WO2024165366A1

WO2024165366A1 - Electrical power supply system for aerosol-generating device

Info

Publication number: WO2024165366A1
Application number: PCT/EP2024/052110
Authority: WO
Inventors: Dalibor PURKOVIC
Original assignee: Jt International Sa
Priority date: 2023-02-09
Filing date: 2024-01-29
Publication date: 2024-08-15

Abstract

An electrical power supply system (101) suits for being part of an aerosol-generating device (100). In said electrical power supply system, a supply terminal (VDD) of a microcontroller (1) is connected to a rechargeable power source (2), so that a voltage of said supply terminal of the microcontroller varies depending on a charge level of the rechargeable power source. No DC-DC converter is used between the rechargeable power source and the microcontroller, so that said microcontroller can monitor the charge level of the rechargeable power source.

Description

ELECTRICAL POWER SUPPLY SYSTEM FOR AEROSOL-GENERATING DEVICE

The invention relates to an electrical power supply system, in particular such system adapted for being part of an aerosol-generating device. It also relates to the aerosol-generating device when it comprises the electrical power supply system of the invention.

- BACKGROUND OF THE INVENTION -

Each aerosol-generating device incorporates a microcontroller which produces several functions, in particular activating and controlling a heater dedicated to heat an aerosol precursor amount for producing the aerosol. The microcontroller is commonly power-fed from a battery through a Low-Drop-Out (LDO) regulator. The LDO regulator ensures that almost constant voltage is supplied to the microcontroller, at a supply terminal of this latter which is usually denoted VDD. It may lead stable and constant operation of the microcontroller. Indeed, many microcontrollers are to be supplied with DC- voltage of about 3.2 V (volt), whereas the output voltage of the battery may vary from less than 2.5 V to more than 4.2 V, depending on the battery type and the current charge level of the battery. If the DC-voltage which is fed into the microcontroller is too high with respect to a nominal value prescribed for this microcontroller, for example 4.0 V instead of 3.2 V, then a clock internal to the microcontroller runs too fast, the energy consumption of the microcontroller is uselessly significantly higher and some peripherals in the microcontroller may be affected. The use duration of the aerosol-generating device between two energy refills is reduced consequently.

The battery monitoring integrated circuit has the function of preventing that the battery output voltage decreases too much, down to a deep depletion state. Before deep depletion state is reached, the battery monitoring integrated circuit triggers isolation of the microcontroller from the battery for suppressing further energy consumption. The battery monitoring integrated circuit also prevents that the battery is charged again after deep depletion has occurred. It would be usually executed incorporated with a charging integrated circuit (charging IC), which stops charging of the battery when complete charge has been achieved. It may lead to secure safety of the aerosol generating device.

But using a LDO regulator and a battery monitoring integrated circuit participates in increasing the unit cost price and an energy consumption of the aerosol-generating device, and also in complexifying the device structure.

Starting from this situation, one object of the present invention consists in alleviating the above-indicated drawbacks.

In particular, the invention allows suppressing redundant components within an electrical power supply system intended for aerosol-generating device. In this way, the invention participates in minimizing a component number within an aerosol-generating device.

- SUMMARY OF THE INVENTION -

For meeting at least one of these objects or others, a first aspect of the present invention proposes an electrical power supply system which is adapted for being part of an aerosol-generating device, and which comprises:

- a microcontroller configured for controlling electrical power that is supplied to a load; and

- a rechargeable power source, that has an output voltage which varies depending on a charge level of this rechargeable power source.

The microcontroller is connected so as to be fed with another electrical power from the rechargeable power source.

According to the invention, a supply terminal of the microcontroller that is dedicated for receiving electrical power so as to allow an operation of this microcontroller, is connected to the rechargeable power source so that a voltage of the supply terminal of the microcontroller varies depending on the charge level of the rechargeable power source. Put another way, the invention proposes connecting the VDD-terminal of the microcontroller to the rechargeable power source so that the microcontroller receives the output voltage of this rechargeable power source as varying depending on its current charge level. In particular, no DC-DC converter or linear regulator such as a LDO regulator is arranged between the output of the rechargeable power source and the VDD-terminal of the microcontroller. Thanks to such supply connection, the microcontroller can sense and monitor the current output voltage of the rechargeable power source and hence can control the management of the rechargeable power source. In particular, the microcontroller can prevent further power supply to the load from the rechargeable power source to avoid that this latter enters deep depletion state. In addition, if the rechargeable power source is already in deep depletion state for any reason, the microcontroller can also prevent recharge for security matter. Also because it senses the output voltage of the rechargeable power source, the microcontroller can detect when complete charge is achieved and then stop charging operation. Because such functions can be produced by the microcontroller, it is unnecessary using a battery monitoring integrated circuit. Thus the electrical power supply system of the invention can be simpler, resulting in a reduction of its unit cost price.

