply voltage-sensitive electronic circuit system, such as operational amplifier 202. Note the voltage node V. OUT It can be coupled to any type of external load (not shown).

[0031] Those skilled in the art will understand that each circuit can be implemented using a variety of analog and digital circuit components. They will further understand that any auxiliary components and circuit systems (such as power supplies, logic gates, operational amplifiers, control logic, etc.) can be used to achieve the purposes of this disclosure.

[0032] Figure 3 This is a flowchart illustrating various embodiments of a process for protecting circuit components from overvoltage conditions according to this disclosure. In an embodiment, process 300 may proceed to step 302, where a voltage sensing circuit detects an overvoltage condition at a voltage node. At step 304, the voltage sensing circuit may generate a signal indicating the overvoltage condition, which may be used at step 306, for example, by a control circuit to control (e.g., activate) a protection circuit coupled to and protecting the circuit to be protected. In an embodiment, the protection circuit may create a high-impedance path between the circuit to be protected and the voltage node to prevent the overvoltage condition at the voltage node from negatively affecting the circuit to be protected.

[0033] Those skilled in the art will recognize that, in this document: (1) certain steps may be performed optionally; (2) the steps may not be limited to the specific order set forth herein; (3) certain steps may be performed in different orders; and (4) certain steps may be performed simultaneously.

[0034] Figure 4 This is a schematic diagram of an exemplary bidirectional high-voltage protection circuit according to various embodiments of this disclosure. Circuit 400 includes an operational amplifier 402; a voltage node to be protected 460; a bias current control circuit 404; current-mode comparators 406, 408; sensing circuit switches 410 to 412; high-voltage resistors 414 to 416; low-voltage resistors 420 to 424; switches 430 to 436; current sources 450 to 458 and 470 to 474; and an output voltage node 462.

[0035] The arrows on switches 430 to 432 indicate the source terminal, while the midpoint between switches 430 and 432 indicates the location of the drain terminal. Note that although switches 430 to 432 are depicted as normally closed N-type MOSFET devices with a body diode, it should be understood that other controlled devices can be used, such as those without a body diode or with different doping, structures, and control mechanisms. For example, this can be implemented using components that can be located externally to the switches, such as relays. Figure 4 The body diode and its function are shown.

[0036] In this embodiment, during normal operation, the voltage V at voltage node 462 is... OUT This can be within the range of VCC to GND. In this case, switches 410 and 412 present essentially zero drain current. Therefore, current-mode comparators 406 and 408 can generate corresponding "low" level signals. Figure 4 These are denoted as CP1 and CP2. In an embodiment, signals CP1 and CP2 can be used to control the state of bias current sources 470 to 474, keeping them active. Bias currents (denoted as IP, IN1, and IN2) flow through the corresponding resistors (denoted as RP1, RN1, and RN2) and generate corresponding voltage drops.

[0037] Because of the parallel circuit structure coupling, the same voltage drop generated across RP1, RN1, and RN2 will also form a gate-to-source voltage across each corresponding switch 430 to 436, thereby turning on the switches 430 to 436, i.e., turning them on. In the embodiment, the voltage at V can be determined by the on-resistance of the two sets of switches (i.e., one set of 430 to 432 in the first path between the protected voltage node 460 and the output voltage node 462, and another set of 434 to 436 in the second path connected in parallel with the first path) and the corresponding current flowing to the output voltage node 462 (e.g., to an external load). LOW With V OUTThe voltage drop generated between them. Those skilled in the art will understand that, at a given current level, the voltage drop between the protected voltage node 460 and the output voltage node 462 decreases as the device size increases because the on-resistance decreases with increasing device size.

[0038] In an embodiment, once the voltage applied at the output voltage node 462 falls outside the range between GND and the supply voltage VCC (plus approximately 1 volt, which in practice may create a dead zone with no circuit activity), the protection feature of the circuit 400 can be activated, for example, by the drain current flowing through the switch 410, which has a substantially non-zero value and causes a voltage drop across the high-voltage resistor 414 equal to the difference between the voltage at the output node 462 and the voltage at the source terminal of the switch 410.

[0039] In an embodiment, the current-mode comparator 406 can compare the drain current flowing through switch 410 with the current from current source 450 to generate a control signal (in Figure 4 (Represented as CP2). Similarly, the current-mode comparator 408 can compare the drain current on switch 412 with the current from current source 452 to generate a control signal (represented as CP1). In this embodiment, the high states of signals CP1 and CP2 indicate that the voltage at output node 462 exceeds the normal operating voltage range between GND and the supply voltage VCC of operational amplifier 402.

