Monitoring circuit and corresponding method

Abstract

The invention relates to a monitoring circuit and a corresponding method. A circuit for monitoring an actual threshold voltage value of a MOSFET includes: a current source coupled to a source terminal of the MOSFET and generating a test current; a voltage generator coupled between the gate terminal and the source terminal of the MOSFET and generating a test voltage below a nominal threshold voltage value of the MOSFET; a detection unit sampling the voltage value at the source terminal during a time to calculate therefrom a value of the voltage value at the source terminal over time and provide the value to an alarm generation unit; the alarm generating unit receives the output voltage, compares the output voltage with a reference voltage, and gives an alarm if the compared output does not correspond to a preset output condition; and the control unit is used for receiving a test mode signal. The control unit selects the coupling or decoupling state of the current source and the source terminal according to the signal, determines the value of the reference voltage, sets the output condition of comparison, and sends a signal to notify the detection unit to execute the sampling operation.

Description

Technical Field

[0001] This specification relates to monitoring circuits. Background Art

[0002] Health monitoring of electronic components is the prediction of potential failure of such components and involves measuring deviations in electrical parameters associated with physical degradation of such components.

[0003] Health monitoring is very important because electronic components are widely used in most of the systems and their failure may lead to malfunction and / or downtime of such systems, so preventing such failures can improve the robustness and reliability of the system.

[0004] Specifically, health monitoring is relevant in the automotive field, where preventing hazards can improve passenger safety.

[0005] In fact, ISO 26262 is the de facto international standard for the functional safety of electrical and / or electronic systems installed in series-produced road vehicles. It defines minimum safety requirements measured using the Automotive Safety Integrity Level (ASIL), a safety level determined through hazard analysis and risk assessment.

[0006] Therefore, fault prediction and health monitoring of vehicle electrical components can improve the vehicle's ASIL safety level, allowing preemptive maintenance or replacement of electronic components deemed to be at risk.

[0007] To meet the requirements of ISO26262, safety-critical environments (such as automotive power distribution environments) can use E-Fuses ("electronic fuses") with high ASIL safety levels. Such E-Fuses are integrated power path protection devices used to limit circuit current and / or voltage to safe levels under fault conditions.

[0008] Typically, such an E-Fuse may perform inrush current control using a power metal oxide semiconductor field effect transistor (MOSFET). Under certain fault conditions, such a power MOSFET may be affected by a short circuit fault, i.e., a fault in which the power MOSFET cannot be controlled to be turned off through its gate, thereby reducing the reliability of the E-Fuse and causing a safety critical situation.

[0009] Such short circuit faults in power MOSFETs can be generated by physical degradation of the gate structure, such as:

[0010] High leakage in the gate oxide, and / or

[0011] The presence of charges trapped in the gate oxide.

[0012] In particular, the last case may result in a reduction in a threshold voltage of a power MOSFET, such threshold voltage corresponding to a voltage for switching the state of such a power MOSFET from a non-conducting state (“OFF”) to a conducting state (“ON”).

[0013] Such a reduction can continue until the power MOSFET, and the corresponding device (i.e., the corresponding E-Fuse) normally remain in the ON state, for example, if the threshold voltage value of the power MOSFET is reduced to zero or a negative value, so that such power MOSFET cannot be controlled to be turned off (i.e., switched to a non-conducting state) through its gate.

[0014] For example, Figure 1 An E-Fuse structure 10 is shown, illustrating the effects of physical degradation of a power MOSFET 100 .

[0015] exist Figure 1 In the example, the gate capacitance C of the power MOSFET 100 is DG (i.e., between the drain terminal D and the gate terminal G of the power MOSFET 100) and C GS (i.e., between the gate terminal G and the source terminal S of the power MOSFET 100) are represented by values ​​equal to C DG The drain-gate capacitor 106 has a value equal to C GS The gate source capacitor 108.

[0016] The controller 102 is configured to send an ON command C to the gate driver 104. ON or OFF command C OFF , so as to set the state of power MOSFET 100 to an ON state (ie, a conducting state) or an OFF state (ie, a non-conducting state), respectively.

[0017] The gate driver 104 is configured to change the gate-source voltage V between the gate terminal G and the source terminal S of the power MOSFET 100 in response to receiving a command from the controller 102. GS The value of .

[0018] In particular, in response to the ON command C ON , the gate driver 104 is configured to convert the gate-source voltage V GS The value is set to be higher than the threshold voltage V of the power MOSFET 100 TH to set the state of such power MOSFET 100 to the ON state.

[0019] On the contrary, in response to the OFF command C OFF , the gate driver 104 is configured to convert the gate-source voltage VGS The value is set to be lower than the threshold voltage V of the power MOSFET 100. TH The second value of is set to zero, for example, so as to set the state of power MOSFET 100 to a non-conductive OFF state.

[0020] The blocking diode 110 is a body drain diode of the power MOSFET 100, which is inherent to the power MOSFET structure itself.

[0021] exist Figure 1 In the embodiment, the controller 102 is configured to send an OFF command C to the gate driver 104. OFF , in response to such an OFF command C OFF The gate driver is configured to receive the gate-source voltage V GS The value of is set to a second value, that is, set to be lower than the threshold voltage V of the power MOSFET 100 TH The value of, for example, is set to zero.

[0022] In this case, if the physical structure of the gate G of the power MOSFET 100 is degraded, for example, resulting in a threshold voltage V TH The value of the relevant decrease, for example, if the threshold voltage V TH If the current value is negative, even if the OFF command is received, C OFF After that, the power MOSFET 100 and the corresponding E-Fuse 10 remain in the ON state, so even if such an OFF command C is received OFF After that, the current I DS It also flows between the drain terminal D and the source terminal S of the power MOSFET 100 .

[0023] Therefore, even if the controller 102 has sent a command requesting to switch such E-Fuse to a non-conductive OFF state, the E-Fuse 10 remains in a conductive ON state, thereby generating a short circuit fault characterized by uncontrolled conduction.

[0024] Such a short-circuit fault seriously undermines the safety requirements specified in ISO26262 because the power MOSFET 100 and the corresponding device (i.e., the corresponding E-Fuse 10) cannot be controlled and turned off if necessary, that is, such an E-Fuse 10 with a corresponding power MOSFET 100 that has a short-circuit fault cannot limit the current and / or voltage to a safe level when necessary.

[0025] In fact, in the case of a short-circuit fault of the E-Fuse 10 with the corresponding power MOSFET 100, the current I flowing between the drain terminal D and the source terminal S of the power MOSFET 100 is DS cannot be interrupted, and therefore, the circuit to be protected coupled to the drain terminal D and / or source terminal S of such a power MOSFET 100 cannot be interrupted (ie, its overcurrent and / or overvoltage cannot be limited), and thus, the protection fails.

[0026] Furthermore, the uncontrolled ON state of the power MOSFET 100 may generate high power dissipation, resulting in high temperature, for example, an increase in the temperature of an ECU (“Electronic Control Unit”) in which the corresponding E-Fuse 10 having the power MOSFET 100 that has a short-circuit fault is installed, thereby causing a fire hazard.

[0027] A solution that facilitates health monitoring of such devices to prevent short circuit failures would facilitate early prediction of degradation of such devices and prevent potential failures leading to uncontrolled turn-on. Summary of the invention

[0028] One or more embodiments help provide solutions that facilitate health monitoring of MOSFETs to prevent short circuit failures, to provide early prediction of degradation of such MOSFETs and corresponding devices (eg, E-Fuse), and to prevent potential failures leading to uncontrolled turn-on.

[0029] One or more embodiments are directed to a circuit having the following features.

[0030] One or more embodiments are directed to a corresponding method.

[0031] The solution described in this article includes a circuit for monitoring the actual threshold voltage value of a power MOSFET, the circuit comprising:

[0032] a current source configured to be coupled to the source terminal of the power MOSFET and to generate a test current,

[0033] a voltage generator configured to be coupled between a gate terminal of the power MOSFET and a source terminal of the power MOSFET and to generate a test voltage, such a test voltage being lower than a nominal threshold voltage value of the power MOSFET,

[0034] a detection unit configured to sample a plurality of voltage values ​​at the source terminal of the power MOSFET during time, to calculate a value of at least a voltage variation of such voltage value at the source terminal of the power MOSFET over time, in particular within a given time period, from such a plurality of voltages, and to provide such calculated value of at least the voltage variation to the alarm generation unit,

[0035] an alarm generating unit configured to receive such calculated voltage variation from the detection unit, compare such calculated voltage variation with a reference voltage, and issue an alarm if an output of such comparison does not correspond to a predetermined output condition, and

[0036] a control unit configured to receive a test mode signal indicating an operating mode,

[0037] wherein such a control unit is further configured to select a coupling or decoupling state of such a current source with a source terminal of the power MOSFET according to such a received test mode signal,

[0038] Determine the value of such a reference voltage,

[0039] Set such an output condition for such a comparison, and

[0040] The detection unit is signaled to perform a plurality of such sampling operations.

[0041] In various embodiments, if such test mode signal indicates the first test mode, such control unit is configured to:

[0042] Decoupling such a current source from the source terminal of the power MOSFET,

[0043] determining a value of such reference voltage so that such reference voltage is a positive voltage that is smaller than any possible value of such calculated voltage variation obtained when the value of the actual threshold voltage is equal to or lower than the test voltage, and

[0044] A result of comparison between such calculated voltage variation and such reference voltage indicating that such calculated voltage variation is higher than such reference voltage is set as such predetermined output condition.

[0045] If such a test mode signal indicates the second mode, such a control unit is further configured to:

[0046] Coupling such a current source to the source terminal of the power MOSFET,

[0047] determining a value of such reference voltage so that such reference voltage is higher than any possible value of such calculated voltage variation obtained when the value of the actual threshold voltage is equal to or lower than the test voltage, and is lower than any possible value of such calculated voltage variation obtained when the value of the actual threshold voltage is higher than the test voltage, and

[0048] A result of comparison between such calculated voltage variation and such reference voltage indicating that such calculated voltage variation is smaller than such reference voltage is set as such predetermined output condition.

[0049] In various embodiments, such a test mode signal is configured to indicate a first sub-mode of such a first test mode and a second sub-mode of such a first mode, wherein in the first sub-mode, such a given time period is shorter than that in the second mode.

[0050] In various embodiments, such a circuit is coupled to an external load via the source terminal of the power MOSFET, and

[0051] The test mode signal selects an operating mode from a set of available operating modes, such a set of available operating modes comprising at least:

[0052] Such a first mode, which is selected when the coupled external load is in the disconnected state,

[0053] Such a first mode includes such a first sub-mode corresponding to a resistive load and such a second sub-mode corresponding to a load including both a capacitive component and a resistive component, and

[0054] Such a second mode is selected when the coupled external load is in the on-state, in the standby mode and the load corresponds to a capacitive load.

[0055] In various embodiments, such a MOSFET is a power MOSFET.

[0056] In various embodiments, such plurality of voltage values ​​includes a first voltage value and a second voltage value, such first voltage value being retrieved at the beginning of a given time period and such second voltage value being retrieved at the end of the given time period; and

[0057] Such a calculation operation for obtaining a voltage variation from such a plurality of voltage values ​​includes subtracting such a second voltage value from such a first voltage value.