Generally for the invention, the rechargeable power source may be a battery (e.g., lithium-ion secondary battery) or a capacitor, or be of any other rechargeable power source type.

Such supply connection may also improve a power consumption of the aerosol-generating device, because power loss at the LDO regulator due to thereof power regulation no longer exists, as well power consumption of the battery monitoring integrated circuit may be eliminated.

Hence, in preferred embodiments of the invention, the microcontroller may be configured to monitor the voltage of its supply terminal, and prevent a charging of the rechargeable power source if this voltage is less than a low- level threshold.

According to an improvement of the invention, the microcontroller may be adapted to operate either in a standard mode or in a low-consumption mode, where a power consumption of this microcontroller is less in the low- consumption mode compared to the standard mode. Then, the microcontroller may be further configured to activate the low-consumption mode for operation when the voltage of its supply terminal is above a voltage threshold, and to switch into standard mode when this voltage of the supply terminal becomes less than the voltage threshold. Useless power overconsumption by the microcontroller due to its VDD-voltage being higher that a nominal value can thus be avoided. Use duration of the aerosol-generating device is thus saved before next recharge of the rechargeable power source is provided. Several kinds of low-consumption mode for the microcontroller may be implemented, depending on the microcontroller type. For example, some modules internal to the microcontroller may be switched into idle mode.

Generally, a clock frequency value of the microcontroller is proportional to its VDD-voltage. One of reason, which power overconsumption by the microcontroller due to high VDD-voltage, can be explained by such the internal high clock frequency value.

Alternatively, when the microcontroller is clocked internally to it, it may be configured so that a clock frequency value that is effective in the low- consumption mode is lower than another clock frequency value that is effective in the standard mode for a same value of the voltage of the supply terminal of the microcontroller. Thanks to such operation, the microcontroller can more stably operate. In general, a variable clock frequency of the microcontroller may cause a thereof unstable operation. By activating the low-consumption mode when the voltage of the supply terminal is less than the voltage threshold, such the variation of the clock frequency may be suppressed.

According to another improvement of the invention, in particular when intended for an aerosol-generating device, the electrical power supply system may further comprise: - a DC-DC converter, which is connected so that the load is fed with electrical power from the rechargeable power source through this DC- DC converter; and

- a MOSFET switch that is serially connected with the load between an output of the DC-DC converter and a ground terminal of the electrical power supply system, and which has a gate connected to a first control output terminal of the microcontroller for this latter to allow or prevent power supply to the load.

According to an optional but preferred additional feature of the invention, the MOSFET switch may be of p-type and connected between the output of the DC-DC converter and the load. Thanks to implementing such configuration, control of the power supply to the load can be achieved by the microcontroller even when the rechargeable power source is in a low-level charge state. Indeed, for performing such control, it is never necessary for the microcontroller to provide the MOSFET switch with a control voltage that might be higher than its VDD voltage, which would not be possible. In detail, a source of the p-type MOSFET switch is connected to the output of the DC-DC converter, a gate of the p-type MOSFET switch is connected to the microcontroller, and a drain of the p-type MOSFET switch is connected to the load. General p-type MOSFET turns ON when an electrical potential of thereof source electrode is higher than an electrical potential of the thereof gate electrode by a predetermined threshold value or more. Since a boosted voltage by the DC-DC converter is supplied to the source terminal of the p-type MOSFET, the microcontroller can turn the p-type MOSFET ON only supplying low- level voltage, which can supply even when the rechargeable power source is in a low-level charge state, to the gate terminal of the p-type MOS-FET.

According to still another improvement of the invention, the microcontroller may comprise a second control output terminal and be configured for supplying this second control output terminal with a control signal of pulsed-width-modulation type. Then, the electrical power supply system may further comprise: - a light-emitting diode, that is connected to the second control output terminal of the microcontroller for this latter to control light emission of the light-emitting diode; and

- a capacitor, that is connected in parallel with the light-emitting diode so as to convert the control signal of pulsed-width-modulation type into a direct current that is conducted through the light-emitting diode and that varies in value in accordance with the control signal of pulsed-width- modulation type.

Generally, a light intensity of the light-emitting diode is proportional to an applied voltage of the light-emitting diode, the microcontroller outputs a voltage only same with its VDD-voltage with continuous waveform manner or pulse waveform manner (e.g., pulsed-width-modulation). It means that the light intensity of the light-emitting diode may be varied based on the charge level of the rechargeable power source. Thanks to such capacitor, the light intensity of the light-emitting diode can be maintained around same level even if the charge level of the rechargeable power source is changed. Since such capacitor may work as a by-pass capacitor or a smoothing capacitor, an applied voltage of the light-emitting diode may be maintained around same level when such control signal of pulsed-width-modulation type is controlled based on the charge level of the rechargeable power source.

