MONITORING CIRCUIT AND CORRESPONDING DC DRIVER AND METHOD

A circuit for monitoring phases of a direct current driver that is configured to drive a load via first and second terminals, comprises first comparison circuitry configured to receive a first voltage of the first terminal and a threshold voltage, compare the first voltage with the threshold voltage, obtaining a first comparison voltage, and provide the first comparison voltage to selection circuitry, second comparison circuitry configured to receive a second voltage of the second terminal and the threshold voltage, compare the second voltage with the threshold voltage, obtaining a second comparison voltage, and provide the second comparison voltage to the selection circuitry, and the selection circuitry configured to receive the first and second comparison voltages, and a selection signal, and select, based on the selection signal, the first or second comparison voltage as a monitored voltage signal.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of Italian Patent Application No. 102024000010366, filed on May 8, 2024, which application is hereby incorporated herein by reference.

TECHNICAL FIELD

The description relates to monitoring circuits and methods.

One or more embodiments can be applied to methods and circuits for monitoring output phases in DC (“Direct Current”) motor drivers.

BACKGROUND

DC (“Direct Current”) motors are ubiquitous in various applications; therefore, efficient control and monitoring of these motors can improve their performance and safety, also extending their operational lifespan.

Such control and monitoring functions are usually implemented via DC motor drivers.

A DC motor driver is an interface between a control system, for instance, a microcontroller, and a respective DC motor that is to be driven.

Such DC motor drivers, in addition to being configured to provide control functions such as regulating and driving the DC motor, can also be configured to provide monitoring and protection functions, such as overcurrent or overvoltage detection.

Therefore, monitoring the functionality and operability of such DC motor drivers is of crucial importance for operating such DC motors correctly.

Known solutions related to circuits for monitoring DC motor drivers are based on current sensing operations, aiming at providing feedback related to control output currents of such DC motor drivers to respective microcontrollers, such output currents of the DC motor drivers being the currents flowing in respective DC motors in operation and used to drive such motors.

FIG. 1A illustrates a block diagram of a known exemplary circuit 10a for performing current sense monitoring operations and short circuit detection in DC motor drivers 100 coupled to a load L, for instance, a DC motor.

The DC motor driver 100 of FIG. 1A is coupled to the load L, that is, the DC motor L, via a first output terminal OUTa and a second output terminal OUTb, and is supplied with a voltage VBAT via a supply terminal.

The DC motor driver 100 comprises a logic control unit 102 coupled between the supply terminal at the voltage VBAT and a ground terminal GND, for instance, via a first ground terminal GNDa and a second ground terminal GNDb.

The DC motor driver 100 further comprises a full-bridge (that is, an H-bridge) circuit comprising:

It is noted that the first output terminal OUTa and the second output terminal OUTb are used to provide to such DC motor L the control output currents used to drive such DC motor L.

Such control output currents are sensed via a current monitoring circuit 104 coupled to the high sides of the H-bridge, for instance, to the current sinking terminal of the third transistor M3 and to the current sinking terminal of the first transistor M1, such current monitoring circuit 104 being configured to implement a current mirror via a split of cell of Power MOS.

Therefore, such current monitoring circuit 104 is configured to provide a monitoring output current IOUT to a microcontroller, such monitoring output current IOUT being indicative of a current flowing either in the current sinking terminal of the third transistor M3 or in the current sinking terminal of the first transistor M1, that is, indicative of the control output currents generated by the DC motor driver 100 that are provided to the DC motor L via the first output terminal OUTa and the second output terminal OUTb.

It is noted that such monitoring output current IOUT can only be provided during on states of the DC motor driver 100.

Then, the microcontroller may be configured to use, during an on-state of the DC motor driver 100, such feedback to implement operations related to diagnostic fault coverage.

An exemplary current monitoring circuit 104 is illustrated in FIG. 1B, which illustrates a circuit 10b for performing current sense monitoring operations coupled to a DC motor driver.

Such exemplary current monitoring circuit 104 may comprise:

In addition, it is possible to provide a circuitry comprising:

Such pull-up resistors Rpu1 and Rpu2 and switches Spu1 and Spu2 driven by the microcontroller are used to provide further feedback related to short circuits, for instance, either to short circuit to battery VBAT or to short circuit to ground GND.

The standard ISO26262, which is the actual international standard related to functional safety of electrical and/or electronic systems that are installed in serial production road vehicles, defines minimum requirements for safety that are measured via the Automotive Safety Integrity Level (ASIL), a safety level determined through hazard analysis and risk assessment.

Such standard ISO26262, for instance, considering the ASIL-B metrics, requires that the functionality of the monitoring device, that is, the DC motor driver 100, is (preferably constantly) monitored in all operation mode, that is, both during the on-state and during an off-state of the DC motor driver 100.

