MICROCONTROLLER COMPRISING A REFERENCE VOLTAGE GENERATING CIRCUIT

Abstract

According to one aspect, a microcontroller is proposed comprising a reference voltage generator circuit (BDGP) comprising: - a first transistor (Q1) and a second transistor (Q2) connected as a diode, - a first variable resistor (R1), - an operational amplifier (AOP), - a second variable resistor (R2), - a current mirror (CMR), - at least one additional current copying branch (BRCH1, BRCH2, BRCH3) connected to the second transistor (Q2) via at least one switch (INT1, INT2, INT3), - a control unit (UC) configured to control said at least one switch (INT1, INT2, INT3) and to adapt the resistive value of the first resistor (R1) and of the second resistor (R2) so as to maintain the reference voltage (VREF) independent of the temperature. Figure for the abstract: Figure 2

Description

Title of the invention: MICROCONTROLLER COMPRISING A REFERENCE VOLTAGE GENERATING CIRCUIT

[0001] Embodiments relate to microcontrollers and more particularly to those comprising a temperature-independent reference voltage generator circuit.

[0002] A microcontroller is generally configured to respond to a dedicated application. The microcontroller comprises several electronic modules configured to implement functionalities within the framework of the application to which this microcontroller responds.

[0003] A microcontroller may comprise a reference voltage generator circuit. This circuit is generally referred to by the English expression "bandgap voltage reference". Such a circuit is configured to generate a reference voltage independent of the absolute temperature. This reference voltage may subsequently be used by different electronic modules of the microcontroller. Furthermore, this circuit may also generate bias currents, currents dependent on the absolute temperature and reference currents.

[0004] The microcontroller can have several operating modes in order to adapt its electrical consumption according to its needs.

[0005] The microcontroller comprises, for example, an operating mode, called normal operation, and another operating mode called low consumption.

[0006] The normal operating mode corresponds to a mode in which the modules of the microcontroller are electrically powered so as to implement their functionalities to meet the application for which the microcontroller is dedicated. For example, in the normal operating mode, the powered electronic modules may be digital processing modules, flash memory, or analog peripheral modules such as an analog-to-digital converter, a digital-to-analog converter and a power management unit.

[0007] The low power mode corresponds to a mode in which most of the modules of the microcontroller are not electrically powered. This low power mode is used when the application for which the microcontroller is dedicated does not require the implementation of the functionalities of the modules of the microcontroller for a certain time. For example, in the low power mode, only the reference voltage generator circuit and a power supply monitoring circuit are powered. This power supply monitoring circuit then serves as the reference voltage to compare it with the supply voltage. The low power mode aims to minimize the power consumption of the microcontroller when the microcontroller's functionalities are not implemented.

[0008] In the normal operating mode, at least some of the powered electronic modules generally require receiving a more accurate reference voltage than that required by the few powered modules in the low power mode. The low power mode generally requires minimizing the power consumption of the reference voltage generator circuit.

[0009] The operating modes of the microcontroller may therefore have opposing needs in terms of precision of the reference voltage and power consumption of the reference voltage generator circuit.

[0010] In order to meet these opposing needs, the microcontroller may comprise two reference voltage generator circuits. A first reference voltage generator circuit may then be optimized to provide an accurate reference voltage for the normal operating mode, and a second reference voltage generator circuit may be optimized to consume relatively little electricity for the low-power mode. This solution has the disadvantage of using two reference voltage generator circuits which clutter the microcontroller and are expensive to manufacture.

[0011] Alternatively, it is possible to provide a single reference voltage generator circuit capable of operating intermittently at different duty cycles depending on the operating mode of the microcontroller. Such a reference voltage generator circuit has the disadvantage of having a complex structure and of using numerous electronic components to adapt its operating duty cycle.

[0012] There is therefore a need to propose a reference voltage generator circuit of simple structure and suitable for generating a precise reference voltage when the microcontroller is in its normal operating mode and for reducing its electrical consumption when the microcontroller is in its low consumption mode.

