JP2009183020A - Power supply circuit device of mobile apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a power supply circuit device which can efficiently use a discharging capacity of each battery, in a mobile apparatus mounted with a plurality of the batteries. <P>SOLUTION: The power supply circuit device comprises: the plurality of built-in batteries 1, 2 which are unexchangeable by a user, or the plurality of exchangeable batteries 1, 2 which are exchangeable by the user; MOSFETs 16 to 19 which are arranged at the battery side and a circuit side one by one so that an anode of an internal parasitic diode faces an output of each battery; and on/off-control terminals 11 to 14 of the MOSFETs 16 to 19. By controlling the MOSFETs 16 to 19 so as to prevent a backflow current between the batteries using the internal parasitic diodes, there can be provided the mobile apparatus which can efficiently use residual capacities of the batteries. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a power supply circuit device of a mobile device such as a mobile phone, a video camera, and a life assistance device.

In the conventional mobile devices, in recent years, the display panel occupies a larger size, and the CPU speed and functions are increasing, and the power consumption tends to increase. As measures against this, low voltage drive of the component IC chip, energy saving drive by subdividing the product operation mode and the minimum necessary circuit operation corresponding to it, and adoption of a large capacity battery, even a little time that can be used by one charge Product design is progressing so that it can be long. Here, as shown in FIG. 6, for example, a configuration in which the battery capacity is increased by mounting two batteries 1 and 2 is considered. For example, accurate information on a plurality of batteries is mainly obtained using a portable personal computer as an example. Provided are a battery control device and an information processing device that can provide a safe usage environment when being driven by a battery while being managed. (See Patent Document 1)
Japanese Patent Laid-Open No. 10-187299

  The problem of the conventional battery capacity will be described with reference to FIG. FIG. 6 shows a configuration in which, for example, two batteries 1 and 2 are mounted as a plurality of batteries, and power is supplied to the load circuit 46 via the battery switching circuit 43 and the rectifier diodes 44 and 45. In the conventional configuration, the rectifier diodes 44 and 45 are inserted so that the current does not flow backward between the batteries 1 and 2 due to the voltage difference between the batteries 1 and 2, but when a forward current flows through the rectifier diodes 44 and 45, Since a voltage drop of at least about 0.6V occurs as the forward voltage, it is necessary to set the operating voltage limit for the system, that is, to set the undercut voltage higher by the forward voltage, and as a result, the battery utilization rate is increased. The problem that it cannot be raised occurs. Here, for example, if a battery charged to 4.2V can be used up to 3.0V, 4.2-3.0 = 1.2V is defined as a 100% usage rate. In the conventional configuration, since the diode drops the voltage by 0.6V, it can be used only up to 3.0 + 0.6 = 3.6V, and the utilization rate is 0.6 / 1.2 × 100 = 50%. Had problems. Therefore, an object of the present invention is to increase the utilization rate.

  In order to achieve this object, the power supply circuit device of the mobile device according to the present invention has a battery side and a load circuit one by one so that the anode of the internal parasitic diode faces the battery plus terminal output of each of the plurality of batteries. And a Pch MOSFET arranged on the side, and an ON / OFF control terminal of these Pch MOSFETs.

  According to the power supply circuit device for a mobile device of the present invention, only one selected battery is connected to the load circuit when discharging with each battery, and since there is no rectifier diode when discharging, there is no order. No directional voltage is generated, and each battery can be discharged at a high utilization rate. As a result, the battery driving time can be extended.

  Embodiments of a power supply circuit device for a mobile device according to the present invention will be described below in detail with reference to the drawings.

(Embodiment 1)
FIG. 1 shows a circuit diagram of a battery unit when two batteries are mounted in a power supply circuit device for a mobile device according to Embodiment 1 of the present invention. The power supply circuit device is controlled by signals input from the microcomputer output port through the control terminals 11 to 14, and supplies power from the power supply output terminal 15.

