Battery system comprising real-time clock to which power is supplied internally, and power supply circuit for real-time clock

Abstract

Embodiments of the present invention relate to a battery system with internally powered real time clock, the battery system includes a plurality of battery cells connected in series and/or in parallel between a first terminal and a second terminal and a real time clock electrically connected to a first node of the plurality of battery cells, a voltage of a single battery cell of the plurality of battery cells applies to the first node, and the real time clock draws power via the first node in a first operation state and in a second operation state of the battery system.

Claims

1. Battery system with internally powered real time clock, comprising: a plurality of battery cells connected in series and/or in parallel between a first terminal and a second terminal of the plurality of battery cells; a real time clock electrically connected to a first node between the first and second terminals of the plurality of battery cells; and at least one passive device connected between the first node and the real time clock, wherein a voltage of a single battery cell of the plurality of battery cells is applied to the first node, wherein the at least one passive device adjusts the voltage applied to the first node, wherein the real time clock draws power via the first node in a first operation state and in a second operation state of the battery system, and wherein the single battery cell is configured to supply the voltage to the first node in the first operation state and in the second operation state of the battery system.

2. Battery system according to claim 1, further comprising a control unit electrically connected to one of the first terminal and the second terminal, wherein the real time clock is electrically connected to a first output of the control unit, and wherein the real time clock draws power via the first node in the first operation state of the battery system and draws power via the first node and via the first output of the control unit in the second operation state of the battery system.

3. Battery system according to claim 2, wherein the control unit is inactive in the first operation state of the battery system and is active in the second operation state of the battery system.

4. Battery system according to claim 2, wherein the control unit is configured for transmitting control information to the real time clock during the second operation state of the battery system, and wherein the real time clock is configured for receiving and processing the control information under additional power consumption.

5. Battery system according to claim 2, wherein the real time clock is configured for transmitting a wake up signal to the control unit in the first operation state of the battery system, and wherein the control unit is configured for transferring the battery system to the second operation state in response to the wake up signal.

6. Battery system according to claim 5, further comprising an energy storage element configured for supplying power to the real time clock for transmitting the wake up signal to the control unit.

7. Battery system according to claim 2, further comprising an active balancing unit electrically connected to the first node of the plurality of battery cells and configured for supplying power to the single battery cell.

8. Battery system according to claim 7, wherein the active balancing unit is electrically connected to a second output of the control unit and comprises a step-down converter.

9. Battery system according to claim 2, wherein the plurality of battery cells, the control unit and the real time clock are arranged in a common housing, and/or wherein the control unit and the real time clock are arranged on a common circuit carrier.

10. The battery system of claim 1, wherein the at least one passive device comprises a resistor.

11. The battery system of claim 1, wherein the at least one passive device comprises a first resistor and a second resistor connected in series between the first node and the real time clock.

12. Power supply circuit for a real time clock, comprising: a central node electrically connected to a power input of the real time clock and a first node electrically connected to the central node; and at least one passive device connected between the first node and the central node, wherein a single battery cell from among a plurality of battery cells connected in series and/or in parallel between a first terminal and a second terminal of the plurality of battery cells is connected between the first node and the first terminal or between the first node and the second terminal to supply a voltage to the first node, wherein the at least one passive device is configured to adjust the voltage supplied to the first node to power the real time clock, and wherein the single battery cell is configured to supply the voltage to the first node in an active state and in an inactive state of the power supply circuit.

13. Power supply circuit according to claim 12, further comprising a battery system control unit that is electrically connected to one of the first terminal and the second terminal of the plurality of battery cells and provides a supply voltage to a first output of the battery system control unit; and a second node electrically connected to the central node and to the first output of the battery system control unit.

14. Power supply circuit according to claim 12, further comprising an active balancing unit electrically connected between the first node and a second output of a battery system control unit and comprising a step-down converter.