[0058] In various embodiments, such a detection unit comprises:

[0059] a sensing unit configured to sense a voltage value at a source terminal of the power MOSFET and forward such sensed voltage value to a first sample-and-hold block and a second sample-and-hold block,

[0060] a first sample-and-hold block configured to sample such a first voltage value in response to receiving a signal from the control unit instructing to perform a first of such sampling operations, hold such a first voltage value for an amount of time greater than such a given period of time, and provide such a first voltage value to the subtraction block,

[0061] a second sample-and-hold block configured to sample such a second voltage value, hold such a second voltage value, and provide such a second voltage value to the subtraction block in response to receiving a signal from the control unit instructing to perform a second sampling operation of such sampling operations,

[0062] A subtraction block is configured to receive a first voltage value from the first sample and hold block and a second voltage value from the second sample and hold block, perform such subtraction of such second voltage value from such first voltage value to obtain such voltage change, and provide such voltage change to an alarm generation unit.

[0063] In various embodiments, such an alarm generating unit comprises:

[0064] a reference voltage generator configured to provide such a reference voltage to the comparator block, and

[0065] A comparator block is configured to receive such calculated voltage variation from the detection unit and such reference voltage from the reference voltage generator, compare such calculated voltage variation with such reference voltage, and issue an alarm in response to an unsuccessful comparison operation.

[0066] In various embodiments, such circuitry further comprises:

[0067] A first switch is configured to couple or decouple such a current source to a source terminal of the power MOSFET in response to receiving a signal from the control unit in accordance with such a test mode signal.

[0068] In various embodiments, such a circuit further comprises an additional switch configured to decouple the gate driver from the gate terminal of the power MOSFET in response to receiving a signal from the control unit indicating the start of such monitoring of the actual threshold voltage value, and to couple the gate driver to the gate terminal of the power MOSFET in response to receiving a signal from the control unit indicating the end of such monitoring of the actual threshold voltage value.

[0069] In various embodiments, such test voltage is fixed, or such test voltage is dynamic, and such control unit is further configured to:

[0070] Choose the initial value of the test voltage so that

[0071] Start monitoring the actual threshold voltage value like this,

[0072] If the alarm generating unit does not issue any alarm before the monitoring of such actual threshold voltage value ends, the value of such test voltage is increased by a given step size and the steps are performed again from the beginning of the monitoring, and

[0073] If the alarm generating unit issues an alarm before such monitoring of the actual threshold voltage value ends, the current value of the test voltage is identified as the value of the actual threshold voltage value.

[0074] In various embodiments, such circuitry is also coupled to a temperature monitoring unit or monitor, such temperature monitoring unit being configured to:

[0075] monitoring the temperature of the power MOSFET to sense at least one temperature value, and

[0076] calculating a value of such test voltage as a function of such at least one sensed temperature value, and

[0077] Such a value of such a test voltage is provided to the circuit to generate a test voltage of such a value by a voltage generator.

[0078] In various embodiments, such a circuit includes another switch configured to couple or decouple such a voltage generator to the gate terminal of the power MOSFET in response to receiving a signal issued in accordance with such a test mode signal from the control unit, and in such a first mode and a second mode, such a voltage generator remains coupled to the gate terminal of the power MOSFET.

[0079] In various embodiments, in such first and second modes, if the test enable signal mode is not set, such a voltage generator is decoupled from the gate terminal of the power MOSFET.

[0080] The solution described herein helps to implement health monitoring of a device (e.g., E-Fuse) by monitoring the corresponding MOSFET to prevent short-circuit failures in such MOSFET. In this way, early prediction of degradation of such MOSFET and corresponding device (i.e., E-Fuse) can be made and potential failures leading to uncontrolled conduction can be prevented. BRIEF DESCRIPTION OF THE DRAWINGS

[0081] One or more embodiments will now be described by way of example with reference to the accompanying drawings, in which:

[0082] Figure 1 An E-Fuse structure is shown, which illustrates the effects of physical degradation of a power MOSFET, as previously described;

[0083] Figure 2 A solution for measuring the value of the threshold voltage in a power MOSFET is shown;

[0084] Figure 3 Shows Figure 2 A solution for measuring a value of a threshold voltage in a power MOSFET coupled to an external device;

[0085] Figure 4 It shows Figure 3 Time diagram of signal behavior in the solution;

[0086] Figure 5 is a block diagram of a monitoring circuit for measuring a value of a threshold voltage in a power MOSFET coupled to an external device according to an embodiment of the present specification;

[0087] Figure 6 This is a diagram showing an embodiment according to the present specification. Figure 5 Timing diagram of signal behavior in a circuit;

[0088] Figure 7 is a diagram showing an example of an embodiment of the present specification when a coupled external device is disconnected and can be modeled as a resistive load. Figure 5 Timing diagram of signal behavior in a circuit;

[0089] Figure 8 is a diagram showing an example of an embodiment of the present specification when a coupled external device is disconnected and can be modeled as a capacitive / resistive load. Figure 5 Time diagram of signal behavior in a circuit;

[0090] Fig. 9 and Fig.10 is a diagram showing an embodiment of the present specification when a coupled external device is in standby mode and can be modeled as a pure capacitive load. Figure 5 timing diagrams of signal behavior in circuits; and

[0091] Fig.11 According to the embodiments of the present specification, Figure 5 A system of circuits and temperature change monitoring units.

[0092] Corresponding numerals and symbols in the different figures generally refer to corresponding parts unless otherwise indicated.

[0093] The figures are drawn to clearly illustrate the relevant aspects of the embodiments and are not necessarily drawn to scale.

[0094] The edges of features drawn in the figure do not necessarily indicate the end of the feature's extent. DETAILED DESCRIPTION

[0095] In the following description, one or more specific details are shown to provide a deeper understanding of the examples of embodiments of the present specification. These embodiments can be obtained without one or more specific details, or using other methods, components, materials, etc. In other cases, known structures, materials, or operations are not shown or described in detail so as not to obscure certain aspects of the embodiments.

[0096] In the framework of this specification, references to "an embodiment" or "one embodiment" are intended to indicate that a particular configuration, structure or characteristic described in connection with the embodiment is included in at least one embodiment. Therefore, phrases such as "in one embodiment" or "in one implementation" that may appear in one or more places in this specification do not necessarily refer to the same embodiment.

[0097] Furthermore, particular configurations, structures, or characteristics may be combined in any suitable manner in one or more embodiments.

[0098] The headings / references used herein are for convenience only, and therefore do not limit the scope of protection or the scope of the embodiments.

[0099] For simplicity and ease of explanation, throughout the specification, unless the context indicates otherwise, the same reference numerals will be used to refer to the same components or elements in the various drawings, and the corresponding description will not be repeated for each drawing.

[0100] In particular, in the following figures, reference has been made to Figure 1 The described parts, components and / or assemblies are indicated by the same reference numerals previously used in the figure, and thus, in order not to overcomplicate the present detailed description, the description of such previously described elements will not be repeated below.

[0101] As previously mentioned, it would be beneficial to find a solution that facilitates MOSFET health monitoring and protection against short circuit failures, so as to provide early prediction of degradation of such MOSFETs and corresponding devices (ie, E-Fuse) and prevent potential failures leading to uncontrolled turn-on.

[0102] According to an embodiment of the present disclosure, the diagnosis described above (i.e., health monitoring of the MOSFET and corresponding devices) can be performed by monitoring the threshold voltage V THvalue is accomplished while such a power MOSFET is coupled to a given circuit to be protected, i.e., it is coupled to a given load.

[0103] Note that even though the following description focuses mainly on solutions using power MOSFETs, e.g., N-channel power MOSFETs or P-channel power MISFETs, the solutions described herein can also be implemented using GaN transistors or SiC power MOSFETs.

[0104] It should be noted that even though the following description focuses mainly on the application of the proposed solution in the automotive field, the solution described in this article can also be used in other application environments, where it is necessary to measure and / or monitor the threshold voltage of a power MOSFET with a coupled load (e.g., resistive and / or capacitive load).

[0105] In many application environments, the standard threshold voltage V TH Measurement, for example, because the E-Fuse 10 (i.e., the corresponding MOSFET) can always be coupled to a resistive and / or capacitive load, i.e., coupled to the circuit to be protected. In addition, such an E-Fuse 10 can be configured to set the corresponding power MOSFET 100 to a conductive ON state by default (in the event of overcurrent and / or overvoltage being detected in such a circuit to be protected, such a power MOSFET 100 can be switched to a non-conductive OFF state), so that in most cases, the threshold voltage V TH The measurement should be performed during the conducting ON state of such power MOSFET 100 .

[0106] Figure 2 The method for measuring the threshold voltage V in the power MOSFET 100 is shown. TH The solution for the value is 20.

[0107] Figure 2 The power MOSFET 100 is configured as:

[0108] A voltage source 202 and a switch 204 are coupled to the drain terminal D thereof, and the voltage source is configured to supply a voltage V to the power MOSFET 100. S The switch is configured to be in a closed state;

[0109] coupling the closed switch 204 to its gate terminal G, so that both the drain terminal D and the gate terminal G are set to the same voltage level; and

[0110] A current source 200 (eg, a current generator) is coupled to its source terminal S, and the current source 200 is configured to generate a current having a value of I TESTThe test current, for example, is the minimum value that allows the state of the power MOSFET 100 to be switched from the non-conducting OFF state to the conducting ON state, that is, the gate-source voltage V GS The voltage between the gate terminal G and the source terminal S of the power MOSFET 100 is set to the current threshold voltage V TH The minimum value of the value.

[0111] like Figure 2 As shown, in such a structure 20, the drain-source voltage V DS (i.e., the voltage between the drain terminal D and the source terminal S) is equal to the gate-source voltage V GS (i.e., the voltage between the gate terminal G and the source terminal S), because the drain terminal D and the gate terminal G are from the same voltage level V S .

[0112] Therefore, in Figure 2 Under the condition of drain-source voltage V DS Equal to the gate-source voltage V GS , and both voltages are equal to the threshold voltage V of the power MOSFET 100 TH The value of .

[0113] Therefore, the threshold voltage V of the power MOSFET 100 is TH The value of can be based on the test current I generated by the current source 200 TEST to evaluate the value.

[0114] However, when a load is coupled to the source terminal S of the power MOSFET 100 , such a solution 20 cannot be used.

[0115] At this point, Figure 3 Shows Figure 2 Solution 20 for measuring a threshold voltage V in a power MOSFET 100 coupled to an external device 300 TH value, i.e., by any capacitive load C LOAD (e.g., load capacitor) and / or resistive load R LOAD (e.g., load resistor) indicates.

[0116] Note that although Figure 3 shows a resistive load R LOAD and capacitive load C LOAD The load 300, but such a load 300 may exhibit only substantially resistive behavior, that is, may correspond to a only resistive load component R LOAD Or it can be modeled with only it, presenting only capacitive behavior, that is, it can correspond to only capacitive load component CLOAD Or it can be modeled with just the resistive component R LOAD and the capacitive component C LOAD Both.

[0117] like Figure 3 As shown, when a load 300 (eg, an ECU) is coupled to the source terminal S of the power MOSFET 100, a test current I generated by the current source 200 TEST The value of cannot be defined and is set to a selected value because its value is affected by a given load 300, i.e., by the voltage V across the load 300. LOAD The influence of the voltage of the source terminal S is determined, and the voltage can also be a variable voltage.

[0118] This may be the case, for example, in an automotive environment, where load 300 may represent an ECU (ie, electronic control unit), which may be modeled as a resistive load R LOAD and capacitive load C LOAD Both (ie, where the capacitor may be a bulk capacitor having a value of approximately 1 mF).

[0119] Considering Figure 3 Note that if the load 300, for example, includes only capacitive components C LOAD , for example, if the load 300 is an ECU in standby mode Sb, it is modeled as a capacitor C LOAD , then the threshold voltage V TH can be measured. In this case, the threshold voltage V TH The value of can be measured by closing switch 204 and waiting for the charging time CT CLOAD to proceed, that is, until the capacitor C LOAD The selected test current I TEST Charge.

