HK1208565B

HK1208565B - Smart battery provided with a power supply voltage management circuit

Info

Publication number: HK1208565B
Application number: HK15109119.0A
Authority: HK
Inventors: Michel Willemin; Marc Degrauwe; Sergio Rota
Original assignee: The Swatch Group Research And Development Ltd.
Priority date: 2013-09-10
Filing date: 2015-09-17
Publication date: 2018-07-13

Description

Intelligent battery equipped with power supply voltage management circuit

Technical Field

The present invention relates to a smart battery equipped with an electronic circuit for managing the supply voltage. The electronic circuit includes an end of battery life (EOL) detector, an oscillation stage, a power management unit, and a communication interface. The electronic circuit may also include a DC-DC converter that is powered on (power on) as soon as the supply voltage approaches or equals the battery EOL threshold. In this way, the life of a product using the battery can be extended by continuously supplying a voltage higher than a minimum limit and extracting the residual power of the battery. The maximum current supplied by the battery can also be limited by the management unit, again in order to extend the life of the battery and thus the life of the product. The battery may be a primary battery or a rechargeable battery.

Background

The battery cell (cell) or battery may comprise, in a known manner, a management circuit, in particular a power management circuit, integrated within the structure of the battery cell or battery. In this regard, reference may be made to U.S. patent No. 6,198,250B1, which discloses such a smart battery cell or battery that includes a control circuit. The control circuit is connected with a single battery power supply terminal or a battery power supply terminal. The control circuit can prolong the service life of the battery. To achieve this, the control circuit includes a DC-DC converter that is clocked by an oscillator to convert the cell voltage or battery voltage to an output voltage, which may be higher than a cutoff voltage or battery end-of-life voltage. The converter may be energized as soon as the battery voltage reaches the battery end-of-life voltage threshold in order to extend battery life.

In the smart battery cell or battery of U.S. patent No. 6,198,250B1, no means is provided in the control circuit for transmitting digital data to the electronics powered by the smart battery. It is a drawback that no information about the end of life of the battery or the type of battery is sent to the outside of the smart cell or battery to ensure that the electronics operate correctly before the battery is replaced.

Reference is also made to WO patent application No. 2005/081787a1, which discloses a battery equipped with an electronic circuit. The electronic circuit of the battery comprises a non-volatile memory, a thermistor, a voltage identification unit, a switch in the form of a FET transistor in series with the thermistor, and a good battery data interface. The data interface terminal is connected to a non-volatile memory which is connected to a terminal of the rechargeable battery. The switch is controlled by the voltage identification unit. If the battery level is low, the switch is open, which means that the measurement cannot be performed via the thermistor, but communication can be established between the charger and the battery circuit through a clock terminal associated with the memory. However, if the voltage level is sufficient, thermistor measurements are performed by the charger to determine the temperature of the battery circuit.

A plurality of terminals for voltage supply and data communication must be provided for the battery containing the electronic circuit in WO patent application No. 2005/081787a 1. Therefore, this complicates the manufacturing process of the battery, and fails to properly optimize the supply of power and the supply of data to the outside of the battery, which is a drawback.

EP patent application No. 1892791a1 discloses a battery pack comprising a battery connected to an electronic mains voltage management circuit. The electronic circuit comprises operating state detection means for detecting current, voltage and temperature. These detection means are connected to the control unit. A communication interface is also provided, which is connected to the control unit, for communication with the electronic instrument via a modulated signal. However, it is a drawback that the electronic circuit is not set to adapt to specific operating parameters.

Disclosure of Invention

It is therefore an object of the present invention to provide a smart battery equipped with an electronic circuit for managing the supply voltage, which is able to transmit data to an electronic device powered by the smart battery and which overcomes the above-mentioned drawbacks of the state of the art.

To this end, the invention relates to a smart battery equipped with an electronic circuit for managing the supply voltage, comprising the features defined in the independent claim 1.

Particular embodiments of the smart battery are defined in the dependent claims 2 to 12.

One advantage of a smart battery is that data is transmitted on the same connection line as one of the power terminals of the smart battery. Preferably, the data is transmitted on a connection line of a high potential terminal of the smart battery. The digital data may be transmitted over the power supply through time windows of different durations, depending on the state of each bit to be transmitted, or possibly by means of phase or frequency modulation. The modulated data to be transmitted may be a digital battery end-of-life signal.

