JP2005534278A - Charging circuit for charging in parallel in many battery systems - Google Patents

Abstract

In a charging circuit for controlling system charging parameters applied to a host rechargeable battery, the host battery includes at least a first battery and a second battery that can be coupled in parallel. The charging circuit can charge rechargeable batteries in parallel at high speed. By independently detecting the current and voltage for each battery, the batteries can be charged in parallel at different charging currents. The charging circuit can be configured to receive either an analog signal or a digital signal from an associated power management unit.

Description

  The present invention relates to a charging circuit, and more particularly to a charging circuit for charging a large number of batteries in parallel.

  This application is a continuation-in-part of Patent Document 1 filed on February 11, 2003, the teachings of which are incorporated herein by reference, and Patent Document 2 filed on March 26, 2003. Claiming the benefit of U.S. Patent Application Publication No. 2003/058400, filed Jul. 3, 2003, the teachings of which are both incorporated herein by reference. This application is also a continuation-in-part application of Patent Document 4 filed on July 14, 2003, and is itself a continuation application of Patent Document 5 filed on December 23, 2002. U.S. Patent No. _ itself, which is a continuation application of Patent Document 6 filed on Sep. 7, 2001, and is currently Patent Document 7, all of which are patent documents filed on Aug. 17, 2001. Claim 8 rights.

  The selection circuit is typically used in a power source for various electronic devices. Such a selection circuit is usually designed to make a selection between a DC power source such as, for example, an AC / DC adapter and a rechargeable battery. In various electronic devices, such as laptop computers, such selection circuits are typically controlled by control signals that communicate via a system management bus (SMBus) according to a specific protocol. In addition, such a selection circuit typically cannot verify, fix, or inform other components in the power supply block independently when the power supply is in a critical situation. In addition, such selection circuitry is not configured to receive control signals from the associated host power management unit.

US Non-Provisional Application No. 10 / 364,228 US Provisional Application No. 60 / 457,826 US Provisional Application No. 60 / 484,635 US Application No. 10 / 618,901 US Application No. 10 / 328,466 US Application No. 09 / 948,828 US Pat. No. 6,498,461 US Provisional Application No. 60 / 313,260

  The charging circuit is typically used to adjust the conditions for charging the battery when the selection circuit selects to charge one or more batteries. Most charging circuits for use with multiple batteries cannot charge multiple batteries in parallel. For a charging circuit that cannot charge a large number of batteries, only the entire current charging the batteries is controlled and maintained to be below the maximum value. Accordingly, the battery charging time increases. For example, in such a case, if two similar batteries are charged in parallel, the average charging current per battery will be the maximum power level from the associated DC power source (eg, AC / DC adapter), for example. If not, it will be only half of the maximum allowed. Accordingly, there is a need in the art for a charging circuit with a more enhanced parallel charging capability.

  A charging circuit is provided for controlling system charging parameters provided to a host battery, wherein the host battery includes at least a first battery and a second battery that can be coupled in parallel. The present charging circuit in accordance with the present invention monitors a first path configured to monitor a first battery charging current level applied to the first battery and a second battery charging current level applied to the second battery. And when the first charging current exceeds a predetermined first maximum charging current level or the second charging current exceeds a predetermined second maximum charging current level, the host battery is And a regulation circuit configured to reduce the system charging parameters provided.

  A method is provided for controlling system charging parameters provided to a host battery, wherein the host battery comprises at least a first battery and a second battery that can be coupled in parallel. The method in accordance with the present invention includes monitoring a first battery charging current level applied to a first battery, monitoring a second battery charging current level applied to a second battery, and a first charging current level. Includes reducing a system charging parameter applied to the host battery when the predetermined first maximum charging current level is exceeded or the second charging current exceeds the predetermined second maximum charging current level.

  According to another aspect of the present invention, a charging circuit is provided for adjusting an output parameter of a DC-DC converter. The output parameter of the DC-DC converter supplies power to the host battery, where the host battery comprises at least a first battery and a second battery that can be coupled in parallel. A charging circuit in accordance with the present invention monitors a first path configured to monitor a first battery charging current level applied to a first battery and a second battery charging current level applied to a second battery. A second path configured to, a third path configured to monitor a first battery charge voltage level applied to the first battery, and a second battery charge voltage level applied to the second battery. And the fourth path configured in the above. The charging circuit also provides direct current when one of the first battery charging current level, the second battery charging current level, the first battery charging voltage level, and the second battery charging voltage level exceeds an associated predetermined maximum level. -It includes an adjustment circuit configured to reduce the output parameters of the DC converter;

  According to still another aspect of the present invention, an electronic device is provided. In parallel with the present invention, an electronic device includes a power management unit configured to provide an output signal representing at least a predetermined first maximum charging current level and a predetermined second maximum charging current level, and A host battery including at least a first battery and a second battery coupled, and a charging circuit for controlling system charging parameters applied to the host battery are included. The charging circuit monitors a first battery charging current level applied to the first battery, and compares the first battery charging current level with a predetermined first maximum charging current level; A second path configured to monitor a second battery charge current level applied to the second battery and compare the second battery charge current level with a predetermined second maximum charge current level; It is configured to reduce the system charging parameter applied to the host battery when the charging current exceeds a predetermined first maximum charging current level or the second charging current exceeds a predetermined second maximum charging current level. And a regulation circuit.

  In a further aspect of the invention, an electronic device is provided that can be powered by one or more host rechargeable batteries or a DC power source. An electronic device in accordance with the present invention includes a power management unit (PMU) configured to execute a power management routine, a charging circuit configured to control charging of a host rechargeable battery, and a PMU And a selection circuit configured to select at least one of the host battery in response to a PMU output signal from the host battery, the host battery being a first battery coupled in parallel And a second battery, wherein the charging circuit monitors a first battery charging current level applied to the first battery and compares the first battery charging current level with a predetermined first maximum charging current level. The second battery charging current level applied to the second battery is monitored and the second battery charging current level is compared with a predetermined second maximum charging current level. First The path and if the first charging current exceeds a predetermined first maximum charging current level or the second charging current exceeds a predetermined second maximum charging current level, the system charging parameter applied to the host battery is reduced. And an adjustment circuit configured to do so.

  The advantages of the present invention will be apparent from the detailed description of the embodiments illustrated below, which should be considered in conjunction with the accompanying drawings.