[0013] According to one aspect, there is provided a microcontroller comprising a reference voltage generator circuit comprising: - a first transistor and a second transistor mounted as a diode, - a first variable resistor, the first transistor and the second transistor being configured to generate a current proportional to the absolute temperature in this first resistor, - an operational amplifier having a first input connected to the first transistor via the first variable resistor, and a second input connected to the second transistor, - a second variable resistor having a first terminal connected to the second transistor and to the second input of the operational amplifier and a second terminal configured to deliver a reference voltage, - a current mirror controlled by an output of the operational amplifier and configured to copy the current proportional to the absolute temperature in the second resistance, - at least one additional current copying branch connected to the second transistor via at least one switch, said at least one additional branch being configured to copy the current proportional to the absolute temperature and inject it through the second transistor, - a control unit configured to control said at least one switch of said at least one additional branch and to adapt the resistive value of the first resistor and of the second resistor so as to maintain the reference voltage independent of the temperature.

[0014] The control unit then makes it possible to inject more or less current through the second transistor. Injecting a larger amount of current through the second transistor makes it possible to have a more precise current and makes it possible to reduce an impact of an offset voltage of the operational amplifier on the reference voltage generated by the reference voltage generator circuit. Injecting a smaller amount of current through the second transistor makes it possible to reduce the electrical consumption of the reference voltage generator circuit.

[0015] Such a reference voltage generator circuit is configured to reduce the impact of the operational amplifier offset voltage to improve the accuracy of the reference voltage, or to reduce its power consumption according to the needs of the microcontroller.

[0016] Such a reference voltage generator circuit has a simple structure and is inexpensive to manufacture.

[0017] Furthermore, because the impact of the offset voltage can be limited, it is possible to use a smaller operational amplifier having a larger offset voltage. In this way, it is possible to reduce the size of the reference voltage generator circuit. Such a reference voltage generator circuit then occupies less space in the microcontroller.

[0018] In an advantageous embodiment, the microcontroller further comprises several electronic modules, the microcontroller having several operating modes making it possible to selectively power said electronic modules, the control unit being configured to control said at least one switch of said at least one additional current copying branch according to the active operating mode of the microcontroller so as to inject more or less current through said second transistor according to this operating mode.

[0019] Such a voltage generator circuit is therefore configured to adapt its operation according to the operating mode of the microcontroller. Such a microcontroller therefore has the advantage of using the same reference voltage generation circuit to generate a reference voltage for different operating modes of the microcontroller.

[0020] Preferably, the control unit is configured to control said at least one switch of said at least one additional current copying branch so as to increase the current injected through said second transistor when the active operating mode of the microcontroller requires increasing the precision of said reference voltage. This active operating mode of the microcontroller may be a normal operating mode.

[0021] Advantageously, the control unit is configured to control said at least one switch of said at least one additional current copying branch so as to reduce the current injected through said second transistor when the active operating mode of the microcontroller requires reducing an electrical consumption of the microcontroller. This active operating mode of the microcontroller may be a low consumption mode.

[0022] In an advantageous embodiment, the control unit is configured to control said at least one switch and to adapt the resistive value of the first resistor and the second resistor according to the operating mode of the microcontroller from a correspondence table associating the different operating modes of the microcontroller with a control of said at least one switch and with resistive values of the first resistor and the second resistor.

[0023] Preferably, the first transistor is a bipolar transistor having an emitter connected to the first resistor, a base and a collector connected to a cold point. Furthermore, the second transistor is a bipolar transistor having an emitter connected to the second input of the operational amplifier and the first terminal of the second resistor, a base and a collector connected to a cold point, the first transistor and the second transistor having different sizes.

[0024] Advantageously, the size of the first transistor is N times greater than the size of the second transistor, N being an integer greater than or equal to 2, for example equal to 8.

[0025] In an advantageous embodiment, the current mirror comprises a first P-channel insulated gate field effect transistor and a second P-channel insulated gate field effect transistor, this first transistor comprising a gate connected to the output of the operational amplifier, a source configured to receive a supply voltage and a drain connected to the first input of the operational amplifier and to the first resistor, this second transistor comprising a gate connected to the output of the operational amplifier, a source configured to receive a voltage and a drain connected to the second resistor, this first transistor and this second transistor being identical.