[0120] The disadvantage is that the capacitive component C LOAD The threshold voltage V TH The measurement delay is up to the charging time C CLOAD , that is, equal to time, because the test current I TEST (e.g., 1 mA current) must be applied to the capacitive component C LOAD flows until the drain-source voltage V DS Keep stable to the threshold voltage V TH value.

[0121] For example, if the capacitive load C LOAD About 1mF, test current I TEST About 1mA, threshold voltage V THAbout 1.5V, the charging time CT CLOAD It is about 1.5s, which is not negligible.

[0122] Figure 4 It is shown Figure 3 Time diagram of the signal behavior in solution 30.

[0123] Current signal I RLOAD Indicates the resistance element R at load 300 LOAD Current flowing inside.

[0124] When the current signal I RLOAD When the value is zero, for example, when the corresponding ECU enters the standby mode Sb, the only remaining component of the load 300 is the capacitive component C LOAD , therefore, the threshold voltage V TH .

[0125] In response to the current signal I RLOAD The value of the switch control signal S ON / OFF For example, the test current I TEST Starting at a capacitive component C of the load 300 LOAD flow in order to make such a capacitive component C LOAD Charge until the voltage V DS Maintains basic stability to the threshold voltage V TH value, that is, during the charging time TC CLOAD after.

[0126] Simplify and increase the threshold voltage V in the transistor TH A solution with improved monitoring accuracy (allowing such monitoring even when a load is coupled to the transistor) would be beneficial for early prediction of device degradation and prevention of potential failures leading to uncontrolled turn-on.

[0127] Figure 5 is a method for measuring the threshold voltage V in the power MOSFET 100 according to an embodiment of the present specification. TH 40 , the power MOSFET is coupled to an external device 300 , ie, a load 300 .

[0128] Note that such a monitoring circuit MC may be embedded in, for example, a power actuator, an electrical fuse, or the like.

[0129] Figure 5 The power MOSFET 100 is configured as:

[0130] A voltage source 202 is coupled to the drain terminal D thereof, the voltage source being configured to supply a voltage V to the power MOSFET 100. S Voltage;

[0131] coupling a first switch 402 and a second switch 406 to gate terminals G thereof, the first switch being configured to couple such MOSFET 100 to a first output terminal of a gate driver 104, the second switch being configured to couple such MOSFET 100 to a voltage generator 404; and

[0132] The second output terminal of the gate driver 104, the third switch 420 configured to couple the MOSFET 100 to the current source 200, and the external load 300 are coupled to the source terminal S thereof, and the external load may be a Figure 3 The same types as already described in .

[0133] The gate driver 104 is configured to respond to a command C received from the controller 102 ON / OFF (Previously described, Figure 5 (not shown) to change the gate-source voltage V of the power MOSFET 100 GS (that is, the value of the voltage between the gate terminal G and the source terminal S).

[0134] To this end, the gate driver 104 has a first output terminal configured to be coupled to the gate terminal G of the power MOSFET 100 , for example via a first switch 402 , and a second output terminal configured to be coupled to the source terminal S of the power MOSFET 100 .

[0135] Therefore, in response to the ON command C ON , the gate driver 104 is configured to convert the gate-source voltage V GS The value is set to be higher than the threshold voltage V of the power MOSFET 100 TH The first value of the value of is set to set the state of such power MOSFET 100 to the ON state.

[0136] On the contrary, in response to the OFF command C OFF , the gate driver 104 is configured to convert the gate-source voltage V GS The value is set to be lower than the threshold voltage V TH The second value of the value of is set to zero, for example, so as to set the state of power MOSFET 100 to a non-conductive OFF state.

[0137] The first switch 402 is configured to couple the first output terminal of the gate driver 104 to the gate terminal G of the power MOSFET 100 in response to receiving a disconnect gate driver signal D from the timing block 400 (e.g., a microcontroller, control logic, or other type of processing unit) indicating that the gate driver 104 is coupled to the power MOSFET 100. GD And is enabled.

[0138] In fact, the first switch 402 is also configured to receive the gate driver disconnect signal D from the timing block 400. GD , and in response to such a turn-off gate driver signal D GD And change its state, that is, change to open or closed.

[0139] Therefore, if the gate driver signal D is disconnected GD Indicating coupling of the gate driver 104 to the power MOSFET 100, such first switch 402 is configured to be closed.

[0140] In contrast, the first switch 402 is configured to disconnect the gate driver signal D GD The gate driver 104 is instructed to be decoupled from the power MOSFET 100 and remain disconnected.

[0141] The current source 200 (eg, a current generator) is configured to be coupled to the source terminal S of the power MOSFET 100, for example, through the third switch 420, and to generate a test current I flowing through the load 300 and / or the source terminal S of the power MOSFET 100. TEST .

[0142] The third switch 420 is configured to couple such current source 200 to the source terminal S of the power MOSFET 100 and the load 300 in response to receiving a connection load test signal C from the timing block 400 indicating that the current source 200 is coupled to such MOSFET 100 and the load 300. LTEST And is enabled.

[0143] In fact, the third switch 420 is also configured to receive the connection load test signal C from the timing block 400. LTEST , and in response to such a connection load test signal C LTEST And change its state, that is, change to open or closed.

[0144] Therefore, if the load test signal C is connected LTEST Indicating coupling of the current source 200 to the power MOSFET 100 and the load 300, such third switch 420 is configured to be closed.

[0145] In contrast, the third switch 420 is configured to respond to the connection load test signal C LTEST It is indicated that the current source 200 is decoupled from the power MOSFET 100 and the load 300 and remains disconnected.

[0146] The voltage generator 404 is configured to supply a voltage V between the gate terminal G and the source terminal S of the power MOSFET 100. TEST The test voltage controls the gate-source voltage V GS value.

[0147] To this end, such a voltage generator 404 is configured to be coupled to the second output terminal of the gate driver 104 (ie to the source terminal S of the power MOSFET 100 ) and to the gate terminal G of the power MOSFET 100 , for example via a second switch 406 .

[0148] Such a value supplied by the voltage generator 404 is V TEST The test voltage is from the threshold voltage V TH The nominal value deviates from the selected amount V GAP The selected amount can be set according to the application under consideration and the safety level to be observed.

[0149] Therefore, since the test voltage V TEST The value is greater than the nominal threshold voltage NV TH Small set value V GAP , when such a test voltage V TEST When applied between the gate terminal G and the source terminal S of the power MOSFET 100, it is expected that the corresponding MOSFET 100 is maintained in a non-conductive OFF state.

[0150] Note that if the actual threshold voltage AV TH From the nominal threshold voltage NV TH offset (e.g., due to physical degradation of the gate structure) equal to or above a selected value V GAP The amount that makes the actual threshold voltage AV TH Equal to or lower than voltage V TEST , then it is possible that, in response to applying a test voltage V between the gate terminal G and the source terminal S of the power MOSFET 100 TEST , such that the MOSFET 100 can be turned into an ON state, that is, the current I DS Starts to flow between the drain terminal D and the source terminal S of the power MOSFET 100 .

[0151] In response to the current I DSThe voltage V across the load 300 is observed. LOAD changes.

[0152] Therefore, the load 300 can be used as a current sensor to check the current I DS Whether or not current flows between the drain terminal D and the source terminal S of the power MOSFET 100 is independent of the circuitry of the load itself and / or independent of the circuitry of the power actuator, in which an embodiment of the proposed solution may be embedded.

[0153] It may be noted that, in general, the power MOSFET 100 may include a current mirror referred to as a FET, and thus, such a current mirror may be used as a current sensor itself.

[0154] However, using such a current mirror as a current sensor may be unreliable because the threshold voltage V TH The drift in the current I flowing between the drain terminal D and the source terminal S of the power MOSFET 100 may change DS The current ratio to the current flowing in such a current mirror makes the sensed current obtained using such a current mirror inside such a MOSFET 100 unreliable.

[0155] In various embodiments, the test voltage V TEST And therefore the selected value V GAP can be fixed. In this case, Figure 5 The monitoring circuit MC is configured as follows: If the actual threshold voltage AV TH Reach the test voltage V TEST (i.e., equal to or lower than voltage V TEST ), an alarm is sounded. Such a situation can be detected by detecting the voltage V on the load 300 LOAD In response to the test voltage V applied to the power MOSFET 100 TEST and switches such a MOSFET 100 from a non-conductive OFF state to a conductive ON state (i.e., generates a current I flowing between the drain terminal D and the source terminal S). DS ) to identify.

[0156] In various embodiments, the test voltage V TEST And therefore the selected value V GAP can be dynamic. In this case, Figure 5 The monitoring circuit MC performs the following operations:

[0157] The test voltage V TEST Sum value V GAP Set to initial value;

[0158] For example, the state of the power MOSFET 100, i.e., the conducting ON state or the non-conducting OFF state, is tested by using the load 300 as a current sensor;

[0159] If the power MOSFET 100 is in the non-conductive OFF state, for example, if no current flowing in the load 300 is detected, the test voltage V TEST The value of is increased by a given step size (step), and the value V GAP Decrease the same given step size and return to the test step again; and

[0160] If the power MOSFET 100 is in the ON state, for example, if it is detected that the current flowing in the load 300 has a voltage V across the load 300 LOAD The corresponding change of the test voltage V TEST The value corresponds to the actual threshold voltage AV TH .

[0161] Therefore, with a dynamic test voltage V TEST In the embodiment, the actual threshold voltage AV can be measured TH , because the actual threshold voltage AV TH Corresponding to the selected voltage V TEST .

[0162] Note that if the current flowing in the load 300 is compatible with the measurable current range of the load 300, the actual threshold voltage AV TH Such measurement, wherein the range of such measurable current depends on the minimum measurable voltage and the resistive component R of the load 300 LOAD The value of .

[0163] The second switch 406 is configured to couple the voltage generator 404 to the gate terminal G of the power MOSFET 100 in response to receiving a voltage equalization signal V from the timing block 400 indicating that the voltage generator 404 is coupled to the gate terminal G of the power MOSFET 100. EQ and is enabled so that the gate-source voltage V GS The value is set to the voltage V TEST Substantially equal values ​​(ie, taking into account a given tolerance range).

[0164] In fact, the second switch 406 is also configured to receive the voltage equal signal V from the timing block 400. EQ , and in response to such a voltage equal signal V EQ And change its state, that is, change to open or closed.

[0165] Therefore, if the voltage is equal to the signal V EQ Indicating coupling of the voltage generator 404 to the power MOSFET 100, such second switch 406 is configured to be closed.

[0166] In contrast, the second switch 406 is configured to respond to the voltage equalization signal V EQ The voltage generator 404 is indicated to be decoupled from the power MOSFET 100 and remain disconnected.

[0167] The timing block 400 is configured to receive at least a test enable signal TE and a test mode signal TM, the test enable signal indicating whether to use Figure 5 The monitoring circuit MC is used to monitor the threshold voltage V of the power MOSFET 100. TH The test mode signal indicates which test mode among multiple test modes is to be used for the test of the value of Figure 5 Such a monitoring circuit MC performs a threshold voltage V of the power MOSFET 100 TH The value of the current test.

[0168] For example, the multiple test modes may include at least:

[0169] a first mode in which the coupled external device is considered to be in an OFF state; and

[0170] The second mode, in which the coupled external device is considered to be in the ON state, in standby mode, and the load 300 may correspond to or may be modeled as a purely capacitive load C LOAD .

