Method for operating power supply and power monitor

Abstract

The invention relates to a method for operating a power supply and a power monitor. The method includes determining a voltage provided from the power source to a power rail of a load device. The method also includes detecting that the voltage of the power rail is greater than or equal to an overvoltage threshold. The method also includes incrementing an overvoltage counter upon detecting that the voltage of the power rail is greater than or equal to the overvoltage threshold. The method also includes detecting that the overvoltage counter is equal to a threshold. The method also includes generating an interrupt signal upon detecting that the overvoltage counter is equal to the threshold.

Description

Technical Field

[0001] The present application relates to the technical field of power management, and in particular to a method for operating a power supply and a power monitor. Background Art

[0002] Vehicles such as passenger cars and trucks may include several different electrical systems for performing various functions. Many such electrical systems include data fusion or data processing system-on-chip (SoC) devices. Data fusion or data processing SoCs may require many power rails, at least some of which may be safety-critical. For example, for reliability, dedicated power-up and power-down should be considered, and the tolerance of the voltage on the power rails should be monitored to ensure computational integrity. Both will affect the functional safety of the SoC and the corresponding electrical system. Any deviation from the specified value should be detected, and specific actions should be performed according to the system to set the system in a safe state (e.g., by initiating a power-down or setting a signaling pin to a predetermined level). Summary of the invention

[0003] Brief overvoltage and undervoltage events do not cause damage to electronic devices. However, in the case of periodic overvoltage and undervoltage events, the life of the system-on-chip (SoC) device may be reduced. Slow spike-resistant comparators are generally unable to detect brief overvoltage and undervoltage events. In addition, current fast diagnostic measurement systems have the following disadvantages: their measurement bandwidth is very large, and their detection thresholds may vary due to circuit noise, which may lead to erroneous positive overvoltage and undervoltage detection. Therefore, the present disclosure provides a power monitor, a power supply circuit and a method, which, in particular, uses programmable thresholds to digitally post-process overvoltage and undervoltage detection from a fast analog comparator to detect safety-critical events.

[0004] The present disclosure provides a method for operating a power supply. The method includes determining a voltage of a power rail provided from the power supply to a load device. The method also includes detecting that the voltage of the power rail is greater than or equal to an overvoltage threshold. The method also includes incrementing an overvoltage counter when detecting that the voltage of the power rail is greater than or equal to the overvoltage threshold. The method also includes detecting that the overvoltage counter is equal to a threshold. The method also includes generating an interrupt signal when detecting that the overvoltage counter is equal to the threshold.

[0005] The present disclosure also provides a power monitor, which in a specific implementation includes a voltage fault detector and a controller. The voltage fault detector is configured to determine the voltage of a power rail provided from a power supply to a load device. The voltage fault detector is also configured to detect when the voltage of the power rail is greater than or equal to an overvoltage threshold. The controller is configured to increment an overvoltage counter when the voltage fault detector detects that the voltage of the power rail is greater than or equal to the overvoltage threshold. The controller is also configured to generate an interrupt signal when the overvoltage counter is equal to the threshold.

[0006] The present disclosure also provides a power supply circuit, which in a specific implementation includes a power supply and a power monitor. The power supply is configured to provide a power rail to a load device. The power monitor is configured to detect when the voltage of the power rail is greater than or equal to an overvoltage threshold. The power monitor is also configured to increment an overvoltage counter whenever the power monitor detects that the voltage of the power rail is greater than or equal to the overvoltage threshold. The power monitor is further configured to generate an interrupt signal when the overvoltage counter is equal to the threshold. BRIEF DESCRIPTION OF THE DRAWINGS

[0007] To describe in detail exemplary implementations, reference will now be made to the accompanying drawings, in which:

[0008] Figure 1 is a block diagram of an example of a power supply circuit for a load device according to some specific implementations;

[0009] Figure 2 It is based on some specific implementations including Figure 1 A block diagram of an example of a power monitor in a power supply circuit;

[0010] Figure 3 It is based on some specific implementations including Figure 2 A partial schematic diagram and a partial block diagram of a voltage fault detector in a power monitor;

[0011] Figure 4 is a flow chart of an example of a method for tracking overvoltage events of a power rail according to some specific implementations;

[0012] Figure 5 is a timing diagram of an example of generating an interrupt signal based on overvoltage detection and undervoltage detection according to some specific implementations;

[0013] Figure 6 is a flow chart of an example of a method for tracking consecutive overvoltage events of a power rail according to some specific implementations;

[0014] Figure 7 is a timing diagram of an example of generating interrupt and shutdown signals based on consecutive overvoltage events and undervoltage events according to some specific implementations;

[0015] Figure 8is a timing diagram of an example of using an overvoltage shutdown threshold and an undervoltage shutdown threshold to generate a shutdown signal according to some specific implementations;

[0016] Fig. 9 is a flow chart of an example of a method for tracking a moving average of overvoltage events of a power rail according to some implementations;

[0017] Fig.10 is a timing diagram of an example of generating an interrupt signal based on a moving average of overvoltage events and undervoltage events according to some specific implementations;

[0018] Fig.11 is a flow chart of an example of a method for operating a power circuit to detect an overvoltage event according to some specific implementations; and

[0019] Fig.12 is a flow chart of an example of a method for operating a power circuit to detect a brown-out event according to some implementations.

[0020] definition

[0021] Various terms are used to refer to specific system components. Different companies may refer to a component by different names - this document is not intended to distinguish between components that differ in name but function the same. In the following discussion and in the claims, the terms "include" and "comprising" are used in an open-ended manner, and therefore, these terms should be interpreted to mean "including but not limited to...". In addition, the terms "couple" or "coupled" are intended to mean either an indirect connection or a direct connection. Thus, if a first device is coupled to a second device, that connection may be made through a direct connection or through an indirect connection via other devices and connections.

[0022] In reference to electrical devices, whether stand-alone or as part of an integrated circuit, the terms "input" and "output" refer to electrical connections to the electrical device and should not be construed as verbs requiring operation. For example, a differential amplifier such as an operational amplifier may have a first differential input and a second differential input, and these "inputs" define electrical connections to the operational amplifier and should not be construed as requiring signal inputs to the operational amplifier.

[0023] "Asserting" shall mean changing the state of a Boolean signal. A Boolean signal may be asserted high or have a higher voltage, and a Boolean signal may be asserted low or have a lower voltage, at the discretion of the circuit designer. Similarly, "deasserting" shall mean changing the state of a Boolean signal to a voltage level opposite to the asserted state.