Generally for the invention, the electrical power supply system may further comprise:

- a charger module, which is arranged for charging the rechargeable power source with energy originating from an external source;

- a first sensing circuit, which is arranged for sensing whether the external source is currently effective with respect to the charger module during a use of the electrical power supply system;

- a second sensing circuit, which is arranged for sensing whether the load is connected to the electrical power supply system so that this load conducts an output current that is supplied by the electrical power supply system; and - a power supply switch, that is arranged serially between the rechargeable power source and the supply terminal of the microcontroller, and connected to the first and second sensing circuits so as to allow the another electrical power to be transferred from the rechargeable power source to the microcontroller only if at least one of both following cases is sensed:

• the external source is currently effective with respect to the charger module, and

• the load is connected to the electrical power supply system.

Thanks to such supply connection scheme, a power supply to the microcontroller is delivered only when charging or discharging of the rechargeable power source is expected. It may lead to further improve an energy consumption of the aerosol-generating device.

In possible simple embodiments, the first sensing circuit may comprise:

- a first sensing resistor, which is parallelly connected between the external source and a ground; and

- a first operational amplifier, which a non-inverting input terminal and an inverting input terminal are connected with both ends of the first sensing resistor, and an output terminal is connected with a control terminal of the power supply switch.

Thanks to such supply connection, a power supply to the microcontroller is automatically formed in response that the external power source is available.

The electrical power supply system may further comprise a pull-up resistor, which is serially connected between the external source and the first sensing resistor. Then, an enable terminal of the charger module may be configured to be inputted with a divided voltage produced by the pull-up resistor and the first sensing resistor. Thanks to such supply connection, the charger module is also automatically enabled in response that the external power source is available, at same time with forming a power supply to the microcontroller. The second sensing circuit may comprise:

- a second sensing resistor, which is serially connected with the load;

- a second operational amplifier, which a non-inverting input terminal and an inverting input terminal are connected with both ends of the second sensing resistor, and an output terminal is connected with the control terminal of the power supply switch; and

- a bypass circuit, which is connected between the rechargeable power source and the load with bypassing the DC-DC converter and the MOSFET switch.

Thanks to such supply connection, the microcontroller may distinguish whether the load is available or not without enabling the DC-DC converter.

The bypass circuit may comprise a backflow prevention diode which an anode is connected with the rechargeable power source and a cathode is connected with the load. Then, the DC-DC converter may be a boost converter. Thanks to such supply connection, a backflow current which may result is unstable operation of the aerosol-generating device through the bypass circuit, can be prevented mainly by the backflow prevention diode.

The bypass circuit may also comprise a current limiting resistor, which is serially connected between the rechargeable power source and the load. Thanks to such supply connection, the microcontroller may distinguish whether the load is available or not with a very low current.

In possible first embodiments of the invention, the electrical power supply system may then further comprise:

- a first NOT-gate which an input terminal is connected with the output terminal of the first operational amplifier;

- a second NOT-gate which an input terminal is connected with the output terminal of the second operational amplifier; and

- a AND-gate which input terminals are connected with the respective output terminals of the first and second NOT-gates each other, and an output terminal of this AND-gate is connected with a control terminal of the power supply switch.

In such first embodiments, the power supply switch may be a p-type MOSFET. Thanks to such supply connection, a power supply to the microcontroller is automatically formed in response that the external power source or the load is available.

Alternatively, in other possible embodiments of the invention, the electrical power supply system may further comprise:

- a NOR-gate which input terminals are connected with the respective output terminals of the first and second operational amplifiers each other, and an output terminal of this NOR-gate is connected with the control terminal of the power supply switch.

In such other embodiments, the power supply switch may be a p-type MOSFET again. Thanks to such supply connection, a power supply to the microcontroller is automatically formed in response that the external power source or the load is available.

Generally for the invention, the microcontroller may be further connected to receive a detection signal that is representative of an electrical current supplied to the load. Feedback control of the electrical power that is currently supplied to the load is thus possible for the microcontroller.

A second aspect of the invention proposes an aerosol-generating device that comprises:

- the electrical power supply system of the first invention aspect; and

- a heater, which is connected to the electrical power supply system so as to be supplied with electrical power by this electrical power supply system, and which forms the load.

These and other features of the invention will be now described with reference to the appended figures, which relate to preferred but not-limiting embodiments of the invention. - BRIEF DESCRIPTION OF THE DRAWINGS -

Figure 1 is a block diagram of an aerosol-generating device in accordance with the invention.