15. Power supply circuit for a real time clock, comprising: a central node electrically connected to a power input of the real time clock and a first node electrically connected to the central node; and at least one passive device connected between the first node and the central node, wherein a single battery cell from among a plurality of battery cells connected in series and/or in parallel between a first terminal and a second terminal of the plurality of battery cells is connected between the first node and the first terminal or between the first node and the second terminal to supply a voltage to the first node, wherein the at least one passive device is configured to adjust the voltage supplied to the first node to power the real time clock, and wherein the power supply circuit further comprises an energy storage element electrically connected to the central node and configured for supplying power to the real time clock for transmitting a wake up signal to a battery system control unit.

Description

DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 illustrates a schematic circuit diagram of a power supply circuit of a real time clock according to the prior art.

(2) FIG. 2 illustrates a schematic connection diagram of a real time clock according to the prior art.

(3) FIG. 3 illustrates a schematic diagram of a battery system according to a first embodiment.

(4) FIG. 4 illustrates a schematic circuit diagram of a power supply circuit of a real time clock according to a first embodiment.

(5) FIG. 5 illustrates a schematic circuit diagram of a power supply circuit of a real time clock according to a second embodiment.

MODE FOR INVENTION

(6) Hereinafter, various exemplary embodiments will be described in detail so that those skilled in the art can easily carry out the present invention with reference to the accompanying drawings. The exemplary embodiments may be implemented in a variety of different forms and are not limited to the exemplary embodiments described herein.

(7) For clear illustration of the exemplary embodiments, parts not related to the description are omitted, and the same reference numerals are used throughout the specification for the same or similar constituent elements. Therefore, the reference numbers of the constituent elements used in previous drawings can be used in following drawings.

(8) The method to electrically connect two constituent elements includes not only a direct connection of two components, but also a connection between two components through a different component. The different component may be a switch, resistor, capacitor, and the like. In describing the embodiments, the expression “connect” means to electrically connect when there is no expression of “directly connect”.

(9) FIG. 1 shows a schematic circuit diagram of a power supply circuit of a real time clock according to the prior art.

(10) Referring FIG. 1, an input voltage CL30 of LDO linear voltage regulator U701 is provided to the anode of diode D701 and the cathode of diode D701 is electrically connected with a first input of LDO U701. The input voltage CL30 of LDO U701 may be supplied from at least one cell of a plurality of battery cells (not shown). Further inputs of LDO U701 are supplied with ground voltage GND. A condenser C701 is connected in parallel to LDO U701 and functions as low-pass for conducting HF parts of the battery voltage to ground. A first output of LDO U701 is electrically connected to a +3V3_RTC node and hence, in a certain range of cell voltage a substantially constant RTC voltage of 3.3 V is provided to the +3V3_RTC node.

(11) FIG. 2 illustrates a schematic connection diagram of a real time clock U702 according to the prior art, wherein the +3V3_RTC node shown in FIG. 1 is connected to various nodes shown in FIG. 2.

(12) Referring to FIG. 2, for supplying power to the RTC U702, the regulated operation voltage of substantially 3.3 V is provided to the VDD input pin of RTC U702. Thus, the RTC U702 is solely supplied power via the output of LDO U701. The RTC U702 is further electrically connected to ground GND and comprises a plurality of input pins electrically connected to a plurality of serial peripheral interfaces SPI. An output pin CLKOUT of the RTC U702 provides a fixed output frequency as clock signal and an output pin/INT is an open drain output configured to output a wake up signal WAKEUP_RTC. As can be seen from the combination of FIGS. 1 and 2, the LDO U701 must be continuously active in order to provide energy to the RTC U702. Thus, power dissipation occurs constantly in the LDO U701 and lowers the efficiency of the system.

(13) FIG. 3 illustrates a schematic diagram of a battery system 10 according to a first embodiment of the invention, and FIG. 4 illustrates a schematic circuit diagram of a power supply circuit 100 of a real time clock U702 of the battery system 10 according to the first embodiment of the invention.