  In FIG. 1, a power supply circuit of a battery 1 that is a power supply source includes a PchMOSFET 3 in which the positive terminal side of the battery 1 is connected to a source (S), a drain (D) of the PchMOSFET 3, and a drain (D) of the load circuit side PchMOSFET. Are connected to the source (S) so that the load circuit side is connected to the source (S), the switch circuit 7 for turning on and off the PchMOSFET 3 by connecting the output terminal of the switch circuit 7 to the gate of the PchMOSFET 3, and the output terminal of the switch circuit 8 Is connected to the gate of the PchMOSFET 4 to turn on and off the PchMOSFET 4, a control terminal 11 for controlling and inputting the switch circuit 7 from the microcomputer port, and a control terminal 12 for controlling and inputting the switch circuit 8 from the microcomputer port A power output terminal 15 for outputting a battery voltage to the load circuit, the internal parasitic diode 16, 17 of the two PchMOSFET3,4, composed of large-capacity capacitor 20.

  The power supply circuit of the battery 2 as a power supply source connects the PchMOSFET 5 having the positive terminal side of the battery 2 connected to the source (S), the drain (D) of the PchMOSFET 5 and the drain (D) of the load circuit side PchMOSFET. Thus, the PchMOSFET 6 having the load circuit side connected to the source (S), the switch circuit 9 for turning on / off the PchMOSFET 5 by connecting the output terminal of the switch circuit 9 to the gate of the PchMOSFET 5, and the output terminal of the switch circuit 10 being the gate of the PchMOSFET 6 A switch circuit 10 for turning on and off the PchMOSFET 6 by being connected to a control terminal 13, a control terminal 13 for controlling and inputting the switch circuit 9 from the microcomputer port, a control terminal 14 for controlling and inputting the switch circuit 10 from the microcomputer port, a battery A power output terminal 15 for outputting a voltage to the load circuit, the internal parasitic diode 18, 19 of the two PchMOSFET5,6, composed of large-capacity capacitor 20.

  Here, the switch circuits 7 to 10 have the same configuration, and the configuration will be described taking the switch circuit 7 as an example. One transistor 78 and three resistors 75 to 77 are included, and the control terminal 11 is an input terminal of the switch circuit. The input terminal is connected to the base of the transistor 78 through the resistor 75, and the base of the 78 is further connected to GND through the resistor 76. The emitter of the transistor 78 is connected to GND, the collector is the output terminal of the switch circuit, and is connected to the + terminal of the battery 1 through the resistor 77.

  The switch circuits 7 to 10 control the on / off of the Pch MOSFETs 3 to 6 by the control voltage applied to the control terminals 11 to 14 from the microcomputer output port, but the control terminals 11 to 14 are at the Hi level, respectively. A voltage for turning on the transistor (generated by a voltage dividing resistor connected to the base (b)) is applied to the base (b) of the NPN transistor, and the emitter (e) and the collector (c) are brought into conduction so that the collector (C) When the potential is lowered to the low level and the gates (G) of the Pch MOSFETs 3 to 6 connected to the collector (c) are also lowered to the low level, the Pch MOSFETs can be turned on. When the control terminals 11 to 14 are at a low level, the NPN transistors of the switch circuits 7 to 10 are in an off state, the emitter (e) and the collector (c) are insulative, and a pull-up resistor connected to the collector (c) As a result, the gate (G) voltages of the Pch MOSFETs 3 to 6 become Hi level, so that the Pch MOSFETs 3 to 6 can be turned off.

  When the battery 1 being discharged is about to end discharge (that is, the battery whose discharging voltage is close to the minimum value of the discharge voltage specified by the battery manufacturer is defined as the battery just before the end of discharge, for example, In the case of a 1-cell lithium ion battery, when the battery terminal voltage reaches approximately 3.0 V), the microcomputer port controls the control terminals 11 to 14 in any sequence in order to switch the discharge to the undischarged battery 2. This will be described with reference to FIG.

  FIG. 2 is a timing chart showing changes in the control voltage of the control terminals 11 to 14 in FIG. 1 and the temporal voltage state of the power output terminal 15 in the power supply circuit device of the mobile device according to the first embodiment of the present invention. It is.

In FIG. 2, during the discharge period 21 in the battery 1 being discharged, the discharge continues while the control terminals 11 and 12 are set to the Hi level, the control terminals 13 and 14 are set to the Low level, and the PchMOSFETs 3 and 4 are turned on. When sufficient time has elapsed and the discharge of the battery 1 has progressed, the discharge period 22 of the battery 1 immediately before the end of discharge is started, and it is necessary to switch to the discharge of the undischarged battery 2. Here, the greatest feature of the present embodiment is that the internal parasitic diodes 17 and 19 are used without using a rectifier diode, thereby preventing a reverse current between batteries during battery switching, and a control method thereof will be described.

