Intelligent electronic switch

Abstract

The present disclosure relates to intelligent electronic switches. Described herein is a circuit that can be used as an electronic fuse. According to one example, the circuit includes an integrated circuit (IC) having a chip contact for connecting a filter circuit during operation. The IC further includes a driver configured to drive a power transistor according to a logic signal, a squaring circuit configured to receive a current sense signal representative of a load current through the power transistor and output a first current representative of a squared load current at the chip contact, a comparator circuit configured to compare a voltage present at the chip contact to a reference voltage, and control logic configured to generate the logic signal and cause turn-off of the power transistor according to an output signal of the comparator circuit.

Description

Technical Field

[0001] This disclosure relates to the field of control / driver circuits for electronic switches such as metal-oxide-semiconductor (MOS) transistors. Background Technology

[0002] Almost every electrical installation (such as in a car, a house, or the electrical subsystems of a larger installation) includes one or more fuses to provide overcurrent protection. A standard fuse consists of a conductor that provides a low-ohmic current path when the current through the fuse is below its rated current. However, when the current through the fuse exceeds its rated current for a certain period of time, this conductor is designed to heat up and melt or evaporate. Once triggered, the fuse must be replaced with a new one.

[0003] Fuse are increasingly being replaced by circuit breakers. A circuit breaker is an automatically operating electrical switch designed to protect circuits from damage caused by overcurrent, overload, or short circuit. Circuit breakers may include electromechanical relays that are triggered to disconnect the protected circuit from the power supply when an overcurrent (i.e., a current exceeding the rated current) is detected. In many applications (such as in automotive power supplies), circuit breakers can be implemented using electronic switches (such as MOS transistors, IGBTs, etc.) to disconnect a protected circuit or subsystem from the power supply in the event of an overcurrent. Such electronic circuit breakers can also be called electronic fuses (e-fuse), smart fuses, or smart switches. In addition to their function as circuit breakers, electronic fuses can also be used to periodically turn loads on and off. Typically, a so-called driver circuit or a simple driver (in the case of a MOS transistor, a gate driver) is used to control the switching state (on / off) of electronic switches such as MOS transistors.

[0004] However, in at least some electronic circuit breakers (electronic fuses or e-fuses), the common driver circuit may be inadequate in terms of fault tolerance and functional safety, which can be particularly problematic in automotive applications where compliance with standards regarding functional safety (such as ISO 26262) is mandatory. In fact, electronic fuses require more than just replacing traditional fuses with electronic switches. The robust implementation of electronic fuses faces various challenges. Furthermore, the current configurability of electronic fuses for different applications and use cases can be an issue. Summary of the Invention

[0005] This section describes a circuit that can be used as an electronic fuse. According to one example, the circuit includes an integrated circuit (IC) with chip contacts for connecting filter circuitry during operation. The IC also includes: a driver configured to drive a power transistor according to a logic signal; a squaring circuit configured to receive a current-sensing signal representing the load current through the power transistor and to output a first current representing the squared load current at the chip contacts; a comparator circuit configured to compare a voltage present at the chip contacts with a reference voltage; and control logic configured to generate a logic signal and cause the power transistor to turn off according to the output signal of the comparator circuit. Attached Figure Description

[0006] The invention can be better understood by referring to the following figures and description. The components in the figures are not necessarily drawn to scale; rather, the focus is on illustrating the principles of the invention. Furthermore, in the figures, the same reference numerals denote corresponding components. In the figures:

[0007] Figure 1 An example of an electronic fuse circuit implemented using a smart switch and a microcontroller is illustrated schematically.

[0008] Figure 2 The illustration shows an embodiment of a smart switch that can be used in an electronic fuse circuit. The characteristics of the electronic fuse can be configured via an externally connected filter circuit.

[0009] Figures 3 to 5 The illustration shows as Figure 2 Various modified embodiments of the example.

[0010] Figure 6 Another embodiment is illustrated, which is also Figure 2 This is a modification of the example and does not require a digital bus interface.

[0011] Figure 7 The diagram shows... Figure 2 Another modification. Detailed Implementation

[0012] In the following detailed description, reference is made to the accompanying drawings. The drawings form part of the specification and, for illustrative purposes, show examples of how the invention can be used and implemented. It should be understood that features of the various embodiments described herein can be combined with each other unless specifically indicated otherwise.