  Referring to FIG. 1, a simplified block diagram of an electronic device 100 that can be powered from a number of power sources 104, 105 is shown. Such a power source may include a plurality of batteries 105 and a DC power source 104. The battery 105 may further be various types of equipment known in the art, such as lithium ion, nickel cadmium, nickel metal oxide batteries. The electronic device 100 supplies power from one of the power sources 104 and 105 in various cases, such as portable electronic devices (laptop computers, mobile phones, pagers, personal digital assistants, etc.), electric vehicles, and power tools. There can be various types of equipment known in the art.

  If electronic device 100 is a laptop computer, it will include various elements known to those skilled in the art not shown in FIG. For example, a laptop may be an input device for inputting data into the laptop, or a central processing unit (CPU) or processor, such as Intel Corporation®, for executing laptop instructions or controlling operations. It may include a Pentium® processor and output devices for outputting data from a laptop, such as an LCD or speaker.

  The DC power source 104 can be coupled to the device 100 for recharging the battery 105 and / or supplying power to the device 100. The DC power source 104 may be an AC / DC adapter configured to receive a conventional 120 volt AC from a wall outlet and convert it to a dc output voltage. The DC power source 104 may also be a DC / DC adapter, such as an adapter resembling a “cigarette lighter” that is configured to plug into such a socket. Although such a DC power source 104 is shown in FIG. 1 as being separate from the device 100, it can be incorporated into some devices.

  The device 100 has a power supply block 106 including at least a selection circuit 114 according to the present invention. The power block 106 may also include a PMU 120 as shown in FIG. Alternatively, the PMU 120 may also be incorporated into the more complex processor of the electronic device 100. The PMU 120 is configured to execute various power management routines known in the art. In general, the power supply block 106 includes various elements that monitor and control the power from each power supply and direct it to each other and to other systems of the device 100 according to various conditions. Advantageously, the selection circuit 114 in accordance with the present invention is configured to be responsive to at least one output signal from the PMU 120, as will now be described in more detail.

  Turning to FIG. 2, a more detailed block diagram of an example power block 206 for multiple battery systems is shown. The power source includes a DC source 204, such as an AC / DC converter, and a number of batteries 205-1, 205-2, 205-k. Such a battery would also be a rechargeable battery. At any time, each of these power supplies 204, 205-1, 205-2, 205-k may or may not be present in the system.

  In general, the power supply block 206 includes a PMU 220, a charging circuit 222, a power conversion element 226, a battery switch network 217, a switch 230, a power supply path 209 from the DC power supply 204 to the system 210, and a battery 205-1. , 205-2, 205-k to the system, a power path 240 to the system, a power path 207 for recharging the rechargeable batteries 205-1, 205-2, 205-k from the DC power source 204, It may include a selection circuit 214 in accordance with the invention and various data paths or communication paths. The battery switch network 217 will further comprise charge switches CSW1, CSW2, CSWk and discharge switches DSW1, DSW2, DSWk for the associated batteries 205-1, 205-2, 205-k.

  The data path or communication path between the various elements of power supply block 206 may be unidirectional or bidirectional, and may conduct analog or digital signals. The data path can carry commands or control signals or data. The number of such data paths greatly depends on the specific characteristics of the batteries 205-1, 205-2, 205-k, the charging circuit 222, the PMU 220, and the specific characteristics of the power supply block 206 as a whole. Yes. For example, if the associated device 100 is a laptop computer, a smart charger circuit and a smart battery may communicate via a system management bus (SMBus) according to a specific protocol. it can.

  In general, selection circuit 214 provides switch control signals through path 250 to battery switch network 217 and switch 230 in response to various input signals from various elements within power supply block 206 including PMU 220. , Control power from each power source under various conditions and communicate to each other and to the system 210.

  For example, a particular set of input signals to the selection circuit 214 indicates that a DC power supply 204 with an acceptable voltage level is present. In response to such an input signal, the selection circuit 214 provides control signals for closing (turning on) the switch 230 and opening (turning off) the discharge switches DSW1, DSW2, DSWk in the battery switch network 217. provide. As such, power from the DC power supply 204 is supplied to the system 210. Alternatively, if the input signal to the selection circuit indicates that there is no DC power supply 204 or a DC power supply with an acceptable voltage level, the selection circuit 214 turns off the switch 230 and discharges the battery switch network. Provide appropriate control signals to turn on the switches DSW1, DSW2, DSWk. As such, one or more of the associated batteries 205-1, 205-2, 205-k provides power to the system 210 as long as the other safety meets the conditions detailed herein. .

  Charging switches CSW1, CSW2, CSWk for each associated rechargeable battery 205-1, 205-2, 205-k are connected from the power line 207 when the charging switch is on for charging purposes. A conductive path is provided to the associated battery. The discharge switches DSW1, DSW2, DSWk are connected to each of the associated batteries 205-1, 205-2, 205-k from one or more batteries depending on which of the discharge switches DSW1, DSW2, DSWk is on. Is provided to the system 210.

  Advantageously, at least one input signal to the selection circuit 214 represents an output signal from the PMU 220. Such exchange between the PMU 220 and the selection circuit 214 is performed through the data path 211. As will be appreciated by those skilled in the art, the PMU 220 may execute host device power management routines. The PMU 220 supplies a host set of signals to the selection circuit 214, in which any of the batteries 205-1, 205-2, 205-k or parallel combinations of batteries are selected for charging or discharging. A signal indicating whether or not. As will be described in more detail herein, the selection circuit 214 is responsive to the PMU 220. However, the selection circuit 220 is further configured to perform an internal check and can override the desired application signal from the PMU under various conditions as described in more detail herein, Provides additional safety and battery power savings. The charger circuit 222 is configured to communicate with the selector 214 through the data path 252 and to interact with the power conversion unit 226, eg, a charger controlled DC-DC converter, through the data path 254. The charger circuit 222 can control supplying charging current through the power path 207 and the power conversion unit to the batteries 205-1, 205-2, 205-k.

  Turning to FIG. 3, an example of a power supply block 306 is shown that operates with three power supplies. The power source includes a DC power source (not shown) coupled to the power block 306 through a power path 309, a first rechargeable battery A, and a second rechargeable battery B. . The power supply block 306 includes a selection circuit 314 according to the present invention and other elements such as an associated PMU 320, charging circuit 322, power conversion unit 216, such as a DC-DC converter. As described in detail above, the PMU 320 is shown as part of the power supply block 306, but the PMU 320 may be outside the power supply block, embedded in a separate element outside the power supply block, or The function of the PMU may be provided by another element of the electronic device, for example, a CPU.