[0171] Such a first mode may also include at least:

[0172] The first sub-mode, where the coupled external device corresponds to or can be modeled as a resistive load R LOAD ;as well as

[0173] The second sub-mode, in which the coupled external device corresponds to or can be modeled as including a capacitive component C LOAD and the resistive component R LOAD Both load 300.

[0174] According to such a test enable signal TE and such a test mode signal TM, the timing block 400 is further configured to generate a plurality of control signals, such a plurality of control signals at least including the following signals:

[0175] Disconnect gate driver signal D GD , which indicates to the first switch 402 whether the gate driver 104 is to be coupled to the gate terminal G of the power MOSFET 100 or to be decoupled therefrom;

[0176] Voltage equal signal V EQ , which indicates to the second switch 406 whether the voltage generator 404 is to be coupled to the gate terminal G of the power MOSFET 100 or to be decoupled therefrom;

[0177] Connect the load test signal C LTEST , which indicates to the third switch 420 whether the current source 200 is to be coupled to the source terminal S of the power MOSFET 100 or to be decoupled therefrom;

[0178] The first load voltage sampling signal S VLOAD,T0 , which indicates to the first sample and hold ("S&H") block 410 whether the received signal is to be sampled; and

[0179] The second load voltage sampling signal S VLOAD,Td , which indicates to the second sample-and-hold ("S&H") block 412 whether the received signal is to be sampled.

[0180] The sense block 408 is configured to have a sense terminal coupled to the source terminal S of the power MOSFET 100 and the load 300 , and an output terminal coupled to the first sample-and-hold block 410 and the second sample-and-hold block 412 .

[0181] Such a sensing block 408 is also configured to:

[0182] The value of the voltage at the source terminal S of the power MOSFET 100 and the load 300 is sensed through its sensing terminal, that is, the voltage V LOAD to monitor its changes, and

[0183] Through its output terminal, the voltage V LOAD The sensed values ​​are forwarded to the first sample and hold block 410 and the second sample and hold block 412 .

[0184] The first sample and hold block 410 is configured to receive the voltage V from the sensing block 408 LOAD The sensed value and the first load voltage sampling signal S received from the timing block 400 VLOAD,T0 , and, in response to receiving such a first load voltage sampling signal S indicating sampling of the received signal VLOAD,T0 , the first sample and hold block 410 is further configured to receive the voltage V LOAD The sensed value is sampled and its value is kept for a given time, for example, longer than the selected time period T d long time while providing it to the subtraction block 414.

[0185] Similarly, the second sample and hold block 412 is configured to receive the voltage V LOADThe sensed value and the second load voltage sampling signal S received from the timing block 400 VLOAD,Td , and, in response to receiving such a second load voltage sampling signal S indicating sampling of the received signal VLOAD,Td The second sample and hold block 412 is further configured to receive the voltage V LOAD The sensed value is sampled and its value is kept for a given time, for example, longer than the selected time period T d Long or short time, and provide it to subtraction block 414 at the same time.

[0186] The subtraction block 414 is configured to receive the voltage V from the first sample and hold block 410 and the second sample and hold block 412. LOAD The sensed value received from the second sample and hold block 412 is subtracted from the sensed value received from the first sample and hold block 410 , and the result of such subtraction is provided to a first input terminal of the comparator 418 .

[0187] In various embodiments, the functions performed by the sense block 408, the first sample and hold block 410, the second sample and hold block 412, and the subtraction block 414 may be performed by detection units or detectors 408-414 configured to:

[0188] The voltage value V at the source terminal S of the sensing power MOSFET 100 and thus across the load 300 is LOAD ,

[0189] The calculation indicates that the sensed voltage value V LOAD In a given time period T d , for example, by subtracting a second voltage value sensed at a second time from a first voltage value sensed at a first time (i.e., before the second time), and

[0190] Provided to comparator 418 or alarm generating unit 416-418 indicating that within a given time period T d Such a sensed voltage value V LOAD The above voltage changes with the change of.

[0191] In fact, these functions performed by the sensing block 408, the first sample and hold block 410, the second sample and hold block 412 and the subtraction block 414 can be performed by different actual implementations. For example, such functions can be implemented without using the first sample and hold block 410 and the second sample and hold block 412.

[0192] In this case, the reference voltage generator 416 and the comparator 418 may be coupled to the ground terminal GND for the first test mode and to a reference voltage having a value of V for the second test mode. SThen, for example, after a delay of T d Thereafter, the voltage change may be acquired by monitoring the output of the comparator 418 .

[0193] The reference voltage generator 416 is configured to supply a value of V to the second input terminal of the comparator 418. REF The reference voltage.

[0194] In various embodiments, such a reference voltage value V generated by the reference voltage generator 416 is REF It may be determined according to the current test mode considered (ie, according to the current value of the test mode signal TM).

[0195] The comparator 418 (for example, implemented by an operational amplifier) ​​is configured to receive the result of the subtraction from the subtraction block 414 or the voltage change provided by the detection units 408-414 at its first input terminal, and receive the reference voltage V from the reference voltage generator 416 at its second input terminal. REF .

[0196] Such comparator 418 is further configured to compare the voltage values ​​received at its first input terminal and the second input terminal, and, if the result of such comparison is unsuccessful, the comparator 418 is configured to generate an alarm signal AL. VTH , to indicate that the corresponding circuit may have a risk of short circuit failure.

[0197] In particular, the result of such a comparison may be considered unsuccessful if the output of the comparison does not correspond to a predetermined output condition, which may depend on the current test mode under consideration, for example:

[0198] If the first test mode or the second test mode described previously is used, if the result of the subtraction received at the first input terminal from the subtraction block 414 is higher than the reference voltage V received at the second input terminal REF , the result of the comparison is considered unsuccessful, therefore, typically, if, for example, the voltage received by the comparator 418 changes above the reference voltage V REF , the comparison result is considered unsuccessful; and

[0199] If the third mode described previously is used, then if the result of the subtraction received at the first input terminal from the subtraction block 414 is lower than the reference voltage V received at the second input terminal REF , the comparison result is considered unsuccessful, therefore, generally, if, for example, the voltage received by the comparator 418 changes below the reference voltage V REF , the comparison result is considered unsuccessful.

[0200] In various embodiments, the reference voltage generator 416 and the comparator 418 may be included in an alarm generating unit or alarm generator 416-418 configured to:

[0201] receiving a sensed voltage value V indicating such LOAD In a given time period T d The voltage change within, for example, the subtraction result from the subtraction block 414 or the output of the detection unit 408-414,

[0202] The received voltage change is compared with the reference value V REF for comparison, the reference value may be generated internally according to the current test mode under consideration, for example using the voltage generator 416, or received from an external unit, and

[0203] For example, by activating the alarm signal AL in response to an unsuccessful comparison operation. VTH Set to a high logic level to generate an alarm (ie, where the compare operation is deemed unsuccessful according to the criteria previously described).

[0204] In summary, the actual threshold voltage value AV used to monitor the MOSFET 100 TH (ie, the threshold voltage V of MOSFET 100 TH The circuit MC of the current value) includes:

[0205] The current source 200 is configured to be coupled to the source terminal S of the MOSFET 100 and to generate a test current I TEST ,

[0206] A voltage generator 404 is configured to be coupled between the gate terminal G of the MOSFET 100 and the source terminal S of the MOSFET 100 and to generate a test voltage V TEST , the above test voltage V TEST Lower than the nominal threshold voltage NV of MOSFET 100 TH , that is, the threshold voltage V of MOSFET 100 TH without any modification due to external influences,

[0207] Detection units 408-414, which are configured to detect during a time period (eg, during a time period T d During the period) a plurality of voltage values ​​V at the source terminal S of the MOSFET 100 are LOAD Sampling is performed, that is, sampling the voltage value on the coupling load 300 to obtain the voltage value V LOADTo calculate the value of at least one voltage varying with time, for example, the voltage value V at the source terminal S of the MOSFET 100 LOAD (especially in a given time period T d and providing the above-calculated value of at least the voltage change to the alarm generating units 416-418,

[0208] The alarm generating units 416-418 are configured to receive the calculated voltage changes from the detection units 408-414, compare the calculated voltage changes with the reference voltage V REF A comparison is made and if the output of the above comparison does not correspond to a predetermined output condition, for example, if the result of such a comparison is unsuccessful, an alarm AL is issued. VTH ,as well as

[0209] a control unit or controller 400, ie a timing block 400, which is configured to receive a test mode signal TM indicating an operating mode, ie depending on the load currently coupled to such a monitoring circuit MC,

[0210] The control unit 400 is further configured to select a coupling or decoupling state between the current source 200 and the source terminal S of the MOSFET 100 according to the received test mode signal TM.

[0211] Determine the reference voltage V REF The value of

[0212] setting the above output condition of the above comparison, i.e., the corresponding condition that the result of such comparison is determined to be unsuccessful according to the coupled load, and

[0213] Signaling detection units 408-414 to perform a plurality of the above-mentioned sampling operations, for example, instructing the first sample and hold block 410 and the second sample and hold block 412 to sample the voltage V on the load received from the sensing block 408 LOAD Take samples.

[0214] Figure 6 This is a diagram showing an embodiment according to the present specification. Figure 5 Timing diagram of the signal behavior in the monitoring circuit MC.

[0215] In particular, Figure 6 The behavior of signals received by or generated from the timing block 400 is shown.

[0216] In response to receiving a test enable signal TE (the signal indicates the use of the test enable signal by switching from a low logic level to a high logic level, for example). Figure 5 The monitoring circuit MC performs the threshold voltage V of the power MOSFET 100. THThe timing block 400 is configured to, for example, sample the signal S at the first load voltage. VLOAD,T0 The first sample and hold block 410 is instructed to perform a voltage test on the voltage V by sending a pulse on the voltage V or by switching it to a high logic level before any change occurs in the operation of the circuit. LOAD The sensed value is sampled.

[0217] In response to the first sample and hold block 410 detecting the voltage V LOAD The sensed value is sampled, the timing block 400 is configured to modify Figure 5 The operation of the monitoring circuit MC is, for example, achieved by placing a voltage equal to the signal V EQ is set to a high logic level, indicating that the voltage generator 404 is coupled to the gate terminal G of the power MOSFET 100, and the gate-source voltage V GS The value is set to be substantially equal to the voltage V TEST The value of .

[0218] Then, at T d After a given time of , the timing block 400 is further configured to, for example, sample the second load voltage signal S VLOAD,Td The second sample and hold block 412 is instructed to change the gate-source voltage V by sending a pulse on or switching it to a high logic level. GS Set to voltage V TEST After that, the voltage V LOAD The sensed value is sampled, so the voltage V LOAD Sampling is performed after the operation of the circuit is changed.

[0219] In this way, the subtraction block 414 can obtain the sense voltage V received from the first sample and hold block 410. LOAD The sense voltage V received from the second sample and hold block 412 is subtracted from the sense voltage V received from the second sample and hold block 412 (ie, before any changes occur in the operation of the circuit) LOAD (That is, when the gate-source voltage V GS Set to voltage V TEST After that, the sensing voltage V LOAD ).

[0220] The available test mode among the plurality of test modes is selected to avoid interfering with the operation of the coupled load 300 (eg, ECU).

[0221] To this end, by setting the test enable signal TE to a high logic level, the monitoring circuit MC can advantageously be activated, for example, under certain operating conditions, for example, when the coupled load 300 is in a disconnected state or in a standby mode, in particular:

[0222] When the coupling load 300 is in the OFF state and can be replaced by a resistive load R LOADWhen modeling;

[0223] When the coupled load 300 is in the OFF state and can be connected with a resistive component R LOAD and the capacitive component C LOAD When modeling both loads 300; and

[0224] When the coupled load 300 is in the ON state, in standby mode, and can be connected with capacitor C LOAD Load modeling.