[0040] In this embodiment, the bias current control circuit 404 can use control signals CP1 and CP2 to turn off the bias currents 470 to 474. Therefore, the voltage drop across the high-voltage resistors 414 to 416 and the gate-to-source voltage of switches 430 to 436 will be essentially zero, thus turning off switches 430 to 436, i.e., creating an open circuit, depending on the polarity of the voltage at output voltage node 462.

[0041] In this embodiment, due to the opposite polarity, bias, or orientation of the reverse-connected body diodes of switches 430 to 436, these body diodes create a bidirectional high-impedance path between the voltage node to be protected 460 and the output voltage node 462. Advantageously, this protects the operational amplifier 402 from unwanted high-voltage conditions.

[0042] Furthermore, the essentially zero bias current generates an essentially zero voltage drop across, for example, a low-voltage resistor 420, which can act as a floating resistor to provide a convenient way to turn off switch 430. Therefore, low-voltage resistors 420 to 424 can be considered as floating gate control devices.

[0043] Notice, Figure 4The bidirectional high-voltage protection circuit shown is not limited to the structural details shown herein or described in the accompanying text. For example, in an embodiment, a high-voltage sensing device can be used to implement the functions of switch 410 and high-voltage resistor 414, which can generate an output current indicating that the voltage at output node 462 exceeds the supply voltage VCC of operational amplifier 402. As another example, the functions of current-mode comparators 406 and 408 can be replaced, for example, by MOS devices. Similarly, switch 410, high-voltage resistor 414, and current-mode comparator 406 can be replaced or integrated into any high-voltage circuit that can detect the presence of a voltage higher than VCC to output, for example, a corresponding high-level (or low-level) signal that causes the state of control signal CP2 to change from low to high (or vice versa).

[0044] In the embodiment, the voltage V at the voltage node 460 to be protected LOW The voltage V at output voltage node 462 can be determined by the output stage state of operational amplifier 402 and can be maintained, for example, from 0 volts to VCC. OUT It can vary between -HV and +HV. Further note that for proper circuit operation, the amplitude of "HV" should be less than the breakdown voltage of switches 430 to 436.

[0045] Figure 5 This is a flowchart of a process for protecting a circuit from positive and negative overvoltages according to various embodiments of this disclosure. In an embodiment, process 500 may begin at step 502, where a high positive or high negative voltage exceeding the operating voltage range of the voltage node to be protected is received.

[0046] At step 504, the high-voltage resistor coupled to the output node can be used to generate a drain current that flows through a high-voltage switch coupled to the high-voltage resistor.

[0047] At step 506, a current sensing circuit can be used to detect the drain current, which indicates an overvoltage condition at the output node. In an embodiment, a protection circuit including a set of switches can be coupled between the output node and the circuit to be protected.

[0048] At step 508, the drain current can be used to generate a digital signal for the bias current controller.

[0049] Finally, at step 510, a bias current controller can be used to control a bias current that turns off the set of switches when applied, thereby creating a high-impedance path between the output node and the circuit to be protected, which prevents overvoltage conditions from negatively affecting the circuit to be protected.

[0050] Aspects of the present invention can be implemented using instructions coded on one or more non-transitory computer-readable media for use with one or more processors or processing units to enable the steps to be executed. It should be noted that the one or more non-transitory computer-readable media should include both volatile and non-volatile memory. It should be noted that alternative implementations are possible, including hardware implementations or software / hardware implementations. The functionality of the hardware implementation can be implemented using ASICs (multiple) ASICs, programmable arrays, digital signal processing circuit systems, etc. Therefore, the term "means" in any claim is intended to cover both software and hardware implementations. Similarly, the term "one or more computer-readable media" as used herein includes software and / or hardware, or a combination thereof, of instruction programs embodied thereon. In consideration of these alternative implementations, it should be understood that the accompanying drawings and description provide functional information that would be required for those skilled in the art to write program code (i.e., software) and / or manufacture circuitry (i.e., hardware) to perform the desired processing.