  For clarity and simplicity of explanation, the DC source and various data connections previously described in FIG. 2 (eg, from charging circuit 306 to power conversion unit 326 and PMU 320, between the battery and PMU 320). Is not shown in FIG. Advantageously, the selection circuit 314 and the charging circuit 322 are combined into a single integrated circuit 390 for convenient operation and implementation.

  The selection circuit 314 includes a controller 315 and a switch driver network 317, which will be described in detail herein. The selection circuit 314 has various input terminals 380 and receives various input data and control signals. Such an input terminal 380 is also coupled to the controller 315. The selection circuit 314 also has various output terminals 382 that supply control signals to the associated switches SW 1, SW 2, SW 3, SW 4, SW 5, SW 6 and supply data to the associated elements of the power supply block 306. Input terminal 380 includes terminals 380-1 through 390-9, which receive control signals and data signals named PSM, USE_A, USE_B, ICHG, VAD, VSYS, BATT_A, BATT_B, and AUXIN, respectively. . The output terminals 382 include terminals 382-1 to 382-10, and control signals and data signals named PWR_AC, PWR_BATT, CHGA, DCHA, ACAV, ALERT, CHGEN, CHGB, DCHB, and AUXOUT, respectively. I will provide a. Each input terminal 380 and output terminal 382 and their associated control and data signals are described generally below.

  The first input terminal 380-1 may receive a power saving mode (PSM) digital input control signal from the PMU 320 that indicates whether the PMU 320 desires a power saving mode. The second and third input terminals 380-2 and 380-3 are a USE_A control signal and a USE_B control signal from the PMU 320 that indicate a battery or combination of batteries that the PMU desires to use in a predetermined charge mode or discharge mode. Can receive. For example, in the embodiment of FIG. 3 with two batteries A and B, if USE_A is low and USE_B is high, the USE_A control signal and the USE_B control signal require battery A to be used. It will be a digital signal. If USE_A is high and USE_B is low, request to use battery B. If USE_A is low and USE_B is low, it is required to use battery A and battery B in parallel. Finally, if USE_A is high and USE_B is high, request that neither battery A nor battery B be used. These high and low signals expressed for USE_A and USE_B are given for illustrative purposes only, as those skilled in the art will recognize that other signal combinations may be selected.

  The fourth input terminal 380-4 can receive a charging current (ICHG) analog signal from the charging circuit 322 representing the charging current applied to the battery. The fifth input terminal 380-5 may receive an analog signal from a DC voltage source 204, eg, an AC / DC adapter (VAD), representing a voltage level provided by the DC power source 204 at a particular time. The sixth input terminal 380-6 can receive an analog signal representing a system power supply voltage level (VSYS). The seventh input terminal 380-7 and the eighth input terminal 380-8 can receive analog signals from the battery A (BATT_A) and the battery B (BATT_B) representing the voltage levels of the respective batteries. Such BATT_A analog signals and BATT_B analog recording signals are obtained by measuring the voltage at the positive electrode of each battery. Finally, the ninth input terminal 380-9 has a general input terminal (AUXIN) that can receive other input control signals and data signals, which are considered to be less important for the description of the present invention. Represents.

  The first output terminal 382-1 can provide a switch control signal (PWR_AC) to the switch SW1. The second output terminal 382-2 can provide a switch control signal (PWR_BATT) to the switch SW2. The third output terminal 382-3 can provide a switch control signal (CHGA) to the charging switch SW3 for the battery A. The fourth output terminal 382-4 can provide a switch control signal (DCHA) to the discharge switch SW4 for the battery A. The fifth output terminal 382-5 may provide a digital DC source enable signal (ACAV) that indicates whether there is a DC power supply 204 with an output voltage greater than an acceptable threshold limit.

  The sixth output terminal 382-6 may provide a digital data signal (ALERT) to inform other elements, including at least the PMU 320, about power supply crisis conditions as will be described in detail later. The seventh output terminal 382-7 can provide a digital data signal (CHGEN) to the charger that indicates whether a chargeable state has been reached. The eighth output terminal 382-8 can provide a switch control signal (CHGB) to the charging switch SW5 for the battery B. The ninth output terminal 382-9 can provide a switch control signal (DCHB) to the discharge switch SW6 for the battery B. Finally, the tenth output terminal 380-10 is a general output terminal that can provide other output control signals and data signals (which are considered to be less important to the description of the invention herein). AUXOUT).

  The controller 315 receives the input data and the control signal from the input terminal 380 of the selection circuit 314, and selects or selects any power source or combination of power sources (for example, DC power source, battery A, battery B). To determine whether to control one or a combination of two or more of the switches SW1 to SW6. The controller 315 also provides data or other data directly to other output terminals, such as output terminals 382-5, 382-6, 382-7, 382-10, to interact with other elements of the power supply block 306. Other control signals can be provided.

  The switch driver network 317 includes a plurality of drivers SD1, SD2, SD3. SD4, SD5 and SD6 are included. Each of the switch drivers SD1, SD2, SD3, SD4, SD5, SD6 is further associated with the associated switches SW1, SW2 to move each switch to the on and off positions as directed by the controller 315 of the selection circuit 314. , SW3, SW4, SW5, SW6.

  Turning to FIG. 4, a more detailed block diagram of the selection circuit 314, in particular the controller 315 of the selection circuit 314, is shown. Generally, the controller 315 includes a selector output circuit 470, a charge enable circuit 472, a battery parallel use enable circuit 476, an input confirmation circuit 478, a power crisis circuit 474, and a plurality of comparators CMP1, CMP2. , CMP3, CMP4.

  In general, the selector output circuit 470 includes a charge enable signal (CHGEN) from the charge enable circuit 472, a diode mode (DM) signal from the power crisis circuit 474, and a valid input (VINP1) from the input confirmation circuit 478. Various internal control signals such as a signal, a battery parallel use enable (PBUE) signal from the battery parallel use enable circuit 476, and a DC power supply enable (ACAV) signal from the comparator CMP1 are received. The selector output circuit 470 also receives an analog signal ICHG from the charger circuit 322 that represents the charging current. As described in further detail herein, the selector output circuit 470 provides a switch driver network 317 to switch the associated switches SW1, SW2, SW3, SW4, SW5, SW6 depending on the state of the various input signals. Turn on or off.

