1. A supply circuit, comprising:
- a supply terminal configured to receive an external supply voltage;
at least one supply generation circuit configured to generate at least one internal supply voltage based on the external supply voltage;
a voltage deviation detection circuit configured to detect a deviation of the at least one internal supply voltage from a predefined voltage range; and
a current limiter arrangement configured to limit a current through the at least one supply generation circuit, which would otherwise exceed a predefined current value, to the predefined current value to enable an external system to identify an error state via identification of the predefined current value upon the deviation of the at least one internal supply voltage from the predefined voltage range.
A supply circuit is provided including a supply generation circuit coupled to a supply terminal. A voltage deviation detection circuit is adapted to detect a voltage deviation in an internal supply voltage. A current limiter arrangement is adapted to limit a current through the supply generation circuit to a predefined value.
- 1. A supply circuit, comprising:
a supply terminal configured to receive an external supply voltage; at least one supply generation circuit configured to generate at least one internal supply voltage based on the external supply voltage; a voltage deviation detection circuit configured to detect a deviation of the at least one internal supply voltage from a predefined voltage range; and a current limiter arrangement configured to limit a current through the at least one supply generation circuit, which would otherwise exceed a predefined current value, to the predefined current value to enable an external system to identify an error state via identification of the predefined current value upon the deviation of the at least one internal supply voltage from the predefined voltage range.
- View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17)
- 18. A circuit, comprising:
a supply terminal configured to receive an first supply voltage, a safety mechanism circuit configured to detect an error associated with a deviation of the first supply voltage, and a current limiter arrangement configured to limit a current drawn through the supply terminal, which would otherwise exceed a predefined current value, to the predefined current value when the safety mechanism circuit detects the error to enable an external system to identify the error via identification of the predefined current value upon the deviation of the first supply voltage.
- View Dependent Claims (19, 20, 21)
- 22. A method, comprising:
detecting an error associated with a deviation of an internal supply voltage, responding to the error, and limiting a current drawn through a supply terminal, which would otherwise exceed a predefined error current level, to the predefined error current level to allow an external system to identify the error via identification of the predefined current value upon the deviation of the internal supply voltage, wherein the supply terminal is configured to receive an external supply voltage.
- View Dependent Claims (23, 24, 25, 26)
The present application relates to supply circuits for supplying a voltage and/or a current and to associated devices and methods.
Electronic circuits, for example integrated chips, often generate one or more internal supply voltages based on an external supply voltage. For example, for generating one or more internal supply voltages one or more DC/DC converters may be used. A part of the circuit or chip supplied by such a voltage converter or other internal power supply is also referred to as a voltage domain. An internal supply voltage of such a voltage domain may be monitored for example to detect an undervoltage, i.e. the supply voltage being below a predetermined threshold voltage. In such a case, the circuit may be brought to a specific state in some cases, also referred to as reset state or error state (referred to simply as reset state in the following).
In some cases it is desirable to signal the presence of this reset state to other entities, for example to a system coupled with the electronic circuit. This may be of particular interest in cases where the system is on a higher infrastructure level than the electronic circuit. For example in some automotive applications, for such signaling a current interface may be used, and a predefined current level may be used to signal a reset state or an error state e.g. to an ECU as the higher level entity or system.
However, in some cases it may not be possible to provide the predefined current in the reset state in conventional applications. For example, when an undervoltage occurs due to a short circuit, a current caused by the short circuit may increase a current above the predefined current level.
It is therefore an object to provide possibilities for maintaining a desired current level, for example a predefined reset level, in such an error case.
It is a further object to provide possibilities for signaling e.g. an error, fault or failure to an entity coupled to or in communication with the electronic circuit, such that the coupled entity can be reliably informed about error within the electronic circuit.
In an aspect, a circuit as defined in claim 1 is provided. In a further aspect, a device as defined in claim 13 is provided. In a further aspect, a circuit as defined in claim 17 is provided. In yet another aspect, a method as defined in claim 21 is provided. The dependent claims define further embodiments. Features defined in one or more claims of one of the aspects may also be applicable to other aspects.
In the following, various embodiments will be described in detail referring to the attached drawings. These embodiments serve illustrative purposes only and are not to be construed as limiting the scope of the present application.
For example, while an embodiment may be described as comprising a plurality of features or elements, this is by way of illustration only, and other embodiments may comprise less features or elements and/or alternative features or elements. In yet other embodiments, additionally or alternatively further features or elements may be provided. Features from different embodiments may be combined to form further embodiments. Also, a variation or modification described with respect to one of the embodiments may also be applicable to other embodiments unless noted otherwise.