[0013] Figure 1 The diagram illustrates an example of an electronic circuit that can be used as an electronic fuse. The electronic circuit includes an electronic switch T. L Integrated circuit (intelligent circuit 1), electronic switch T LIt can be a metal-oxide-semiconductor (MOS) field-effect transistor (FET), an insulated-gate bipolar transistor (IGBT), or any other type of transistor. Electronic switch T L There is a load current path connecting the two circuit nodes, specifically between the power supply terminal VS and the output terminal OUT in this example. The subsystem protected by the electronic fuse circuit is connected to the electronic load Z. LOAD Indicated. In the example depicted, electronic switch T L It is an n-channel MOSFET in a high-side configuration (high-side switching). Therefore, transistor T L The drain electrode is connected to the power supply terminal VS, and transistor T L The source terminal is connected to the output terminal OUT. When transistor T... L When in the ON state, the power supply voltage V present at the power supply terminal VS during operation. S Applied to load Z L .

[0014] Gate driver 11 is used to determine the logic signal S ON Transistor T L Driven to the on or off state (i.e., turn on and turn off). Suitable gate drivers are known and therefore will not be discussed in more detail here. Logic signal S ON It can be by Figure 1 The logic circuit marked "Control Logic 10" is generated. Control Logic 10 can be configured to output a specific logic level (e.g., a high level to turn on transistor T). L and low level to turn off transistor T L The logic signal S ON Control logic 10 can also be configured to generate a logic signal S in response to the receipt of a switching command. ON The switching command can be received from an external controller circuit, for example, via a digital communication link. In one example, the external controller circuit is a microcontroller 2 capable of communicating with the smart switch 1 via a Serial Peripheral Interface (SPI) bus. In this example, the microcontroller 2 can send a digital switching command to the control logic 10 of the smart switch 1 to trigger transistor T. L The switch is turned on or off. Additionally or alternatively, the input signal S applied at the input pin IN of smart switch 1... IN The logic level can be interpreted as a switching command. In this case, a high level of the input signal can trigger transistor T. L A high level signals the switch to be on, while a low level signals it to be off (or vice versa). It is understood that logic circuit 10 can provide other functions depending on the actual implementation of smart switch 1. Such functions may include, in particular, overheat protection, undervoltage detection, etc.

[0015] The smart switch 1 also includes a current sensing circuit 12, which is coupled to the electronic switch T. L And is configured to provide a representation of the load current i L The current sensing signal i CS For example, current sensing circuit 12 may include a so-called sensing transistor, which is coupled to transistor T. L And (approximately) in relation to transistor T L Operating at the same operating point, the current through the sensing transistor is compared with the load current i. L Proportional. The current of the sensing transistor can be used as a current sensing signal i. CS The sensing transistor used to measure the load current of the (power) transistor is known and will not be explained in more detail here. It should be understood that other current sensing concepts can be used. In a simple example, the current sensing circuit 12 includes transistor T coupled to... L A low-ohm sensing resistor is used between the output terminal OUT and the sensor. In this case, the voltage drop across the sensing resistor can be used to generate a current sensing signal.

[0016] According to the illustrated example, the smart switch 1 includes a diagnostic circuit 13 configured to output diagnostic information about the operation of the smart switch 1 upon request. In this example, the diagnostic circuit 13 is configured to output a diagnostic current i at terminal IS upon receiving a diagnostic request. S Diagnostic requests can be made by applying an enable signal S to the diagnostic terminal DEN. DEN A specific logic level (for the diagnostic enable signal) is indicated to the diagnostic circuit 13. In this example, the microcontroller 2 can output a signal S with a high level. DEN So that the diagnostic circuit 13 outputs a diagnostic current i at terminal IS. S The diagnostic current i S Equal to (or indicating) the current sensing signal i CS .

[0017] In the illustrated example, the diagnostic current i S via resistor R connected between terminal IS of smart switch 1 and ground IS Discharge. Voltage drop V across the resistor. IS Equal to R IS •I S This voltage can be supplied to the analog input of microcontroller 2. This allows microcontroller 2 to obtain information about the load current i. L Information and based on the load current i L The microcontroller 2 controls the operation of the smart switch 1. For example, the microcontroller 2 can monitor the load current i by periodically requesting diagnostic information from the smart switch 1. LAnd when the load current is too high at a certain time interval, transistor T is triggered. L The shutdown function. To perform this function, microcontroller 2 may include an analog-to-digital converter. It should be understood that the DEN and IS terminals are optional; diagnostic information can also be requested and sent via a digital communication link such as an SPI bus.