Figure 2 is a diagram that illustrates a mode management possible for a microcontroller used in the aerosol-generating device of Figure 1 .

Figure 3 is a detailed diagram of a first embodiment possible for the aerosol-generating device of Figure 1 .

Figure 4 corresponds to Figure 3 for a second embodiment possible for the aerosol-generating device of Figure 1.

For clarity sake, same reference numbers which are indicated in different ones of these figures denote identical elements or elements with identical functions.

- DETAILED DESCRIPTION OF THE INVENTION -

With reference to Figure 1 , an aerosol-generating device 100 comprises a microcontroller 1 , a battery 2, a heater 3 and a DC-DC converter 4. The following labels have been added for clarity of the figures:

“MCU” for the microcontroller 1 , standing for Microcontroller Unit,

“Boost DC-DC” for the DC-DC converter 4,

“Over-Voltage Protection” for a charging input port 5, and

“Charger” for a charging circuit 6.

The heater 3 is intended to heat an amount of aerosol precursor originating from a pod 102 under control of the microcontroller 1 , so as to produce an aerosol for a user of the aerosol-generating device 100 to inhale it. The heater 3 is power-fed from the battery 2 through the DC-DC converter 4 for adapting the voltage supplied to the heater 3 whatever the current output voltage value of the battery 2. In general, the DC-DC converter 4 produces a voltage increase. Therefore, it can be a boost converter, which is a converter type well-known in the art. The operation of the DC-DC converter 4 is controlled by the microcontroller 1 based on the current output voltage value of the battery 2. The DC-DC converter 4 may be a buck-boost converter.

For allowing charging of the battery 2, the aerosol-generating device 100 may further comprise the charging input port 5 and the charger module 6. The charging input port 5 may contain input protection chip directly connected to USB-C receptacle or a wireless receiving coil. Reference number 200 denotes an external source, to be connected to the charging input port 5 physically or wirelessly for charging of the battery 2. The charging input port 5 preferably incorporates an input protection and an input cut-off. Concretely, the charging input port 5 may incorporate with a protection IC. The input cut-off may be accessed by the microcontroller 1 , in particular for preventing a new charge of the battery 2 if the output voltage of the battery 2 as sensed by the microcontroller 1 unveils deep depletion of the battery. The deep depletion state of the battery 2 may be detected by the microcontroller 1 when the VDD- value as monitored becomes lower than a predetermined low-level threshold. The charger module 6 may have the function of adapting voltage and current charge values to the actual charge level of the battery 2. Concretely, the charger module 6 may be or comprise a charging IC.

According to the invention, the battery 2 (e.g., lithium-ion secondary battery) is connected to the VDD-terminal of the microcontroller 1 without intermediate voltage converter. In this way, the microcontroller 1 can measure the current output voltage of the battery 2 and control the operation of the DC- DC converter 4 based on the measurement result. For such power supply connection configuration, the microcontroller 1 is compatible with a wide range for the VDD-voltage value. For example, it can operate with VDD-value ranging from 1.7 V to 5.5 V.

As commonly known, having the microcontroller 1 operating with an actual VDD-value which is different from a nominal value that is prescribed for this microcontroller may cause a microcontroller power consumption to be higher. But such increase in the consumption of electrical power by the microcontroller 1 is unnecessary for the delivery of aerosol by the aerosolgenerating device 100, so that the operation of the microcontroller 1 can be switched from a standard mode to a low-consumption mode when the current VDD-value generates overconsumption. This may be such when the VDD- value is above a threshold value, for example 2.55 V, in particular because a clock frequency internal to the microcontroller 1 may be then too high. Therefore, it is advantageous that the microcontroller 1 is configured to run in a low-consumption mode when VDD-voltage is higher than the threshold value, and to switch back to standard mode when VDD-voltage becomes lower than this threshold value. Figure 2 shows possible variations of the clock frequency of the microcontroller 1 as a function of the VDD-voltage. The horizontal axis shows values of the VDD-voltage expressed in volts (V), and the vertical axis shows values of the clock frequency expressed in megahertz (MHz) and noted CLK. Normal mode for the operation of the microcontroller 1 may correspond to clock frequency values as resulting directly from the VDD-values according to the diagram of Figure 2. Then, in possible improvements of the invention, this normal mode may be implemented only when the current VDD-value is less than 2.55 V, corresponding to a frequency value of less than 9 MHz. When the current VDD-value is higher than 2.55 V, a low-consumption mode may be implemented so that the effective clock frequency is lowered to less than or equal to 9 MHz. It may also lead a stable operation of the microcontroller 1 , because the variation of the VDD-value may be suppressed.