Known solutions, as previously described, can monitor, that is, providing feedback to the microcontroller, DC motor drivers 100 only during their on-state, thus, not allowing a monitoring during their off-state and not reaching the required safety results.

Therefore, solutions that improve a monitoring of a device used for driving a DC motor, that is, a DC motor driver, facilitating performing monitoring operations, for instance, both during on-states and during off-states of such DC motor driver, would be beneficial in order to increase a functional safety of such device.

SUMMARY

An object of one or more embodiments is to contribute in providing solutions for improving a monitoring of a device used for driving a DC motor, that is, a DC motor driver, facilitating performing monitoring operations, for instance, both during on-states and during off-states of such DC motor driver.

According to one or more embodiments, that object is achieved via a circuit having the features set forth in the claims that follow.

One or more embodiments concern a corresponding method.

One or more embodiments concern a corresponding DC driver.

The claims are an integral part of the technical teaching provided in respect of the embodiments.

Solutions as described herein include a circuit for monitoring phases of a Direct Current, DC, driver, the DC driver being configured to drive a load via a first terminal and a second terminal coupled to respective load terminals switching a polarity there applied;

In various embodiments, the first comparison circuitry is configured to receive the first voltage via a first node; and the second comparison circuitry is configured to receive the second voltage via a second node;

In various embodiments, the first switch and the second switch integrate a protection circuitry, in particular, wherein the first switch and the second switch are Vertical Intelligent Power, VIPower switches.

In various embodiments, the selection circuitry is configured to drive, based on a comparison voltage selected out of the first comparison voltage and the second comparison voltage, a transistor via its control terminal, the transistor having:

In various embodiments, the monitored voltage signal is provided to a control unit, in particular, a control unit external to the DC driver, the control unit being configured to, based on a current operation mode of the DC driver:

In various embodiments, the control unit is configured to operate, based on the current operation mode of the DC driver the first switch and/or the second switch for performing pull-up operations.

In various embodiments, the DC driver comprises:

In various embodiments, the load is a DC motor.

In various embodiments, the circuit is integrated in the DC driver, in particular, in a DC driver control unit; or the circuit is external to the DC driver and, in particular, is implemented using discrete components.

Therefore, solutions as described herein facilitate improving the monitoring of devices used for driving DC motors, that is, DC motor drivers, facilitating performing monitoring operations, for instance, both during on-states and during off-states of such DC motor drivers, in order to increase a functional safety of such devices.

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

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

The edges of features drawn in the figures do not necessarily indicate the termination of the extent of the feature.

DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS

Moreover, particular configurations, structures, or characteristics may be combined in any adequate way in one or more embodiments.

The headings/references used herein are provided merely for convenience and hence do not define the extent of protection or the scope of the embodiments.

For simplicity and ease of explanation, throughout this description, and unless the context indicates otherwise, like parts or elements are indicated in the various figures with like reference signs, and a corresponding description will not be repeated for each and every figure.

As previously described, solutions as described herein aim at facilitating improving the monitoring of devices used for driving DC (“Direct Current”) motors, that is, DC motor drivers, facilitating performing monitoring operations, for instance, both during on-states and during off-states of such DC motor drivers, in order to increase a functional safety of such devices.

It is noted that, even if the following description is mainly focused on automotive applications, solutions as described herein may be used also in other applications where an improved monitoring of DC motor drivers is required.

Examples of possible applications comprising driving a DC motor that can use the solutions disclosed herein may be, for instance, automotive applications such as door locking, window lifting, powering lift gates, electric parking braking, seat adjustment, powering window, steering column, or the like.

In addition, it is noted that, even if the following description is mainly focused on a driver implemented via full-bridge architecture (that is, an H-bridge), such driver may also be implemented via any other architecture having two terminals coupled to respective terminals of a load and allowing to switch the polarity applied to such terminals of the load coupled thereto.

For instance, different solutions may consider two half-bridges (“H-bridges”) used with legs parallelization to supply a load L, for instance, a motor.

For instance, other solutions may consider a cascade configuration, provided using two H-bridges for driving three loads L (such as motors), which are supplied by respective output pins. It is noted that in such a type of solution it is possible to supply one motor L at once.

It is also noted that, even if the following description is mainly focused on a load implemented via a DC motor, other loads that can be driven via two terminals using a switching polarity may also be considered.

It is noted that circuits for monitoring an output phase of DC motor drivers as described herein may be integrated within the same integrated circuit of such DC motor drivers.

For instance, FIG. 2 illustrates an exemplary block diagram 20 of a circuit 30 (either a circuit 30a or 30b as described in the following) for performing phase monitoring operations in DC drivers 200, for instance, DC motor drivers, coupled to respective loads L, for instance, DC motors, the DC motor driver 200 being configured to comprise the circuit 30 according to embodiments of the present description.