[0026] Preferably, said at least one current copying branch comprises a P-type channel insulated gate field effect transistor comprising a gate connected to the output of the operational amplifier, a source configured to receive a voltage and a drain connected to the first terminal of the second resistor via said at least one switch, this transistor being identical to the first transistor and to the second transistor of the current mirror.

[0027] Advantageously, the first input of the operational amplifier is an inverting input and the second input of the operational amplifier is a non-inverting input.

[0028] In an advantageous embodiment, the microcontroller further comprises a capacitive element having a first terminal connected to the output of the operational amplifier and a second terminal configured to receive a supply voltage.

[0029] Advantageously, the microcontroller further comprises a temperature sensor comprising: - a P-type channel insulated gate field effect transistor comprising a gate connected to the output of the operational amplifier, a source configured to receive a supply voltage, and a drain, and - a resistor having a first terminal connected to the drain of this transistor and a second terminal connected to a cold point.

[0030] Other advantages and characteristics of the invention will appear on examining the detailed description of embodiments, which are in no way limiting, and the appended drawings in which:

[0031] [Fig.l]

[0032] [Fig.2]

[0033] [Fig.3] illustrate embodiments and implementations of the invention.

[0034] [Fig.l] illustrates a microcontroller MCU comprising different electronic modules MD1, MD2, MD3 and a reference voltage generator circuit BDGP. Here, only three electronic modules MD1, MD2, MD3 are shown. However, it is possible to provide more electronic modules.

[0035] For example, the electronic modules MD1, MD2, MD3 may comprise electronic modules such as an analog-to-digital converter, a power management unit, a voltage regulator, and a reset circuit.

[0036] The reference voltage generator circuit BDGP is configured to generate a reference voltage VREF independent of the temperature (the reference voltage generator circuit is designated in English by the expression “bandgap voltage reference”). This reference voltage can then be used by certain electronic modules MD2, MD3 of the microcontroller MCU. The reference voltage is in particular independent of the temperature over a temperature range which can be between -40°C and 140°C. The reference voltage can be 1.2 Volts.

[0037] Furthermore, the microcontroller MCU has several operating modes making it possible to electrically power said electronic modules MD1, MD2, MD3 selectively.

[0038] The MCU microcontroller comprises for example an operating mode, called normal operating mode, and another operating mode, called low consumption mode. The normal operating mode corresponds to a mode in which at least most of the electronic modules MD1, MD2, MD3 of the MCU microcontroller are electrically powered. The low consumption mode corresponds to a mode in which most of the electronic modules MD1, MD2, MD3 of the MCU microcontroller are not electrically powered.

[0039] In particular, the normal operating mode corresponds to a mode in which the electronic modules of the MCU microcontroller are electrically powered so as to implement their functionalities to respond to an application for which the MCU microcontroller is dedicated. For example, in the normal operating mode, the powered electronic modules may be digital processing modules, a flash memory, or even analog peripheral modules such as an analog-to-digital converter, a digital-to-analog converter and a power management unit.

[0040] The low power mode corresponds to a mode in which most of the electronic modules of the MCU microcontroller are not electrically powered. This low power mode is used when the application for which the MCU microcontroller is dedicated does not require the implementation of the functionalities of the modules of the MCU microcontroller for a certain time. For example, in the low power mode, only the reference voltage generator circuit and a power supply monitoring circuit are powered. This power supply monitoring circuit then uses the reference voltage to compare it with the supply voltage. The low power mode aims to minimize the consumption electrical of the MCU microcontroller when the MCU microcontroller features are not implemented.

[0041] In the normal operating mode, at least some of the powered electronic modules generally require receiving a more accurate reference voltage than that required by the few powered modules in the low power mode. The low power mode generally requires minimizing the power consumption of the reference voltage generator circuit.

[0042] The reference voltage generator circuit is configured to adapt its operation to the active operating mode of the microcontroller so as to improve the accuracy of the reference voltage when the microcontroller is in its normal operating mode and so as to reduce its power consumption when the microcontroller is in its low consumption mode.

[0043] [Fig.2] illustrates an embodiment of the reference voltage generator circuit BDGP.