Getting back to Figure 1 , a p-type MOSFET switch 7 may be serially inserted between the DC-DC converter 4 and the heater 3. The drain of the p- MOSFET switch 7 may be connected to a supply terminal of the heater 3, and its source connected to the output terminal (VOIIT) of the DC-DC converter 4. The other supply terminal of the heater 3 is connected to a ground of the aerosol-generating device 100. The gate of the p-MOSFET switch 7 is connected to a first control output terminal of the microcontroller 1 so that this latter can drive the switch 7 into blocked state or conducting state so as to activate, adjust or prevent an operation of the heater 3. Thanks to using a switch 7 of p-MOSFET type, it can be controlled by the microcontroller 1 even if the current VDD-value is low. Since boosted voltage by the DC-DC converter 4 is supplied to the source of the p-MOSFET switch 7, the microcontroller 1 can drive the switch 7 into conductive state by only applying low-level voltage (e.g., 0V corresponding to electrical potential of the ground) onto the gate of the p- MOSFET switch 7.

Within the aerosol-generating device 100, the microcontroller 1 and the battery 2 connected to each other as previously described form together a minimum constitution of an electrical power supply system according to the invention. Such electrical power supply system has reference number 101 in the figures. The charging input port combined with the over-voltage protection IC 5, and the charger module 6 may advantageously be further included in this electrical power supply system 101. Addition of the DC-DC converter 4 and p- type MOSFET switch 7 into the electrical power supply system 101 suits especially for the application to the aerosol-generating device 100. The heater 3 constitutes an electrical load for this power supply system 101 .

The electrical power supply system 101 may further comprise a sensing circuit 30 suitable for detecting whether the heater 3 is actually connected to this electrical power supply system 101. Preferably, the sensing circuit 30 may be further adapted to measure an electrical output current that is currently supplied by the electrical power supply system 101 to the heater 3. Results of such measurements may advantageously be used by the microcontroller 1 to adjust the aerosol generation using a loop configuration with feedback control.

Possibly, the microcontroller 1 may be further adapted to control a user interface 9 such as a light-emitting-diode (LED). To this end, the microcontroller 1 may be provided with a second control output terminal 12 suitable for delivering a signal of pulsed-width-modulation type. Then, this second control output terminal of the microcontroller 1 may be provided with a capacitor 10 so that this capacitor is connected in parallel with the LED 9 between the microcontroller output terminal and the ground of the aerosol-generating device 100. In this way, a light intensity emitted by the LED 9 can be tuned by the microcontroller 1. The capacitor 10 smoothens the electrical current which is supplied to the LED 9 in such operation. That is, the capacitor 10 may work a by-pass capacitor or a smoothing capacitor. In detail, an applied voltage of the LED 9, which corresponds to the light intensity emitted by the LED 9 may be maintained around same level when such control signal of pulsed-width- modulation type is controlled based on the charge level of the battery 2.

Description of the aerosol-generating device 100 is continued now with reference to Figure 3 for a first embodiment. Elements thereof that are additional to those already described are only explained now. In this figure, VBUS denotes the charging DC-voltage that may be supplied from the external source 200 (not represented in Figure 3) to the charging input port combined with the over-voltage protection IC 5, VBAT denotes the output voltage of the battery 2, and VHTR denotes the voltage that is supplied to the heater 3 from the output terminal of the DC-DC converter 4. Terminal acronyms indicated on the integrated circuits have the following common meanings: IN for direct voltage input, OVLO for over-voltage lock out comparator, GND for ground terminal, OUT for direct voltage output, SW for switch terminal, CE for enabling the charger module 6, SYS for power path function, BAT for the terminal of the charger module 6 to be connected to the battery 2, VIN for the direct voltage input terminal of the DC-DC converter 4, EN for enabling terminal, VOUT for the output terminal of the DC-DC converter 4, FB for feedback terminal, VDD for the power supply terminal of the microcontroller 1 and I/O for its input or output control terminals. The charging input port combined with the overvoltage protection IC 5 may disconnect with the external power source based on an input voltage of the OVLO terminal. If the input voltage of the OVLO terminal, which corresponds to a divided VBUS, exceeds threshold, the charging input port combined with the over-voltage protection IC 5 may judge occurrence of over-voltage input into the electrical power supply system 101. Reference number 11 denotes the first control output terminal of the microcontroller 1 which is connected to the gate of the p-MOSFET switch 7 so that the microcontroller 1 allows or prevent power supply from the DC-DC converter 4 to the heater 3. Reference number 12 denotes the second control output terminal of the microcontroller 1 which is connected to the LED 9 and the capacitor 10 so that the microcontroller 1 controls the intensity of the light emission by the LED 9. In the first embodiment in Figure 3 and an alternative embodiment in Figure 4 (described later), the CE terminal of the charger module 6 and the EN terminal for DC/DC converter 4 work according to positive logic. It means that the charger module 6 and the DC/DC converter 4 are enabled once high level voltage is inputted into respective enabling terminals. Alternatively, the CE terminal of the charger module 6 and/or the EN terminal for DC/DC converter 4 may work according to negative logic.