(14) Referring to FIGS. 3 and 4, a single battery cell CE101 of a plurality of battery cells 101 constituting the battery system 10 is connected with a first node 111 of the power supply circuit 100 such that solely the voltage of the first battery cell CE101 is applied to the first node 111. This is either realized by connecting a first clamp (not shown) and a second clamp (not shown) to the first node 111 and by electrically connecting the single battery cell CE101 between the first clamp and the second clamp. In this case, the output voltage of the single battery cell CE101 may be divided by the first and second clamps, and the divided voltage may be applied to the first node 111. The plurality of battery cells 101 is electrically connected in series and/or in parallel between a first terminal (T1) and a second terminal (T2) and the single battery cell CE101 is electrically connected between one of these terminals and the first node 111.

(15) The first node 111 is electrically connected to a central node 110. A first ohmic resistor R707 with a resistance of 100 kOhm and a second ohmic resistor R708 with a resistance of 100 kOhm may be electrically connected between the first node 111 and the central node 110. The central node 110 is electrically connected to the supply node +3V3_RTC that is electrically connected to the VDD input pin of the RTC U702. The central node 110 is further electrically connected to a second node 112 that is electrically connected with a first output of a control unit U703. The control unit U703 is electrically connected to a plurality of battery cells 101 and supplies a voltage of 3.3 V to its first output while it is active. A diode D701 is electrically connected between the second node 112 and the first output of the control unit U703. Further a condenser C703 is electrically connected as an energy storage element between the central node 110 and GND.

(16) In a first operation state of the battery system 10, the control unit U703 is inactive and thus no voltage is applied to the first output. In this first operation state, the single battery cell CE101 provides a first voltage of approximately 4V to the first node 111. The RTC U702 that is connected to the node +3V3_RTC has a nominal current consumption between 0.6 μA and 1.2 μA as the inactive control unit U703 does not conduct any communication with the RTC U702. Typically, the RTC U702 requires an input voltage of 3.3 V. At a current between 0.6 μA and 1.2 μA, the resistors R707 and R708 effect a voltage drop such that a voltage of approximately 3.3 V applies to the central node 110 and the second node 112. The diode D701 prevents that the inactive control unit U703 functions as current sink. Referring to FIG. 4, a voltage is applied to the node +3V3_RTC via the central node 110 and this voltage is utilized to power the RTC U702. Thus, in the first operation state, the RTC U702 is powered without operating any active switching means and thus power consumption of the battery system 10 comprising the power supply circuit 100 as shown in FIG. 4 is reduced and no switching noise occurs.

(17) The first output of the control unit U703 and thus the second node 112 are set to a supply voltage of 3.3 V if the control unit is active in a second state of a battery system. In the second operation state, the control unit U703 communicates with the RTC U702. That is, the control unit U703 transmits control information to the RTC U702. Receiving and processing the control information as well as transmitting an RTC response to the control unit U703 increases the power demand of the RTC U702. Particularly, the current consumption of the RTC U702 increases at the fixed input voltage of 3.3 V and thus the voltage drop at the resistors R707 and R708 increases. Hence, the single battery cell CE101 is not sufficient to provide the operation voltage to the RTC U702. However, as the control unit U703 is active, it supplies a voltage of 3.3 V to its first output and thus a voltage of approximately 2.6 V is provided to second node 112. Thereby, sufficient power for supplying RTC U702 is provided to the central node 110 via the first node 111 and the second node 112. Thus, the increased power demand of the RTC U702 can be met as it passively draws current via the first node 111 and the second node 112, i.e. the first output of the control unit U703

(18) The condenser C703 comprises a capacity of 2.2 μC and is charged in the second operation state. At the end of the first operation state, the RTC U702 transmits a wake up signal WAKEUP_RTC via output/INT to the control unit U703. The additional power required for generating and transmitting this signal is provided by condenser C703 that is discharged. In response to the wake up signal, the control unit U703 wakes up and thus initiates the second operation state, in which the condenser C703 is again charged. Thus, the RTC U702 is securely power supplied in all of its operation states via the simple power supply circuit 100 as shown in FIG. 4 without any active switching means and thus with increased efficiency.