[0044] The reference voltage generator circuit BDGP comprises an operational amplifier AGP, two bipolar transistors Ql, Q2 and a current mirror CMR comprising two transistors Ml and M2 of PMOS type (i.e. P-channel metal-oxide gate field effect transistors ("MOSFET")). The reference voltage generator circuit BDGP also comprises two variable resistors RI, R2. The reference voltage generator circuit BDGP also comprises a control unit UC configured to control the resistive value of each variable resistor RI, R2 via a command RV, as described below. Here, the reference voltage generator circuit BDGP comprises the control unit, however, alternatively it is possible to provide a control unit located outside this reference voltage generator circuit BDGP.

[0045] The transistors Ql, Q2 each have a base, an emitter and a collector. Each transistor Ql, Q2 is connected as a diode. In particular, the base of each transistor Ql, Q2 is connected to its collector and to a cold point, in particular to a ground GND. The transistors Ql and Q2 may have different sizes. The size of a bipolar transistor Ql, Q2 corresponds to the surface area of the emitter of this bipolar transistor. The size ratio between the transistors Ql and Q2 is in particular equal to N. The transistor Ql then has a size N times larger than that of the transistor Q2. For example, N may be greater than or equal to 2, for example equal to 8.

[0046] The operational amplifier AOP has an inverting input connected to the emitter of the transistor Q1 via the variable resistor RL. The operational amplifier AOP also has a non-inverting input connected to the emitter of the transistor Q2.

[0047] Transistor Ml has a gate connected to an output of the op amp rational AOP so as to receive the signal Pg generated by the operational amplifier AOP, a source configured to receive a voltage VDD and a drain connected to the inverting input of the operational amplifier AOP and to the variable resistor RI.

[0048] The transistor M2 has a gate connected to the output of the operational amplifier AOP so as to receive the signal Pg generated by the operational amplifier AOP, a source configured to receive a voltage VDD and a drain connected to the non-inverting input of the operational amplifier AOP and to the emitter of the second bipolar transistor Q2 via the variable resistor R2.

[0049] Each variable resistor RI, R2 comprises several resistive elements that can be activated or deactivated so as to adjust the resistive value of this variable resistor RI, R2. In particular, each variable resistor RI, R2 can be digitally controlled by the control unit UC. Each variable resistor RI, R2 can in particular comprise MOSFET type transistors controlled by the control unit UC so as to individually activate or deactivate the resistive elements of this variable resistor RI, R2.

[0050] The reference voltage generator circuit BDGP has an output connected to a node between the drain of the transistor M2 and the variable resistor R2. This output makes it possible to generate a voltage VREF independent of the temperature.

[0051] The operational amplifier AOP has a direct offset voltage Vos (in English "offset"). This offset voltage Vos impacts the reference voltage VREF generated at the output of the reference voltage generator circuit BDGP.

[0052] The reference voltage generator circuit BDGP is configured to adjust the current injected into the bipolar transistor Q2 to limit the impact of the offset voltage Vos of the operational amplifier AOP on the reference voltage VREF.

[0053] In particular, the reference voltage generator circuit BDGP comprises several current copying branches BRCH1, BRCH2, BRCH3. These current copying branches BRCH1, BRCH2, BRCH3 are parallel to each other between the power supply and the emitter of the bipolar transistor Q2. For example, in the embodiment illustrated in [Fig.l], the reference voltage generator circuit BDGP comprises three current copying branches BRCH1, BRCH2, BRCH3. Nevertheless, it is possible to provide a reference voltage generator circuit comprising more or fewer current copying branches. The reference voltage generator circuit BDGP notably comprises a number of current copying branches corresponding to the number of operating modes of the microcontroller MCU.

[0054] Each current copying branch BRCH1, BRCH2, BRCH3 comprises a PMOS type transistor M3, M4, M5. Thus, a first current copying branch current BRCH1 comprises a PMOS type transistor M3, the second current copy branch BRCH2 comprises a PMOS type transistor M4 and the third current copy branch BRCH3 comprises a PMOS type transistor M5.

[0055] The transistors M3, M4, M5 each have a gate connected to the output of the operational amplifier AOP so as to receive the signal Pg generated by the operational amplifier AOP, a source configured to receive a voltage VDD and a drain connected to the non-inverting input of the operational amplifier AOP and to the emitter of the second bipolar transistor Q2.