[0024] “Controller” shall mean, alone or in combination, an individual circuit component, an application specific integrated circuit (ASIC), one or more microcontrollers with control software, a reduced instruction set computer (RISC) with control software, a digital signal processor (DSP), one or more processors with control software, a programmable logic device (PLD), a field programmable gate array (FPGA), or a programmable system on a chip (PSOC) configured to read inputs and drive outputs in response to those inputs. DETAILED DESCRIPTION

[0025] This application claims priority to and the benefit of U.S. utility patent application serial number 18 / 366,895, filed on August 8, 2023, entitled “Diagnosing Power Rail Over-Voltageand Under-Voltage Conditions,” the entire disclosure of which is incorporated herein by reference for all purposes.

[0026] The following discussion relates to various specific implementations of the present invention. Although one or more of these specific implementations may be preferred, the disclosed specific implementations should not be interpreted or otherwise used to limit the scope of the present disclosure, including the claims. In addition, it should be understood by those skilled in the art that the following description has broad application, and the discussion of any specific implementation is only intended to be an example of that specific implementation, and is not intended to indicate that the scope of the present disclosure, including the claims, is limited to that specific implementation.

[0027] Various examples relate to methods and systems for power management with overvoltage and undervoltage tracking. More specifically, various examples relate to power supplies and related power monitors that track various statistics of overvoltage events and undervoltage events in power rails. Still more specifically, various examples relate to power supplies and related power monitors that use fast analog comparators to detect overvoltage events and undervoltage events in power rails. The specification now turns to an exemplary system to guide the reader.

[0028] Figure 1 is a block diagram of an example of a power circuit 102 for a load device 104 according to some implementations of the present disclosure. Figure 1 The power supply circuit 102 shown includes a system power supply 106, a power monitor 108, a safety power supply 110, and a safety controller 112. In some implementations, the power supply circuit 102 may include a system power supply 106, a power monitor 108, a safety power supply 110, and a safety controller 112. Figure 1The components shown may be more components, fewer components, or different components. For example, in addition to the connections described below, there will be additional input connections and output connections (e.g., data connections, additional power connections, reference voltage connections, and additional ground connections), but those additional input connections and output connections are not shown so as not to overly complicate the drawing. In addition, in some implementations, the safety controller 112 can be located outside the power circuit 102.

[0029] In some specific implementations, the load device 104 includes a system on chip (SoC) device or other powered system. For example, the load device 104 may include a vehicle SoC device configured for data fusion. The vehicle SoC device may be configured to collect sensor data from one or more vehicle sensors. For example, the vehicle SoC device may receive sensor data from a radar sensor, a LIDAR sensor, an ultrasonic sensor, an image sensor, or a combination thereof. The vehicle SoC device may also be configured to process sensor data. For example, the vehicle SoC device may use sensor data to determine the position and relative movement of vehicles, pedestrians, and other objects located around the target vehicle.

[0030] Different components included in the load device 104 can be configured to operate at specific direct current (DC) voltages. For example, some components in the load device 104 can be configured to operate at 0.6 volts, and other components in the load device 104 can be configured to operate at 1.2 volts. In some implementations, the load device 104 is configured to receive several DC voltages, each of which is referred to as a power rail. For example, the load device 104 can include a SoC device configured to receive twenty power rails. Figure 1 The illustrated load device 104 includes a rail supply connection 114 coupled to the system power supply 106 to receive a rail supply therefrom. The load device 104 may include additional rail supply connections for each power rail, but these additional connections are not shown so as not to unduly complicate the drawing.

[0031] Figure 1 The load device 104 shown also includes a reference connection 116 coupled to a reference terminal 118 (eg, a ground terminal). The voltage of the power rail is equal to the difference between the voltage of the rail supply present at the rail supply connection 114 and the reference voltage present at the reference terminal 118. Figure 1 The illustrated load device 104 also includes a data connection 120 for communicating with the power monitor 108 . Figure 1 The illustrated load device 104 also includes a first control input 122 coupled to the power monitor 108 to receive an interrupt signal (INTB) therefrom. Figure 1The illustrated load device 104 also includes a second control input 124 coupled to the power monitor 108 to receive a shutdown signal (ERRB) therefrom. In some implementations, when the load device 104 receives the shutdown signal, the load device 104 may stop communicating with other devices external to the load device 104.

[0032] The system power supply 106 is configured to generate one or more power rails for the load devices 104 . Figure 1 The illustrated system power supply 106 includes a rail power output 126 coupled to the rail power connection 114 of the load device 104 to provide rail power thereto. In some implementations, the system power supply 106 can include additional rail power outputs for providing different rail powers to the load device 104. Figure 1 The illustrated system power supply 106 also includes a reference connection 128 coupled to the reference terminal 118 .

[0033] The system power supply 106 includes a battery (not shown) or is coupled to a battery. In some specific implementations, a single battery is sufficient. In alternative specific implementations, multiple batteries (e.g., in series or in parallel) can be used. Depending on the type of load device 104, various types of batteries can be used in the power supply circuit 102. In some specific implementations, the battery provides a supply voltage of about 12 volts. In some specific implementations, the battery is rechargeable. In alternative specific implementations, the battery is disposable.

[0034] The system power supply 106 may include any suitable device configured to generate one or more power rails based on a supply voltage from a battery. For example, the system power supply 106 may include a charge pump configured to generate an output voltage that may be a predetermined ratio of the supply voltage. The ratio may be programmed to any suitable value. Suitable values ​​may include ratios such as '1 / 1' (LDO mode, charge pump disabled), '4 / 5', '3 / 4', '2 / 3', '1 / 2', and '1 / 3'. Thus, by changing the ratio and / or the operating frequency, the voltage of the power rail may be selectively controlled. In some specific implementations, the system power supply 106 may include a switch mode power converter configured to generate a modified output voltage by changing the duty cycle of the switching device. Alternatively or additionally, the system power supply 106 may include a linear regulator including a buck converter configured to modify the voltage of the power rail. Alternatively or additionally, the linear regulator may be combined with another device (e.g., a charge pump or a switch mode power converter) to supply and regulate the voltage of the power rail.

[0035] Each power rail may include a range of acceptable voltages. For example, 4.75 volts to 5.25 volts may be a range of acceptable voltages for a 5 volt power rail. When the voltage of the power rail rises above the range of acceptable voltages, an overvoltage event occurs in the power rail. Additionally, when the voltage of the power rail drops below the range of acceptable voltages, an undervoltage event occurs in the power rail. The power monitor 108 is configured to detect overvoltage events and undervoltage events in one or more power rails provided to the load device 104.