[0018] In the illustrated example, microcontroller 2 is powered by a stable supply voltage V. DD Power supply. It should be understood that microcontroller 2 is merely an example of controller circuitry. Microcontroller 2 may include a processor and memory for storing software instructions for the processor, which can be executed by the processor to enable the microcontroller to perform the functions described herein. It should be understood that other controllers may not rely on software instructions (or only partially) and may have hard-wired circuitry.

[0019] Traditional fuses interrupt the current path between the load and the power source by melting at a specific point. This melting occurs when the fuse material carries a specific current for a specific period of time. To implement an electronic fuse, the microcontroller 2 can monitor the load current i. L (Through the aforementioned diagnostic mechanism) and based on the load current, trigger transistor T L The shutdown (e.g., by outputting a signal S with a low level) IN The microcontroller 2 can be configured to calculate (based on load current information) a value representing electrical power that potentially heats the output terminal OUT of the connected smart switch 1 and the load Z. LOAD The cable. A thermal model of the cable can be used to trigger shutdown. In Figure 1 In the middle, the current i GND This indicates the current consumption of the smart switch itself.

[0020] Use the above reference Figure 1 The concept discussed is implementing such protection functionality in a microcontroller. That is, the microcontroller determines when to trigger transistor T. L The circuit is turned off. This gives the user of the circuit maximum flexibility because the trigger transistor T... L The shutdown algorithm is under complete user control, allowing the microcontroller to be programmed. However, this approach is clearly prone to errors, and in many applications, protection features independent of user-provided software are desired.

[0021] According to another concept, the protection function is moved from the microcontroller 2 to the smart switch 1. However, this avoids the need for user-provided software, but complicates the process of enabling users to configure the protection function and adapt it to the circuit / subsystem to be protected by the electronic fuse.

[0022] Figure 2The illustration depicts a concept that implements a protection function (i.e., the function of determining when to trigger shutdown due to overcurrent) in a smart switch 1, while providing the user with high flexibility to configure the protection function and adapt it to the circuit / subsystem to be protected by an electronic fuse. An electronic switch T is connected between terminals VS and OUT. L The gate driver 11 and the current sensing circuit 12 are basically the same as Figure 1 The same as in the example above, and refer to the description above. Similar to... Figure 1 For example, control logic 10 provides logic signal S to the gate driver. ON Indicator electronic switch T L The input signal S in the desired state (on / off) IN Provided by a digital communication interface (e.g., SPI). In one example, in response to receiving an enable command via the communication interface, signal S... IN The signal S is set to high level and responds to a received shutdown command. IN It is set to low level. As mentioned above, the on / off command can be sent by the microcontroller or any other external controller device.

[0023] according to Figure 2 For example, smart switch 1 includes a square circuit 14, which is configured to receive indications via electronic switch T. L Load current i L The current sensing signal i CS And at the dedicated chip contact FILT, a current i2 representing the squared load current is output, i.e., i CS = g ‧i CS 2 = K ‧i L 2 ,in g and K This represents a constant factor (gain or attenuation). Current sensing signal i CS This can be provided by the current sensing circuit 12, which has been referenced above. Figure 1 A discussion was held.

[0024] The chip contact FILT (chip terminal) allows the user to connect an external (i.e., external to the chip including the smart switch) filter circuit 3, where current i2 is discharged from the filter circuit 3 (towards ground), thereby causing a voltage V at the chip contact. T Voltage V T Depending on the filter characteristics, this will be discussed in more detail later.

[0025] The smart switch 1 also includes a comparator circuit 15, which is configured to convert the voltage V present at the chip contact FILT into a comparator circuit.T With reference voltage V REF A comparison is performed. The output of comparator circuit 15 is coupled to control logic 10, which is configured to trigger electronic switch T based on the output signal of comparator circuit 15. L The comparator circuit 15 is turned off. In one embodiment, the reference voltage V used by the comparator circuit 15 is... REF It can be configured based on information received from the digital communication interface (e.g., by an external controller via the digital communication interface).

[0026] Essentially, when the voltage V T Reaching or exceeding the reference voltage V REF When, the electronic switch T is triggered L The shutdown. In the example depicted ( Figure 2 In this circuit, the reference voltage is provided by a controllable voltage source 16. Many different implementations of the controllable voltage source and comparator circuit are known, so they will not be discussed in more detail here.