  The controller 315 includes a first comparator CMP1 configured to compare an analog signal representing the voltage level of the DC power supply with a first threshold level VT1. The first threshold value VT1 is set to be higher than the minimum power supply voltage VT3 that the system can accept. If a DC power supply exists and is a power supply voltage higher than the first threshold level VT1, the first comparator CMP1 supplies a high ACAV control signal to the selector output circuit 470. Otherwise, the first comparator provides a low ACAV signal. The ACAV signal will also be supplied to the power crisis circuit 474.

  If the selector output circuit 470 receives a high ACAV signal from the first comparator CMP1, the switch SW1 is turned on so that power to the system 210 is supplied by the DC power supply and the battery is not recharged. Provide an appropriate switch control signal to turn off SW6 (assuming the DC power supply voltage is not greater than the second threshold VT2 as will be described in detail below). The selection circuit 314 uses the DC power point in this example regardless of the USE_A control signal and the USE_B control signal from the PMU. As such, the selection circuit 314 can prioritize the control signal from the PMU to use battery A and battery B; instead, there is a DC power supply and the appropriate voltage is greater than VT1. Requests system 210 to supply power whenever there is a voltage level. Advantageously, this feature extends battery life by ensuring the use of a DC power source in the proper environment.

  The charge enable (CHGEN) signal must be active in order to be able to power the system 210 from a DC power source and charge one or more batteries. The active CHGEN signal in this embodiment is a high CHGEN signal. The charge enable circuit 472 provides a high CHGEN signal if it receives an appropriate CHGP signal from the second comparator CMP2 and an appropriate valid signal VINP1 from the input verification circuit 478. The second comparator CMP2 supplies an appropriate CHGP signal if VT2> VT1 and VT1> VT3, if the power supply voltage from the DC power supply is greater than the second threshold level VT2. The input confirmation circuit 478 supplies a valid signal VINP1. If the USE_A and USE_B control signals from the PMU assert the use of at least one battery A or B, the appropriate valid signal VINP1 is provided. If the USE_A and USE_B control signals do not assert for use of either battery A or B, for example if both USE_A and USE_B are high, the appropriate valid signal VINP1 is not sent. The charge enable circuit 472 also requires another auxiliary valid input signal (AUXIN) from the general input terminal 380-9 to generate an active CHGEN signal.

  During charging, the charging circuit 322 provides an ICHG signal representing the charging current level to the selection circuit 314. Select circuit 314 receives the ICHG signal at input terminal 380-4 and provides the signal to selector output circuit 470. The selection output circuit 470 compares the ICHG signal with the charging threshold level ICHT. Based on this comparison, the selection output circuit 470 determines whether the charging current level is high or low, and turns on or off the various switches based on this result and other input data described herein in more detail. To do. As described in detail in the table of FIG. 5, in this embodiment, a low charging current is represented by a low control signal and a high charging current is represented by a high control signal.

  With battery parallel use, circuit 476 provides a battery parallel use enable (PBUE) signal to selector output circuit 470. The selector output circuit 470 responds to the high PBUE signal by allowing parallel use of the batteries, and for the low PBUE signal, such as USE_A and USE_B are low, Even if there is a request from the PMU 320 through the USE_A signal and the USE_B signal indicating that it is desired to use the batteries in parallel, it responds by not permitting the parallel use of the batteries. As such, the selection circuit 314 adds precaution and protection to using battery A and battery B in parallel if there are no suitable conditions.

  For example, the concern for using two or more batteries in parallel, such as battery A and battery B, is quite significant in the possibility that these batteries are connected in parallel to create an unexpectedly high current state. There is a difference. As such, the fourth comparator CMP4 of the controller 315 is configured to compare the signal BATT_A with the signal BATT_B. Such BATT_A and BATT_B signals may be analog signals taken from the positive terminals of battery A and battery B. If the difference between the two signals BATT_A and BATT_B is less than or equal to a predetermined limit, the comparator CMP4 will supply a BATTCOMP signal to the battery parallel use enable circuit 476. In addition to receiving an active BATTCOMP signal from the fourth comparator CMP4, the battery parallel use enable circuit 476 should also receive an appropriate input valid signal VINP2 from the input verification circuit 478. If the USE_A and USE_B control signals assert the parallel use of battery A and battery B, for example when USE_A and USE_B are low, the appropriate valid signal VINP2 is provided.

  If the USE_A and USE_B control signals from the PMU indicate that parallel use of the batteries is desired by the PMU, the voltage difference between the batteries A and B is not within the predetermined limit. If the PBUE signal is not active, the selector output circuit 474 will charge a battery with a lower voltage level than the others. Under similar conditions, when there is no effective DC source, the selector output circuit will cause the battery at a higher voltage level to provide the system with discharge power than others.

  Advantageously, the selection circuit 314 also includes a power supply circuit 474 designed to independently monitor and confirm a power supply crisis condition, depending on the detected power crisis situation, an appropriate diode. A mode (DM) control signal is provided to the selector output circuit 470. The selector output circuit 470 causes the switch driver from the switch driver network 317 to keep the switches SW2, SW4, and SW6 on in response to an appropriate DM control signal from the power equipment circuit 474, while the switch SW1 , SWS3, SW5 are maintained in the off state. As such, the highest voltage power supply (battery A or battery B or DC power supply) feeds the system through one of the diodes D1, D3 or D5 in this diode mode, respectively. In addition, the selection circuit 314 will also provide an ALERT status signal to the output terminal 382-6 indicating a power crisis. This ALERT signal could be supplied to many components, including at least PMU 320.

  Power crisis situations include invalid outputs or invalid inputs. An invalid output occurs whenever the source that powers the power supply or system fails to maintain a system voltage level that is at the minimum system threshold voltage level VT3. The system voltage level is compared with the minimum threshold voltage level VT3 by the comparator CMP3, and a system check control signal VSYSOK is sent to the power crisis circuit 474 based on this comparison. A power crisis situation with low system voltage can occur if one or more power supplies are intentionally or accidentally disconnected.