[0036] The power monitor 108 generates an interrupt signal to notify the load device 104 and the safety controller 112 of a possible risk that there is still time to react. The power monitor 108 is configured to generate an interrupt signal upon detecting an overvoltage condition that may reduce the life of the load device 104 or a potential undervoltage condition that may indicate an undesirable operation of the load device 104, as will be described in more detail below. The power monitor 108 may generate a shutdown signal to notify the load device 104 and the safety controller 112 of an immediate risk that requires an emergency shutdown of the system power supply 106. In some specific implementations, the power monitor 108 generates a shutdown signal upon detecting an overvoltage condition that may almost immediately cause damage to components of the load device 104 or an undervoltage condition that may almost immediately cause an undesirable operation of the load device 104, as will be described in more detail below.

[0037] Figure 1 The illustrated power monitor 108 includes a rail power connection 132 coupled to the rail power connection 114 of the load device 104 to receive a rail power provided to the load device 104. In some implementations, the power monitor 108 can include additional rail power connections for receiving different rail powers provided to the load device 104. Figure 1 The illustrated power monitor 108 also includes a reference connection 134 coupled to the reference terminal 118 . Figure 1 The power monitor 108 shown also includes a first data connection 136 for communicating with the load device 104. The data connection 120 of the load device 104 and the first data connection 136 of the power monitor 108 together form a system interface. The system interface can be a two-wire based interface, such as an I2C interface, an I3C interface, or a universal asynchronous receiver / transmitter (UART). The system interface can also be a three-wire or four-wire based interface, such as a serial peripheral interface (SPI), a dual SPI (DSPI), and a quad SPI (QSPI). Figure 1 The illustrated power monitor 108 also includes a second data connection 138 for communicating with the safety controller 112 . Figure 1The illustrated power monitor 108 also includes a first control output 140 coupled to the first control input 122 of the load device 104 to send an interrupt signal thereto. The first control output 140 is also coupled to the safety controller 112 to send an interrupt signal thereto. Figure 1 The illustrated power monitor 108 also includes a second control output 142 coupled to the second control input 124 of the load device 104 to send a shutdown signal thereto. The second control output 142 is also coupled to the safety controller 112 to send a shutdown signal thereto.

[0038] The safety power supply 110 is configured to supply power to the safety controller 112 independently of the system power supply 106 . Figure 1 The illustrated safety power supply 110 includes a power output 144 coupled to the safety controller 112 to provide power thereto. Figure 1 The illustrated safety power supply 110 also includes a reference connection 146 coupled to the reference terminal 118. The safety power supply 110 may include any suitable device configured to generate power for the safety controller 112 based on a supply voltage from a battery (including, for example, a device similar to any device described above with respect to the system power supply 106). The safety power supply 110 may include or be coupled to a device (not shown) configured to monitor the power supplied to the safety controller 112.

[0039] Figure 1 The illustrated safety controller 112 includes a power connection 148 coupled to the safety power source 110 to receive power therefrom. Figure 1 The illustrated safety controller 112 also includes a reference connection 150 coupled to the reference terminal 118 . Figure 1 The illustrated safety controller 112 also includes a data connection 152 for communicating with the power monitor 108. The data connection 152 of the safety controller 112 and the second data connection 138 of the power monitor 108 together form a system interface. Figure 1 The illustrated safety controller 112 also includes a first control input 154 coupled to the first control output 140 of the power monitor 108 to receive an interrupt signal therefrom. Figure 1 The illustrated safety controller 112 also includes a second control input 156 coupled to the second control output 142 of the power monitor 108 to receive a shutdown signal therefrom.

[0040] Figure 2 is an example of a block diagram of a power monitor 108 according to some implementations of the present disclosure. Figure 2 The power monitor 108 shown includes a voltage fault detector 202 and a controller 204. In some implementations, the power monitor 108 may include a voltage fault detector 202 and a controller 204. Figure 2The components shown may be more components, fewer components, or different components. For example, in addition to the connections described below, there will be additional input connections and output connections (e.g., power connections, reference voltage connections, and ground connections), but those additional input connections and output connections are not shown so as not to unduly complicate the drawing.

[0041] The voltage fault detector 202 is configured to detect undervoltage events and overvoltage events in the power rail provided to the load device 104. The voltage fault detector 202 may include a fast analog comparator. Figure 2 The illustrated voltage fault detector 202 includes a first voltage input 206 coupled to the rail supply connection 132 to receive the rail supply provided to the load device 104 . Figure 2 The illustrated voltage fault detector 202 also includes a second voltage input 208 coupled to the reference connection 134 to receive a reference voltage provided to the load device 104 . Figure 2 The illustrated voltage fault detector 202 also includes a first control output 210 coupled to the controller 204 to send an overvoltage detection signal thereto, as will be described in greater detail below. Figure 2 The illustrated voltage fault detector 202 also includes a second control output 212 coupled to the controller 204 to send an undervoltage detection signal thereto, as will be described in greater detail below.

[0042] The controller 204 is configured to track overvoltage events and undervoltage events in the power rail. Figure 2 The controller 204 shown includes a first control input 214, a second control input 216, a first data connection 218, a second data connection 220, a first control output 222, and a second control output 224. The first control input 214 is coupled to the first control output 210 of the voltage fault detector 202 to receive an overvoltage detection signal therefrom. The second control input 216 is coupled to the second control output 212 of the voltage fault detector 202 to receive an undervoltage detection signal therefrom. The first data connection 218 of the controller 204 is coupled to the first data connection 136 of the power monitor 108. The second data connection 220 of the controller 204 is coupled to the second data connection 138 of the power monitor 108. The first control output 222 of the controller 204 is coupled to the first control output 140 of the power monitor 108 to send an interrupt signal. The controller 204 is configured to generate an interrupt signal when certain overvoltage conditions and undervoltage conditions are detected, as will be described in more detail below. The second control output 224 of the controller 204 is coupled to the second control output 142 of the power monitor 108 to send a shutdown signal. In some implementations, the controller 204 is configured to generate a shutdown signal upon detecting certain overvoltage and undervoltage conditions, as will be described in more detail below.

[0043] Figure 3 is an example of a partially schematic and partially block diagram of a voltage fault detector 202 according to some implementations of the present disclosure. Figure 3 The voltage fault detector 202 shown includes a voltage monitoring section 302, an overvoltage comparator 304, and an undervoltage comparator 306. In some implementations, the voltage fault detector 202 may include a comparator. Figure 3 The components shown may be more components, fewer components, or different components. For example, there would be power connections, reference voltage connections, and additional ground connections for power, sensing, or other purposes, but those additional connections are not shown so as not to overly complicate the drawing.