[0225] Thus, in various embodiments, monitoring circuit MC may be activated when coupled load 300 is in an OFF state, ie, when no current flows in such load 300, for example, in case a power actuator directly activates resistive and / or capacitive loads.

[0226] In this case, when the coupled load 300 is in the OFF state, the voltage V on the load 300 is LOAD is a very low voltage, for example, a voltage close to zero, and therefore, the corresponding gate-source voltage V GS Basically zero.

[0227] Figure 7 is a diagram showing that when the coupled external device 300 (ie, the coupled load 300) is in the OFF state and can be modeled as a resistor R according to an embodiment of the present specification LOAD Load Figure 5 Timing diagram of the signal behavior in the monitoring circuit MC.

[0228] like Figure 7 As shown, the connection load test signal C supplied by the timing block 400 to the third switch 420 LTEST is set to, for example, a low logic level to indicate that such third switch 420 is turned off so as to decouple the current source 200 from the source terminal S of the power MOSFET 100. Therefore, the test current I TEST does not flow in the load 300 .

[0229] Under such conditions, if the test is enabled, for example, by setting the test enable signal TE to a high logic level, the timing block 400 is configured to sample the signal S at the first load voltage, for example. VLOAD,T0 The first sample and hold block 410 is instructed to send a pulse on the power MOSFET 100 or to switch it to a high logic level before any change occurs in the operation of the monitoring circuit MC (i.e., when the gate-source voltage V GS is essentially equal to zero and the load is in a non-conducting OFF state) for the voltage V LOAD The sensed value is sampled.

[0230] As described above, in response to the first sample and hold block 410 detecting the voltage V LOAD The sensed value is sampled, and the timing block 400 is configured to, for example, equalize the voltage signal V EQ is set to a high logic level to indicate to the second switch 406 that the voltage generator 404 is to be coupled to the gate terminal G of the power MOSFET 100 to modify the gate-source voltage V GS to set its value substantially equal to the voltage V TEST The value of .

[0231] Note that in various embodiments, for example, Figure 7 In the embodiment, the voltage equals the signal V EQ can be set equal to the test voltage V supplied by the voltage generator 404 TEST The voltage level of 404 is determined so as to instruct the second switch 406 to couple the voltage generator 404 to the power MOSFET 100.

[0232] Therefore, when the second switch 406 couples the voltage generator 404 with the gate terminal G of the power MOSFET 100, such a voltage generator 404 supplies a test voltage V between the gate terminal G and the source terminal S of the power MOSFET 100. TEST , thereby modifying the gate-source voltage V GS The value of .

[0233] If the actual threshold voltage AV TH is higher than the test voltage V supplied by the voltage generator 404 TEST , the power MOSFET 100 remains in the non-conducting OFF state, so there is no current I in the load 300 LOAD flows, and the voltage V on the load 300 LOAD is held to be the same value as the value previously sampled by the first sample and hold block 410 .

[0234] In this case, the voltage V sampled by the second sample and hold block 412 is LOAD The sensed value of will be substantially equal to the voltage sampled by the first sample and hold block 410. Therefore, the subtraction result from the subtraction block 414 or the voltage change provided by the detection cells 408-414 will result in a value substantially equal to zero.

[0235] On the contrary, as mentioned above, if the actual threshold voltage AV TH From the nominal threshold voltage NV TH Shifts, for example, due to physical degradation of the gate structure, make the actual threshold voltage AV TH is equal to or lower than the test voltage V supplied by the voltage generator 404 TEST (like Figure 7 As shown), the power MOSFET 100 can change its state from the non-conductive OFF state to the conductive ON state because the voltage applied between its gate terminal G and the source terminal S (i.e., the test voltage V TEST ) is higher than the actual threshold voltage AV TH value.

[0236] In response to the power MOSFET 100 changing its state to the ON state, the current I DS Starts to flow between the drain terminal D and the source terminal S of the power MOSFET and thus flows within the load 300 (ie, a resistive load).

[0237] Therefore, if Figure 7 As shown, it can be observed that the voltage V on the load 300 LOAD and the current I in the load 300 LOAD The changes of the two, in particular, such a current I LOAD The value of can be obtained using the following formula:

[0238] I LOAD =(V TEST -AV TH *G M

[0239] Among them G M is the transconductance of the power MOSFET, and the voltage V on the load 300 LOAD The value of can be obtained using the following formula:

[0240] V LOAD =I LOAD *R LOAD

[0241] Therefore, only the resistor element R LOAD The constructed resistive load 300 can be used as a current sensor to check whether the power MOSFET 100 has changed its state from the non-conductive OFF state to the conductive ON state.

[0242] The actual threshold voltage AV TH The value of T d After a given time of , the timing block 400 is further configured to, for example, sample the second load voltage signal S VLOAD,Td The second sample and hold block 412 is instructed to respond to the voltage V by sending a pulse on it or switching it to a high logic level. LOAD The sensed value is sampled.

[0243] In the gate-source voltage V GS Set to voltage V TEST Such a time Td After that, the power MOSFET 100 may have changed its state from the non-conductive OFF state to the conductive ON state, and the voltage V LOAD and the current I in the load 300 LOAD Changes in both can already be observed.

[0244] In particular, if the actual threshold voltage AV TH is higher than the test voltage V supplied by the voltage generator 404 TEST , then the voltage V sampled by the second sample and hold block 412 LOAD The sensed value of is substantially equal to the voltage sampled by the first sample and hold block 410 .

[0245] On the contrary, if the actual threshold voltage AV TH is equal to or lower than the test voltage V supplied by the voltage generator 404 TEST , then the voltage V sampled by the second sample and hold block 412 LOAD The sensed value of is different from (ie, higher than) the voltage sampled by the first sample and hold block 410 and is equal to V LOAD =I LOAD *R LOAD .

[0246] Therefore, the subtraction block 414 can receive the sensing voltage V from the first sample and hold block 410. LOAD (ie, the voltage V sensed before any modification in the operation of the monitoring circuit MC LOAD , i.e., when such load 300 is in a non-conductive OFF state) minus the sensing voltage V received from the second sample and hold block 412 LOAD (i.e., the gate-source voltage V GS Set to voltage V TEST Such a time T d After that, the sensed voltage V LOAD , i.e. when such a load 300 may have changed its state to a conducting state), to obtain an indication in such a time period T d The value of the voltage change on the load 300 during the period.

[0247] If the actual threshold voltage AV TH is equal to or lower than the test voltage V supplied by the voltage generator 404 TEST , then such a value indicating a voltage change on the load 300 indicates a voltage change between a conductive state of such load 300 and a non-conductive OFF state of such load 300.

[0248] Note that such a value indicating a voltage change across the load 300 may indicate a current I LOADIs it in time period T d During this time, current flows in the load 300 .

[0249] In fact, if the value of the voltage change is substantially zero, the voltage V across the load 300 LOAD During the entire time period T d The actual threshold voltage AV TH Higher than the test voltage V TEST , and the current I LOAD At such a time T d The period does not flow in such a load 300 .

[0250] On the contrary, if the value of the voltage change is different from zero, the voltage V on the load 300 LOAD In time period T d period changes, so the actual threshold voltage AV TH Equal to or lower than the test voltage V TEST And at such a time T d During this period, the current I flowing in such a load 300 LOAD .

[0251] If the reference voltage generator 416 is correctly configured to supply the reference voltage V REF (like Figure 7 The value is:

[0252] When the actual threshold voltage AV TH Equal to or lower than the test voltage V TEST any possible voltage changes that can be obtained when

[0253] If the value is higher than the minimum value, for example, a value slightly higher than zero, the comparator 418 may generate an alarm signal AL VTH , to indicate if the acquired voltage changes to a value higher than such a properly defined reference voltage V REF , the power MOSFET 100 and the corresponding device (eg, E-Fuse) may be at risk of short circuit failure.

[0254] In various embodiments, if the first mode or the second mode is selected, the reference voltage V REF can be the voltage of the reference ground terminal GND, since the power MOSFET is initially in the non-conducting OFF state. In this case, for example, the reference voltage V REF You can Figure 7 and Figure 8 As shown, there is a double arrow between a first level indicating a corresponding ground voltage (ie having a value of substantially zero) and a second level indicating a voltage value that satisfies the above two conditions for correctly configuring the reference voltage generator.

[0255] The method for determining such a time T is described below. d The size of the standard.

[0256] Figure 8 is a diagram showing that when the coupled external device 300 is in the OFF state and can be modeled as a capacitive / resistive load according to an embodiment of the present specification Figure 5 Timing diagram of the signal behavior in the monitoring circuit MC.

[0257] Figure 8 Most of the signals shown behave as corresponding signals, i.e. Figure 7 Signals shown and described are denoted by the same reference numerals. For this reason, the description of the behavior and timing of such signals will not be repeated below in order not to overburden this detailed description.

[0258] Figure 7 The signal behavior in Figure 8 The difference between the signal behavior in is obtained by adding a capacitive component in the load 300.

[0259] If the actual threshold voltage AV TH is higher than the test voltage V supplied by the voltage generator 404 TEST , then use Figure 8 The test mode shown obtains signal behavior equal to that obtained using Figure 7 The behavior of the test mode acquisition shown is therefore not described in detail below in order not to overburden this specification.

[0260] Even in the Figure 8 In the embodiment shown, if the actual threshold voltage AV TH From the nominal threshold voltage NV TH until it reaches a value equal to or lower than the test voltage V supplied by the voltage generator 404. TEST The power MOSFET 100 changes its state from the non-conducting OFF state to the conducting ON state, thereby causing the voltage V on the load 300 to LOAD and the current I in the load 300 LOAD Changes in both.

[0261] In response to adding such a capacitive component C in the load 300 LOAD , the voltage on the load 300 V LOAD With the capacitive component C of the load 300 LOAD is charged and slowly changes its value (such as Figure 8 shown).

[0262] In particular, such a current I LOADThe value of can be obtained again using the following formula:

[0263] I LOAD =(V TEST -AV TH *G M

[0264] The voltage V on the load 300 LOAD The value of can be obtained using the following formula:

[0265]

[0266] Therefore, even when using Figure 8 In the embodiment of the test mode shown, the load 300 can also be used as a current sensor to check whether the power MOSFET 100 has changed its state from the non-conducting OFF state to the conducting ON state, provided that the sensing voltage V LOAD The delay time T between the first sampling and the second sampling d is sized so as to allow the capacitive component C of the load 300 to be sensed prior to the second sampling operation. LOAD Fully charge.

[0267] Therefore, the load 300 may include a capacitive component C LOAD In various embodiments, the sensing voltage V LOAD The delay time T between the first sampling and the second sampling d is sized so as to allow a current I to flow within such a coupled load 300. LOAD For such a capacitive component C LOAD Charge.

[0268] The load 300 is not configured to include a capacitive component C LOAD The resistive component R LOAD In various embodiments, even if the sensing voltage V LOAD There is a delay time T between the first sampling and the second sampling. d , such a time T d The load 300 may also include a capacitive component C LOAD The embodiment of the present invention is much shorter because it only includes a resistive component R LOAD The voltage on the load 300 V LOAD The change ratio also includes the capacitive component C LOAD The load on 300 is much faster.

[0269] In various embodiments, when the load 300 is in standby mode, that is, when there is a power supply voltage V FUSEWhen the load 300 is supplied but no current flows in such load 300, for example, when the electronic fuse ensures that the power supply voltage V FUSE While such a load 300 is in standby mode and no current flows therethrough, the monitoring circuit MC may be activated.