  Invalid inputs can also cause problems with power equipment. An invalid input may be that the PMU asserts a situation that it wishes to cause the system to lose power through the USE_A and USE_B signals. For example, the USE_A and USE_B signals go high, and the USE_A and USE_B signals can be asserted when no battery is used (VINP1 signal is low), and no DC power is available (ACAV signal is low). Or the system cannot be maintained at the minimum VT3 voltage level (VSYSOK signal is low). If the USE_A and USE_B signals from the PMU are logically correct, another situation can occur where the input is invalid if the system loses power. For example, the USE_A signal and the USE_B signal may indicate power supply from a single battery that does not exist or has been accidentally removed. Using such a battery, the voltage level on the system will drop below the VT3 threshold and a VSYSOK signal indicating this situation will be provided to the power equipment circuit 374.

  It is not appropriate to maintain the DM supply mode for a long time due to power consumption in the diodes D1, D3, or D5. Advantageously, the power crisis circuit 474 continuously monitors its input and deactivates the DM signal as soon as the power crisis situation is improved. Thus, as soon as the power crisis situation is improved (eg, when lost power is coupled into the system), the internal DM signal from the power crisis circuit becomes inactive and normal power mode is resumed. The

  Turning to FIG. 5, in combination with FIGS. 2-4, table 500 shows the switch states of each of switches SW1-SW6 according to various input signals to selection circuit 314 and selector output circuit 470. Table 500 shows the state of the various switches when power to system 210 is supplied by DC power supply 204 rather than battery 305. As such, the ACAV signal is high and the selector output circuit 470 sends the appropriate switch control signal to the switch driver network 317 so that SW1 is on and SW2 is as shown in each column of table 500. Is off.

  The CHGEN signal is “high” in each column except for the last column 522 of the table 500. As such, not only is the DC power supply present, but other conditions (the voltage from the DC power supply> VT2 and the correct input valid signal VINP1 is present) are satisfied to supply a high CHGEN signal. As such, charging is allowed in columns 502 to 520 of table 500.

  In columns 502 and 504, the USE_A and USE_B signals are low and high, indicating whether the PMU wants to use battery A, respectively. As such, switches SW5 and SW6 to battery B are off in both cases. In the column 502, the charging current signal is “low”, indicating that the charging current from the power conversion unit 226 to the battery 305 is lower than the threshold charging current level ICHT. As such, in response to the charging current signal, the selector output circuit 470 sends an appropriate control signal to the switch drive network 317 to turn on SW3 and turn off SW4. As such, the charging current to battery A flows through closed SW3 and diode D4 in parallel with open SW4. Since the charging current is low, the flow through the diode D4 produces very little power consumption.

  Conversely, the charging current in column 504 is high as indicated by the “high” charging current signal. As such, both switches SW3 and SW4 are on. Therefore, in this example, since current flows through the closed switch SW4, no extra power is consumed in the diode D4. Normally, at comparable current levels, the switches SW1-SW6 consume less power than the corresponding parallel diodes D1-D6 when in the on state. This difference is particularly important at high current levels.

  Looking at the columns 506 and 508, the USE_A and USE_B signals are high and low indicating whether the PMU wants to use battery B, respectively. As such, switches SW3 and SW4 to battery A are off. Column 506 is somewhat similar to column 502, and is the low charging current as represented by the low charging current signal. As such, the switch SW5 is on and the switch SW6 is off. The charging current for battery B therefore flows through closed switch SW5 and diode D6 in parallel with open switch SW6. Conversely, the charging current in column 508 is high as represented by a high charging current signal. As such, the switches SW5 and SW6 are on, and no power is consumed by the diode D6 in this example.

  Looking at columns 510 and 520, the USE_A and USE_B signals are low and low, respectively, in response to the PMU wishing to use battery A and battery B in parallel. If the battery parallel use enable (PBUE) signal is high as shown in columns 510 and 520, it is allowed to charge battery A and battery B in parallel. Switches SW3-SW6 will all be on if the charge current is high as shown in column 512 (charge current signal is high). If the charge current is low as shown in column 510 (charge current signal is low), switches SW3 and SW5 are on and switches SW4 and SW6 are off.

  If the USE_A signal and the USE_B signal indicate that the PMU wants to use battery A and battery B in parallel, but the PBUE signal is low, the selection circuit 314 may It will not allow the operation, thereby not allowing the PMU to override the desired parallel operation. If all else is acceptable, the selection circuit 314 will allow the battery at the low voltage level to be charged. For example, suppose columns 514 and 516 indicate that battery A is at a low voltage level. In that case, the switches SW5 and SW6 to the battery B are off. Switch SW3 to battery A is on in column 510 because the charging current is low, and switches SW3 and SW4 are on in column 512 because the charging current is high. Similarly, if battery B is at a low voltage level, switches SW3 and SW4 to battery A will remain off as shown in columns 518 and 520. Switches SW5 and SW6 to battery B will turn on depending on the charge current level.

  In contrast to the power supplied by the DC power supply, the power can also be supplied by one or more batteries in various battery power system supply modes. In the battery power supply mode, the selection circuit 314 instructs the switch SW1 to be turned off and the switch SW2 to be turned on. The selection circuit 314 instructs to start the battery power supply mode if the DC power supply does not exist or if the voltage is not higher than the first threshold value VT1 determined by the comparator CMP1 even if it exists. As such, the ACAV signal from the first comparator CMP1 to the selection output circuit 470 is low indicating the battery power supply mode. If the ACAV signal is low, the selector output circuit 470 instructs SW1 to switch off and SW2 to switch on.

  In the embodiment of FIG. 3, there are basically two normal battery system supply modes. In the normal battery system supply mode 1 (nbssm1), the USE_A signal and the USE_B signal from the PMU indicate only one of the batteries A and B to be used, and the target battery is present and has a VT3 threshold level. It is possible to provide at least one voltage level that can provide a higher voltage level to the system. In normal battery system supply mode 2 (nbssm2), the USE_A signal and the USE_B signal indicate that the batteries A and B are used in parallel, both batteries being there and at a voltage level greater than the VT3 threshold level. At least one voltage level provided to the system, both batteries having respective voltage levels within a determined voltage range of each other.

  FIG. 6 is a diagram of a table 600 showing various input signals for both battery system supply modes nbssm1 and nbssm2 and the corresponding states of switches SW1-SW6. As shown before, since the battery system supply mode starts, the switch SW1 is turned off and the switch SW2 is turned on. Columns 602 and 604 of table 600 indicate the first battery power supply mode nbssm1, which is intended or desired to use battery A (column 602) or battery B (column 604). In these examples, the input valid signals VBNP1 and VINP2 are at a level within the accomplice (VINP1 is high and VINP2 is low). Thus, if power is supplied by battery A, switches SW3 and SW4 will be on and switches SW5 and SW6 will be off. Conversely, if power is supplied by battery B, switches SW5 and SW6 will be on and switches SW3 and SW4 will be off.