[0044] The voltage monitor 302 is configured to determine the voltage of the power rail. Figure 3 The illustrated voltage monitor 302 includes a first voltage input 308 coupled to the first voltage input 206 to receive a rail supply provided to the load device 104 . Figure 3 The illustrated voltage monitor 302 also includes a second voltage input 310 coupled to the second voltage input 208 to receive a reference voltage provided to the load device 104 . Figure 3 The voltage monitor 302 shown also includes a voltage output 312 coupled to the overvoltage comparator 304 and the undervoltage comparator 306. The voltage monitor 302 determines the voltage of the power rail as the difference between the voltage of the rail supply and the voltage of the reference voltage. In this way, the voltage monitor 302 takes into account, among other things, changes in the reference voltage.

[0045] The overvoltage comparator 304 is configured to detect an overvoltage event in the power rail provided to the load device 104 . Figure 3 The overvoltage comparator 304 shown includes a non-inverting input 314, an inverting input 316, and an output 318. The non-inverting input 314 of the overvoltage comparator 304 is coupled to the voltage output 312 of the voltage monitor 302 to receive the voltage of the power rail therefrom. The inverting input 316 of the overvoltage comparator 304 is coupled to a reference voltage representing an overvoltage threshold (OV_THR). The overvoltage threshold is the minimum voltage level of the power rail that can reduce the life of the load device 104. The overvoltage threshold can be set based on the technology used in the load device 104. In some specific implementations, the overvoltage threshold is set to be 5% greater than the target voltage of the power rail. The output 318 of the overvoltage comparator 304 is coupled to the first control output 210. When the voltage of the power rail is greater than or equal to the overvoltage threshold, the overvoltage comparator 304 generates a logic high signal at the output 318. Alternatively, when the voltage of the power rail is less than the overvoltage threshold, the overvoltage comparator 304 generates a logic low signal at the output 318 .

[0046] The undervoltage comparator 306 is configured to detect an undervoltage event in the power rail provided to the load device 104 . Figure 3 The undervoltage comparator 306 shown includes a non-inverting input 320, an inverting input 322, and an output 324. The non-inverting input 320 of the undervoltage comparator 306 is coupled to the voltage output 312 of the voltage monitor 302 to receive the voltage of the power rail therefrom. The inverting input 322 of the undervoltage comparator 306 is coupled to a reference voltage representing an undervoltage threshold (UV_THR). The undervoltage threshold is a maximum voltage level to which the power rail is exposed for a long time or multiple times in a short period of time (e.g., within 100 microseconds) to increase the possibility of calculation errors in the load device 104. The undervoltage threshold can be set based on the technology used in the load device 104. In some specific implementations, the undervoltage threshold is set to be 5% less than the target voltage of the power rail. The output 324 of the undervoltage comparator 306 is coupled to the second control output 212. When the voltage of the power rail is less than or equal to the undervoltage threshold, the undervoltage comparator 306 generates a logic high signal at the output 324. Alternatively, when the voltage of the power rail is greater than the undervoltage threshold, the undervoltage comparator 306 generates a logic low signal at the output 324 .

[0047] Back to Figure 2 , the controller 204 is configured to track overvoltage events using an overvoltage counter. For example, each time the controller 204 receives an overvoltage detection signal from the voltage fault detector 202, the controller 204 may increment the overvoltage counter. In some implementations, the controller 204 may increment the overvoltage counter by increasing the value of the overvoltage counter by one. For example, when the controller 204 receives an overvoltage detection signal from the voltage fault detector 202, the controller 204 may increase the overvoltage counter from three to four. In an alternative implementation, the controller 204 may increment the overvoltage counter by decreasing the value of the overvoltage counter by one. The controller 204 is also configured to generate an interrupt signal based on the value of the overvoltage counter, as will be described in more detail below.

[0048] In some implementations, the controller 204 can generate an interrupt signal when the overvoltage counter indicates that the total number of overvoltage events is equal to the reporting threshold. Figure 4 4 is a flow chart of an example of a method 400 for tracking overvoltage events of a power rail according to some specific implementations. To simplify the description, the method 400 is described as a series of operations performed by the controller 204. However, operations according to the method 400 may be performed by different components. At block 402, the controller 204 detects that the voltage of the power rail is greater than or equal to an overvoltage threshold. For example, when the controller 204 receives an overvoltage detection signal from the voltage fault detector 202, the controller 204 may detect that the voltage of the power rail is greater than or equal to the overvoltage threshold.

[0049] Next, at block 404, the controller 204 increments the overvoltage counter. For example, Figure 5 The timing diagram of the overvoltage counter is shown in Figure 1. Figure 5 As shown, the overvoltage counter value increases by one each time the voltage of the power rail is greater than or equal to the overvoltage threshold of 630 mV. Return to Figure 4 , at block 406, the controller 204 determines whether the overvoltage counter is equal to the reporting threshold. The reporting threshold is an example of a "threshold" or a "first threshold." When the overvoltage counter is not equal to the reporting threshold, the method 400 returns to block 402 to detect again that the voltage of the power rail is greater than or equal to the overvoltage threshold. Alternatively, when the overvoltage counter is equal to the reporting threshold, the controller 204 generates an interrupt signal at block 408. For example, Figure 5 In the example, when the value of the overvoltage counter reaches the reporting threshold of twenty at about 44 microseconds, an interrupt signal is generated. As described above, the interrupt signal is sent to the load device 104 and the safety controller 112. Figure 4 After block 408 in block 410, the controller 204 sends the value of the overvoltage counter at block 410. In some implementations, in response to receiving the interrupt signal, the load device 104 can read the value of the overvoltage counter via a system interface formed between the first data connection 136 of the power monitor 108 and the data connection 120 of the load device 104. Alternatively or additionally, in response to receiving the interrupt signal, the safety controller 112 can read the value of the overvoltage counter via a system interface formed by the second data connection 138 of the power monitor 108 and the data connection 152 of the safety controller 112.