In particular, such circuit 30 may be comprised in a logic control unit 202 of the DC motor driver 200.

Alternatively, circuits for monitoring the output phase of DC motor drivers as described herein may be provided via elements that are external to such integrated circuit comprising the DC motor driver 200′, for instance, by using discrete components.

It is also noted that such circuits for monitoring the output phase of DC motor drivers as described herein may be provided via elements that are comprised in the integrated circuit comprising the DC motor driver 200′ but are external to a logic control unit 202′ of the DC motor driver 200′.

For instance, FIG. 3 illustrates an exemplary block diagram 20′ of a circuit 30′ (either a circuit 30′a or 30′b as described in the following) for performing phase monitoring operations in DC drivers 200′, for instance, DC motor drivers, coupled to respective loads L, for instance, DC motors, the circuit 30′ being configured to be external to the DC motor driver 200′ (and, for instance, to be composed by discrete components) according to embodiments of the present description.

Hence, solutions as described herein aim at providing, for instance, to an additional control unit such as a microcontroller, a microprocessor, a logic unit, or the like, a monitoring signal POUT, that is, a feedback signal.

Such monitoring signal POUT, preferably a real-time feedback signal, can be available both during on-states and during off-states of the DC motor driver 200 or 200′ and is configured to provide feedback related to the output status of the DC motor driver 200 or 200′ and, in particular, to an output phase of such DC motor driver.

Therefore, the additional control unit may be further configured to detect, using the received monitoring signal POUT, and to react to anomalous or faulty conditions.

To this purpose, circuits 30 and 30′ used to monitor the output phases of DC motor drivers are configured to sense the output voltages of the power stages of such DC motor drivers, for instance, a first voltage V_OUTa is sensed from a first output terminal OUTa and a second voltage V_OUTb is sensed from a second output terminal OUTb, and to compare such sensed output voltages V_OUTa and V_OUTb with a given threshold voltage Vth, for instance, a fixed threshold voltage.

The result of such comparison operation is related to the power status of a DC motor diver 200 or 200′ and may correspond to the monitoring signal POUT, thus, being the feedback of the output status, that is, a phase of the DC motor driver, provided to the additional control unit, for instance, via a phase output terminal.

The DC driver 200, for instance, the DC motor driver, of FIG. 2 is coupled to the load L, for instance, the DC motor L, via the first output terminal OUTa and the second output terminal OUTb, and is supplied with a voltage VBAT via a supply terminal.

The DC motor driver 200 comprises a logic control unit 202 coupled between the supply terminal at the voltage VBAT and a ground terminal GND, for instance, via a first ground terminal GNDa and a second ground terminal GNDb.

The DC motor driver 200 further comprises a full-bridge circuit comprising:

It is noted that the first output terminal OUTa and the second output terminal OUTb are used to provide to such DC motor L the control output currents used to drive such DC motor L.

The first output terminal OUTa and the second output terminal OUTb are coupled, via a voltage sensing circuitry comprised in the DC motor driver 200, to a circuit 30.

Therefore, such circuit 30, comprised in the DC motor driver 200, is configured to receive the first voltage V_OUTa sensed from the first output terminal OUTa and the second voltage V_OUTb sensed from the second output terminal OUTb, to determine a monitoring signal POUTrelated to an output phase of the DC motor driver 200, and to provide such monitoring signal POUT to a phase output terminal of the DC motor driver 200.

The monitoring signal POUT may be retrieved by an additional control unit, for instance, a microcontroller, a microprocessor, a logic unit, or the like, from such phase output terminal of the DC motor driver in order to implement operations related to diagnostic fault coverage, such as detecting, based on such monitoring signal POUT, and reacting to failures.

It is noted that FIG. 3 comprises same parts, elements, and/or components of FIG. 2, except for the fact that the circuit 30 (referred to as 30′ in FIG. 3) is external to the DC driver 200 (referred to as 200′ in FIG. 3 to underline the fact that it do not comprise the circuit 30), for instance, the DC motor driver, therefore, such parts, elements, and/or components which have already been described with reference to FIG. 2 will not be described again in order to avoid overburdening the present description.

The first output terminal OUTa and the second output terminal OUTb are coupled, via a voltage sensing circuitry not comprised in the DC motor driver 200′, to a circuit 30′.

Therefore, such circuit 30′, not comprised in the DC motor driver 200′, is configured to receive the first voltage V_OUTa sensed from the first output terminal OUTa and the second voltage V_OUTb sensed from the second output terminal OUTb, to determine a monitoring signal POUT related to an output phase of the DC motor driver 200′, and to provide such monitoring signal POUT to a phase output terminal of the circuit 30′.