[0027] exist Figure 2 In the example, filter circuit 3 consists of resistor R F and capacitor C F The first-order low-pass (RC filter) is composed of resistor R. F and capacitor C F Parallel coupling is established between terminal FILT and ground. In some embodiments, a higher-order filter (e.g., a cascaded RC filter) may be used. The concepts explained here allow the user to select resistor R... F Capacitor C F and (optionally) reference voltage V REF The value is used to flexibly configure the characteristics of the electronic fuse. Filter circuit 3 basically represents a thermal model, which converts the electrical power, represented by the squared load current i2, into temperature information. Therefore, the voltage V... T This can be interpreted as a temperature value. In one embodiment, voltage V T Indicates the load current i L The temperature of the conductor is measured, while filter circuit 3 simulates the thermal behavior of the conductor. In another embodiment, voltage V... T This represents the temperature of a more complex subsystem that consumes load current i. L Meanwhile, the thermal behavior of the filter circuit 3 simulation subsystem was also studied.

[0028] In this embodiment, the current sensing circuit 12 provides an analog current sensing signal, and the squaring circuit 14 includes an analog multiplier. Figure 3 and Figure 4 An exemplary embodiment is Figure 2A modification of the illustrated embodiment is provided, wherein the current sensing circuit 12 provides a digital current sensing signal CSDIG. Suitable current sensing circuits 12 with digital outputs are known and will not be discussed in detail here. For example, such a current sensing circuit may include a sensing transistor and a successive approximation register (SAR) analog-to-digital converter (ADC) to generate the digital current sensing signal CSDIG.

[0029] exist Figure 3 In one embodiment, the smart switch 1 includes a digital squaring circuit 14' configured to square the digital current sensing signal CSDIG. That is, the digital squaring circuit 14' includes a multiplier that calculates the square of CSDIG × CSDIG and provides the product as a digital output signal i2DIG. To obtain the analog current i2 output at the chip terminal FILT, the smart switch 1 includes a current output digital-to-analog converter 17. In addition to the digital implementation of current sensing and squaring (and therefore the additional digital-to-analog converter 17), Figure 3 Examples and Figure 2 The examples are the same, and refer to the above description to avoid unnecessary repetition.

[0030] exist Figure 4 In one embodiment, the smart switch 1 includes a digital-to-analog converter 17' configured to convert a digital current sensing signal CSDIG into a corresponding analog signal i0, which in the depicted example is an analog current signal. Therefore, it can be used as in... Figure 2 The analog squaring circuit 14 is used as in the example. Therefore, the squaring circuit 14 is configured to provide an analog current signal i2, which is proportional to the square of the current i0, i.e., i2 = g ‧i0 2 ,in g This represents a constant factor (gain or attenuation). In addition to the digital implementation of current sensing and the resulting digital-to-analog converter 17', Figure 4 Examples and Figure 2 The examples are the same, and refer to the above description to avoid unnecessary repetition.

[0031] exist Figures 2-4 In the example, the reference voltage V used for comparator 15 REF Configured via a digital communication link (e.g., by an external controller). Figure 5 In the example, the reference voltage V REF It depends on the external circuit components connected to the other chip terminal REF, especially on resistors such as R. REF Passive circuit components. To generate the reference voltage V for comparator 15. REF The smart switch 1 may include a current source 16' (replacing) Figures 2-4The voltage source 16 shown is configured to output a reference current i at the chip terminal REF. REF For example from Figure 5 As can be seen in the diagram, the resistor R... REF The resulting voltage drop V REF Comparator 15 is used as a reference voltage (V) REF =R REF ‧i REF ). Figure 5 This method allows users to set the filter characteristics of filter 3 and the reference voltage V by selecting appropriate parameters of external passive circuit components (such as resistors and capacitors). REF Besides the reference voltage V REF How can it be provided to comparator 15 in a way other than... Figure 5 Examples and Figure 2 The examples are the same, and refer to the above description to avoid unnecessary repetition.

[0032] Figure 6 Another embodiment is illustrated, which can also be considered as Figure 2 A variation of the example. According to Figure 6 Reference voltage V REF The current is generated by an external controller (e.g., microcontroller 2) and supplied to smart switch 1 at the chip terminal REF. Therefore, current source 16' is not required in this example (see...). Figure 5 If the analog output AO of controller 2 can sink current, then it is not necessary to remove current source 16'.