[0050] Upon receiving the value of the overvoltage counter, the load device 104 may use the value of the overvoltage counter to predict the end of the life of the load device 104. For example, the load device 104 may track the total number of overvoltage events during its life and determine when the load device 104 may fail due to excessive overvoltage events. When the voltage of the power rail is outside the range of acceptable voltages of the load device 104 due to a fault in the system power supply 106, the load device 104 may not be able to correctly determine the appropriate response after receiving the interrupt signal. However, as described above, the safety controller 112 receives power from an independent power supply (i.e., the safety power supply 110). Therefore, upon receiving the interrupt signal and the value of the overvoltage counter, the safety controller 112 may determine whether any corrective action needs to be taken. For example, the safety controller 112 may instruct the system power supply 106 to adjust the target voltage of the power rail to accommodate voltage drift and other effects that may affect the power rail. In addition, the safety controller 112 may instruct the system power supply 106 to perform a normal power-off sequence based on the type of flag included in the interrupt signal. For example, safety controller 112 may send one or more control signals to system power supply 106 that cause system power supply 106 to sequentially disable power rails in a predetermined sequence. In addition, safety controller 112 may identify abnormal power rail behavior by detecting when the frequency of interrupt signals increases over time.

[0051] Return to Figure 4 , after sending the value of the overvoltage counter at block 410, the overvoltage counter is reset to a minimum value at block 412. In some implementations, the overvoltage counter is reset as part of a read operation. For example, the load device 104 or the safety controller 112 may perform a clear-by-read operation to read and reset the value of the overvoltage counter. Alternatively or additionally, the value of the overvoltage counter is overwritten. For example, the load device 104 or the safety controller 112 may perform a clear-by-write operation to reset the overvoltage counter. For example, at Figure 5 In FIG. 1 , the overvoltage counter is reset to zero after the value of the overvoltage counter is sent to the load device 104 approximately 55 microseconds. Figure 4 After block 412 in FIG. 4 , the method 400 returns to block 402 to again detect that the voltage of the power rail is greater than or equal to the overvoltage threshold.

[0052] The controller 204 is configured to track undervoltage events using an undervoltage counter. For example, each time the controller 204 receives an undervoltage detection signal from the voltage fault detector 202, the controller 204 may increment the undervoltage counter. In some implementations, the controller 204 may increment the undervoltage counter by increasing the value of the undervoltage counter by one. For example, Figure 5 The timing diagram of the overvoltage counter is shown in Figure 1. Figure 5 As shown, each time the voltage of the power rail is less than or equal to the undervoltage threshold of 570 millivolts, the value of the undervoltage counter is increased by one. In an alternative implementation, the controller 204 can increment the undervoltage counter by decreasing the value of the undervoltage counter by one. The controller 204 is also configured to generate an interrupt signal based on the value of the overvoltage counter. In some implementations, the controller 204 can generate an interrupt signal when the undervoltage counter indicates that the total number of undervoltage events has reached the reporting threshold. For example, when the value of the undervoltage counter is equal to the reporting threshold of twenty at approximately 69 microseconds, the interrupt signal is generated at Figure 5 The reporting threshold for undervoltage events (an example of a "second threshold") may be the same as or different from the reporting threshold for overvoltage events.

[0053] In some implementations, the controller 204 can generate an interrupt signal when the overvoltage counter indicates that the number of consecutive overvoltage events is equal to the consecutive event warning threshold. In addition, in some implementations, the controller 204 can generate a shutdown signal when the overvoltage counter indicates that the number of consecutive overvoltage events is equal to the consecutive event shutdown threshold that is greater than the consecutive event warning threshold. Figure 6 6 is a flow chart of an example of a method 600 for tracking consecutive overvoltage events of a power rail according to some specific implementations. To simplify the description, the method 600 is described as a series of operations performed by the controller 204. However, operations according to the method 600 may be performed by different components. At box 602, the controller 204 determines whether the voltage of the power rail is greater than or equal to the overvoltage threshold. When the voltage of the power rail is less than the overvoltage threshold, at box 604, the controller 204 resets the overvoltage counter to a minimum value. For example, the controller 204 can reset the overvoltage counter by setting the value of the overvoltage counter to zero. Next, the method 600 returns to box 602 to again determine whether the voltage of the power rail is greater than or equal to the overvoltage threshold.

[0054] When the voltage of the power rail is greater than or equal to the overvoltage threshold, the controller 204 increments the overvoltage counter at block 606. For example, Figure 7 FIG. 1 shows a timing diagram of an overvoltage counter that counts consecutive overvoltage events. Figure 7 As shown in FIG. 1 , whenever the voltage of the power rail is greater than or equal to the overvoltage threshold of 630 mV, the overvoltage counter value is increased by one. In addition, whenever the voltage of the power rail is less than the overvoltage threshold, the overvoltage counter value is increased by one. Figure 7 The overvoltage counter in is reset to zero. Return to Figure 6 At block 608, the controller 204 determines whether the overvoltage counter is equal to the continuous event warning threshold. Generally, the continuous event warning threshold is less than the continuous event warning threshold described above. Figure 4The continuous event warning threshold is an example of a “threshold” or “first threshold”. When the overvoltage counter is equal to the continuous event warning threshold, the controller 204 generates an interrupt signal at block 610. For example, Figure 7 In the example, when the overvoltage counter value equals the four consecutive event warning threshold at approximately 98 microseconds, an interrupt signal is generated. Figure 6 After block 610 in FIG. 6 , method 600 returns to block 602 to again determine whether the voltage of the power rail is greater than or equal to the overvoltage threshold.

[0055] Returning to block 608, when the overvoltage counter is not equal to the continuous event warning threshold, the controller 204 determines at block 612 whether the overvoltage counter is equal to the continuous event shutdown threshold. The continuous event shutdown threshold is greater than the continuous event warning threshold. For example, the continuous warning shutdown threshold may be four, and the continuous event shutdown threshold may be eight. The continuous event shutdown threshold is an example of a "second threshold." When the overvoltage counter is not equal to the continuous event shutdown threshold, the method 600 returns to block 602 to again determine whether the voltage of the power rail is greater than or equal to the overvoltage threshold. Alternatively, when the overvoltage counter is equal to the continuous shutdown event threshold, the controller 204 generates a shutdown signal at block 614. For example, Figure 7 In , when the value of the overvoltage counter equals the continuous event shutdown threshold of eight at approximately 112 microseconds, a shutdown signal is generated. Upon receiving the shutdown signal, the safety controller 112 can instruct the system power supply 106 to perform an emergency shutdown. For example, the safety controller 112 can send one or more control signals to the system power supply 106 that cause the system power supply 106 to immediately disable all power rails. Figure 6 After block 614 in FIG. 6 , method 600 returns to block 602 to again determine whether the voltage of the power rail is greater than or equal to the overvoltage threshold.