  In the second normal battery power supply mode (nbssm2), the BATTCOMP signal from the comparator CMP4 is high indicating that the voltages of the batteries A and B are within an acceptable range. The battery parallel use enable (PBUE) signal is also high, indicating that all other conditions for battery parallel use (including the high VINP2 signal) monitored by the battery parallel use enable circuit 476 are satisfactory. is there. In that case, switches SW3 and SW4 coupled to battery A are on, and switches SW5 and SW6 coupled to battery B are off.

  Somewhat similar to the charging situation, but if the USE_A and USE_B signals want to be used in parallel with batteries A and B, but the PBUE signal is not enabled (eg, PBUE is low). Then, a battery having a higher voltage level than the others is selected to supply discharge power to the system. In that case, the state of the switch is as in column 602 if the voltage of battery A is high, and as in column 604 if the voltage of battery B is high.

  The PMU 320 also issues a power saving mode request to the selection circuit 314 if a DC power supply is not present and low power consumption is desired to extend battery life. If the power saving mode request is received by the selection circuit 314, the controller 315 turns off the switch SW1, turns off the switch SW2, turns off the switch SW3, turns on the switch SW4, turns off the switch SW5, SW6 is turned on. In that case, the high voltage battery A or B would supply power through the associated diode D3 or D5, respectively. In addition, the supply current of the selection circuit 314 itself is greatly reduced as compared with normal operation, and contributes to power saving of the entire device in this power saving mode.

  In addition to the selection circuit for using two or more batteries detailed above in parallel, a charging circuit is also provided. In general, the charging circuit according to the present invention reduces the time to charge the batteries in parallel by maximizing the charging current applied to each battery.

  Turning to FIG. 7, an example charging circuit 733 in accordance with the present invention is shown. The charging circuit 733 is illustrated as part of a power supply system 700 that includes various power sources such as an AC / DC adapter 732 and host batteries such as batteries A and B that can supply power to the system 731. Is done. The power supply system 700 will also include a selection circuit 734 for controlling the state of the switches SW1, SW2, SW3, SW4 and a DC-DC converter 770 controlled by the charging circuit 733. The selection circuit 734 and the charging circuit 733 can be realized as separate integrated circuits, or can be integrated in the same integrated circuit as shown in the drawing for convenience of introduction and operation. The host power management unit (PMU) 735 can also provide control signals to the charging circuit 733 and the selection circuit 734, as detailed herein.

  In the battery charging operation mode, the selection circuit 734 closes the switch SW1 and opens the switch SW2. The selection circuit closes the switch SW3 to charge the battery B, closes the switch SW4 to charge the battery A, or switches SW3 and SW4 to apply a charging current to the battery A and the battery B in parallel. Close both. That is, when each switch is open, the power path between the battery A or B associated with the charging circuit 733 is completely cut off. The selection circuit 734 makes such a determination based on the control signal USE_A signal and the USE_B signal from the PMU 735. As previously described in detail, even though the USE_A signal and the USE_B signal control signal indicate that battery A and battery B are desired to be used in parallel, the selection circuit 734 determines the voltage levels at battery A and battery B. It is checked and the parallel operation can be performed only when the voltage of the battery A is within a predetermined voltage range of the voltage of the battery B. If the battery is not within the predetermined voltage range, the selection circuit 734 first selects the low voltage battery that needs to be charged.

  Once the selection circuit 734 selects the charging mode, the charging circuit 733 takes over control of the DC-DC converter 770. The output of the DC-DC converter 770 provides the host battery with charging parameters such as, for example, system charging current and voltage levels. The host batteries include a plurality of rechargeable batteries and, in this example, batteries A and B that can be coupled in parallel. Battery A and Battery B can be in any state of 0% to 100% charge. The DC-DC converter 770 may be any type of DC-DC converter known to those skilled in the art and may be controlled by any type of control signal from the charging circuit 733. In one of many embodiments, the DC-DC converter is a buck converter having a high side switch SW5, a low side switch SW6, and an inductor 708. The control signal from the charging circuit 733 may be a pulse width modulated (PWM) signal. In this example, as is well known, the duty cycle of the PWM control signal controls the states of the switches SW5 and SW6 so that the switches are alternately turned on and off. In that case, the system charging current through the inductor 705 and the system charging output voltage of the DC-DC converter are controlled by the PWM signal.

  The charging circuit 733 generally includes a plurality of paths that provide related control signals to the regulation circuit 716. As described in further detail herein, the regulator circuit 716 then provides an output control signal to control the DC-DC converter 770 based on the control signal. For example, the adjustment circuit 716 can provide a PWM control signal that changes the duty cycle to control the state of the high-side switch SW5 and the low-side switch SW6.

  Advantageously, the charging circuit 733 has a path that receives the input signal at terminals 790 and 791 and provides a signal representing the charging current supplied to the battery A to the error amplifier 724. A voltage drop across sense resistor 708 provides an input to terminals 790 and 791. Since the sense resistance is typically very small, amplifier 718 can also be used to amplify the signal received at terminals 790 and 791 before being applied to error amplifier 724. Error amplifier 724 compares the signal representing the charging current to battery A with the maximum charging current level. In the embodiment of FIG. 7, the maximum charge current level ISET is provided directly as an analog signal from the host PMU 735.

  Similarly, the charging circuit 733 can also have a path for receiving an input signal at the terminals 790 and 793 and supplying a signal representing the charging current supplied to the battery B to the error amplifier 723. A voltage drop across sense resistor 707 provides input to terminals 790 and 793. Since sense resistor 707 is typically very small, amplifier 717 can also be used to amplify the signal received at terminals 790 and 793 before applying it to error amplifier 723. Error amplifier 723 compares the signal representing the charging current to battery B with the maximum charging current level for battery B. In the embodiment of FIG. 7, the maximum charge current level ISET for battery B is substantially close to the maximum charge current level of battery A, so both error amplifiers receive the same ISET signal from PMU 735.