[0056] Preferably, the transistors M1, M2, M3, M4 and M5 are identical.

[0057] The reference voltage generator circuit BDGP also comprises a DC capacitive element between the power supply and the gates of the transistors M3, M4 and M5. The DC capacitive element ensures stability of the reference voltage generator circuit BDGP.

[0058] Furthermore, the current copying branches BRCH1, BRCH2, BRCH3 are connected to the emitter of the transistor Q2 via switches INT1, INT2, INT3. These switches are controlled by the control unit UC. The switches INT1, INT2, INT3 are controlled by the control unit UC so as to adjust the quantity of current injected through the bipolar transistor Q2.

[0059] In particular, the current injected through the bipolar transistor Q2 is expressed according to the following formula:

[0060] / 0= Av^vos = * / n((l + M)JV)+Vcw)'where A vbe csl the difference of voltages between the voltage across transistor Q1 and the voltage across transistor Q2, Vos is the offset voltage of the operational amplifier AOP, RI is the resistive value of resistor RI, kB is a constant is the Boltzmann constant, q is the charge of an electron, T is the temperature, N is the ratio between the size of bipolar transistors Q1 and Q2, and M is the number of parallel current feedback branches used to inject current through bipolar transistor Q2 (depending on the switches INT1, INT2, INT3 being closed). In the embodiment illustrated in Figure 1, M is between 0 and 3.

[0061] The reference voltage VREF generated by the reference voltage generator circuit BDGP is then expressed by the expression:

[0062] VREF = RZIq + Vd = §*(AVbe + Vos) + Vd

[0063] VREF = ( 1 + M)N)+ Vos) ) + Vd' oû vdestlatensionde diode of bipolar transistor Q2, R2 is the resistive value of resistor R2.

[0064] Increasing the number M of current copying branches connected to transistor Q2 makes it possible to inject more current through bipolar transistor Q2 of

[0065]

[0066]

[0067]

[0068] way to increase the difference of voltages AVbe to reduce the impact of the offset voltage Vos of the operational amplifier AOP. The voltage difference is proportional to the absolute temperature (designated by the acronym "PT AT" from the English "proportional to absolute temperature") and the diode voltage is complementary to the absolute temperature (designated by the acronym "CTAT" from the English "complementary to absolute temperature"). In order to maintain the reference voltage independent of the absolute temperature when the number M of current feedback branches used to inject current through the bipolar transistor Q2 varies, the control unit is configured to adapt the value of the ratio A- according to the number M of feedback branches Aeî current by adapting the resistive value of the resistors RI and R2. In particular, the switches INT1, INT2, INT3 allow different configurations to be defined by varying the number M of current copy branches BRCH1, BRCH2, BRCH3 used to inject current through the bipolar transistor Q2. Each of these configurations is associated with a pair of resistive values of the resistors RI and R2 allowing the reference voltage to be maintained independent of the absolute temperature. The control unit UC is configured to adapt the resistive values RV of the resistors according to the configuration chosen using the switches INT1, INT2, INT3. The configuration set using the INT1, INT2, INT3 switches is chosen depending on the active operating mode of the MCU microcontroller.

[0069] In particular, the control unit UC is configured to receive the active operating mode OPM from the microcontroller MCU and to generate a first command CMD to control the switches INT1, INT2, INT3 and a second command RV to adapt the resistive value of the resistors RI and R2.

[0070] In particular, a processor of the microcontroller may be configured to generate a signal indicating the active operating mode OPM upon request from the user of the microcontroller and to transmit this signal to the control unit UC.

[0071] In order to improve this precision in the normal operating mode, the control unit UC is configured to control the switches INT1, INT2, INT3 so as to increase the number M of current feedback branches connected to the transistor Q2 to inject more current through the transistor Q2 to reduce the impact of the offset voltage Vos of the operational amplifier AOP on the reference voltage VREF. For example, the control unit UC can be configured to close the switches INT1, INT2 and INT3 in order to use all of the current feedback branches BRCH1, BRCH2, BRCH3 to inject current through the transistor Q2. The control unit UC then adapts the resistive value of the re resistors RI and R2 as a function of the number M of current copying branches used to inject more current through transistor Q2 so as to maintain the reference voltage VREF independent of temperature.