The monitoring signal POUT may be retrieved by an additional control unit, for instance, a microcontroller, a microprocessor, a logic unit, or the like, from such phase output terminal of the circuit 30′ in order to implement operations related to diagnostic fault coverage, such as detecting, based on such monitoring signal POUT, and reacting to failures.

It is noted that if the circuit 30′ is comprised in the DC motor driver 200′ but is external to the logic control unit 202′ of the DC motor driver 200′, the monitoring signal POUT may be provided to a phase output terminal of the DC motor driver 200′ and the voltage sensing circuitry may either be comprised or not comprised in such DC motor driver 200′.

FIG. 4 illustrates an exemplary circuit 30a, 30′a able to generate a feedback signal, that is, the monitoring signal POUT, that allows monitoring operations on the phases of a DC motor driver according to embodiments of the present description.

It is noted that most of the elements of FIG. 4 are also present in FIG. 5, which illustrates an exemplary circuit 30b, 30′b able to generate a feedback signal, that is, the monitoring signal POUT, that allows monitoring operations on the phases of a DC motor driver according to embodiments of the present description.

To this regard, the elements described in the following refers both to FIG. 4 and FIG. 5, thus, such exemplary circuit is generally referred to as circuit 30 or 30′.

Circuits for monitoring the output phases of DC motor drivers as described herein 30, 30′ may comprise a selection unit PDa,b, for instance, implemented via a multiplexer, and a plurality of switches SW comprising pull-up impedances SW_PU1 and SW_PU2.

Such selection unit PDa,b and, if present, such plurality of switches SW, are configured to provide the power stage state monitoring function (that is, the monitoring of the phases of the DC motor driver via the feedback signal—that is, the monitoring signal POUT) during both on-states and off-states of the DC motor driver 200 or 200′, and, more in general, in various working conditions of the full-bridge circuit.

It is noted that solutions as described herein may provide a feedback signal, that is, the monitoring signal POUT, related to the first voltage V_OUTa sensed from the first output terminal OUTa and the second voltage V_OUTb sensed from the second output terminal OUTb, thus, related to the phases of the DC motor driver 200 or 200′, to the additional control unit, for instance, in real-time, during an operative mode of the DC motor driver 200 or 200′.

It is noted that the operative modes of the DC motor driver 200 or 200′ may comprise a clock mode, a counter clock mode, a braking to voltage VBAT mode, and a braking to ground GND mode.

It is noted that during the operative modes, such monitoring signal POUT may be obtained without operating the plurality of switches SW.

It is noted that such plurality of switches SW comprising pull-up impedances SW_PU1 and SW_PU2 is operated if diagnostic operations are to be performed, for instance, operations for detecting a faulty component, that is, a fault detection function.

Therefore, solutions as described herein may provide, during fault detection conditions, a fault detection function that allows detecting a faulty component based on the states, that is, conductive or non-conductive, of the pull-up SW_PU1 and SW_PU2 impedance switches.

For instance, such fault detection function may allow to detect if a transistor out of the first transistor M1, the second transistor M2, the third transistor M3, and the fourth transistor M4 remains permanently in an on-state, that is, in a conductive state, or in an off-state, that is, in a non-conductive state, independently from an input state, that is, the state of the transistor set by the DC motor driver in order to drive the respective DC motor, being an on-state or an off-state.

In addition, solutions as described herein, using the circuit 30 or 30′, may be able to follow the toggling of the first voltage V_OUTa sensed from the first output terminal OUTa and the second voltage V_OUTb sensed from the second output terminal OUTb up to a frequency of about 20 kHz.

The circuits for monitoring the output phases of DC motor drivers 30, 30′ may comprise, as previously described, the plurality of switches SW comprising pull-up impedances SW_PU1 and SW_PU2, wherein:

The circuits for monitoring the output phases of DC motor drivers 30, 30′ may further comprise:

It is noted that the plurality of switches SW may also be implemented via VIPower (“Vertical Intelligent Power”) technologies, allowing to integrate on a same die a Power MOSFET with an intelligent signal/protection circuitry.

It is noted that the plurality of switches SW is configured to pull-up, via the first pull-up impedance switch SW_PU1 and the second pull-up impedance switch SW_PU2 the power outputs, that is, the first node N1 and/or the second node N2.

The first node N1 may be configured to be supplied with the first voltage V_OUTa sensed from the first output terminal OUTa, while the second node N2 may be configured to be supplied with the second voltage V_OUTb sensed from the second output terminal OUTb.

The first node N1 may be coupled to a first input terminal of a first comparator AMP1, such first comparator AMP1 being configure to perform a comparison operation.

A second input terminal of the first comparator AMP1 may be coupled to a third node N3 supplied with a threshold voltage Vth, for instance, implemented via a voltage supply coupled between such third node N3 and the internal ground terminal supplied with the voltage Vss.