  In addition to the path for monitoring the charging current applied to each battery A and B, an additional path monitors the charging voltage applied to each battery A and B. The path for monitoring the charging voltage applied to battery A includes resistors 721 and 722 that form a resistor divider that reduces the voltage at terminal 798. The reduced voltage level is then provided to error amplifier 726. The error amplifier 726 compares the signal representing the voltage of the battery A with the maximum charging voltage for the battery A. In the embodiment of FIG. 7, the maximum charging voltage VSET for battery A is provided by PMU 735. If the VSET level is exceeded by the voltage on battery A, the regulator circuit 716 can reduce the output voltage of the DC-DC converter 770. In addition, alternatively, the selection circuit 734 can open the switch SW4 and disconnect the battery A of this example.

  The path for monitoring the charging voltage applied to battery B may include resistors 719 and 720 that form a resistor divider that reduces the voltage at terminal 799. The reduced voltage level will then be provided to error amplifier 725. Error amplifier 725 compares the signal representing the voltage of battery B with the maximum charge voltage for battery B. In the embodiment of FIG. 7, since the maximum charging voltage for battery B is substantially close to the maximum charging voltage for battery A, both error amplifiers 725 and 726 receive the same VSET signal from PMU 735. If the VSET level is exceeded by the voltage on battery B, the regulator circuit 716 can reduce the output voltage of the DC-DC converter 770. In addition or alternatively, the selection circuit 734 can open the switch SW3 and disconnect the battery in this example.

  Still other control paths that monitor the current provided by the AC adapter 732 may include an amplifier 714 and an error amplifier 727. The voltage drop across sense resistor 702 provides an input to terminals 794 and 795 of charging circuit 733. Since sense resistor 702 is typically very small, amplifier 714 can also be used to amplify the signal received at terminals 794 and 795 before applying it to error amplifier 727. Error amplifier 727 compares the signal representing the current from AC adapter 732 with the maximum current level for the AC adapter or IAD_SET provided by PMU 735 in this example.

  A plurality of error amplifiers 771, such as error amplifiers 723, 724, 725, 726, 727, etc., from a plurality of paths, such that an error amplifier that first detects a condition that exceeds the associated maximum level controls regulator circuit 716. It is configured as a connection form by analog “wired OR”. For example, if error amplifier 723 first detects a charge current to battery B that exceeds the ISET level, error amplifier 723 will control regulator circuit 716. Then, for example, by reducing the duty cycle of the PWM control signal provided to the high-side switch SE5 and the low-side switch SW6, the adjustment circuit 716 will reduce the charging current provided by the DC-DC converter 770. If none of the maximum conditions monitored by error amplifiers 723, 724, 725, 726, 727 are met, capacitor 713 is charged until at least one condition is met. In that case, in the embodiment of FIG. 7, the error amplifier 723 limits the charging current to the battery B to the ISET level. Error amplifier 724 limits the charging current to battery A to the ISET level. Error amplifier 725 limits the charging voltage to battery B to the VSET level. Error amplifier 726 limits the charging current to battery A to the VSET level. Finally, error amplifier 727 limits the current level provided by the AC adapter to the IAD_SET level.

  FIG. 8 shows another embodiment of charging circuit 833 in accordance with the present invention. In general, the charging circuit 833 can recognize variously set maximum charging parameters for each battery. For example, error amplifier 823 may receive an ISET_B signal from PMU 835 that represents the maximum charge current for a particular battery B. Conversely, error amplifier 824 can receive an ISET_B signal from PMU 835 that represents the maximum charge current for a particular battery A. Similarly, error amplifiers 825 and 826 can receive separate VSET_B and VSET_A signals representing different maximum charge voltage levels for batteries B and A. Thus, a clear combination of maximum charging current value and maximum charging voltage value can be set independently for each individual battery. If the selection circuit 834 can charge the batteries A and B in parallel, the charging circuit 833 has one of the predetermined maximum charging current value or the maximum charging voltage value for any one of the batteries to be charged in parallel. Until the output charge parameter of the DC to DC converter 870 is increased.

  FIG. 9 shows another embodiment of a charging circuit 933 according to the present invention. In this embodiment, the PMU 935 provides the charging circuit 933 with a digital signal as opposed to an analog signal. The digital interface 930 receives this digital signal. The digital interface may be either a type such as an SM bus or a 12C interface. A multiplexer (MUX) and digital-to-analog converter (DAC) 929 are also provided. In the embodiment of FIG. 9, the MUX is a 5-channel MUX that provides five control signals to each error amplifier 923, 924, 925, 926 representing the maximum parameter condition. Of course, the number of MUX channels is determined in part by the total number of error amplifiers. The PMU 935 can also provide separate VSET and ISET signals to an error amplifier 923, 924, 925, 926 similar to that described in detail in FIG. Alternatively, PMU 935 can provide the same VSET signal to error amplifiers 925 and 926 and the same ISET signal to error amplifiers 923 and 924, similar to those described in detail in FIG.

  However, the embodiments described herein are only a few of the several that have utilized the present invention, are shown individually for purposes of illustration, and are not intended to be limiting. Many other embodiments that will be readily apparent to those skilled in the art may be made without substantially departing from the spirit and scope of the invention as defined in the appended claims.

FIG. 6 is a high level simplified block diagram of an electronic device with a power supply block having a selection circuit in accordance with the present invention that selects in response to an output signal from a power management unit (PMU). FIG. 2 is a more detailed block diagram of the power supply block portion of FIG. 1 having a selection circuit according to the present invention for selecting between a DC power supply and a plurality of batteries. Selection in accordance with the present invention with a controller configured to supply a signal for selection between a DC power source and a plurality of batteries via an associated switching drive network and an associated switching device 1 is a block diagram of one embodiment of a circuit. FIG. 4 is a more detailed block diagram of the selection circuit of FIG. 3, illustrating various parts of the control portion in more detail. 6 is an example of a table showing how a selection circuit drives various switches to an on state and an off state by various input signals when the electronic device is powered by a DC power source. 6 is an example of a table showing how a selection circuit drives various switches to an on state and an off state by various input signals when an electronic device is powered on by various battery combinations. FIG. 2 is a circuit diagram of an example of a charging circuit according to the present invention for using similar batteries with similar maximum charging parameters. FIG. 6 is a circuit diagram of another example of a charging circuit according to the present invention, each battery having a different maximum charging parameter. FIG. 6 is a circuit diagram of another example of a charging circuit that receives a digital signal from an associated power management unit and is in accordance with the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 100 ... Electronic device 104 ... DC power supply 105 ... Battery 106 ... Power supply block 110 ... System 204 ... AC / DC converter 210 ... Host system 214, 314, 734, 834, 934 ... Selector 220 ... Power supply management unit 222, 322 ... Charging 226, 326 ... Charger controlled DC-DC converter 320, 735, 835 ... PMU
315: Controller 470: Selector output circuit 472 ... Charge enable circuit 474 ... Power supply crisis circuit 476 ... Battery parallel use enable circuit 716 ... Adjustment circuit 732, 832 ... AC adapter 733, 833, 933 ... Charge circuit 930 ... Digital interface 935 ... Host PMU