[0072] In order to reduce the consumption of the reference voltage generator circuit in the low consumption mode, the control unit UC is configured to control the switches INT1, INT2, INT3 to reduce the current injected through the transistor Q2 by disconnecting at least a portion of the current copying branches BRCH1, BRCH2, BRCH3. For example, the control unit UC can be configured to open all of the switches INT1, INT2 and INT3 in order to disconnect all of the current copying branches BRCH1, BRCH2, BRCH3 to reduce the current injected through the bipolar transistor Q2. The control unit UC then adapts the resistive value RV of the resistors RI and R2 to maintain the reference voltage VREF independent of the temperature.

[0073] The resistive values of the resistors RI and R2 adapted for the different configurations that can be defined using the switches INT1, INT2 and INT3 are determined by simulation for example. In particular, the greater the number M of current copying branches used to inject current into the bipolar transistor Q2, the more it is appropriate to reduce the value of the ratio âZ.

[0074] The reference voltage generator circuit BDGP is therefore configured to reduce the impact of the offset voltage Vos of the operational amplifier AOP to improve the accuracy of the reference voltage. It is therefore possible to use a smaller operational amplifier AOP with a larger offset voltage Vos. In this way, it is possible to reduce the size of the reference voltage generator circuit. Such a reference voltage generator circuit then occupies less space in the microcontroller.

[0075] Such a BDGP reference voltage generator circuit also makes it possible to adapt its electrical consumption according to the operating mode of the microcontroller.

[0076] Furthermore, such a BDGP reference voltage generator circuit has the advantage of having a simple structure.

[0077] The microcontroller MCU may also comprise a temperature sensor TEMPS as illustrated in [Fig.3]. The temperature sensor comprises a P-type channel insulated gate field effect transistor M6 comprising a gate connected to the output of the operational amplifier AOP of the reference voltage generator circuit BDGP so as to receive the signal Pg generated by the operational amplifier, a source configured to receive a voltage VDD and a drain. The temperature sensor also comprises a resistor Rs having a first terminal connected to the drain of this transistor M6 and a second terminal connected to ground GND. The resistor Rs is then crossed by a current proportional to the absolute temperature (PTAT) or independent of the absolute temperature (ZTAT). The voltage V_TEMPS across the resistor Rs is thus also proportional to the absolute temperature. It is thus possible to measure this temperature from the voltage V_TEMPS. Such a temperature sensor is more accurate because the impact of the offset voltage Vos of the operational amplifier on the current through the resistor Rs is limited thanks to the reference voltage generator circuit BDGP described previously.

Claims

Claims

1. Microcontroller comprising a reference voltage generator circuit (BDGP) comprising: - a first transistor (Ql) and a second transistor (Q2) mounted as a diode, - a first variable resistor (RI), the first transistor (Ql) and the second transistor (Q2) being configured to generate a current proportional to the absolute temperature in this first resistor (RI), - an operational amplifier (AOP) having a first input connected to the first transistor via the first variable resistor, and a second input connected to the second transistor, - a second variable resistor (R2) having a first terminal connected to the second transistor (Q2) and to the second input of the operational amplifier and a second terminal configured to deliver a reference voltage (VREF), - a current mirror (CMR) controlled by an output of the operational amplifier and configured to copy the current proportional to the absolute temperature in the second resistor (R2), - at least one additional current copying branch (BRCH1, BRCH2, BRCH3) connected to the second transistor (Q2) via at least one switch (INT1, INT2, INT3), said at least one additional branch (BRCH1, BRCH2, BRCH3) being configured to copy the current proportional to the absolute temperature and inject it through the second transistor (Q2), - a control unit (UC) configured to control said at least one switch (INT1, INT2, INT3) of said at least one additional branch (BRCH1, BRCH2, BRCH3) and to adapt the resistive value of the first resistor (RI) and of the second resistor (R2) so as to maintain the reference voltage (VREF) independent of the temperature.