[0033] Figure 6 The example does not require a digital communication interface because the input signal S IN The signal is generated by controller 2 and output at the controller's general purpose input / output (GPIO) pins, while smart switch 1 receives the input signal S at the input terminal IN. IN (and Figure 1 (Similar examples exist). However, it should be understood that this example does not preclude the additional use of digital communication interfaces. Besides how to... (The sentence is incomplete and requires more context to be fully translated.) REF The method provided to comparator 15 and the generation of input signal S IN In addition to the methods, Figure 6 Examples and Figure 2 The examples are the same, and refer to the above description to avoid unnecessary repetition.

[0034] Figure 7 Another embodiment is illustrated, which can also be considered as Figure 2 A variation of the example. Figure 2 and Figure 7 The only difference is how the power transistor T is turned off in the event of an overcurrent (signed by comparator 15).L In this way. According to Figure 7 By connecting the power transistor T L Another transistor T0 between the gate and source is used to realize the power transistor T. L The transistor T0 is turned off. Control logic 10 activates (turns on) transistor T0 in response to a signal from comparator 15 indicating an overcurrent. In this example, transistor T0 is activated by signal S. OFF Activation. Upon activation, transistor T0 forces power transistor T... L The gate-source voltage is close to zero, causing the gate of the power transistor to discharge and turn it off. The additional transistor T0 can be considered part of control logic 10. However, to better illustrate its function, in Figure 7 In the example, it is depicted as a separate element.

[0035] The examples described in this article are summarized below. It should be understood that this is not an exhaustive list of examples, but rather an exemplary overview. Combinations are possible. Figures 2-7 Different elements are shown in the examples and discussed in detail above to obtain other examples.

[0036] According to one example, the circuit includes an integrated circuit (IC) having chip contacts / terminals for connecting filter circuitry during operation. The IC also includes: a driver configured to drive a power transistor according to a logic signal; and a squaring circuit configured to receive a current-sensing signal representing the load current through the power transistor, and to output a first current representing the squared load current at the chip contacts (see, for example, [link to example]). Figures 2-7 (current i2); comparator circuit, configured to compare the voltage present at the chip contacts (see example, current i2); Figures 2-7 Voltage V T The voltage is compared with a reference voltage; and control logic is configured to generate logic signals and cause the power transistor to turn off based on the output signal of the comparator circuit.

[0037] Current sensing circuits can provide analog or digital current sensing signals, and can be squared using analog or digital multipliers.

[0038] In some examples, the current sensing signal received by the squaring circuit is an analog current signal, and the squaring circuit includes an analog multiplier configured to square the analog current signal to generate a first current.

[0039] In some examples, the current sensing signal received by the squaring circuit is a digital signal, wherein the squaring circuit includes a digital multiplier and a digital-to-analog converter, the digital multiplier being configured to square the digital signal, and the digital-to-analog converter being configured to generate a first current based on the digital output signal of the digital multiplier (see example...). Figure 3 ).

[0040] In some examples, the current sensing signal received by the square circuit is a digital signal, wherein the square circuit includes a digital-to-analog converter and an analog multiplier, the digital-to-analog converter being configured to generate an analog sensing current based on the digital signal (see, for example, [link to relevant documentation]). Figure 4 The analog multiplier (i0, i0) is configured to square the analog sensed current to generate a first current.

[0041] In some examples, the IC includes a digital communication interface configured to communicate with an external controller (see [link]). Figures 2-5 and Figure 7 (The interface marked "I / F").

[0042] In some examples, the reference voltage used by the comparator circuit can be configured based on information received from the digital communication interface. Alternatively, the reference voltage can be based on a chip terminal connected to the IC (see, for example, [link to IC]). Figure 5 The parameters of the passive external circuit components (terminal REF) are configured. Alternatively, the external controller configures the components via dedicated chip terminals (see...). Figure 6 The reference voltage is set using the REF terminal.

[0043] The voltage present at the chip contacts to which the filter circuit is connected during operation represents the temperature of the conductor carrying the load current. The filter circuit can be a passive RC filter. The filter can be a first-order low-pass filter or a higher-order filter.

[0044] In some examples, the circuitry includes a controller coupled to the IC. In some examples, the controller can be configured to configure a reference voltage used by the IC's comparator circuitry.