[0056] Extreme overvoltage events can cause damage to components in the load device 104 almost immediately. Therefore, in some implementations, the controller 204 can generate a shutdown signal when the voltage of the power rail is greater than or equal to the overvoltage shutdown threshold. The overvoltage shutdown threshold is the minimum voltage level of the power rail that can cause damage to components in the load device 104 almost immediately. The overvoltage shutdown threshold is much higher than the overvoltage threshold described above. The overvoltage shutdown threshold can be set based on the technology used in the load device 104. For example, Figure 8 is a timing diagram of an example of using the overvoltage shutdown threshold and undervoltage shutdown threshold to generate a shutdown signal. Figure 8 As shown, the overvoltage threshold is 630 mV and the overvoltage shutdown threshold is 720 mV. When the voltage of the power rail is greater than 720 mV at about 79 microseconds, Figure 8The overvoltage threshold is an example of a “first overvoltage threshold”. The overvoltage shutdown threshold is an example of a “second overvoltage threshold”.

[0057] An extreme undervoltage event in the power rail can almost immediately cause a calculation error in the load device 104. Therefore, in some implementations, the controller 204 can generate a shutdown signal when the voltage of the power rail is less than or equal to the undervoltage shutdown threshold. The undervoltage shutdown threshold is the maximum voltage level of the power rail that can almost immediately cause a calculation error in the load device 104. This undervoltage threshold is much lower than the above-mentioned undervoltage threshold. The undervoltage shutdown threshold can be set based on the technology used in the load device 104. For example, in Figure 8 , the undervoltage warning threshold is 570 mV, and the undervoltage shutdown threshold is 480 mV. The undervoltage threshold is an example of a “first overvoltage threshold.” The undervoltage shutdown threshold is an example of a “second overvoltage threshold.”

[0058] In some implementations, the controller 204 can generate an interrupt signal when the overvoltage counter indicates a moving average of overvoltage events equal to a rolling average threshold. Fig. 9 9 is a flow chart of an example of a method 900 for tracking a moving average of overvoltage events of a power rail according to some specific implementations. To simplify the description, the method 900 is described as a series of operations performed by the controller 204. However, operations according to the method 900 may be performed by different components. At block 902, the controller 204 determines whether the voltage of the power rail is greater than or equal to the overvoltage threshold. When the voltage of the power rail is less than the overvoltage threshold, at block 904, the controller 204 determines whether the overvoltage counter is greater than a minimum value. When the overvoltage counter is equal to the minimum value (e.g., equal to zero), the method 900 returns to block 902 to determine again whether the voltage of the power rail is greater than or equal to the overvoltage threshold. Alternatively, when the overvoltage counter is greater than the minimum value, the controller 204 decrements the overvoltage counter at block 906. For example, when the value of the overvoltage counter is greater than zero, the controller 204 may reduce the value of the overvoltage counter by one. Next, the method 900 returns to block 902 to determine again whether the voltage of the power rail is greater than or equal to the overvoltage threshold.

[0059] When the voltage of the power rail is greater than or equal to the overvoltage threshold, the controller 204 increments the overvoltage counter at block 908. For example, Fig.10 Figure 1 shows the timing diagram of the overvoltage counter tracking the moving average. Fig.10 As shown in FIG. 1 , whenever the voltage of the power rail is greater than or equal to the overvoltage threshold of 630 mV, the overvoltage counter value is increased by one. In addition, whenever the voltage of the power rail is less than the overvoltage threshold, the overvoltage counter value is increased by one. Fig.10 The overvoltage counter value in is reduced by one. Return to Fig. 9, at block 910, the controller 204 determines whether the overvoltage counter is equal to a rolling average threshold. A rolling average threshold is an example of a "threshold." When the overvoltage counter is not equal to the rolling average threshold, the method 900 returns to block 902 to again determine whether the voltage of the power rail is greater than or equal to the overvoltage threshold. Alternatively, when the overvoltage counter is equal to the rolling average threshold, the controller 204 generates an interrupt signal at block 912. For example, Fig.10 In the example, an interrupt signal is generated when the overvoltage counter value is equal to the rolling average threshold of seven at approximately 94 microseconds. Fig. 9 After block 912 in , method 900 returns to block 902 to again determine whether the voltage of the power rail is greater than or equal to the overvoltage threshold. In some implementations, controller 204 can generate an interrupt signal when the undervoltage counter indicates that the moving average of undervoltage events is equal to the rolling average threshold.

[0060] The controller 204 can determine the average voltage of the power rail based on a moving average of overvoltage events and a moving average of undervoltage events. In some implementations, the controller 204 can determine the average voltage of the power rail using a weighted formula (eg, the following formula 1):

[0061]

[0062] Where RAIL_AVG is the average voltage of the power rail, OV_MA is the moving average of overvoltage events, OV_THR is the overvoltage threshold, UV_MA is the moving average of undervoltage events, and UV_THR is the undervoltage threshold. For example, when the moving average of overvoltage events is 10, the overvoltage threshold is 630 millivolts, the moving average of undervoltage events is 6, and the undervoltage threshold is 570 millivolts, the controller 204 can determine that the average voltage of the power rail is 604.6 millivolts.

[0063] As described above, the controller 204 may use an overvoltage counter to track the total number of overvoltage events, the number of consecutive overvoltage events, the moving average of overvoltage events, or a combination thereof. In some implementations, the controller 204 is configured to implement separate overvoltage counters to track different overvoltage statistics. For example, the controller 204 may use a first overvoltage counter to track the total number of overvoltage events, a second overvoltage counter to track the number of consecutive overvoltage events, and a third overvoltage counter to track the moving average of overvoltage events. In addition, the controller 204 may use separate undervoltage counters to track different undervoltage statistics.

[0064] Fig.111 is a flow chart of an example of a method 1100 for operating a power supply circuit 102 to detect an overvoltage event according to some specific implementations. At block 1102, the controller 204 determines a voltage of a power rail provided from the system power supply 106 to the load device 104. At block 1104, the controller 204 detects that the voltage of the power rail is greater than or equal to an overvoltage threshold. At block 1106, when it is detected that the voltage of the power rail is greater than or equal to the overvoltage threshold, the controller 204 increments an overvoltage counter. At block 1108, the controller 204 detects that the overvoltage counter is equal to the threshold. For example, the controller 204 may detect that the overvoltage counter is equal to the threshold as described above with respect to Figure 4 and Figure 5 The reporting thresholds described above Figure 6 and Figure 7 Continuous event warning thresholds described above, or Fig. 9 and Fig.10 At block 1110 , when it is detected that the overvoltage counter is equal to the threshold, the controller 204 generates an interrupt signal.