Advantageously, the single-wire interface controlled by the management unit of the electronic mains voltage management circuit provides modulated digital data or command signals through the positive terminal of the smart battery. Since the management unit is clocked by a clock signal from the clock oscillator stage, the single wire interface is able to provide a modulated data signal related to the upper second signal of the electronic device comprising the smart battery.

Drawings

The objects, advantages and features of a smart battery equipped with an electronic supply voltage management circuit will become more apparent from the following description of a non-limiting simplified embodiment based on the attached drawings, in which:

FIG. 1 shows a simplified diagram of the components of a smart battery equipped with an electronic supply voltage management circuit according to the invention, an

Fig. 2 shows a graph of the evolution of the supply voltage provided by a smart battery according to the invention compared to the evolution of the supply voltage provided by a conventional battery.

Detailed Description

In the following description, only those electronic components of the electronic battery circuit that are well understood by those skilled in the art are described in a simplified manner.

Fig. 1 shows a schematic overview of all components of a smart battery 1. The battery may take the form of a button cell that can be placed within a battery housing of an electronic device, such as a watch, as a power source for electronic components in the electronic device.

The smart battery 1 comprises an electronic supply voltage management circuit 10 connected to the two positive and negative supply terminals of the battery 2. When the voltage of the battery 2 approaches the battery end-of-life threshold, the electronic circuit 10 first allows to control the battery discharge in an optimal way while indicating the end of the battery life. The electronic circuit 10 may be integrated within the structure of the battery 2 or be provided on the outer surface of the battery structure.

The electronic circuit 10 comprises a battery end-of-life detector 3, a specified EOL, an oscillating stage 4 whose oscillator can be connected to a conventional quartz resonator 5, a DC-DC converter 6, a management unit 7, a single-wire (1-wire) interface 8 for transmitting or receiving data or command signals, and a switch 9 controlled by the management unit. The management unit 7 is also connected to the battery end-of-life detector 3, the oscillating stage 4, the DC-DC converter 6 and the single-wire interface 8. Therefore, the management unit 7 controls the operations of the DC-DC converter 6, the one-wire interface 8, and the switch 9 according to the voltage level of the battery 2 detected by the battery end-of-life detector 3.

The end of battery life detector 3 is connected to the positive terminal of the battery 2 in order to determine when the value of the voltage supplied by the battery 2 reaches a determined end of battery life threshold. In the button cell example, the end of battery life threshold may be set to 1.2 volts, for example, but may also be set to a lower value. In order to be able to perform a battery end-of-life detection, the detector 3 may comprise a comparator having a first input connected to a reference voltage set according to a defined battery end-of-life threshold value and a second input connected to a node of a capacitive voltage divider connected between the positive and negative terminals of the battery 2. Once the battery voltage level reaches the battery end-of-life threshold, the comparator provides an output signal to the management unit 7, which controls the energisation of the DC-DC converter 6.

The switch 9 of the electronic circuit takes the form of a power supply selector. The switch 9 is preferably connected at a first input to the positive terminal of the battery 2 and at a second input to the output of the DC-DC converter 6 for receiving an output voltage 16 from the converter during operation thereof. The output of the switch 9 is preferably connected to the external positive terminal of the electronic battery 1 to provide the voltage of the battery 2 when the voltage level of the battery 2 is above the battery end-of-life threshold detected by the detector 3. However, when the voltage level of the battery 2 is equal to or below the battery end-of-life threshold, the output of the switch 9 provides the output voltage 16 from the DC-DC converter 6. In this case, the management unit 7 supplies the command signal 17 to the switch 9 to connect the output of the DC-DC converter to the external positive terminal of the smart battery 1. Thus, the end-of-life duration of the battery may be extended by energizing the DC-DC converter 6, which is preferably a boost converter. The boost converter may boost the voltage present on the external terminals of the smart battery 1 when the battery 2 reaches an end-of-battery-life threshold.

The oscillating stage 4 is used to clock the operations in the DC-DC converter 6, the management unit 7 and the single-wire interface 8. The oscillating stage 4 may preferably be formed by an oscillator connected to a clock quartz resonator 5 to provide an oscillating signal with a frequency of about 32,768Hz and a series-connected frequency divider for dividing the oscillating signal frequency. The number of divide-by-two dividers (divider-by-two) may be equal to 15, for example, to allow the frequency of the oscillating signal to be divided to provide a 1Hz clock signal to clock the elements of the electronic circuit 10.