An output terminal of the first comparator AMP1 may be coupled to a first input terminal of the selection unit PDa,b, such output terminal being configured to provide to the selection unit PDa,b a result of a comparison between such first voltage V_OUTa received from the first node N1 and the threshold voltage Vth received from the third node N3.

Similarly, the second node N2 may be coupled to a first input terminal of a second comparator AMP2, such second comparator AMP2 being configure to perform a comparison operation.

A second input terminal of the second comparator AMP2 may be coupled to the third node Ng supplied with the threshold voltage Vth.

An output terminal of the second comparator AMP2 may be coupled to a second input terminal of the selection unit PDa,b, such output terminal being configured to provide to the selection unit PDa,b a result of a comparison between such second voltage V_OUTb received from the second node N2 and the threshold voltage Vth received from the third node N3.

The selection unit PDa,b may be configured to receive, at a selection input terminal, a selection signal SEL, indicating to couple the first input terminal of the selection unit PDa,b or the second input terminal of the selection unit PDa,b with an output terminal of the selection unit PDa,b, thus, indicating to provide as output either the result of the comparison between the first voltage V_OUTa and the threshold voltage Vth, that is, an information related to a phase of the first output terminal OUTa, or the result of the comparison between the second voltage V_OUTb and the threshold voltage Vth, that is, an information related to a phase of the second output terminal OUTb, respectively.

In embodiments such as that illustrated in FIG. 5, such output terminal of the selection unit PDa,b may be provided as output of either the circuit 30′b or, if the circuit 30b is considered, of the DC motor driver 200, thus, being the feedback signal, that is, the monitoring signal POUT. It is noted that in such embodiments, a fifth transistor M5 illustrated in such FIG. 5 may also not be present.

It is noted that if such fifth transistor M5 is present in embodiments as that of FIG. 5, such fifth transistor M5 may be configured to have:

It is noted that such fifth transistor M5 may be configured as an “open drain/collector” transistor, thus, being configured to act as an inverting switch that:

Alternatively, in embodiments such as that illustrated in FIG. 4, such output terminal of the selection unit PDa,b may be configured to drive a fifth transistor, for instance, a MOSFET M5, via its control terminal, such fifth transistor M5 being comprised in the circuit 30a or 30′a.

A current source terminal of such fifth transistor M5 is coupled to the internal ground terminal supplied with the voltage Vss and a current sinking terminal of such fifth transistor M5 is the terminal supplying the feedback signal, that is, the monitoring signal POUT, to the additional control unit, either via the phase output terminal of the circuit 30′a or, if the circuit 30a is considered, via the phase output terminal of the DC motor driver 200.

Even in embodiments as that of FIG. 4, such current sinking terminal of such fifth transistor M5 may be coupled, for instance, via a resistor, to an external voltage supply (not shown in FIG. 4).

Therefore, even in embodiments according to FIG. 4, such fifth transistor M5 may be configured as an “open drain/collector” transistor, thus, being configured to act as an inverting switch that:

To summarize, solutions as disclosed herein are related to a circuit 30 or 30′ for monitoring phases of driving signals outputted by a Direct Current, DC, driver 200 or 200′ respectively, for instance, a driving signal used to drive a corresponding DC motor L, therefore, allowing the monitoring of the phase of such DC motor L.

Such DC driver 200 or 200′ is configured to drive a load L, for instance, a DC motor but also other loads can be considered (as described above), via a first terminal, that is, the first output terminal OUTa, and a second terminal, that is, the second output terminal OUTb, coupled to respective load terminals, and to switch a polarity applied thereon (that is, the polarity applied on the first output terminal OUTa and the second output terminal OUTb).

In addition, in embodiments of solutions disclosed herein, such first comparison circuitry AMP1 may be configured to receive such first voltage V_OUTa via a first node N1, and such second comparison circuitry AMP2 may be configured to receive such second voltage V_OUT® via a second node N2.

In such a case, the circuit 30 or 30′ may comprise:

In embodiments of solutions disclosed herein, such first switch SW_PU1 and such second switch SW_PU2 may integrate a protection circuitry, in particular, such first switch SW_PU1 and such second switch SW_PU2 may be Vertical Intelligent Power, VIPower switches.

In embodiments of solutions disclosed herein, such selection circuitry PDa,b may be configured to drive, based on a comparison voltage selected out of such first comparison voltage and such second comparison voltage, a transistor, for instance, the fifth transistor M5, via its control terminal, such transistor M5 having:

In embodiments of solutions disclosed herein, the DC driver 200 or 200′ may comprise:

In embodiments of solutions disclosed herein, the load L coupled to the DC driver 200 or 200′ may be a DC motor.