First, in the discharge period 23 of the battery 1 using the internal parasitic diode 17, the control terminal 11 is set to Hi level, the control terminals 12, 13, and 14 are set to Low level, and the discharge in the battery 1 is performed with the PchMOSFET 3 turned on. to continue. However, during this discharge period 23, a forward voltage of the internal parasitic diode 17 is generated, so that a voltage drop 30 of the power output terminal 15 occurs during the discharge period 23. This voltage drop 30 occurs when the control terminal 12 is set to the Low level, but by providing the large-capacitance capacitor 20 or the like at the power output terminal 15 portion, the voltage drop 30 can be set to the voltage 31 when the voltage drop is prevented. In other words, the power for the voltage drop is supplemented by the large-capacity capacitor, but if the time for generating the voltage drop 30 is not shortened as much as possible, the power that can be compensated by the large-capacitance capacitor 20 is limited. It goes down toward the voltage. Therefore, it is necessary to prevent the voltage drop 30 by setting the control terminal 13 to the Hi level immediately after setting the control terminal 12 to the Low level.

  Thus, the discharge of the battery 2 that has started discharging can be shifted to the discharge period 24 performed in parallel with the battery 1 as quickly as possible. However, the state of the discharge period 24 does not use the rectifier diode that is the greatest feature of this embodiment. By using the internal parasitic diodes 17 and 19, a reverse current between the batteries during battery switching is prevented. The role of power supply to the power supply circuit of the battery 1 in the discharge period 24 has already disappeared, and the battery 1 can be electrically disconnected from the power supply circuit by setting the control terminal 11 to the low level.

  As a result, the discharge period 25 is started. However, since the voltage of the battery 2 is supplied to the power output terminal 15 via the internal parasitic diode 19, a voltage drop corresponding to the forward voltage of the internal parasitic diode 19 occurs. Has occurred. For example, if the voltage of the battery 2 having a sufficient remaining capacity is 4.2 V and the forward voltage of the internal parasitic diode 19 is 0.6 V, 4.2−0.6 = 3.6 V is the supply voltage to the power output terminal 15. It turns out that. Also in this state, as in the discharge period 24, the forward voltage of the internal parasitic diode is wasted. Therefore, the control terminal 14 can be shifted to the discharge period 26 by setting it to the Hi level.

  A series of battery switching sequences in the case of two batteries are completed as described above, and when a sufficient time has elapsed and discharging of the battery 2 proceeds, a transition is made to a discharging period 27 in the battery 2 just before the end of discharging. In the discharge period 27, since there is no remaining capacity in both the battery 1 and the battery 2, the set is turned off by performing an undercut process.

  The internal parasitic diode 16 acts so that the battery 1 when the control terminal 11 is set to the low level is completely disconnected from the load circuit so that the voltage of the battery 1 is not output to the load circuit. The battery 2 when the terminal 13 is set to the Low level is completely disconnected from the load circuit so that the voltage of the battery 2 is not output to the load circuit.

  As described above, the forward voltage of the diode is not generated by turning on the Pch MOSFETs 3 and 4 or 5 and 6 between the discharging battery 1 or 2 and the power supply output terminal as in the discharging period 21 and the discharging period 26. Thus, the battery voltage can be supplied without loss.

  Further, the difference will be described with reference to a conventional circuit configuration diagram and a schematic diagram of an embodiment of the present invention.

  A conventional circuit configuration is shown in FIG. The battery 1, the battery 2, the battery switching circuit 43, the rectifier diodes 44, 45, and the load circuit 46, and when the battery switching circuit 43 switches between the battery 1 and the battery 2, the current flow between the batteries is reversed. In order to prevent this, the rectifier diodes 44 and 45 are inserted. Even after the battery is switched, the rectifier diodes 44 and 45 generate a voltage drop of about 0.6 V. Therefore, the voltage applied to the load circuit 46 is applied to the battery 1 or the battery. It is clear that the input voltage is 0.6V lower than the voltage of 2, and the battery voltage cannot be efficiently input to the load circuit.