[0270] Typically, in automotive applications, load 300 may include a large-capacitance capacitor placed in parallel with the automotive load, and the corresponding quiescent current (i.e., the current flowing within the integrated circuit when the integrated circuit is in a quiescent state (e.g., in standby mode)) has a very low value, so that load 300 can be modeled as a purely capacitive load, while neglecting resistive components.

[0271] therefore, Fig. 9 and Fig.10 The embodiments are described with consideration of a purely capacitive load, i.e., a load comprising only a capacitive component C LOAD The load is 300.

[0272] In embodiments where the load 300 can be modeled as a purely capacitive load, the power MOSFET 100 or a corresponding device (eg, an E-Fuse) can be switched on and off for a short period of time (ie, within a delay equal to T d The load 300 can be turned off within a short time and a low test current I can be drawn from the load 300 in such a short time. TEST , for example, by using a pseudo load as the current generator 200. If such a test current I TEST is low enough, then the capacitive component (eg, bulk capacitor) discharges low enough to avoid such an undervoltage condition on the load 300 .

[0273] Fig. 9 and Fig.10 FIG. 1 is a diagram showing a state when a coupled external device 300 modeled as a pure capacitive load is in an ON state and a standby mode according to an embodiment of the present specification. Figure 5 Timing diagram of the signal behavior in the monitoring circuit MC.

[0274] In particular, Fig. 9 When coupled to an external device 300 Figure 5 The behavior of the signal in the monitoring circuit MC, the external device is modeled as a pure capacitive load, in the on state and standby mode, and the threshold voltage AV TH The actual value is less than or equal to the test voltage V TEST , and is therefore less than or equal to the threshold voltage NV TH Nominal value.

[0275] like Fig. 9As shown, if the test is enabled, for example, by setting the test enable signal TE to a high logic level, the timing block 400 is configured to sample the signal S at the first load voltage, for example. VLOAD,T0 The first sampling and holding block 410 sends a pulse or switches it to a high logic level to instruct the first sampling and holding block 410 to stop before any change in the operation of the circuit occurs (i.e., when the gate-source voltage V GS is substantially equal to zero and the load 300 is in standby mode, that is, when there is a power supply voltage V FUSE is supplied to the load 300, but no current flows in the load 300) LOAD The sensed value is sampled.

[0276] In response to the first sample and hold block 410 detecting the voltage V LOAD The sensed value is sampled, and the connection load test signal C supplied to the third switch 420 by the timing block 400 LTEST For example, the third switch 420 switches from a low logic level to a high logic level to indicate that the third switch 420 is closed so as to couple the current source 200 to the source terminal S of the power MOSFET 100. In this way, the test current I TEST Starts to flow within the load 300 , thereby discharging the capacitive components of such load 300 .

[0277] In addition, in response to the first sampling and holding block 410, the voltage V LOAD The sensed value is sampled, and the timing block 400 is configured to, for example, equalize the voltage signal V EQ is set to a high logic level to indicate to the second switch 406 that the voltage generator 404 is to be coupled to the gate terminal G of the power MOSFET 100 to modify the gate-source voltage V GS to set its value substantially equal to the voltage V TEST The value of .

[0278] Even in the Fig. 9 In the embodiment shown, it should also be noted that, for example, the voltage equals the signal V EQ can be set equal to the test voltage V supplied by the voltage generator 404 TEST The voltage level of 404 is determined so as to instruct the second switch 406 to couple the voltage generator 404 to the power MOSFET 100.

[0279] Therefore, when the second switch 406 couples the voltage generator 404 with the gate terminal G of the power MOSFET 100, such a voltage generator 404 supplies a test voltage V between the gate terminal G and the source terminal S of the power MOSFET 100. TEST , thereby modifying the gate-source voltage V GS The value of .

[0280] like Fig. 9 As shown, if the actual threshold voltage AV TH From the nominal threshold voltage NV TH The actual threshold voltage AV TH is equal to or lower than the test voltage V supplied by the voltage generator 404 TEST , the power MOSFET 100 changes its state from the non-conducting OFF state to the conducting ON state because the voltage applied between its gate terminal G and source terminal S (i.e., the test voltage V TEST ) is higher than the actual threshold voltage AV TH value.

[0281] In response to the power MOSFET 100 changing its state from the non-conductive OFF state to the conductive ON state, the current I DS Starts to flow between the drain terminal D and the source terminal S of the power MOSFET, such that the current I DS corresponds substantially to the test current I generated by the current source 200 TEST .

[0282] Since the test current I generated by the current source 200 TEST The current mainly flows in the power MOSFET 100, and thus corresponds to the voltage V on the load 300. LOAD The amount may be changed by less than a given threshold, for example, less than the reference voltage V generated by the reference voltage generator 416. REF And the selected value.

[0283] Therefore, the reference voltage V generated by the reference voltage generator 416 is REF can be regarded as a threshold and is used to check whether the power MOSFET 100 has changed its state from the non-conducting OFF state to the conducting ON state.

[0284] In fact, if the voltage V on the load 300 LOAD The amount of change is less than the threshold value, that is, the reference voltage V REF The value of the power MOSFET 100 corresponds to the actual threshold voltage AV TH The value is smaller than the test voltage V supplied by the voltage generator 404. TEST , i.e., less than the selected minimum value, and there may be a risk of short-circuit failure.

[0285] Then, at T d After a given time of , the timing block 400 is further configured to, for example, sample the second load voltage signal S VLOAD,TdThe second sample and hold block 412 is instructed to increase the gate-source voltage V by sending a pulse on or switching it to a high logic level. GS Set to voltage V TEST Afterwards, when the power MOSFET 100 has changed its state from the non-conducting OFF state to the conducting ON state and the test current I generated by the current source 200 is TEST When the current flows in the MOSFET 100, the voltage V LOAD The sensed value is sampled.

[0286] In this way, the subtraction block 414 can obtain the sense voltage V received from the first sample and hold block 410. LOAD (i.e., in Figure 5 The monitoring circuit MC senses the voltage V before any change occurs in the operation of the LOAD ) minus the sense voltage V received from the second sample and hold block 412 LOAD (i.e., the voltage V sensed after the power MOSFET 100 changes its state from the non-conductive OFF state to the conductive ON state) LOAD ) to obtain the indication at time T d The value of the voltage change on the load 300 during the period.

[0287] Such an instruction at time T d The value of the voltage change on the load 300 during the period can indicate that the test current I TEST The current I LOAD Is it at time T d During this time, current flows in the load 300 .

[0288] In fact, if the value of the voltage change is less than the selected threshold, that is, the reference voltage V REF , then the voltage V on the load 300 LOAD At time T d The period decreases by an amount less than the selected threshold value and is therefore equal to the test current I TEST The value of the current I LOAD flows in the power MOSFET 100, and during such a time T d The internal current does not flow in such a load 300 .

[0289] on the contrary, Fig.10 When coupled to an external device 300 Figure 5 The behavior of the signal in the monitoring circuit MC, the external device is modeled as a pure capacitive load, in the on-state and standby mode, and where the threshold voltage AV TH The actual value is included in the test voltage V TEST With threshold voltage NV THrange between the nominal values ​​of (e.g., without losing the generality of the following description, Fig.10 In the threshold voltage AV TH The actual value is considered to be equal to the threshold voltage NV TH nominal value).

[0290] Note that the following does not repeat Fig.10 The description of the signal that is identical to the corresponding signal in Fig. 9 Signals shown and described herein are represented by the same reference numerals so as not to overburden the present detailed description.

[0291] In this case, the power MOSFET 100 will not respond to the connected load test signal C LTEST and voltage equal to signal V EQ The state of the third switch 420 is changed to the ON state. The connection load test signal indicates closing the third switch 420 to couple the current source 200 to the source terminal S of the power MOSFET. The voltage equal signal indicates closing the second switch 406 to couple the voltage generator 404 to the gate terminal G of the power MOSFET 100.

[0292] Even in this case, the gate-source voltage V GS Also set to test voltage V TEST However, due to the actual threshold voltage AV TH Above this test voltage V TEST , the power MOSFET 100 is kept in the non-conducting OFF state.

[0293] Therefore, the current I DS The test current I does not flow between the drain terminal D and the source terminal S of the power MOSFET 100 and is generated by the current source 200 TEST The capacitive component of the load 300 is discharged, thereby reducing the voltage V across the load 300. LOAD The value of .

[0294] In response to the test current I TEST The capacitive component of the load 300 is discharged, and the voltage V on the load 300 is LOAD decreases over time by an amount that is above a given threshold, for example, above the reference voltage V generated by the reference voltage generator 416. REF The selected value.

[0295] Therefore, if the voltage V on the load 300 LOAD The amount of change is higher than such a threshold, that is, higher than such a reference voltage V REF , then the corresponding power MOSFET 100 is determined by the actual threshold voltage AVTH The value is higher than the test voltage V provided by the voltage generator 404. TEST , i.e., above the selected minimum value, and there is no risk of a short-circuit failure.

[0296] In such Fig.10 In the embodiment shown, when the voltage V on the load 300 LOAD At time T d When the amount of decrease during the period is higher than such a selected threshold, the value of the voltage change provided by the subtraction block 414 is higher than the selected threshold, that is, the reference voltage V REF , so at such a time T d During this period, it is equal to the test current I TEST The value of the current I LOAD Flows within such a load 300 to discharge the capacitive components of such a load 300 .

[0297] Therefore, if the reference voltage generator 416 is correctly configured to supply the reference voltage V REF (like Fig. 9 The value is:

[0298] is higher than any possible voltage variation obtained when the power MOSFET 100 is in the ON state, and

[0299] is less than any possible voltage variation obtained when the power MOSFET 100 is in the non-conducting OFF state,

[0300] The comparator 418 may generate an alarm signal AL VTH , to indicate if the value of the acquired voltage change is less than such a properly defined reference voltage V REF (like Fig. 9 As shown in FIG. 1 , the power MOSFET 100 and the corresponding device (eg, E-Fuse) may be at risk of short circuit failure.

[0301] Otherwise, if the comparator 418 detects that the value of the acquired voltage change is higher than such a properly defined reference voltage V REF , then the alarm signal AL VTH will not be set, for example, held at a low logic level (such as Fig.10 shown).

[0302] In various embodiments, if the third mode is selected, the reference voltage V REF Can be the reference voltage V S voltage because the power MOSFET is initially in the ON state. In this case, for example, the reference voltage V REF You can Fig. 9 and Fig.10 As shown, in the indication such voltage V S There is a double arrow between the first level of and the second level indicating a voltage value that satisfies the above two conditions for correctly configuring the reference voltage generator.

[0303] exist Fig. 9 and Fig.10 In the embodiment shown, in order to correctly set the reference voltage V generated by the reference voltage generator 416 REF The value of can be considered as follows:

[0304]

[0305] in is provided by the subtraction block 414 or the detection units 408-414 in the time period T d Voltage changes within.

[0306] In various embodiments, the load 300 may be modeled as a purely capacitive component, such as Fig. 9 and Fig.10 As shown in the embodiment, the sensing voltage V LOAD The delay time T between the first sampling and the second sampling d may be shorter than in embodiments where the load 300 may include both resistive and capacitive components, such as Figure 8 As shown in the embodiments.

[0307] In fact, in Fig. 9 and Fig.10 In the embodiment of the present invention, the voltage change ratio measured on the load 300 can allow the detection of abnormalities. Figure 8 is much smaller in the embodiment of , since the capacitive component will be partially rather than fully discharged / charged, thus having a shorter time period T d .

[0308] Fig.11 is a system 50 according to an embodiment of the present specification, the system comprising Figure 5 Monitoring circuit MC and temperature change monitoring units 506-508.