A first sensing circuit 60 is dedicated to sensing whether the external source 200 is currently effective with respect to the charger module 6. As shown in Figure 3, this first sensing circuit 60 may comprise a voltage dividing resistor bridge connected between the VBIIS terminal of the charger module 6 and the ground GND of the electrical power supply system 101. It comprises a first sensing resistor 61 and a pull-up resistor 63 which are serially connected to each other so that the voltage dividing resistor bridge is formed. High level voltage is inputted into the CE terminal of the charger module 6 through the pull-up resistor 63 while the external source 200 is effective. As described above, since the CE terminal of the charger module 6 works according to the positive logic, the charger module 6 is automatically enabled once the external source 200 is available. The sensing resistor 61 is connected between the CE terminal of the charger module 6 and the ground GND, and the pull-up resistor 63 is connected between the VBIIS and CE terminals of the charger module 6. The first sensing circuit 60 also comprises a first operational amplifier 62, which has its non-inverting input terminal connected to the node between the sensing resistor 61 and the pull-up resistor 63, and its inverting input terminal connected to the ground GND of the electrical power supply system 101 . In this way, an output terminal of the operational amplifier 62 is at high level once the external source 200 is connected to the charging input port 5 and this latter forwards electrical power to the charger module 6.

The sensing circuit 30 is primarily dedicated to sensing whether an electrical current can flow through the load as formed by the heater 3. This circuit 30 has been called second sensing circuit 30 in the general part of the present description. To this purpose, it comprises a second sensing resistor 31 which is serially connected with the heater 3, for example between this latter and the ground GND of the electrical power supply system 101 . In addition, the second sensing circuit 30 comprises a second operational amplifier 32 and a bypass circuit which directly supplies the heater 3 with a test current from the battery 2, without transiting through the DC-DC converter 4. The input terminals of the operational amplifier 32 are connected to either end of the sensing resistor 31 so that the output terminal of this operational amplifier 32 is at high level once the heater 3 is connected to the electrical power supply system 101 , independently of whether the microcontroller 1 activates a heating operation or not. This is because the test current from the battery 2 automatically flows in the second sensing circuit 30 once the heater 3 is connected to the electrical power supply system 101. Small value for the test current through the sensing resistor 31 is appropriate, so that the bypass circuit comprises a current limiting resistor 34. For example, a resistance value of the current limiting resistor 34 may be larger than 1 kQ, and this value may also be larger than resistance value (e.g., the heater 3) of other resistors in the electrical power supply system 101. The bypass circuit also comprises a backflow prevention diode 33, oriented so as to prevent current from flowing from the output terminal of the DC-DC converter 4 back to the battery 2 when the DC-DC converter 4 produces voltage increase, for example when of boost type. In detail, an anode of the backflow prevention diode 33 is connected to the battery 2, and a cathode of the backflow prevention diode 33 is connected to the current limiting resistor 34.

The VDD-terminal of the microcontroller 1 may be connected to the battery 2 through a dedicated power supply switch 40 which is controlled by the sensing circuits 60 and 30. In this way, the microcontroller 1 can be prevented from being power-supplied if the heater 3 is disconnected and the external source 200 unavailable to the electrical power supply system 101. The power supply switch 40 may be a p-type MOSFET with its source S connected to the battery 2 and its drain D connected to the VDD-terminal of the microcontroller 1 . The gate G of the switch 40 is controlled by the sensing circuits 60 and 30, for example using two NOT-gates 64 and 35 and an AND-gate 41. The output terminal of the first operational amplifier 62 is connected to the input terminal of the NOT-gate 64, and the output terminal of the NOT-gate 64 is connected to a first input terminal of the AND-gate 41 , denoted A in Figure 3. Simultaneously, the output terminal of the second operational amplifier 32 is connected to the input terminal of the NOT-gate 35, and the output terminal thereof is connected to a second input terminal of the AND-gate 41 , denoted B. The output terminal of the AND-gate 41 is connected to the gate G of the p-MOSFET switch 40. Thus, the truth table of the power supply to the microcontroller 1 is the following one:

Thus, the microcontroller 1 is power-supplied from the battery 2 or the charger module 6 unless both the heater 3 and the external source 200 are simultaneously unavailable or disconnected. Put another way, the microcontroller 1 is power-supplied once at least one of the external source 200 and the heater 3 is available or connected to the electrical power supply system 101 . This avoids that the microcontroller 1 operates from the battery 2 whereas no aerosol can be generated by the aerosol-generating device 100, for saving battery charge.