  FIG. 3 is a circuit diagram showing a schematic configuration of a power supply circuit device for a mobile device according to the first embodiment of the present invention. The battery 1, the battery 2, the battery switching circuit 53, the rectifier diodes 54 and 55, the MOSFET switch operations 56 and 57, and the load circuit 46, and the battery switching circuit 53 switches between the battery 1 and the battery 2. The internal parasitic diodes 54 and 55 are used to prevent the reverse current flow between the batteries at the time, and after the battery is switched, the switch operation 56 or 57 by the MOSFET is turned on, whereby the internal parasitic diodes 54 and 55 are turned on. Therefore, the voltage drop of about 0.6 V is not generated, and the voltage of the battery 1 or the battery 2 is directly applied to the load circuit 46, and the battery voltage can be efficiently input to the load circuit 46.

  That is, in the present embodiment, the internal parasitic diodes 17 and 19 instead of the rectifier diodes 44 and 45 having the conventional circuit configuration act to prevent the backflow of current between the batteries only at the time of switching the battery. The voltage drop is not generated by turning on. By repeating these configurations and the battery switching sequence, it is possible to switch the battery while efficiently supplying the battery voltage to the load circuit even when three or more batteries are mounted. As described above, the merit obtained by designing a battery that can mount a plurality of batteries is that a small-capacity battery can be used even in a device that cannot adopt a large-capacity single-solid battery due to mechanical constraints and design constraints. By adopting more than one, it is possible to extend the battery driving time while balancing the weight of the equipment. In addition, by enabling the installation of inexpensive small general-purpose batteries that are already on the market for small mobile devices, it is expected to reduce design and mass production costs and shorten evaluation time by adopting actual batteries rather than designing new batteries. Therefore, it can be expected to greatly reduce the product price.

  Further, since the same effect can be obtained by a combination of a switch element circuit and an external rectifier diode instead of the MOSFET, this will be described in the second embodiment.

(Embodiment 2)
FIG. 4 shows a circuit diagram of the battery unit when two batteries are mounted in the power supply circuit device for a mobile device according to the second embodiment of the present invention.

  In FIG. 4, the power supply circuit of the battery 1 that is a power supply source includes a diode 65 in which the positive terminal side of the battery 1 is connected to the cathode, a load that connects the anode of the diode 65 and the anode of the load circuit side diode. A diode 66 whose circuit side is connected to the cathode, a switch 61 connected in parallel to the diode 65, a switch 62 connected in parallel to the diode 66, a control terminal 71 for controlling and inputting the switch 61 from the microcomputer port, and a switch 62 includes a control terminal 72 for controlling and inputting 62 from the microcomputer port, a power output terminal 15 for outputting a battery voltage to the load circuit, and a large-capacitance capacitor 20.

  The power supply circuit of the battery 2, which is a power supply source, has a diode 67 with the positive terminal side of the battery 2 connected to the cathode, and a cathode on the load circuit side so as to connect the anode of the diode 67 and the anode of the load circuit side diode. The diode 68 connected to the diode 67, the switch 63 connected in parallel to the diode 67, the switch 74 connected in parallel to the diode 68, the control terminal 73 for controlling and inputting the switch 63 from the microcomputer port, and the switch 64 to the microcomputer port The control terminal 74 is configured to control input from the power source, the power output terminal 15 outputs the battery voltage to the load circuit, and the large capacity capacitor 20.

  FIG. 5 is used to explain in what sequence the microcomputer port controls the control terminals 71 to 74 in order to switch the discharge to the undischarged battery 2 when the remaining amount of the battery 1 is being discharged. To do.

  FIG. 5 is a timing chart showing the control voltage of the control terminals 71 to 74 in FIG. 4 and the temporal voltage change of the power output terminal 15 in the power supply circuit device of the mobile device according to the second embodiment of the present invention. .

  In FIG. 5, in the discharging period 21 in the battery 1 being discharged, the control terminals 71 and 72 are set to the high level, the control terminals 73 and 74 are set to the low level, and the switch element circuits 61 and 62 are turned on. to continue. When sufficient time has elapsed and the discharge of the battery 1 has progressed, the discharge period 22 of the battery 1 immediately before the end of discharge is started, and it is necessary to switch to the discharge of the undischarged battery 2. Here, the feature of the second embodiment is that the rectifier diodes 66 and 68 are used to prevent the backflow current between the batteries at the time of battery switching, and the control method will be described.