[0309] The threshold voltage V of the power MOSFET 100 TH In response to the increase in temperature, the test voltage V supplied by the voltage generator 404 is reduced. TEST The temperature effect is compensated, i.e., so that the test voltage V TEST The threshold voltage NV varies with temperature TH Keep the same selected gap amount between the nominal values ​​V GAP .

[0310] Threshold voltage V caused by temperature change TH The drift of is compensated using a thermal sensor 506 which is configured to monitor the temperature of the power MOSFET 100 junction (dashed arrow) and send the sensed temperature value to a compensation block 508.

[0311] Such compensation block 508 is configured to receive a sensed temperature value from the thermal sensor 506 and calculate a test voltage V according to such sensed temperature value. TEST The corresponding value of the test voltage V TEST Will be with Figure 5 The voltage generator 404 of the monitoring circuit 504 corresponding to the monitoring circuit MC generates.

[0312] In this way, the test voltage V can be dynamically updated according to the temperature change of the power MOSFET 100. TEST The calculated value is used so that the nominal threshold voltage NV TH With test voltage V TEST Keep constant value V GAP gap.

[0313] Such compensation block 508 is also configured to convert such a test voltage V TEST The calculated value is provided to the monitoring circuit 504, in particular, to the voltage generator 404.

[0314] Monitoring circuit 504 (corresponding to Figure 5 The monitoring circuit MC, in particular the voltage generator 404, is configured to generate a test voltage V equal to the value received from the compensation block 508. TEST The calculated value of the voltage.

[0315] In various embodiments, the monitoring circuit 504 may also receive current feedback and / or voltage feedback via the ammeter 512 and the voltmeter 510 , respectively.

[0316] In various embodiments, the monitoring circuit 504 may be coupled to the communication interface 502 , for example, to receive a test enable signal TE and a test mode signal TM from an external unit.

[0317] In various embodiments, the thermal sensor 506 and the compensation block 508 may be integrated into the same unit, for example, into a smart power actuator including a thermal sensor integrated into a power MOSFET structure.

[0318] In various embodiments, system 50 may be used in automotive applications, for example, by coupling upper pin 514 to an automotive power distribution source, such as a battery, and coupling lower pin 516 to a vehicle utility system or ECU.

[0319] In various embodiments, the system 50 may be used in automotive applications such as vehicle diagnostic and monitoring systems, multiple and standby power systems, redundant braking systems, redundant electric steering systems, and the like.

[0320] In various embodiments, Figure 5 The monitoring circuit MC can be embedded in the power actuator or E-Fuse.

[0321] The various units and blocks discussed in this disclosure include, for example, various electronic components and circuit systems configured to perform the functions of the above-described units.

[0322] The solution described in this article helps to obtain a monitoring circuit for early detection of short-circuit faults in MOSFETs. This can be achieved by measuring the actual threshold voltage value of a given MOSFET when it is coupled with a corresponding load.

[0323] Therefore, the solution described in this article helps to implement health monitoring of devices (e.g., E-Fuse) by monitoring the corresponding MOSFET to prevent short-circuit failures in such MOSFETs. In this way, the degradation of such MOSFETs and corresponding devices can be predicted early and potential failures leading to uncontrolled conduction can be prevented.

[0324] The details and embodiments may vary, even significantly, with respect to what is described by way of example, without affecting the underlying principle and without departing from the scope of the embodiments.

[0325] A method for monitoring the actual threshold voltage value (AV) of a MOSFET (100) TH The circuit (MC) of the present invention can be summarized as comprising: a current source (200) configured to be coupled to the source terminal (S) of the MOSFET (100) and to generate a test current (I TEST ); a voltage generator (404) configured to be coupled between the gate terminal (G) of the MOSFET (100) and the source terminal (S) of the MOSFET (100) and to generate a test voltage (V TEST ), the above test voltage (V TEST ) is lower than the nominal threshold voltage (NV) of the MOSFET (100) TH ); a detection circuit system (408-414) configured to detect a plurality of voltage values ​​(V LOAD ) is sampled, based on the above multiple voltages (V LOAD ) to calculate the above voltage value (V LOAD ) over time, especially over a given period of time (T d), and providing the calculated value of at least the voltage change to an alarm generating unit (416-418), the alarm generating unit (416-418) being configured to receive the calculated voltage change from the detection unit (408-414), compare the calculated voltage change with the reference voltage (V REF ) and an alarm is issued if the output of the above comparison does not correspond to a predetermined output condition (AL VTH ); and a control unit (400) configured to receive a test mode signal (TM) indicating an operation mode, wherein the control unit (400) is further configured to select a coupling or decoupling state between the current source (200) and the source terminal (S) of the MOSFET (100) according to the received test mode signal (TM), determine the reference voltage (V REF ), setting the output condition of the comparison, and sending a signal to the detection unit (408-414) to perform multiple sampling operations.

[0326] If the test mode signal (TM) indicates the first test mode, the control unit (400) may be configured to: decouple the current source (200) from the source terminal (S) of the MOSFET (100), determine the reference voltage (V REF ) makes the reference voltage (V REF ) is a positive voltage that is less than the actual threshold voltage (AV TH ) is equal to or lower than the test voltage (V TEST ) and compare the calculated voltage change with the reference voltage (V REF ) indicates that the calculated voltage change is higher than the reference voltage (V REF ) is set as the predetermined output condition. If the test mode signal (TM) indicates the second mode, the control unit (400) may also be configured to: couple the current source (200) to the source terminal (S) of the MOSFET (100), determine the reference voltage (V REF ) value, so that the reference voltage (V REF ) is higher than the actual threshold voltage (AV TH ) is equal to or lower than the test voltage (V TEST ) and is less than the actual threshold voltage (AV TH ) is higher than the test voltage (V TEST ) and compare the calculated voltage change with the reference voltage (V REF) indicates that the calculated voltage change may be smaller than the reference voltage (V REF ) is set as the above-mentioned predetermined output condition.

[0327] The test mode signal (TM) may be configured to indicate a first sub-mode of the first test mode and a second sub-mode of the first test mode, wherein in the first sub-mode, the given time period (T d ) is shorter than the period in the second mode.

[0328] The circuit (MC) can be coupled to an external load (300) via a source terminal (S) of the MOSFET (100), and a test mode signal (TM) can select an operation mode from a set of available operation modes, wherein the set of available operation modes at least includes: the first mode, which is selected when the coupled external load (300) is in an off state, the first mode including the first sub-mode and the second sub-mode, the first sub-mode corresponding to a resistive load (R LOAD ), the second sub-mode corresponds to a capacitive component (C LOAD ) and the resistive component (R LOAD ) both loads; and the second mode, which is in the on state, standby mode and the load may correspond to a capacitive load (C LOAD ) is selected.

[0329] The MOSFET (100) mentioned above may be a power MOSFET.

[0330] The above multiple voltage values ​​(V LOAD ) may include a first voltage value (410) and a second voltage value (412), wherein the first voltage value (410) is within the time period (T d ) is retrieved at the beginning of the period (T d ) is retrieved at the end of the process and is used to determine the voltage values ​​(V LOAD ) to obtain the voltage change includes subtracting (414) the second voltage value (412) from the first voltage value (410).

[0331] Circuit (MC), wherein the above-mentioned detection unit (408-414) may include: a sensing unit (408), which is configured to sense the voltage value (V LOAD ) and the sensed voltage value (V LOAD) is forwarded to the first sampling and holding block (410) and the second sampling and holding block (412); the first sampling and holding block (410) is configured to sample the first voltage value in response to receiving a signal from the control unit (400) indicating the execution of the first sampling operation in the sampling operation, and to keep the first voltage value greater than the given time period (T d ) amount of time, and providing the above-mentioned first voltage value to the subtraction block (414); the above-mentioned second sampling and holding block (412), which is configured to sample the above-mentioned second voltage value in response to receiving a signal from the above-mentioned control unit (400) indicating the execution of the second sampling operation in the above-mentioned sampling operation, hold the above-mentioned second voltage value, and provide the above-mentioned second voltage value to the above-mentioned subtraction block (413); and the subtraction block (414), which is configured to receive the first voltage value from the first sampling and holding block (410) and the second voltage value from the second sampling and holding block (412), perform subtraction (414) of the above-mentioned second voltage value from the above-mentioned first voltage value to obtain the above-mentioned voltage change, and provide the above-mentioned voltage change to the alarm generation unit (416-418).

[0332] The alarm generating unit (416-418) may include: a reference voltage generator (416) configured to provide the reference voltage (V REF ); and a comparator block (418) configured to receive the calculated voltage change from the detection unit (408-414) and the reference voltage (V REF ), and compare the calculated voltage change with the reference voltage (V REF ) and issues an alarm (AL) in response to an unsuccessful comparison operation VTH ).

[0333] The circuit (MC) may further include: a first switch (420) configured to couple the current source (200) to the source terminal (S) of the MOSFET (100) or decouple it in response to receiving a signal from the control unit (400) issued in accordance with the test mode signal (TM).

[0334] The circuit (MC) may further include an additional switch (402) configured to start monitoring the actual threshold voltage value (AV TH ) signal to decouple the gate driver (104) from the gate terminal (G) of the MOSFET (100), and in response to receiving an instruction from the control unit (400) to end monitoring the actual threshold voltage value (AV TH) signal to couple the gate driver (104) to the gate terminal (G) of the MOSFET (100).

[0335] The above test voltage (V TEST ) can be fixed, or the above test voltage (V TEST ) may be dynamic, and the control unit (400) may also be configured to: select the test voltage (V TEST ) initial value, starting from the actual threshold voltage (AV TH ) monitoring, if the alarm generating unit (416-418) is above the actual threshold voltage (AV TH ) monitoring ends before any alarm is issued (AL VTH ), then the above test voltage (V TEST ) is increased by a given step size, and the steps are performed again from the beginning of monitoring, and if the alarm generating unit (416-418) is above the actual threshold voltage (AV TH ) before the monitoring is completed (AL VTH ), then the test voltage (V TEST ) is identified as the actual threshold voltage value (AV TH ) value.

[0336] The circuit (MC) may be further coupled to a temperature monitoring unit (506-508), wherein the temperature monitoring unit (506-508) is configured to: monitor (506) the temperature of the MOSFET (100) to sense at least one temperature value, and calculate (508) the test voltage (V TEST ) value, and the above test voltage (V TEST ) is provided (508) to the circuit (MC) to generate the test voltage (V TEST ).

[0337] The circuit (MC) may include another switch (406) configured to couple the voltage generator (404) to or decouple the gate terminal (G) of the MOSFET (100) in response to receiving a signal from the control unit (400) in accordance with the test mode signal (TM), and in the first mode and the second mode, the voltage generator (404) remains coupled to the gate terminal (G) of the MOSFET (100).

[0338] In the first mode and the second mode, if the test enable signal mode (TE) is not set, the voltage generator (404) can be decoupled from the gate terminal (G) of the MOSFET (100).