(19) FIG. 5 illustrates a schematic circuit diagram of a power supply circuit 100 of a real time clock RTC U702 of a battery system (not shown) according to a second embodiment of the invention.

(20) Referring to FIG. 5, an active balancing circuit 201 is electrically connected to the power supply circuit 100. The active balancing circuit 201 comprises a n-channel FET R705 (with free-wheeling diode) and a balancing control unit AB301 that controls the gate of the n-channel FET R705. The source of FET R705 is electrically connected to a second output of the control unit (see reference numeral U703 in FIG. 3) that supplies a voltage of 5 V. The drain of FET R705 is electrically connected to the conductor between the first node 111 and the central node 110 via a first ohmic resistor R715 with 24 kOhm resistance and a second ohmic resistor R716 with 24 kOhm resistance. The balancing control unit AB301 sets the conductance of FET R705 dependent on an actual voltage measurement of one or more of the plurality of battery cells (see reference numeral 10 in FIG. 3). The resistors R715 and R716 provide a voltage drop and thus adapt the output voltage of FET R705 to the charging voltage requirements of the single battery cell CE101. The balancing occurs in the second operating state of the battery system (see reference numeral 10 in FIG. 3), while the control unit (see reference numeral U703 in FIG. 3) is active. Thus, misbalancing between the battery cells can be avoided and the nominal capacity of the battery system might be increased. The further components of the power supply circuit 100 are identical to the components of the power supply circuit shown in FIG. 4. and hence their description is omitted.

(21) The electronic or electric devices and/or any other relevant devices or components according to embodiments of the present invention described herein may be implemented utilizing any suitable hardware, firmware (e.g. an application-specific integrated circuit), software, or a combination of software, firmware, and hardware. For example, the various components of these devices may be formed on one integrated circuit (IC) chip or on separate IC chips. Further, the various components of these devices may be implemented on a flexible printed circuit film, a tape carrier package (TCP), a printed circuit board (PCB), or formed on one substrate. The electrical connections or interconnections described herein may be realized by wires or conducting elements, e.g. on a PCB or another kind of circuit carrier. The conducting elements may comprise metallization, e.g. surface metallizations and/or pins, and/or may comprise conductive polymers or ceramics. Further electrical energy might be transmitted via wireless connections, e.g. using electromagnetic radiation and/or light.

(22) Further, the various components of these devices may be a process or thread, running on one or more processors, in one or more computing devices, executing computer program instructions and interacting with other system components for performing the various functionalities described herein. The computer program instructions are stored in a memory which may be implemented in a computing device using a standard memory device, such as, for example, a random access memory (RAM). The computer program instructions may also be stored in other non-transitory computer readable media such as, for example, a CD-ROM, flash drive, or the like.

(23) Also, a person of skill in the art should recognize that the functionality of various computing devices may be combined or integrated into a single computing device, or the functionality of a particular computing device may be distributed across one or more other computing devices without departing from the scope of the exemplary embodiments of the present invention.

(24) The detailed description of the invention described in the drawings and described above is merely illustrative of the present invention, and it is used only for the purpose of describing the present invention and not for restricting the meanings or limiting the scope of the present invention described in the claims. It will therefore be apparent to those skilled in the art that numerous variations and equivalents of other embodiments are possible. Therefore, the true technical protection scope of the present invention should be determined by the technical concepts of the accompanying claims.

DESCRIPTION OF SYMBOLS

(25) 10 battery system

(26) 100 power supply circuit

(27) 101 plurality of battery cells

(28) 110 central node

(29) 111 first node

(30) 112 second node

(31) 201 active balancing circuit

(32) +3V3_RTC supply node

(33) CE101 single battery cell

(34) U702 RTC

(35) U703 control unit

(36) R707, R708, R715, R716 resistor

(37) C703 condenser

(38) D701 diode

(39) R705 FET

(40) AB301 balancing control unit