In embodiments of solutions disclosed herein, the circuit 30, 30′ may be:

It is noted that the selection signal SEL may be provided by the additional control unit, for instance, a microcontroller or the like, according to the phase that is to be monitored, if the DC motor driver is in an operative mode, or to the fault that is to be detected, if the DC motor driver is in a fault detection condition.

The additional control unit may be configured to provide monitoring and protection functions by retrieving, based on:

The additional control unit may be further configured to:

It is noted that such verification voltage threshold may be chosen in order to be higher than a voltage equal to zero and lower than the minimum voltage of the received feedback signal when such received feedback signal is related to an active state, that is, a high voltage level state such as the first given voltage V1 of FIG. 5, of the corresponding first voltage V_OUTa or second voltage V_OUTb that is monitored.

In addition, the additional control unit may be further configured to:

It is noted that if the DC motor driver is in a fault detection condition, the plurality of switches SW can be operated based on the fault that is to be detected, for instance, via an internal logic configured to manage such plurality of switches SW according to switch states related to the fault that is to be detected, for instance, provided by the additional control unit on the base of data stored in such table.

It is noted that even the selection signal SEL provided by the additional control unit may be set according to a selection value, for instance, stored in such table.

If an anomalous condition is detected (either in the operative mode or in the fault detection mode), the additional control unit may be configured to provide a reaction for limiting the effects of such detected anomalous condition.

Therefore, such monitoring signal POUT can provide both a static and dynamic feedback to the additional control unit for facilitating performing safety-relevant functions, such feedback being indicative of the state of such first output terminal OUTa and such second output terminal OUTb.

Such safety-relevant functions may comprise, for instance, the fault detection function described previously.

FIG. 6 illustrates exemplary signals 40 flowing during the operative mode of the circuit 30, 30′ of FIG. 4 according to embodiments of the present description.

FIG. 6 illustrates an exemplary behavior of a sensed voltage V_OUTx, corresponding to the first voltage V_OUTa sensed from the first output terminal OUTa and/or the second voltage V_OUTb sensed from the second output terminal OUTb, that:

Therefore, being the circuit 30 or 30′ operating in the operative mode, the feedback signal, that is, the monitoring signal POUT, is related to such sensed voltage V_OUTx, corresponding to the first voltage V_OUTa sensed from the first output terminal OUTa and/or the second voltage V_OUTb sensed from the second output terminal OUTb, thus, such monitoring signal POUT is a voltage signal that:

Therefore, such monitoring signal POUT, that is, the waveform of such signal, follows, that is, is correlated to, the behavior, that is, the waveform, of the sensed voltage V_OUTx, for instance, after a given delay that is illustrated in FIG. 6 with the references t1 and t2, thus, providing to the additional control unit information related to the output status of the DC motor driver, that is, related to a phase of the DC motor driver.

Each operative and/or diagnostic condition that is to be analyzed, that is, each condition considered in solutions as described herein, may be characterized by:

In the following, exemplary operative and diagnostic conditions and respective values for the expected level related to the monitoring signal POUT, the respective switch states related to a fault that is to be detected, and the respective selection value for the selection signal SEL are described.

It is noted that such respective switch states may not be present in embodiments where the plurality of switches SW is not present.

It is noted that operative and diagnostic conditions different from those reported herein may also be present.

Such exemplary operative and diagnostic conditions and respective values for the expected level related to the monitoring signal POUT, the respective switch states related to a fault that is to be detected, and the respective selection value for the selection signal SEL may be stored in a table managed by the additional control unit.

The additional control unit may, for instance, based on the values comprised in the table and on a current mode of the DC motor driver, that is, either an operative mode or a fault detection mode and, in this last case, based also on the type of fault that is to be detected, be configured to:

Therefore, such additional control unit may be further configured to, based on:

To summarize, circuits 30 or 30′ as described herein may provide the monitored voltage signal POUT to a control unit, in particular, a control unit external to the DC driver 200 or 200′.

Such control unit may be configured to, based on a current operation mode, that is, based on the phase that is to be monitored (if the DC motor driver is in an operative mode) or the fault that is to be detected (if the DC motor driver is in a fault detection condition), either of the DC driver 200 or 200′:

In various embodiments, if the plurality of switches SW is present, such control unit may be configured to operate, based on the current operation mode of the DC driver 200 or 200′ the first switch SW_PU1 and/or the second switch SW_PU2 for performing pull-up operations.

A first operative condition may be related to the monitoring of the first voltage V_OUTa sensed from the first output terminal OUTa of the DC motor driver 200 or 200′ while the DC motor L is operated clockwise.