Various elements shown in the drawings are not necessarily to scale with each other, and the spatial arrangement of the various elements and various implementations may be different to the spatial arrangement shown in the drawings. Elements shown in the drawings may be replaced by other elements performing essentially the same function without departing from the scope of the present application.
Any electrical connections or couplings between elements shown in the drawings or described herein may be direct connections or couplings, i.e. connections or couplings without additional intervening elements (for example simple wires or metal layers), but may also be indirect connections or couplings with one or more additional intervening elements, as long as the general purpose of the connection or coupling, for example to transmit a certain kind of signal, voltage, current and/or information, is essentially maintained.
Terminology used herein may correspond to terminology as used in International Standard ISO 26262 related to functional safety for road vehicles. For example, the term error may refer to any discrepancy between a computed, observed or measured value or condition and the true, specified or theoretically correct value or condition. In the present application, an error may for example be present when a voltage is below a specified voltage range. An error may for example be due to a fault.
A fault may refer to an abnormal condition that can cause an element or an item (e.g. a sensor) to fail. A failure may refer to a termination of the ability of an element to perform a function as required.
A safe state may refer to an operating mode of an item without an unreasonable level of risk. Examples may include a normal operating mode, a degraded operating mode or a switched-off mode. It may be required that upon detection of a fault an entity (e.g. item, system etc.) transitions to a safe state within a fault tolerant time interval.
In some embodiments, a supply circuit may comprise one or more supply generation circuits, e.g. voltage converters, to generate one or more internal supply voltages based on an external supply voltage. Furthermore, an interface circuit coupled to an external supply voltage terminal may be provided. The interface circuit may be disabled upon detection of an undervoltage or other voltage deviation in the one or more internal supply voltages. A current limiter arrangement may be provided operably coupled to the supply generation circuits. The current limiter arrangement in some embodiments may limit a current through the supply generation circuits to a predefined value, for example a predefined reset value.
The one or more supply generation circuits may for example comprise voltage converters like DC/DC converters. The interface circuit may be adapted to provide various current levels through the supply voltage terminal.
Turning now to the figures, in
Device 10 comprises a first terminal 11 and a second terminal 12. In some implementations, first terminal 11 may be a terminal for receiving an external positive supply voltage, and second terminal 12 may be a ground terminal. Furthermore, first terminal 11 may be used by device 10 to provide a current signal, for example by drawing a predefined current. For example, to transmit digital signals in an implementation a current of 7 mA may correspond to a value of logical 0, and a current of 14 mA may correspond to a value of logical 1, although this is only an example and other values may be used as well. It should be noted that while in the embodiment of
Circuit 15 may use an interface circuit 17 to provide a desired current level through first terminal 11. For example, in some embodiments a stand-by current consumption of circuit 15 may be 3.5 mA. To output a current level of 7 mA corresponding to logical 0, circuit 15 may draw an additional 3.5 mA via interface circuit 17, and to provide a current level of 14 mA corresponding to logical 1, circuit 15 may draw another 10.5 mA via interface circuit 17. These values serve only as examples, and other current levels may also be used. In other embodiments, instead of current-based signaling voltage-based signaling may be used, and interface circuit 17 may be configured to provide a desired voltage level at first terminal 11.
In some embodiments, besides current levels for logical 0 and logical 1, a further predefined current level may be provided as a reset level. The reset level may for example indicate a state where device 10 is deactivated and/or has encountered an error. It will be appreciated that a deactivation may be caused in response to the encountered error or as a safety measure in circumstances where the error indicates the circuit is no longer working with sufficient reliability, for example where the error indicates a fault, failure or possible fault or failure of the circuit. In some embodiments, this predefined further current level may correspond to the above-mentioned stand-by current consumption of circuit 15 via supply generation circuit 14, for example 3.5 mA.
The device 10 of
In some embodiments, for example in a fault-free state only the stand-by current is drawn by circuit 15, which as explained previously may correspond to a predefined reset level. Therefore, by detecting a current corresponding to the reset level, an external system 18 may be informed of the reset state, in this case for example the disabled state of interface 17. In automotive applications the system 18 could be implemented as an electronic control unit (ECU).