For allowing the microcontroller 1 to check that the heater 3 is actually supplied appropriately, it is further possible that the output of the second operational amplifier 32 is also connected to an input terminal 13 of the microcontroller 1. However, the sensing resistor 31 and the operational amplifier 32 can be exclusively dedicated for detecting flow of the test current conducted by the bypass circuit including the diode 33 and the resistor 34, and another sensing resistor (not represented) may be arranged serially with that 31 , with voltage measurement means appropriate for providing quantitative assessments of the current flowing through the heater 3. The results of such heater current measurements may also be transmitted to a dedicated input terminal of the microcontroller 1 for quantitative feedback control of the heater operation.

Figure 4 shows an alternative embodiment where the AND-gate 41 together with the NOT-gates 64 and 35 are replaced with a NOR-gate 42. An A-input terminal of the NOR-gate 42 is connected directly to the output terminal of the first operational amplifier 62, and a B-input terminal of the same NOR- gate 42 is connected directly to the output terminal of the second operational amplifier 32. The truth table of the power supply to the microcontroller 1 is then:

This truth table for the power-supply of the microcontroller 1 is the same as that of the embodiment of Figure 3. The invention embodiment of Figure 4 also implements a p-MOSFET transistor for the switch 40.

The following variants shown in Figure 4 are also compatible with the embodiment of Figure 3:

- an additional output control terminal 14 of the microcontroller 1 may be dedicated to activating the DC-DC converter 4. This output control terminal 14 is connected to the enabling terminal EN of the DC-DC converter 4 instead of using a bias resistor for connecting this enabling terminal EN of the DC-DC converter 4 to its VIN terminal as shown in Figure 3; and

- another additional output control terminal 15 of the microcontroller 1 may be dedicated to activating the charger module 6. Such output control terminal 15 may be connected to the enabling terminal CE of the charger module 6 instead of connecting this enabling terminal CE to the node intermediate between the pull-up resistor 63 and the sensing resistor 61 . This may be another way to prevent charging of the battery 2 if deep depletion thereof is sensed by the microcontroller 1 through its VDD-terminal.

Anyone will understand that variations and adaptations may be brought with respect to the detailed embodiments of the invention here-above provided, while maintaining at least some of the advantages mentioned. In addition, all numeral values which have been cited were only for illustrating purpose and may be changed depending on each implementation of the invention.

Claims

C L A I M S

1. An electrical power supply system (101), adapted for being part of an aerosol generating device (100), and comprising:

- a microcontroller (1 ) configured for controlling electrical power that is supplied to a load; and

- a rechargeable power source (2), that has an output voltage which varies depending on a charge level of said rechargeable power source, wherein the microcontroller (1 ) is connected so as to be fed with another electrical power from the power source (2), characterized in that a supply terminal (VDD) of the microcontroller (1 ) that is dedicated for receiving electrical power so as to allow an operation of said microcontroller, is connected to the rechargeable power source (2) so that a voltage of said supply terminal of the microcontroller varies depending on the charge level of the rechargeable power source.

2. The electrical power supply system (101 ) according to claim 1 , wherein the microcontroller (1 ) is configured to monitor the voltage of the supply terminal (VDD) of said microcontroller, and prevent a charging of the rechargeable power source (2) if said voltage of the supply terminal of the microcontroller is less than a low-level threshold.

3. The electrical power supply system (101 ) according to claims 1 or 2, wherein the microcontroller (1) is adapted to operate either in a standard mode or in a low-consumption mode, wherein a power consumption of said microcontroller is less in the low-consumption mode compared to the standard mode, and the microcontroller is further configured to activate the low- consumption mode for operation when the voltage of the supply terminal (VDD) is above a voltage threshold, and to switch into standard mode when said voltage of the supply terminal becomes less than the voltage threshold.

4. The electrical power supply system (101 ) according to claim 3, wherein the microcontroller (1) is clocked internally to said microcontroller, and is configured so that a clock frequency value of said microcontroller that is effective in the low-consumption mode is lower than another clock frequency value that is effective to the standard mode for a same value of the voltage of the supply terminal (VDD) of the microcontroller.