[0065] Fig.12 is a flow chart of an example of a method 1200 for operating the power supply circuit 102 to detect an undervoltage event according to some implementations. In some implementations, the operations of the method 1200 described below can be performed sequentially with the operations of the method 1100 described above. At box 1202, the controller 204 determines the voltage of a power rail provided from the system power supply 106 to the load device 104. At box 1204, the controller 204 detects that the voltage of the power rail is less than or equal to an undervoltage threshold. At box 1206, when it is detected that the voltage of the power rail is less than or equal to an overvoltage threshold, the controller 204 increments an undervoltage counter. At box 1208, the controller 204 detects that the undervoltage counter is equal to a threshold. For example, the controller 204 may detect that the undervoltage counter is equal to the threshold described above with respect to Figure 4 and Figure 5 The reporting thresholds described above Figure 6 and Figure 7 The continuous event warning threshold described above, or Fig. 9 and Fig.10 At block 1210 , when it is detected that the undervoltage counter is equal to the threshold, the controller 204 generates an interrupt signal.

[0066] Consistent with the above disclosure, the examples of systems and methods listed in the following clauses are specifically contemplated and intended as a non-limiting set of examples.

[0067] Clause 1. A method for operating a power supply, the method comprising:

[0068] determining a voltage of a power rail provided from the power supply to a load device;

[0069] Detecting that the voltage of the power rail is greater than or equal to an overvoltage threshold;

[0070] When it is detected that the voltage of the power rail is greater than or equal to the overvoltage threshold, incrementing an overvoltage counter;

[0071] detecting that the overvoltage counter is equal to a threshold; and

[0072] When it is detected that the overvoltage counter is equal to the threshold, an interrupt signal is generated.

[0073] Clause 2. A method according to any clause herein, wherein the threshold is a first threshold, and wherein the method further comprises:

[0074] detecting that the voltage of the power rail is less than or equal to an undervoltage threshold;

[0075] When it is detected that the voltage of the power rail is less than or equal to the undervoltage threshold, incrementing an undervoltage counter;

[0076] detecting that the undervoltage counter is equal to a second threshold; and

[0077] When it is detected that the undervoltage counter is equal to the second threshold, the interrupt signal is generated.

[0078] Clause 3. A method according to any clause herein, further comprising:

[0079] determining a first moving average of overvoltage events of the power rail;

[0080] determining a second moving average of undervoltage events for the power rail; and

[0081] An average value of the voltage of the power rail is determined based on the first moving average value and the second moving average value.

[0082] Clause 4. A method according to any clause herein, wherein the overvoltage threshold is a first overvoltage threshold, and wherein the method further comprises:

[0083] detecting that the voltage of the power rail is greater than or equal to a second overvoltage threshold, wherein the second overvoltage threshold is greater than the first overvoltage threshold; and

[0084] When it is detected that the voltage of the power rail is greater than or equal to the second overvoltage threshold, a shutdown signal is generated.

[0085] Clause 5. A method according to any clause herein, further comprising:

[0086] When the interrupt signal is generated, sending the value of the overvoltage counter; and

[0087] After sending the value of the overvoltage counter, resetting the overvoltage counter to a minimum value.

[0088] Clause 6. The method of any clause herein, further comprising resetting the overvoltage counter to a minimum value when the voltage of the power rail is not detected to be greater than or equal to the overvoltage threshold.

[0089] Clause 7. A power monitor comprising:

[0090] A voltage fault detector is configured to:

[0091] determining the voltage of a power rail provided from a power supply to a load device; and

[0092] detecting when the voltage of the power rail is greater than or equal to an overvoltage threshold; and

[0093] A controller, the controller being configured to:

[0094] incrementing an overvoltage counter when the voltage fault detector detects that the voltage of the power rail is greater than or equal to the overvoltage threshold; and

[0095] When the overvoltage counter is equal to a threshold value, an interrupt signal is generated.

[0096] Clause 8. A power monitor as described in any clause herein, wherein the threshold is a first threshold, wherein the voltage fault detector is further configured to detect when the voltage of the power rail is less than or equal to an undervoltage threshold, and wherein the controller is further configured to:

[0097] incrementing an undervoltage counter when the voltage fault detector detects that the voltage of the power rail is less than or equal to the undervoltage threshold; and

[0098] When the undervoltage counter is equal to a second threshold, the interrupt signal is generated.

[0099] Clause 9. A power monitor according to any clause herein, wherein the controller is further configured to:

[0100] determining a first moving average of overvoltage events of the power rail,

[0101] determining a second moving average of undervoltage events of the power rail, and

[0102] An average value of the voltage of the power rail is determined based on the first moving average value and the second moving average value.

[0103] Clause 10. A power monitor as described in any clause herein, wherein the overvoltage threshold is a first overvoltage threshold, wherein the voltage fault detector is further configured to detect when the voltage of the power rail is greater than or equal to a second overvoltage threshold, wherein the second overvoltage threshold is greater than the first overvoltage threshold, and wherein the controller is further configured to generate a shutdown signal when the voltage fault detector detects that the voltage of the power rail is greater than or equal to the second overvoltage threshold.

[0104] Clause 11. A power monitor as described in any clause herein, wherein the voltage fault detector comprises a fast analog comparator.

[0105] Clause 12. A power monitor as described in any clause herein, wherein the controller is further configured to reset the overvoltage counter to a minimum value when the voltage fault detector does not detect that the voltage of the power rail is greater than or equal to the overvoltage threshold.

[0106] Clause 13. A power monitor according to any clause herein, wherein the controller is further configured to decrement the overvoltage counter when:

[0107] The voltage fault detector does not detect that the voltage of the power rail is greater than or equal to the overvoltage threshold; and

[0108] The overvoltage counter is greater than a minimum value.

[0109] Clause 14. A power circuit comprising:

[0110] a power supply configured to provide a power rail to a load device; and

[0111] A power monitor, the power monitor being configured to:

[0112] detecting when a voltage of the power rail is greater than or equal to an overvoltage threshold;

[0113] incrementing an overvoltage counter each time the power monitor detects that the voltage of the power rail is greater than or equal to the overvoltage threshold; and

[0114] When the overvoltage counter is equal to a threshold value, an interrupt signal is generated.

[0115] Clause 15. A power circuit according to any clause herein, further comprising a safety controller configured to:

[0116] receiving the interrupt signal;

[0117] When the interrupt signal is received, reading the value of the overvoltage counter from the power monitor; and

[0118] After the value of the overvoltage counter is read out, the overvoltage counter is reset to a minimum value.

[0119] Clause 16. The power supply circuit of any clause herein, wherein the safety controller is further configured to adjust a target voltage of the power rail based on the value of the overvoltage counter.