However, some faults causing an error to be detected by safety circuit 16, for example an undervoltage, may also influence the current drawn by circuit 15. As an example, faults causing a detection of an undervoltage may include a short circuit fault, which would cause circuit 15 to draw additional current without further measures. Short circuits may for example be caused by so-called random hardware failures. The additional current could change the current sensed through first terminal 11 by system 20, such that system 18 may not recognize the reset state correctly, as the current level is higher than the predefined error state current.
To prevent such a misinterpretation of a current level, in the embodiment of
It should be noted that in some embodiments current limiter 13 may also cause undervoltage detection circuit 16 to react faster in case of a short circuit and similar errors. As mentioned, errors like undervoltage errors could without the presence of current limiter 13 increase the current consumption of circuit 15. Supply generation circuit 14 may then try to meet this required additional current consumption, which, however, is limited by current limiter 13. This may cause a voltage generated by supply generation circuit 14 to break down faster than in a case without current limiter 13, which in turn may cause a faster detection by safety circuit 16. In some embodiments, this may then lead to a faster deactivation of interface circuit 17 and/or a faster presence of the predetermined error current level at first terminal 11. Therefore, a failure may be detected faster than without current limiter 13 in some embodiments.
It should be noted that in the embodiment of
While a single supply generation circuit 14 is shown in
Furthermore, the external supply voltage on supply voltage line 21 may be converted to an internal analog supply voltage by an analog supply generation circuit 23 and/or to an internal digital supply voltage by a digital supply generation circuit 24. The internal analog supply voltage may be used to supply analog parts of a circuit like circuit 15 of
Furthermore, an analog safety circuit 26 is coupled to an output of analog supply generation circuit 23. Safety circuit 26 may detect voltage deviations, for example an undervoltage (e.g. a voltage below a predetermined threshold) or an overvoltage (e.g. a voltage above a further predetermined threshold), and may deactivate interface circuit 25 upon detection of a voltage deviation condition, for example an undervoltage and/or an overvoltage of the internal analog supply voltage. Furthermore, a digital safety mechanism circuit 27 may be provided (optionally implemented as a digital circuit) monitoring an output voltage of digital supply generation circuit 24 to detect a voltage deviation like an undervoltage or an overvoltage. It should be noted that providing a digital safety mechanism circuit monitoring the output of digital supply generation circuit 24 may be of particular importance as generally, safety features may be comparatively easy to implement in digital circuit portions by programming or designing elements like digital signal processors accordingly, compared to implementations in analog circuit portions. However, providing a correct supply voltage may still be crucial, as without such a correct supply voltage the complete digital circuit portion may fail.
Upon detection of such a voltage deviation, digital safety mechanism circuit 27 may deactivate interface 25. Safety mechanism circuits 26, 27 may for example be implemented using comparators. In some embodiments, disabling interface 25 may imply that after disabling interface 25 essentially does not draw current from terminal 20. In some embodiments, deactivating interface 25 may serve to signal an error (e.g. the voltage deviation) to a system coupled to terminal 20. In other embodiments, additionally or alternatively to disabling interface 25 other measures may be taken. Examples include disabling one or more circuits portions coupled to terminal 20 (e.g. including circuit portions shown in
A current drawn by circuit portions supplied by analog supply generation circuit 23 is labeled I_ana in
As explained previously with respect to
To prevent incorrect recognition of predefined current levels, in the embodiment of
Moreover, provision of current limiter 22 may improve the detection of undervoltage conditions by safety mechanism circuits 26, 27, as was explained for undervoltage detection circuit 16 of
In the example supply circuit of
In the embodiment of
Compared to the embodiment of
Therefore, in embodiments generally a current limiter arrangement may be provided, which may comprise one current limiter as shown in
At 40, an error at a supply generation circuit, for example a DC/DC converter, is detected. For example, at 40 the method may comprise detecting an undervoltage at an output of the supply generation circuit.
At 41, a response measure in response to detecting the error is performed. For example, in an embodiment a current interface may be disabled. In normal operation, the current interface may be used to provide desired current levels at an external supply voltage terminal, for example to transmit data.
In other embodiments, additionally or alternatively to disabling the current interface other measures may be taken. Examples for such other measures include disabling one or more circuit portions or communicating an error to an external entity, e.g. a system. Other examples include using correction mechanisms to correct e.g. current values being output, e.g. using override/default values, or implementing other mechanisms that may compensate or mitigate the error.
At 42, in the error condition a current is limited to a predefined error level (also referred to as reset level), e.g. 3.5 mA, which may be used for signaling the error condition to an external system. Other techniques may also be employed.
The above-described embodiments serve merely as examples, and other implementations are also possible.