[0051] It should be noted that embodiments of the present invention may further relate to computer products having a non-transitory tangible computer-readable medium having computer code thereon for performing various computer-implemented operations. The medium and computer code may be media and computer code specifically designed and constructed for the purposes of the present invention, or they may belong to a class well known or available to those skilled in the art. Examples of tangible computer-readable media include, but are not limited to: magnetic media, such as hard disks, floppy disks, and magnetic tapes; optical media, such as CD-ROMs and holographic devices; magneto-optical media; and hardware devices specifically configured to store or store and execute program code, such as application-specific integrated circuits (ASICs), programmable logic devices (PLDs), flash memory devices, and ROM and RAM devices. Examples of computer code include machine code generated by a compiler and files containing higher-level code executed by a computer using an interpreter. Embodiments of the present invention may be implemented wholly or partially as machine-executable instructions that may reside in program modules executed by a processing device. Examples of program modules include libraries, programs, routines, objects, components, and data structures. In a distributed computing environment, program modules may be physically located in a local, remote, or both setting.

[0052] Those skilled in the art will recognize that no computing system or programming language is essential for the practice of this invention. They will also recognize that the various elements described above can be physically and / or functionally divided into multiple sub-modules or combined together.

[0053] It will be understood by those skilled in the art that the foregoing examples and embodiments are exemplary and not limited to the scope of this disclosure. It is intended that all arrangements, enhancements, equivalents, combinations, and modifications thereof that will be apparent to those skilled in the art upon reading this specification and studying the accompanying drawings are included within the true spirit and scope of this disclosure. It should also be noted that the elements of any claim can be arranged in different ways, including having multiple dependencies, configurations, and combinations.

Claims

1. An overvoltage protection method, comprising: A high-voltage resistor coupled to a voltage node is used to generate the drain current of the switch. A current sensing circuit is used to detect the drain current that indicates an overvoltage condition at the voltage node; Use a current-mode comparator to convert the current into a control signal; as well as A control circuit is used that, in response to receiving the control signal, shuts off a set of switching devices coupled to the voltage node to be protected, thereby creating a high-impedance electrical path between the voltage node and the voltage node to be protected.

2. The overvoltage protection method according to claim 1 further includes using the drain current as the control signal and using the control circuit as a bias current controller.

3. The overvoltage protection method according to claim 2, wherein, The bias current controller applies a bias current to the group of switching devices to turn them off, thereby creating the high-impedance electrical path.

4. A bipolar high-voltage protection circuit, comprising: A protection circuit coupled to the voltage node to be protected and the output voltage node is a switching network that presents high impedance and thus protects the voltage node to be protected from the effects of high voltages that may exist at the output voltage node. A voltage sensing circuit that detects the voltage at the output voltage node and generates an output signal indicating the overvoltage condition in response to the detection of an overvoltage condition at the output voltage node; as well as A control circuit coupled to the voltage sensing circuit, in response to receiving the output signal, causes the protection circuit to present a high impedance to isolate the voltage node to be protected from the overvoltage condition.

5. The circuit according to claim 4, wherein, The overvoltage condition is a high positive voltage or a high negative voltage that exceeds the operating voltage range of the voltage node to be protected. The protection circuit includes two sets of low-voltage switches, each set including opposite body diodes.

6. The circuit according to claim 4, wherein, The voltage sensing circuit includes a switch coupled to the output voltage node, which generates the output signal in the form of current.

7. The circuit of claim 5, further comprising a current sensing circuit coupled to the voltage sensing circuit, the current sensing circuit outputting a status signal in response to receiving the current, the status signal controlling a set of bias currents, the set of bias currents controlling a switch in the protection circuit to turn off.

8. The circuit according to claim 4, wherein, The voltage drop between the protected voltage node and the output voltage node is determined by the on-resistance of these switches and the load current flowing through the output voltage node.

9. A switching network for bidirectional high-voltage protection of voltage nodes, the switching network comprising: Two sets of switches, each set of switches is coupled to the voltage node to be protected and the output voltage node, which presents a voltage within a certain voltage range during normal operation; A set of comparators, each of which is coupled to a switch in a third set of switches and generates a low-level signal, which is used to control the bias current to turn on the two sets of switches, so that the voltage drop between the protected voltage node and the output voltage node is determined by the on-resistance of the two sets of switches and the load current flowing through the output voltage node. as well as In response to the voltage at the output voltage node falling outside the voltage range, the drain current exceeding the current value causes the corresponding comparator in the set of comparators to generate a high-level signal. This high-level signal causes these bias currents and thus turns off both sets of switches, thereby creating a high-impedance path between the voltage node to be protected and the output voltage node. The voltage at the voltage node to be protected is controlled within the voltage range by the output stage state of the operational amplifier, and the voltage at the output voltage node presents a value between negative high voltage and positive high voltage.

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