  First, in the discharge period 23 in the battery 1 using the rectifier diode 66, the control terminal 71 is set to the Hi level, the control terminals 72, 73, and 74 are set to the Low level, and the switch element circuit 61 is turned on. Continue discharging. However, since the forward voltage of the rectifier diode 66 is generated during the discharge period 23, the voltage drop 30 of the power output terminal 15 occurs during the discharge period 23. This voltage drop 30 occurs when the control terminal 72 is set to the Low level, but the voltage drop 30 can be made the voltage 31 when the voltage drop is prevented by providing the large-capacitance capacitor 20 or the like at the portion of the power output terminal 15. That is, the power for the voltage drop is supplemented from the large-capacitance capacitor 20, but if the time for generating the voltage drop 30 is not made as short as possible, the power that can be compensated by the large-capacitance capacitor 20 is limited. It goes down toward the voltage. Therefore, it is necessary to prevent the voltage drop 30 by setting the control terminal 73 to the Hi level immediately after setting the control terminal 72 to the Low level.

  Thus, the discharge of the battery 2 can be shifted to the discharge period 24 performed in parallel with the battery 1 as quickly as possible. Here, the state of the discharge period 24 uses the rectifier diodes 66 and 68 that are the features of the second embodiment, so that the battery It becomes the state which prevents the backflow current between batteries at the time of switching. The role of power supply to the power supply circuit of the battery 1 during the discharge period 24 has already disappeared, and the battery 1 can be electrically disconnected from the power supply circuit by setting the control terminal 71 to the low level.

  As a result, the discharge period 25 is started. However, since the voltage of the battery 2 is supplied to the power output terminal 15 via the rectifier diode 68, a voltage drop corresponding to the forward voltage of the rectifier diode 68 occurs. is doing. For example, if the voltage of the battery 2 having a sufficient remaining capacity is 4.2 V and the forward voltage of the rectifier diode 68 is 0.6 V, 4.2−0.6 = 3.6 V is the supply voltage to the power output terminal 15. It will be. Also in this state, as in the discharge period 24, the forward voltage of the rectifier diode is wasted. Therefore, the control terminal 74 can be shifted to the discharge period 26 by setting it to the Hi level.

  A series of battery switching sequences in the case of two batteries are completed as described above, and when a sufficient time has elapsed and discharging of the battery 2 proceeds, a transition is made to a discharging period 27 in the battery 2 just before the end of discharging. In the discharge period 27, since there is no remaining capacity in both the battery 1 and the battery 2, the set is turned off by performing an undercut process.

  The rectifier diode 65 acts so that the battery 1 when the control terminal 71 is set to the low level is completely disconnected from the load circuit so that the voltage of the battery 1 is not output to the load circuit. When the battery is set to the low level, the battery 2 is completely disconnected from the load circuit so that the voltage of the battery 2 is not output to the load circuit.

  As described above, by turning on the switch element circuits 61 and 62 or 63 and 64 between the battery 1 or 2 being discharged and the power supply output terminal as in the discharge period 21 and the discharge period 26, the forward voltage of the diode is set. By not generating it, the voltage of the battery can be supplied without loss.

  In the power supply circuit device for a mobile device according to the present invention, when discharging with each battery, only one battery is connected to the load circuit, and when discharging, a forward voltage is generated because there is no rectifier diode. Without using it, the entire battery capacity can be used and the battery driving time can be extended. Furthermore, even in a device that cannot employ a large-capacity single solid battery due to mechanical constraints, design constraints, etc., it is possible to extend the battery driving time while balancing the weight of the device by adopting a plurality of batteries. Finally, when a battery that can keep the mass production cost low is adopted, there is no need to design a new battery, and it can be expected to greatly reduce costs, and special mobile devices that emphasize weight distribution and design are mainly used. This is useful for applications such as power supply circuit devices.