2. Microcontroller according to claim 1, further comprising several electronic modules (MD1, MD2, MD3), the microcontroller (MCU) having several operating modes allowing selectively powering said electronic modules (MD1, MD2, MD3), the control unit (UC) being configured to control said at least one switch (INT1, INT2, INT3) of said at least one additional branch current copying function (BRCH1, BRCH2, BRCH3) according to the active operating mode of the microcontroller (MCU) so as to inject more or less current through said second transistor (Q2) depending on this operating mode.

3. Microcontroller according to claim 2, wherein the control unit (UC) is configured to control said at least one switch (INT1, INT2, INT3) of said at least one additional current copying branch (BRCH1, BRCH2, BRCH3) so as to increase the current injected through said second transistor (Q2) when the active operating mode of the microcontroller (MCU) requires increasing the precision of said reference voltage.

4. Microcontroller according to any one of claims 2 or 3, wherein the control unit (UC) is configured to control said at least one switch of said at least one additional current copying branch (BRCH1, BRCH2, BRCH3) so as to reduce the current injected through said second transistor (Q2) when the active operating mode of the microcontroller (MCU) requires reducing an electrical consumption of the microcontroller (MCU).

5. Microcontroller according to one of claims 2 to 4, wherein the control unit is configured to control said at least one switch (INT1, INT2, INT3) and to adapt the resistive value of the first resistor (RI) and of the second resistor (R2) according to the operating mode of the microcontroller (MCU) from a correspondence table associating the different operating modes (OPM) of the microcontroller with a control of said at least one switch (INT1, INT2, INT3) and with resistive values of the first resistor (RI) and of the second resistor (R2).

6. Microcontroller according to one of claims 1 to 5, wherein the first transistor (Q1) is a bipolar transistor having an emitter connected to the first resistor (RI), a base and a collector connected to a cold point (GND), and wherein the second transistor (Q2) is a bipolar transistor having an emitter connected to the second input of the operational amplifier and the first terminal of the second resistor (R2), a base and a collector connected to a cold point (GND), the first transistor (Q1) and the second transistor (Q2) having different sizes.

7. A microcontroller according to claim 6, wherein the size of the first transistor (Ql) is N times larger than the size of the second transistor (Q2), N being an integer greater than or equal to 2.

8. Microcontroller according to one of claims 1 to 7, wherein the current mirror (CMR) comprises a first P-type channel insulated gate field effect transistor (Ml) and a second P-type channel insulated gate field effect transistor (M2), this first transistor (Ml) comprising a gate connected to the output of the operational amplifier, a source configured to receive a supply voltage (VDD) and a drain connected to the first input of the operational amplifier (AOP) and to the first resistor (RI), this second transistor (M2) comprising a gate connected to the output of the operational amplifier, a source configured to receive a voltage (VDD) and a drain connected to the second resistor (R2), this first transistor (Ml) and this second transistor (M2) being identical.

9. Microcontroller according to claim 8, wherein said at least one current copying branch (BRCH1, BRCH2, BRCH3) comprises a P-type channel insulated gate field effect transistor (M3, M4, M5) comprising a gate connected to the output of the operational amplifier, a source configured to receive a voltage (VDD) and a drain connected to the first terminal of the second resistor (R2) via said at least one switch (INT1, INT2, INT3), this transistor being identical to the first transistor (M1) and to the second transistor (M2) of the current mirror (CMR).

10. Microcontroller according to one of claims 1 to 9, wherein the first input of the operational amplifier (AOP) is an inverting input and the second input of the operational amplifier (AOP) is a non-inverting input.

11. Microcontroller according to one of claims 1 to 10, further comprising a capacitive element (CC) having a first terminal connected to the output of the operational amplifier (AOP) and a second terminal configured to receive a supply voltage (VDD).

12. Microcontroller according to one of claims 1 to 11, further comprising a temperature sensor comprising: - a P-type channel insulated gate field effect transistor (Ms) comprising a gate connected to the output of the operational amplifier, a source configured to receive a supply voltage (VDD), and a drain, and - a resistor (Rs) having a first terminal connected to the drain of this transistor and a second terminal connected to a cold point (GND).

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