Claims (17)

In a charging circuit for controlling system charging parameters given to a host battery, the host battery includes at least a first battery and a second battery that can be coupled in parallel,
The charging circuit is
A first path configured to monitor a first battery charging current level applied to the first battery;
A second path configured to monitor a second battery charging current level applied to the second battery;
When the first charging current exceeds a predetermined first maximum charging current level or the second charging current exceeds a predetermined second maximum charging current level, the system charging parameter provided to the host battery is A charging circuit comprising: an adjustment circuit configured to be small.   The charging circuit according to claim 1, wherein the predetermined first maximum charging current level is substantially equal to the predetermined second maximum charging current level. A third path configured to monitor a first battery charge voltage level applied to the first battery;
A fourth path configured to monitor a second battery charge voltage level applied to the second battery;
When the first charging voltage level exceeds a predetermined first maximum charging voltage level or the second charging voltage level exceeds a predetermined second maximum charging voltage level, the adjustment circuit causes the host battery to The charging circuit of claim 1, wherein the charging circuit is configured to reduce the given system charging parameter.   4. The charging circuit according to claim 3, wherein the predetermined first maximum charging voltage level is substantially equal to the predetermined second maximum charging voltage level.   The first path receives a first monitoring signal representing the first battery charging current level and a first comparison signal representing the predetermined first maximum charging current level, and the first path and the first monitoring signal A first error amplifier configured to provide a first control signal to the adjustment circuit based on a difference from the first comparison signal, wherein the second path represents a second battery charge current level; Receiving a monitoring signal and a second comparison signal representing the predetermined second maximum charging current level, and adjusting the second control signal based on a difference between the second monitoring signal and the second comparison signal; The charging circuit of claim 1, further comprising a second error amplifier configured to feed the circuit. In a method for controlling system charging parameters provided to a host battery, the host battery comprises at least a first battery and a second battery that can be coupled in parallel, the method comprising:
Monitoring a first battery charge current level applied to the first battery;
Monitoring a second battery charge current level applied to the second battery;
The system charging parameter applied to the host battery when the first charging current level exceeds a predetermined first maximum charging current level or the second charging current level exceeds a predetermined second maximum charging current level. The method comprising the steps of:   The method of claim 6, wherein the predetermined first maximum charging current level is substantially equal to the predetermined second maximum charging current level. Monitoring a first battery charge voltage level applied to the first battery;
Monitoring a second battery charge voltage level applied to the second battery;
When the first charging voltage level exceeds a predetermined first maximum charging voltage level or the charging voltage level exceeds a predetermined second maximum charging voltage level, the system charging parameter given to the host battery is decreased. The method of claim 6, further comprising:   87. The method of claim 86, wherein the predetermined first maximum charge voltage level is substantially equal to the predetermined second maximum charge voltage level. In a charging circuit for adjusting an output parameter of a DC-DC converter, the output parameter of the DC-DC converter supplies power to a host battery, and the host battery can be coupled in parallel. The battery pack includes at least a first battery and a second battery, and the charging circuit includes:
A first path configured to monitor a first battery charging current level applied to the first battery;
A second path configured to monitor a second battery charging current level applied to the second battery;
A third path configured to monitor a first battery charge voltage level applied to the first battery;
A fourth path configured to monitor a second battery charge voltage level applied to the second battery;
One of the first battery charge current level, the second battery charge current level, the first battery charge voltage level, and the second battery charge voltage level is coupled in parallel with the first battery and the second battery. And a regulating circuit configured to reduce the output parameter of the DC-DC converter when an associated predetermined maximum level is exceeded. A power management unit configured to provide an output signal representative of at least a predetermined first maximum charging current level and a predetermined second maximum charging current level;
A host battery including at least a first battery and a second battery coupled in parallel;
An electronic device comprising: a charging circuit for controlling a system charging parameter applied to the battery of the host;
A first path configured to monitor a first battery charging current level applied to the first battery and compare the first battery charging current level with the predetermined first maximum charging current level;
A second path configured to monitor a second battery charge current level applied to the second battery and compare the second battery charge current level with the predetermined second maximum charge current level;
If the first charging current exceeds the predetermined first maximum charging current level or the second charging current exceeds the predetermined second maximum charging current level, the system charge provided to the host battery And an adjustment circuit configured to reduce a parameter.   The electronic device according to claim 11, wherein the output signal from the power management unit comprises an analog signal.   12. The electronic device according to claim 11, wherein the output signal from the power management unit comprises a digital signal. The charging circuit further includes:
A digital interface configured to receive the digital signal from the power management unit and provide an interface output signal;
14. The electronic device of claim 13, comprising: a DAC configured to receive the interface output signal and convert the signal to an analog signal representative of the interface output signal.   The charging circuit further includes a multiplexer for dividing the analog signal into a plurality of analog signals representing at least the predetermined first maximum charging current level and the predetermined second maximum charging current level. The electronic device according to claim 14. In an electronic device that can be powered by a rechargeable battery or a DC power source of one or more hosts, the electronic device comprises:
A power management unit (PMU) configured to execute a power management routine;
A charging circuit configured to control charging of the rechargeable battery of the host;
Responsive to a PMU output signal from the PMU, the DC power supply and a selection circuit configured to select at least one of the host batteries, wherein the host batteries are coupled in parallel The charging circuit includes at least a first battery and a second battery, and the charging circuit monitors a first battery charging current level applied to the first battery, and the first battery charging current level and the predetermined first maximum charging current A first path configured to compare levels, and a second battery charge current level applied to the second battery, to monitor the second battery charge current level and the predetermined second maximum charge current level. A second path configured to compare, and if the first charging current exceeds the predetermined first maximum charging current level or the second charging current exceeds the predetermined second maximum charging current level When And an adjustment circuit configured to reduce the system charging parameter given to the battery of the host. 17. The electronic apparatus according to claim 16, wherein the charging circuit and the selection circuit are integrated on one integrated circuit.

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