1 is a circuit diagram of a power supply circuit device for a mobile device according to Embodiment 1 of the present invention. Timing chart showing the control voltage of the control terminal and the temporal voltage change of the power output terminal in the same device 1 is a circuit diagram showing a schematic configuration of a power supply circuit device for a mobile device according to a first embodiment of the present invention. Circuit diagram of power supply circuit device for mobile device in Embodiment 2 of the present invention Timing chart showing control voltage of control terminal and temporal voltage change of power supply output terminal in apparatus of embodiment 2 The circuit diagram which shows schematic structure of the power supply circuit device of the conventional mobile device

Explanation of symbols

1, 2, Battery 3, 4, 5, 6 PchMOSFET
7 Switch circuit for turning on / off PchMOSFET 3 8 Switch circuit for turning on / off PchMOSFET 4 9 Switch circuit for turning on / off PchMOSFET 5 10 Switch circuit for turning on / off PchMOSFET 6 11 Control terminal for controlling and inputting switch circuit 7 from microcomputer port 12 Controlling switch circuit 8 from microcomputer port Input control terminal 13 Control terminal for controlling and inputting switch circuit 9 from microcomputer port 14 Control terminal for controlling and inputting switch circuit 10 from microcomputer port 15 Power supply output terminal 15 for outputting battery voltage to power supply circuit
16 Internal parasitic diode of PchMOSFET 3 17 Internal parasitic diode of PchMOSFET 4 18 Internal parasitic diode of PchMOSFET 5 19 Internal parasitic diode of PchMOSFET 6 20 Large-capacitance capacitor 21 Discharge period of battery 1 with sufficient remaining capacity 22 Discharge of battery 1 with little remaining capacity Period 23 Discharge period in battery 1 using internal parasitic diode 17 24 Discharge period in battery 1 and battery 2 using internal parasitic diodes 17 and 19 25 Discharge period in battery 2 using internal parasitic diode 19 26 Remaining Discharge period in battery 2 with sufficient capacity 27 Discharge period in battery 2 with little remaining capacity 30 Voltage drop voltage in discharge period 23 31 Voltage when voltage drop is prevented 43 Battery cut Circuit 44, 45 rectifier diode 46 load circuit 53 battery switching circuit 54, 55 internal parasitic diode 56, 57 switch operation by MOSFET 61, 62, 63, 64 switch element circuit 65, 66, 67, 68 rectifier diode 71 switch 61 Control terminal 72 for control input from the microcomputer port 72 Control terminal for control input of the switch 62 from the microcomputer port 73 Control terminal for control input of the switch 63 from the microcomputer port 74 Control terminal 75, 76, 77 for control input of the switch 64 from the microcomputer port 78 transistors

Claims (6)

A plurality of batteries, one PchMOSFET arranged on the battery side and one on the load circuit side so that the anodes of the internal parasitic diodes face the battery plus terminal output of each of the plurality of batteries, and the PchMOSFETs A power supply circuit device for a mobile device having an on / off control terminal. When the discharge switching from the discharging battery to one of the undischarged batteries among the plurality of batteries is performed, the ON / OFF control terminal of the PchMOSFET of each battery is controlled to supply power in parallel to the load circuit. Item 2. A power supply circuit device for a mobile device according to Item 1. When one of the discharging battery just before the end of discharging and the undischarged battery that has started discharging supply power in parallel to the circuit, a reverse current between the batteries is prevented by the action of an internal parasitic diode. The power supply circuit device for a mobile device according to claim 2. 4. The power supply circuit device for a mobile device according to claim 3, wherein the on-off control terminal of the discharging PchMOSFET just before the end of discharging is controlled to disconnect the discharging battery just before the end of discharging from the circuit. 5. Controlling the on / off control terminal of the PchMOSFET from a state in which one of the undischarged batteries that have started discharging supplies power to the circuit, and controlling the on / off control terminal of the PchMOSFET to eliminate the voltage drop due to the internal parasitic diode The power supply circuit device for a mobile device according to claim 4. A power supply circuit device for a mobile device in which a plurality of batteries are connected in parallel to a power supply output terminal, and a switching circuit is interposed between each of the batteries and the power supply output terminal. The first rectifier diode having the cathode as the cathode and the second rectifier diode having the output terminal as the cathode are connected in series with the anode facing each other, and a switch is connected in parallel to each diode. , Power circuit device for mobile devices.

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