[0339] For monitoring the actual threshold voltage value (AV) of the MOSFET (100) by the circuit (MC) according to any of the aforementioned embodiments TH ), the method can be summarized as comprising: receiving a test mode signal (TM) indicating an operation mode through a control unit (400); coupling a current source (200) to / decoupling a source terminal (S) of a MOSFET (100) through the control unit (400) according to the received test mode signal (TM); coupling a voltage generator (400) to / decoupling a gate terminal (G) of the MOSFET (100) through the control unit (400) according to the received test mode signal (TM); generating a test current (I TEST ); if the voltage generator (404) is coupled between the gate terminal (G) of the MOSFET (100) and the source terminal (S) of the MOSFET (100), a test voltage (V TEST ), the above test voltage (V TEST ) is lower than the nominal threshold voltage (NV) of the MOSFET (100) TH ); determining a reference voltage (V REF ); determining, by a control unit (400), a condition for detecting an unsuccessful comparison operation according to the test mode signal (TM) detected above; in response to receiving a signal from the control unit (400) indicating that a plurality of sampling operations are to be performed according to the received test mode signal (TM), sampling a plurality of voltage values ​​(VLOAD) at a source terminal (S) of the MOSFET (100) by a detection unit (408-414); and determining, by a detection unit (408-414), a condition for detecting an unsuccessful comparison operation according to the test mode signal (TM) detected above. LOAD ) to calculate the voltage change, which indicates the voltage change in a given time period (T d ) within the above multiple voltage values ​​(V LOAD ) changes; the above calculated voltage change and the reference voltage (V REF ) for comparison; and issuing an alarm (AL) in response to an unsuccessful comparison operation by an alarm generating unit (416-418) VTH ).

[0340] The various embodiments described above can be combined to provide other embodiments. These and other changes can be made to the embodiments according to the above specific implementations. In general, in the following claims, the terms used should not be interpreted as limiting the claims to the specific embodiments disclosed in the specification and claims, but should be understood to include all possible embodiments and the full range of equivalents to which these claims are entitled. Therefore, the claims are not limited by this disclosure.

Claims

1. A circuit for monitoring a threshold voltage value of a metal oxide semiconductor field effect transistor (MOSFET), the circuit comprising: a current source configured to be coupled to a source terminal of the MOSFET and to generate a test current; a voltage generator configured to be coupled between a gate terminal of the MOSFET and a source terminal of the MOSFET and to generate a test voltage, the test voltage being lower than a nominal threshold voltage value of the MOSFET; The detection circuit system is configured to: sampling a plurality of voltage values ​​at the source terminal of the MOSFET; as well as determining a voltage change of the plurality of voltage values ​​at the source terminal of the MOSFET within a time period based on the plurality of voltage values; An alarm generating circuit system is configured to: receiving the determined voltage change from the detection circuitry; comparing the determined voltage change with a reference voltage; as well as issuing an alarm if the output of said comparison of said determined voltage variation with said reference voltage does not correspond to a predetermined output condition; as well as The controller is configured as: receiving a test mode signal indicating an operating mode; selecting a state in which the current source and the source terminal of the MOSFET are coupled or decoupled from each other according to the received test mode signal; determining a value of the reference voltage; Setting the predetermined output condition; as well as The detection circuitry is signaled to perform a plurality of samplings of the plurality of voltage values.

2. The circuit according to claim 1, wherein If the test mode signal indicates the first mode, the controller is configured to: decoupling the current source from the source terminal of the MOSFET; determining a value of the reference voltage so that the reference voltage is a positive voltage that is smaller than a value of the determined voltage variation obtained when the threshold voltage value is equal to or lower than the test voltage; as well as setting as the predetermined output condition a result of the comparison of the determined voltage variation with the reference voltage indicating that the determined voltage variation is higher than the reference voltage, and If the test mode signal indicates the second mode, the controller is configured to: coupling the current source to the source terminal of the MOSFET; Determining a value of the reference voltage so that the reference voltage is higher than a value of a determined voltage change obtained when the threshold voltage value is equal to or lower than the test voltage, and so that the reference voltage is lower than a value of a determined voltage change obtained when the threshold voltage value is higher than the test voltage; as well as A result of the comparison of the determined voltage variation with the reference voltage indicating that the determined voltage variation is less than the reference voltage is set as the predetermined output condition.

3. The circuit according to claim 2, wherein The test mode signal is configured to indicate a first sub-mode of the first mode and a second sub-mode of the first mode, and The time period in the first sub-mode is shorter than the time period in the second mode.

4. The circuit according to claim 3, wherein The circuit is coupled to an external load through the source terminal of the MOSFET, and The test mode signal selects an operating mode from a set of available operating modes, the set of available operating modes comprising: The first mode is selected when the coupled external load is in a disconnected state, the first mode comprising the following sub-modes: the first sub-mode corresponding to a resistive load and a second sub-mode corresponding to a load comprising both a capacitive component and a resistive component, and The second mode is selected when the coupled external load is in an on state or a standby mode and the coupled external load corresponds to a capacitive load.

5. The circuit of claim 1, wherein the MOSFET is a power MOSFET.

6. The circuit of claim 1, wherein The plurality of voltage values ​​include a first voltage value and a second voltage value, the first voltage value being retrieved at the beginning of the time period and the second voltage value being retrieved at the end of the time period, and The determining of the voltage change includes subtracting the second voltage value from the first voltage value.

7. The circuit of claim 6, wherein the detection circuit system comprises: a sensing circuit system configured to sense a voltage value at the source terminal of the MOSFET and forward the sensed voltage value to a first sample and hold block and a second sample and hold block; the first sample and hold block configured to: sample the first voltage value in response to receiving a signal from the controller indicating that a first sampling of the plurality of voltage values ​​is to be performed, hold the first voltage value for an amount of time greater than the time period, and provide the first voltage value to a subtraction block; the second sample and hold block configured to: sample the second voltage value in response to receiving a signal from the controller instructing to perform a second sampling of the plurality of voltage values, hold the second voltage value, and provide the second voltage value to the subtraction block; as well as The subtraction block is configured to: receive the first voltage value from the first sample and hold block and the second voltage value from the second sample and hold block, subtract the second voltage value from the first voltage value to obtain the voltage change, and provide the voltage change to the alarm generation circuit system.

8. The circuit of claim 1 , wherein the alert generating circuitry comprises: a reference voltage generator configured to provide the reference voltage to the comparator block; and The comparator block is configured to receive the determined voltage change from the detection circuitry and the reference voltage from the reference voltage generator, compare the determined voltage change with the reference voltage, and issue an alarm in response to an unsuccessful comparison operation.

9. The circuit of claim 1 , further comprising: A first switch is configured to couple the current source to the source terminal of the MOSFET or decouple the current source from the source terminal of the MOSFET in response to receiving a signal issued from the controller in accordance with the test mode signal.

10. The circuit of claim 1, further comprising: a switch configured to decouple a gate driver from the gate terminal of the MOSFET in response to receiving a signal from the controller indicating the start of the monitoring of the threshold voltage value, and to couple the gate driver to the gate terminal of the MOSFET in response to receiving a signal from the controller indicating the end of the monitoring of the threshold voltage value.

11. The circuit of claim 1, wherein The test voltage is fixed, or The test voltage is dynamic, and the controller is configured to: selecting an initial value of the test voltage; starting said monitoring of said threshold voltage value; If the alarm generation circuitry does not issue an alarm before the monitoring of the threshold voltage value ends, increasing the value of the test voltage by a given step size and repeating the monitoring of the threshold voltage value; and If the alarm generation circuitry issues an alarm before the monitoring of the threshold voltage value ends, a current value of the test voltage is identified as the value of the threshold voltage value.

12. The circuit of claim 1 , wherein the circuit is coupled to temperature monitoring circuitry, the temperature monitoring circuitry being configured to: monitoring a temperature of the MOSFET to sense at least one temperature value; calculating a value for the test voltage based on the at least one sensed temperature value; and A value for the test voltage is provided to the circuit to generate a test voltage of the value by the voltage generator.

13. The circuit of claim 2, further comprising: a switch configured to, in response to receiving a signal issued from the controller in accordance with the test mode signal, couple the voltage generator to the gate terminal of the MOSFET or decouple the voltage generator from the gate terminal of the MOSFET, wherein the voltage generator remains coupled to the gate terminal of the MOSFET in the first mode and the second mode.

14. The circuit of claim 13, wherein in the first mode and the second mode, if a test enable signal mode is not set, the voltage generator is decoupled from the gate terminal of the MOSFET.

15. A method for monitoring a threshold voltage value of a metal oxide semiconductor field effect transistor (MOSFET), the method comprising: receiving, by the controller, a test mode signal indicating an operating mode; coupling or decoupling, by the controller, a current source and a source terminal of the MOSFET to each other according to the received test mode signal; coupling or decoupling, by the controller, a voltage generator and a gate terminal of the MOSFET to each other according to the received test mode signal; generating a test current if the current source is coupled to the source terminal of the MOSFET; generating a test voltage lower than a nominal threshold voltage value of the MOSFET if the voltage generator is coupled between the gate terminal of the MOSFET and the source terminal of the MOSFET; The controller determines a value of a reference voltage according to the received test mode signal; determining, by the controller, a condition for detecting an unsuccessful comparison operation based on the received test mode signal, sampling, by detection circuitry, a plurality of voltage values ​​at the source terminal of the MOSFET in response to receiving a signal from the controller instructing sampling to be performed in accordance with the received test mode signal; determining a voltage change by the detection circuit system based on the plurality of voltage values, the determined voltage change indicating a change of the plurality of voltage values ​​within a time period, comparing, by the alarm generating circuitry, the determined voltage change with the reference voltage, and An alarm is issued by the alarm generating circuitry in response to the unsuccessful comparison operation.

16. The method according to claim 15, wherein If the test mode signal indicates a first mode, the method comprises: decoupling, by the controller, the current source from the source terminal of the MOSFET; determining, by the controller, a value of the reference voltage so that the reference voltage is a positive voltage that is smaller than a value of a determined voltage variation obtained when the threshold voltage value is equal to or lower than the test voltage; as well as a predetermined output condition for detecting the unsuccessful comparison operation is set by the controller, the predetermined output condition being set to indicate that the result of the comparison of the determined voltage variation with the reference voltage indicates that the determined voltage variation is higher than the reference voltage, and If the test mode signal indicates a second mode, the method comprises: coupling, by the controller, the current source to the source terminal of the MOSFET; The controller determines the value of the reference voltage so that the reference voltage is higher than the value of the determined voltage change obtained when the threshold voltage value is equal to or lower than the test voltage, and the reference voltage is lower than the value of the determined voltage change obtained when the threshold voltage value is higher than the test voltage; and The following is set as the predetermined output condition by the controller: a result of the comparison of the determined voltage change with the reference voltage indicates that the determined voltage change is less than the reference voltage.

17. A device comprising: Metal Oxide Semiconductor Field Effect Transistor MOSFET; a first switch coupled to a source of the MOSFET; a current source coupled to the first switch, the current source configured to generate a test current; a second switch coupled to the gate of the MOSFET; a voltage generator coupled to the second switch and the source of the MOSFET, the voltage generator being configured to generate a test voltage lower than a nominal threshold voltage value of the MOSFET; a detection circuit system configured to sample a plurality of voltage values ​​at the source of the MOSFET and determine a voltage change of the plurality of voltage values ​​over a time period; as well as The alarm generating circuit system is configured to output an alarm based on the voltage change and a reference voltage.

18. The apparatus of claim 17, further comprising: The controller is configured as: Turning off the first switch to decouple the current source from the source of the MOSFET; as well as The reference voltage is set so that the reference voltage is a positive voltage that is smaller than a value of the voltage change acquired when a threshold voltage of the MOSFET is equal to or lower than the test voltage.

19. The apparatus of claim 17, further comprising: The controller is configured as: closing the first switch so that the current source is coupled to the source of the MOSFET; as well as The reference voltage is set so that the reference voltage is higher than the value of the voltage change obtained when the threshold voltage of the MOSFET is equal to or lower than the test voltage, and so that the reference voltage is lower than the value of the voltage change obtained when the threshold voltage is higher than the test voltage.

20. The apparatus of claim 17, further comprising: A controller is configured to open and close the second switch based on a test mode of the MOSFET.

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