It is further noted that the oscillator stage 4 may be formed by an RC oscillator and the above-mentioned frequency divider. Such an RC oscillator may be fully integrated within an electronic integrated circuit, which is not a quartz resonator. However, the oscillating signal provided by the RC oscillator is less accurate than the oscillating signal generated by a quartz resonator oscillator.

The single-wire interface 8 is directly connected to the management unit and is used to transmit information through one of the external terminals of the smart battery 1. Preferably, the single wire interface is connected to the external positive terminal of the smart battery 1 to allow modulated data or command signals 18 to be transmitted to the electronic device including the smart battery via the single wire bus. The single-wire interface may be a Dallas type interface and may be created as described in the AVR318 circuit of Atmel corporation. The single wire Dallas interface protocol allows asynchronous two-way communication. In the digitized modulated data or command signal, one data bit is transmitted by the bus of the single-wire interface 8 per a defined time window. To transmit a data bit in the "1" state, the interface consumes current or reduces voltage for a first period of time, and to transmit a data bit in the "0" state, the interface consumes current or reduces voltage on the power supply for a second period of time, the second period of time being greater than the first period of time, as introduced in AVR 318.

The single-wire interface 8, controlled by the management unit 7 clocked by the clock signal of the oscillating stage 4, makes it possible to send the modulated data signal preferably through the external positive terminal of the smart battery 1. The modulated data signal includes information about the end of battery life, the battery type, the remaining battery autonomy (autonomy), or any other type of information to be sent to the electronic device. The single-wire interface may also transmit a modulated data signal as a top second signal (top second signal) that represents a predefined code transmitted every second.

Of course, the single-wire interface 8 may also receive modulated data or command signals 18 from the electronic device. The modulated signal received by the single-wire interface 8 may, for example, relate to the setting of a battery end-of-life voltage threshold, after which the DC-DC converter 6 must be energized, or other instructions or data. This battery end-of-life threshold received by the single-wire interface 8 must be stored, for example, in a non-volatile memory of the management unit 7. The management unit 7 may adjust (adapt) the end of battery life threshold of the detector 3 by modifying the reference voltage or the capacitive divider. The single-wire interface 8 may also receive a modulated signal, in particular for calibrating the oscillating stage 4 via the management unit 7 equipped with a processor, if the smart battery is placed inside the watch.

It is noted that the electronic supply voltage management circuit 10 may also be connected to the rechargeable battery 2 to define the smart battery 1. In this case, a current meter may also be provided to meter the battery power consumed, as well as the power supplied to the battery.

Fig. 2 shows a graph representing the evolution of the supply voltage provided by a smart battery according to the invention compared to the evolution of the supply voltage provided by a conventional battery. As long as electricity is suppliedCell voltage V_BATNear battery end-of-life voltage threshold V_EOLThe electronic management unit energizes the DC-DC converter. Thus, the energy drawn from the smart battery is provided via the converter, which may extend the life of the built-in battery connected to the electronic circuit before replacing the smart battery of the electronic device containing said battery. Upon discharge of the smart battery, it is also conceivable to limit the maximum current provided to further extend the life of the battery.

It is also noted that the energy impact of the electronic supply voltage management circuit 10, in particular on the battery life, may also be limited. It is conceivable to introduce a power-on and power-off period defining a period ratio (cyclic ratio) or duty cycle to allow the voltage of the battery 2 to be measured at longer or shorter time intervals depending on the battery state, in particular by the detector 3. In general, at least the management unit 7 and the oscillating stage 4 can be continuously powered on, so as to switch the detector 3 on and off with a determined periodicity ratio.

Setting a first long measuring time interval when the battery is started to be used, wherein the voltage V_BATWell above the end of life limit of the battery. A second voltage threshold may be set in the electronic circuit to determine the voltage V_BATIs much higher than the second voltage threshold. When the voltage V is_BATA second short measurement time interval is set near a critical end of battery life threshold that is below a second threshold.

Such cycles may be controlled internally, where only a small portion of the electronic circuit performs operations in accordance with the above, and is able to wake up other components of the circuit when necessary. This requires several tens of nanoamperes of power to be consumed. Such periods may also be controlled by the electronic circuitry of the electronic device or the electronic circuitry of the product containing the smart battery.