[0120] Clause 17. The power circuit of any clause herein, wherein the power supply is a system power supply, and wherein the power circuit further comprises a safety power supply configured to provide power to the safety controller independently of the system power supply.

[0121] Clause 18. The power supply circuit of any clause herein, wherein the power monitor is further configured to reset the overvoltage counter when the power monitor does not detect that the voltage of the power rail is greater than or equal to the overvoltage threshold.

[0122] Clause 19. A power supply circuit according to any clause herein, wherein the threshold is a first threshold, and wherein the power monitor is further configured to:

[0123] detecting when the overvoltage counter is equal to a second threshold, wherein the second threshold is greater than the first threshold; and

[0124] When the power monitor detects that the overvoltage counter is equal to the second threshold, a shutdown signal is generated.

[0125] Clause 20. The power circuit of any clause herein, wherein the load device comprises a system on chip (SoC) device.

[0126] Many electrical connections in the drawings are shown as directly coupled without intervening devices, but are not explicitly described as such in the above description. However, for electrical connections shown in the drawings without intervening devices, this paragraph should serve as an antecedent basis for the claims for referring to any electrical connection as "directly coupled."

[0127] The above discussion is intended to illustrate the principles and various specific implementations of the present invention. Once the above disclosure is fully understood, many variations and modifications will become apparent to those skilled in the art. The following claims are interpreted as being intended to include all such variations and modifications.

[0128] List

[0129] 102 Power Circuit

[0130] 104 Load Devices

[0131] 106 System Power

[0132] 108 Power Monitor

[0133] 110 Safety Power Supply

[0134] 112 Safety Controller

[0135] 114 rail power supply connection

[0136] 116 Reference Links

[0137] 118 Reference terminal

[0138] 120 Data Connections

[0139] 122 First control input

[0140] 124 Second control input

[0141] 126 rail power output

[0142] 128 Reference Links

[0143] 132 rail power supply connection

[0144] 134 Reference Links

[0145] 136 First Data Connection

[0146] 138 Second data connection

[0147] 140 First control output

[0148] 142 Second control output

[0149] 144 Power output terminal

[0150] 146 Reference Links

[0151] 148 Power supply connection

[0152] 150 Reference Links

[0153] 152 Data Connections

[0154] 154 First control input

[0155] 156 Second control input

[0156] 202 Fault Voltage Detector

[0157] 204 Controller

[0158] 206 first voltage input terminal

[0159] 208 Second voltage input terminal

[0160] 210 First control output

[0161] 212 Second control output terminal

[0162] 214 First control input terminal

[0163] 216 Second control input

[0164] 218 First Data Connection

[0165] 220 Second data connection

[0166] 222 First control output

[0167] 224 Second control output

[0168] 302 Voltage Monitor

[0169] 304 Overvoltage Comparator

[0170] 306 Undervoltage Comparator

[0171] 308 first voltage input terminal

[0172] 310 Second voltage input terminal

[0173] 312 Voltage output terminal

[0174] 314 Non-inverting input terminal

[0175] 316 Input

[0176] 318 Output

[0177] 320 Non-inverting input

[0178] 322 Input

[0179] 324 Output

Claims

1. A method for operating a power supply, characterized in that The method comprises: determining a voltage of a power rail provided from the power supply to a load device; Detecting that the voltage of the power rail is greater than or equal to an overvoltage threshold; When it is detected that the voltage of the power rail is greater than or equal to the overvoltage threshold, incrementing an overvoltage counter; detecting that the overvoltage counter is equal to a threshold; and When it is detected that the overvoltage counter is equal to the threshold, an interrupt signal is generated.

2. The method according to claim 1, wherein: The threshold is a first threshold, and wherein the method further comprises: detecting that the voltage of the power rail is less than or equal to an undervoltage threshold; When it is detected that the voltage of the power rail is less than or equal to the undervoltage threshold, incrementing an undervoltage counter; detecting that the undervoltage counter is equal to a second threshold; and When it is detected that the undervoltage counter is equal to the second threshold, the interrupt signal is generated.

3. The method according to claim 2, wherein: The method further comprises: determining a first moving average of overvoltage events of the power rail; determining a second moving average of undervoltage events for the power rail; and An average value of the voltage of the power rail is determined based on the first moving average value and the second moving average value.

4. The method according to claim 1, wherein: The overvoltage threshold is a first overvoltage threshold, and wherein the method further comprises: detecting that the voltage of the power rail is greater than or equal to a second overvoltage threshold, wherein the second overvoltage threshold is greater than the first overvoltage threshold; and When it is detected that the voltage of the power rail is greater than or equal to the second overvoltage threshold, a shutdown signal is generated.

5. The method according to claim 1, wherein: The method further comprises: When the interrupt signal is generated, sending the value of the overvoltage counter; and After sending the value of the overvoltage counter, resetting the overvoltage counter to a minimum value.

6. A power monitor, characterized in that: The power monitor comprises: A voltage fault detector is configured to: determining the voltage of a power rail provided from a power supply to a load device; and detecting when the voltage of the power rail is greater than or equal to an overvoltage threshold; and A controller, the controller being configured to: incrementing an overvoltage counter when the voltage fault detector detects that the voltage of the power rail is greater than or equal to the overvoltage threshold; and When the overvoltage counter is equal to a threshold value, an interrupt signal is generated.

7. The power monitor of claim 6, wherein: The threshold is a first threshold, wherein the voltage fault detector is further configured to detect when the voltage of the power rail is less than or equal to an undervoltage threshold, and wherein the controller is further configured to: incrementing an undervoltage counter when the voltage fault detector detects that the voltage of the power rail is less than or equal to the undervoltage threshold; as well as When the undervoltage counter is equal to a second threshold, the interrupt signal is generated.

8. The power monitor of claim 6, wherein: The overvoltage threshold is a first overvoltage threshold, wherein the voltage fault detector is further configured to detect when the voltage of the power rail is greater than or equal to a second overvoltage threshold, wherein the second overvoltage threshold is greater than the first overvoltage threshold, and wherein the controller is further configured to generate a shutdown signal when the voltage fault detector detects that the voltage of the power rail is greater than or equal to the second overvoltage threshold.

9. The power monitor of claim 6, wherein: The controller is further configured to reset the overvoltage counter to a minimum value when the voltage fault detector does not detect that the voltage of the power rail is greater than or equal to the overvoltage threshold.

10. The power monitor of claim 6, wherein: The controller is further configured to decrement the overvoltage counter when: The voltage fault detector does not detect that the voltage of the power rail is greater than or equal to the overvoltage threshold; and The overvoltage counter is greater than a minimum value.

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