5. The electrical power supply system (101) according to any one of the preceding claims, further comprising:

- a DC-DC converter (4), connected so that the load is fed with electrical power from the rechargeable power source (2) through the DC-DC converter; and

- a MOSFET switch (7) that is serially connected with the load between an output of the DC-DC converter (4) and a ground terminal (GND) of the electrical power supply system (101), and which has a gate connected to a first control output terminal (11 ) of the microcontroller (1 ) for said microcontroller to allow or prevent power supply to the load, wherein the MOSFET switch (7) is of p-type and connected between the output of the DC-DC converter (4) and the load.

6. The electrical power supply system (101) according to any one of the preceding claims, wherein the microcontroller (1 ) comprises a second control output terminal (12) and is configured for supplying the second control output terminal with a control signal of pulsed-width-modulation type, and the electrical power supply system (101) further comprises:

- a light-emitting diode (9), that is connected to the second control output terminal (12) of the microcontroller (1) for said microcontroller to control light emission of the light-emitting diode; and

- a capacitor (10), that is connected in parallel with the light-emitting diode (9) so as to convert the control signal of pulsed-width-modulation type into a direct current that is conducted through said light-emitting diode and that varies in value in accordance with said control signal of pulsed-width-modulation type.

7. The electrical power supply system (101) according to any one of the preceding claims, further comprising:

- a charger module (6), arranged for charging the rechargeable power source (2) with energy originating from an external source (200);

- a first sensing circuit (60), arranged for sensing whether the external source (200) is currently effective with respect to the charger module (6) during a use of the electrical power supply system (101 );

- a second sensing circuit (30), arranged for sensing whether the load is connected to the electrical power supply system (101) so that said load conducts an output current that is supplied by the electrical power supply system; and

- a power supply switch (40), that is arranged serially between the rechargeable power source (2) and the supply terminal (VDD) of the microcontroller (1 ), and connected to the first (60) and second (30) sensing circuits so as to allow said another electrical power to be transferred from the rechargeable power source to the microcontroller only if at least one of both following cases is sensed:

• the external source (200) is currently effective with respect to the charger module (6), and

• the load is connected to the electrical power supply system (101).

8. The electrical power supply system (101 ) according to claim 7, wherein the first sensing circuit (60) comprises:

- a first sensing resistor (61 ), which is parallelly connected between the external source (200) and a ground (GND); and

- a first operational amplifier (62), which a non-inverting input terminal and an inverting input terminal are connected with both ends of the first sensing resistor (61 ), and an output terminal is connected with a control terminal of the power supply switch (40).

9. The electrical power supply system (101 ) according to claim 8, further comprising a pull-up resistor (63), which is serially connected between the external source (200) and the first sensing resistor (61 ), wherein an enable terminal (CE) of the charger module (6) is configured to be inputted with a divided voltage produced by the pull-up resistor (63) and the first sensing resistor (61).

10. The electrical power supply system (101 ) according to claim 5 and any one of claims 7 to 9, wherein the second sensing circuit (30) comprises:

- a second sensing resistor (31), which is serially connected with the load;

- a second operational amplifier (32), which a non-inverting input terminal and an inverting input terminal are connected with both ends of the second sensing resistor (31 ), and an output terminal is connected with the control terminal of the power supply switch (40); and

- a bypass circuit (33), which is connected between the rechargeable power source (2) and the load with bypassing the DC-DC converter (4) and the MOSFET switch (7).

11. The electrical power supply system (101) according to claim 10, wherein the bypass circuit comprises a backflow prevention diode (33) which an anode is connected with the rechargeable power source (2) and a cathode is connected with the load, and wherein the DC-DC converter (4) is a boost converter.

12. The electrical power supply system (101) according to claims 10 or 11 , wherein the bypass circuit comprises a current limiting resistor (34), which is serially connected between the rechargeable power source (2) and the load.

13. The electrical power supply system (101) according to claim 8 or 9 and any one of claims 10 to 12, further comprising:

- a first NOT-gate (64) which an input terminal is connected with the output terminal of the first operational amplifier (62); - a second NOT-gate (35) which an input terminal is connected with the output terminal of the second operational amplifier (32); and

- a AND-gate (41 ) which input terminals are connected with the respective output terminals of the first (64) and second (35) NOT-gates each other, and an output terminal of said AND-gate is connected with a control terminal (G) of the power supply switch (40), wherein the power supply switch (40) is a p-type MOSFET.

14. The electrical power supply system (101) according to claim 8 or 9 and any one of claims 10 to 12, further comprising: - a NOR-gate (42) which input terminals are connected with the respective output terminals of the first (62) and second (32) operational amplifiers each other, and an output terminal of said NOR-gate is connected with a control terminal (G) of the power supply switch (40), wherein the power supply switch (40) is a p-type MOSFET.

15. The electrical power supply system (101) according to any one of the preceding claims, wherein the microcontroller (1) is further connected to receive a detection signal that is representative of an electrical output current supplied to the load.