Such first operative condition can be obtained by:

It is noted that other conditions described in the following that are related to the monitoring of the first voltage V_OUTa sensed from the first output terminal OUTa of the DC motor driver 200 or 200′ comprise setting the selection signal SEL in order to indicate to couple the first input terminal of the selection unit PDa,b to the output terminal of such selection unit PDa,b, thus, indicating to provide as output the information related to the phase of the first output terminal OUTa, for instance, by setting such selection signal SEL to a binary logic level equal to a high logic level.

Therefore, such setting operation of the selection signal SEL will be not repeated in the following.

A second operative condition may be related to the monitoring of the first voltage V_OUTa sensed from the first output terminal OUTa of the DC motor driver 200 or 200′ while the DC motor L is operated counter clockwise.

Such second operative condition can be obtained by, in addition to setting the selection signal SEL:

A further operative condition may be related to the monitoring of the first voltage V_OUTa sensed from the first output terminal OUTa of the DC motor driver 200 or 200′ while the DC motor L is braking to the voltage VBAT, that is, the DC motor L brakes and decelerates since both of its terminals are coupled to the voltage VBAT.

Such further operative condition can be obtained by, in addition to setting the selection signal SEL:

A further operative condition may be related to the monitoring of the first voltage V_OUTa sensed from the first output terminal OUTa of the DC motor driver 200 or 200′ while the DC motor L is braking to ground GND, that is, the DC motor L brakes and decelerates since both of its terminals are coupled to ground GND.

Such further operative condition can be obtained by, in addition to setting the selection signal SEL:

A first diagnostic condition may be related to the monitoring of the first voltage V_OUTa sensed from the first output terminal OUTa of the DC motor driver 200 or 200′ while the DC motor driver is configured to perform fault detection operations and, in particular, a high-side fault detection operation.

Such first diagnostic condition can be obtained by, in addition to setting the selection signal SEL:

It is noted that the diagnostic condition related to the high-side fault detection operation may be performed also by configuring the DC motor driver 200 or 200′ in order to operate the first transistor M1, making such first transistor M1 conductive.

A further diagnostic condition may be related to the monitoring of the first voltage V_OUTa sensed from the first output terminal OUTa of the DC motor driver 200 or 200′ while the DC motor driver is configured to perform fault detection operations and, in particular, a low-side fault detection operation.

Such further diagnostic condition can be obtained by, in addition to setting the selection signal SEL:

A further diagnostic condition may be related to the monitoring of the first voltage V_OUTa sensed from the first output terminal OUTa of the DC motor driver 200 or 200′ while the DC motor driver is configured to perform fault detection operations and, in particular, a fault detection operation performed during an off-state of such DC motor driver.

Such a condition can be obtained by, in addition to setting the selection signal SEL:

Further conditions may be related to the monitoring of the second voltage V_OUTb sensed from the second output terminal OUTb of the DC motor driver 200 or 200′.

For instance, another operative condition may be related to the monitoring of such second voltage V_OUTb sensed from the second output terminal OUTb of the DC motor driver 200 or 200′ while the DC motor L is operated clockwise.

Such operative condition can be obtained by:

Even in this case, it is noted that other conditions described in the following that are related to the monitoring of the second voltage V_OUTb sensed from the second output terminal OUTb of the DC motor driver 200 or 200′ comprise setting the selection signal SEL to indicate to couple the second input terminal of the selection unit PDa,b to the output terminal of such selection unit PDa,b, thus, indicating to provide as output the information related to the phase of the second output terminal OUTb, for instance, by setting such selection signal SEL to a binary logic level equal to a low logic level.

Therefore, such setting operation of the selection signal SEL will be not repeated in the following.

A further operative condition may be related to the monitoring of the second voltage V_OUTb sensed from the second output terminal OUTb of the DC motor driver 200 or 200′ while the DC motor Lis operated counter clockwise.

Such operative condition can be obtained by, in addition to setting the selection signal SEL:

A further operative condition may be related to the monitoring of the second voltage V_OUTb sensed from the second output terminal OUTb of the DC motor driver 200 or 200′ while the DC motor Lis braking to the voltage VBAT.

Such further operative condition can be obtained by, in addition to setting the selection signal SEL:

A further operative condition may be related to the monitoring of the second voltage V_OUTb sensed from the second output terminal OUTb of the DC motor driver 200 or 200′ while the DC motor Lis braking to ground GND.

Such further operative condition can be obtained by, in addition to setting the selection signal SEL:

A first diagnostic condition may be related to the monitoring of the second voltage V_OUTb sensed from the second output terminal OUTb of the DC motor driver 200 or 200′ while the DC motor driver is configured to perform fault detection operations and, in particular, a high-side fault detection operation.

Such first diagnostic condition can be obtained by, in addition to setting the selection signal SEL:

It is noted that the condition related to the high-side fault detection operation may be performed also by configuring the DC motor driver 200 or 200′ in order to operate the third transistor M3, making such third transistor M3 conductive.