[0045] In some examples, the IC includes a digital communication interface, in which the controller is configured to communicate with the integrated circuit via the digital communication interface. The digital communication interface may be a serial bus interface (e.g., a serial peripheral interface, SPI).

[0046] While the invention has been shown and described with respect to one or more implementations, substitutions and / or modifications may be made to the illustrated examples without departing from the spirit and scope of the appended claims. In particular, with respect to the various functions performed by the foregoing components or structures (units, components, devices, circuits, systems, etc.), unless otherwise specified, the terminology used to describe these components (including references to “means”) is intended to correspond to any component or structure that performs the specified function of the described component (e.g., is functionally equivalent), even if it is not structurally equivalent to the disclosed structure that performs the function in the exemplary implementation of the invention shown herein.

Claims

1. A circuit comprising: Integrated circuit (1) includes chip contacts (FILTs) for connecting filter circuit (3) during operation. The integrated circuit (1) further includes: The driver is configured to respond to logic signals (S) ON ) drive power transistor (T) L ); The square circuit (14, 14', 17, 17') is configured to receive a load current (i) representing the current through the power transistor (TL). L The current sensing signal (iCS, CS) DIG ), and outputs a squared load current (i) at the chip contact (FILT). L The first current (i2); The comparator circuit (15) is configured to compare the voltage (V) present at the chip contact (FILT). T ) and reference voltage (V REF ) for comparison; and Control logic is configured to generate the logic signal (S) ON ), and the power transistor (T) is induced according to the output signal of the comparator circuit (15). L () is turned off.

2. The circuit according to claim 1, The current sensing signal received by the square circuit is an analog current signal (i CS );as well as The squaring circuit includes an analog multiplier (14) configured to multiply the analog current signal (i... CS Squaring the current (i2) generates the first current.

3. The circuit according to claim 1, The current sensing signal received by the square circuit is a digital signal (CSDIG); and The square circuit mentioned above includes: A digital multiplier (14') and a digital-to-analog converter (17), the digital multiplier (14') being configured to square the digital signal (CSDIG), and the digital-to-analog converter (17) being configured to generate the first current (i2) based on the digital output signal (i2DIG) of the digital multiplier (14').

4. The circuit according to claim 1, The current sensing signal received by the square circuit is a digital signal (CSDIG); and The squaring circuit includes a digital-to-analog converter (17') and an analog multiplier (14), the digital multiplier (14') being configured to generate an analog sense current (i0) from the digital signal (CSDIG), and the digital-to-analog converter (17) being configured to square the analog sense current (i0) to generate the first current (i2).

5. The circuit according to any one of claims 1 to 4, further comprising: The digital communication interface is configured to communicate with an external controller.

6. The circuit according to claim 5, The reference voltage (V) REF It can be configured based on the information received from the digital communication interface.

7. The circuit according to any one of claims 1 to 6, The voltage (V) present at the chip contact (FILT) T () indicates the temperature of the conductor carrying the load current.

8. The circuit according to any one of claims 1 to 7, The filter circuit (3) mentioned above includes a resistor (R). F ) and capacitor (C F (a first-order low-pass filter or a passive higher-order low-pass filter) 9. The circuit according to any one of claims 1 to 8, The integrated circuit (1) further includes a passive circuit component (R) for connecting during operation. REF Another chip contact (REF), The reference voltage (V) REF ) depends on the passive circuit component (R) REF The parameters of ).

10. The circuit according to claim 9, The passive circuit component mentioned above is a resistor (R). REF ), The integrated circuit (1) further includes a current source (16') configured to output a reference current (i) at the other chip contact (REF). REF ),as well as The reference voltage (V) REF ) depends on the resistor (R) REF The resistance of ).

11. The circuit according to any one of claims 1 to 10, further comprising a controller (2) coupled to the integrated circuit (1).

12. The circuit according to claim 11, The controller (2) is configured to configure the reference voltage (V) used by the comparator circuit (15) of the integrated circuit (1). REF ).

13. The circuit according to claim 11 or 12, The integrated circuit (1) mentioned therein includes a digital communication interface (I / F), and The controller (2) is configured to communicate with the integrated circuit (1) via the digital communication interface (I / F).

14. The circuit according to claim 13, The digital communication interface (I / F) mentioned therein is a serial bus interface.

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