From the description just given, a person skilled in the art can envisage many variants of smart batteries equipped with an electronic supply voltage management circuit, without departing from the scope of the invention as defined in the claims. The end of battery life detector may include a resistive divider on the comparator input instead of a capacitive divider. The DC-DC converter may be a buck-boost converter. The variation of the frequency of the clock signal provided by the oscillating stage may be controlled via the management unit by selecting one of the outputs of each divide-by-two frequency divider.

Claims

1. Intelligent battery (1) comprising an electronic power supply voltage management circuit (10) connected to a battery (2), said electronic power supply voltage management circuit comprising a battery end-of-life detector (3), a management unit (7), an oscillating stage (4), and a data or command communication interface (8),

characterized in that said data or command communication interface (8) is connected to one of the supply voltage terminals of said smart battery to send and receive modulated digital data or command signals through one of said supply voltage terminals, an

The data or command communication interface (8) is arranged to receive a modulated signal from the smart battery powered electronic device, the modulated signal received by the interface comprising a command for setting an end of battery life threshold, after which the DC-DC converter (6) of the electronic supply voltage management circuit (10) is powered by the management unit (7) to provide the supply voltage of the smart battery.

2. Smart battery (1) according to claim 1, characterised in that said data or command communication interface (8) is controlled by said management unit (7) connected to said battery end-of-life detector (3) to send a modulated signal comprising at least battery end-of-life information.

3. Smart battery (1) according to claim 1, characterized in that said electronic supply voltage management circuit (10) comprises a DC-DC converter (6) which is energized when the supply voltage of said battery (2) is close to or equal to a battery end-of-life threshold, so that said converter provides the supply voltage of said smart battery.

4. Smart battery (1) according to claim 3, characterised in that said management unit (7) is connected to said battery end-of-life detector (3), to an oscillating stage (4), to a DC-DC converter (6) and to a data or command communication interface (8), and in that said management unit (7) operates said DC-DC converter (6) as soon as said battery end-of-life detector (3) provides an output signal to said management unit when the supply voltage of said battery (2) is close to or equal to a battery end-of-life threshold.

5. Smart battery according to claim 1, characterized in that the data or command communication interface (8) is connected to the external positive supply voltage terminal of the smart battery for transmitting the modulated signal.

6. Intelligent battery (1) according to claim 5, characterized in that the positive terminal of the battery (2) is connected to a first input of a switch (9) of said electronic supply voltage management circuit (10) and a second input of said switch (9) is connected to the output of a DC-DC converter (6), said converter being powered when the supply voltage of said battery (2) is close to or equal to the battery end-of-life threshold; the output end of the switch (9) is connected with the external positive terminal of the intelligent battery; and the switch (9) is controlled by a command signal (17) from the management unit (7) to supply the voltage of the battery (2) to the external positive terminal when the battery voltage is above the battery end-of-life threshold and to supply the output voltage of the DC-DC converter (6) when the battery voltage is equal to or below the battery end-of-life threshold.

7. Smart battery (1) according to claim 1, characterised in that said oscillating stage (4) comprises an oscillator connected to a quartz resonator (5) to provide an oscillating signal, and a series of frequency dividers for dividing the oscillating signal frequency to provide a clock signal to clock the operation of said management unit (7).

8. Smart battery (1) according to claim 7, characterized in that the quartz resonator is a clocked quartz resonator, so that the oscillator provides an oscillating signal with a frequency of 32,768 Hz.

9. Smart battery (1) according to claim 8, characterised in that said frequency dividers are divide-by-two frequency dividers, the number of which is fifteen, in order to divide the oscillation signal frequency to provide a 1Hz clock signal, allowing the data or command communication interface (8) to send a modulated data signal per second as a superordinate second signal.

10. Smart battery (1) according to claim 1, characterised in that said management unit (7) comprises a non-volatile memory storing an end of battery life voltage threshold in order to adjust said end of battery life detector (3).

11. Smart battery (1) according to claim 1, characterised in that the battery end-of-life detector (3) can be powered on and off at time intervals set according to the duty cycle or cycle ratio determined by the management unit (7) clocked by the oscillating stage (4) to measure the voltage level of the battery (2).

12. Smart battery (1) according to claim 11, characterized in that said detector (3) can be powered on and off at a first time interval if said voltage level of said battery (2) is higher than a second voltage threshold, wherein the second voltage threshold is higher than the first battery end-of-life threshold; and if the voltage level of the battery (2) is below the second voltage threshold, the detector (3) can be powered on and off at a second time interval shorter than the first time interval.