A further diagnostic condition may be related to the monitoring of the second voltage V_OUTb sensed from the second output terminal OUTb of the DC motor driver 200 or 200′ while the DC motor driver is configured to perform fault detection operations and, in particular, a low-side fault detection operation.

Such further diagnostic condition can be obtained by, in addition to setting the selection signal SEL:

A further diagnostic condition may be related to the monitoring of the second voltage V_OUTb sensed from the second output terminal OUTb of the DC motor driver 200 or 200′ while the DC motor driver is configured to perform fault detection operations and, in particular, a fault detection operation performed during an off-state of such DC motor driver.

Such further diagnostic condition can be obtained by, in addition to setting the selection signal SEL:

Further diagnostic conditions may also be related to the monitoring of the DC motor driver 200 or 200′ during a stand by state.

It is noted that if the monitoring functions are not to be provided in cases where the pull-up impedance switches are operated, such plurality of switches SW may also be absent.

In such a case, the first voltage V_OUTa sensed from the first output terminal OUTa and the second voltage V_OUTb sensed from the second output terminal OUTb are provided directly to the first input terminal of the first comparator AMP1 and to the first input terminal of the second comparator AMP2, respectively.

It is also noted that, based on the monitoring functions considered, such plurality of switches SW may comprise only a single pull-up impedance switch.

Solutions as described herein facilitate achieving a circuit for monitoring phases of a Direct Current motor driver, for instance, by monitoring the states of its output signals OUTa and OUTb via the monitoring signal POUT in order to monitor a phase of a load coupled thereto, for example, the phase of a DC motor L, such DC motor driver being configured to drive the DC motor via a first and a second terminal.

The circuit according to solution as disclosed herein comprises:

In embodiments of the circuit as described herein, such first comparison circuitry may be configured to receive such first voltage via a first node and such second comparison circuitry may be configured to receive such second voltage via a second node.

Thus, such circuit may comprise:

It is noted that solutions as described herein also apply to a DC driver, for instance, the DC motor driver 200 of FIG. 2, in particular comprising an H-bridge, configured to drive a load L, in particular a DC motor, via a first terminal, that is, the first output terminal OUTa, and a second terminal, that is, the second output terminal OUTb, coupled to respective load terminals, wherein such DC driver 200 comprises the circuit 30.

It is further noted that such DC driver is configured to switch a polarity applied to the terminals of the load L.

It is noted that solutions as described herein also apply to a method for monitoring phases of a Direct Current, DC, driver 200 or 200′ through the circuit 30 or 30′ respectively, such DC driver 200 or 200′ being configured to drive a load L, for instance, a DC motor, via a first terminal, for instance, the first output terminal OUTa, and a second terminal, for instance, the second output terminal OUTb, coupled to respective load terminals by switching a polarity applied thereto.

Such method comprises:

In embodiments of solutions described herein, such operation of receiving, by the first comparison circuitry AMP1, the first voltage V_OUTa may be performed via a first node N1, and such operation of receiving, by the second comparison circuitry AMP2, the second voltage V_OUTb may be performed via a second node N2.

In such a case, the method may comprise performing pull-up operations via a first switch, for instance, the first pull-up impedance switch SW_PU1, coupled between such first node N1 and a supply terminal VBAT and/or a second switch, for instance, the second pull-up impedance switch SW_PU2, coupled between such second node N2 and such supply terminal VBAT.

In embodiments of solutions described herein, such method may comprise driving, via such selection circuitry PDa,b and based on a comparison voltage selected out of such first comparison voltage and such second comparison voltage, a transistor, for instance, the fifth transistor M5, via its control terminal, such transistor M5 having:

Thus, solutions as described herein facilitate improving the monitoring of devices used for driving DC motors, that is, DC motor drivers, facilitating performing monitoring operations both during on-states and during off-states of such DC motor drivers in order to increase a functional safety of such devices.

In such a way, solutions as described herein can have a higher ASIL-B metric at system level and, if the solution is integrated in the DC motor driver 200 as in FIG. 2 (therefore, if such DC motor driver 200 is implemented without discrete components), solutions as described herein can also reduce the external circuitry requested for performing the monitoring function.

In addition, solutions as described herein can facilitate saving costs and area of the PCB (“Printed Circuit Board”), also in case of an implementation with discrete components as in FIG. 3, such advantages being a result of a higher integration level.

It is noted that, if the plurality of switches SW is present, the PCB area can be even further reduced since such plurality of switches SW facilitate, without using additional components, testing various operative and fault detection conditions, allowing a more detailed diagnostic of the power stages as every output power can be checked.

Without prejudice to the underlying principles, the details and the embodiments may vary, even significantly, with respect to what has been described by way of example only without departing from the scope of the embodiments.

The extent of protection is determined by the annexed claims.