JP2009086724A - Electronic device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electronic device for achieving a stable operation while securing current supply quantity. <P>SOLUTION: A capacitor 25, a current limit circuit 19, and a current limit circuit 20 are connected to the power stage of a power amplifier 24. The current limit circuit 19 limits output currents to 100mA, and the current limit circuit 20 limits output currents to 150mA. The switch changeover of LDO13, HSSW14, SW15 and SW16 is performed according to power supply configurations from a USB power source input circuit 11 and an AC adaptor power source input circuit 12, and the supply current quantity to the power amplifier 24 and the capacitor 25 is controlled. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an electronic device that can instantaneously consume a large amount of power while having a small amount of power supply.

  Conventionally, portable USB devices that are driven by bus power are known. However, USB bus power can only supply a current of 100 mA (at most about 500 mA), and a USB device that consumes a large current is generally connected to an AC adapter.

Thus, for example, Japanese Patent Application Laid-Open No. H10-228561 discloses a device that is supplied with power from two USB cables using a conversion cable between a DC connector and a USB connector.
JP-A-2005-141732

  However, the power supply method disclosed in Patent Document 1 is not used within the USB standard and does not guarantee stable operation. Further, in a device such as a power amplifier that requires a current of about several A instantaneously, the supply amount is still insufficient.

  Therefore, an object of the present invention is to provide an electronic device that realizes a stable operation while securing a current supply amount.

  An electronic apparatus according to the present invention includes a plurality of power input units that are supplied with different amounts of current, and a plurality of current limiting circuits that output the currents input from the plurality of power input units with different output values. A main drive circuit connected to a subsequent stage of the plurality of current limit circuits, a storage circuit connected between the plurality of current limit circuits and the main drive circuit, and each of the plurality of power input units And a control unit that switches a connection mode between the plurality of power supply input units and the current limiting circuit based on a current supply mode.

  In this configuration, a plurality of power input units that receive supply of different current amounts are provided. The current input from these power supply input units is limited by a current limiting circuit and output to a main drive circuit (for example, a power amplifier). The limit value of the current limiting circuit varies depending on the amount of current received from the power input unit. A power storage circuit (capacitor) is connected between the current limiting circuit and the main drive circuit to store electric power. When the main drive circuit consumes more power than the output current value of the current limiting circuit, current is supplied from the storage circuit. Here, the connection mode between the power input unit and the current limiting circuit is switched based on the current supply mode from the power input unit. For example, when a large current is supplied, the power input unit is connected to a current limiting circuit having a large output value, and a large current is supplied to the main drive circuit and the storage circuit. On the other hand, when a small current is supplied, the power input unit is connected to a current limiting circuit having a small output value, and a small current is supplied to the main drive circuit and the storage circuit. This realizes stable driving.

  In the present invention, the plurality of power input units further include a bus power power input unit that receives power from a host device, and a self-power power input unit that receives power from an AC adapter, When receiving a current supply from the bus power power input unit, the control unit connects the bus power power input unit to a current limiting circuit having a small current output value among the plurality of current limiting circuits, and When receiving a current supply from the power supply input unit for self power, the power supply input unit for self power is connected to a current limit circuit having a large current output value among the plurality of current limit circuits.

  In this configuration, the bus power from the host device and the self power by the AC adapter are switched and driven. In the case of bus power drive, a bus power supply input unit is connected to a current limiting circuit having a small output value, and a small current is supplied to the main drive circuit and the storage circuit. In the case of self-power driving, a power input unit for self-power is connected to a current limiting circuit having a large output value, and a large current is supplied to the main driving circuit and the storage circuit. Note that when a current is supplied from both the host device and the AC adapter, a larger current can be supplied.

  Further, according to the present invention, the power input unit for bus power includes a USB interface, and the control unit includes a current limiting circuit having an output value of the small current when negotiation with the host device is established. The bus power supply input unit is connected.

  In this configuration, the host device is connected via the USB interface, and bus power driving is performed when negotiation is established. If negotiation is not possible, the power may be turned off.

  Furthermore, the present invention is further characterized in that the power storage circuit is an electric double layer capacitor.

  According to the present invention, a stable operation can be realized while securing a current supply amount.

  Hereinafter, the electronic apparatus according to the present embodiment will be described. The electronic device of this embodiment is a portable speaker device that is driven by bus power by USB connection, self-power by AC adapter connection, or both bus power and self-power.

  FIG. 1 is a block diagram showing a power circuit configuration of the speaker device according to the present embodiment. As shown in the figure, the speaker device 1 includes a USB power input circuit 11, an AC adapter power input circuit 12, a regulator (LDO) 13, a switch (HSSW) 14, a switch (SW) 15, a switch (SW) 16, a DC A DC converter (DC-DC) 17, a regulator (LDO) 18, a current limiting circuit 19, a current limiting circuit 20, a CPU 21, a digital circuit 22, an analog circuit 23, a power amplifier 24, and a capacitor 25 are provided.

  The CPU 21 is a control unit that comprehensively controls the speaker device 1. The digital circuit 22 and the analog circuit 23 are circuits that perform various audio processes. The audio signal processed by the digital circuit 22 and the analog circuit 23 is amplified by the power amplifier 24 and emitted to the outside.

  The USB power input circuit 11 is an interface that receives power supply from an information processing apparatus (host) such as a PC, and receives power supply of 100 mA or 500 mA. The speaker device 1 performs bus power driving by supplying current input from the USB power input circuit 11 to the CPU 21, the digital circuit 22, and the analog circuit 23. When a USB device is connected to a host, it first receives a power supply of 100 mA, and if a subsequent negotiation is established, it can receive a power supply of 500 mA.

  The AC adapter power input circuit 12 is an interface that receives power supply from the AC adapter, and receives power supply of about 700 mA, for example. The speaker device 1 performs self-power drive by supplying current input from the AC adapter power input circuit 12 to the CPU 21, digital circuit 22, and analog circuit 23.

  The LDO 13 is turned on / off in conjunction with the power supply input, and is turned on when power is supplied from the USB power supply input circuit 11 to stabilize the output voltage to 3.3V. When power is supplied from the AC adapter power input circuit 12, the power is turned off.

  The HSSW 14 is a switch circuit controlled by the CPU 21 and is turned on when bus power driving is performed, and turned off in other cases.

  The SW 15 is a switch circuit controlled by the CPU 21 and is turned on when performing bus power driving.

  The SW 16 is turned on when power is supplied from the AC adapter power input circuit 12.

  The DC-DC converter 17 performs transformation, and transforms the supply voltage to the digital circuit 22 and the CPU 21 from 5V to 3.3V.

  The LDO 18 is always turned on and stabilizes the supply voltage to the analog circuit 23 to 3.3V.

  The current limiting circuit 19 and the current limiting circuit 20 are circuits that limit the amount of current supplied to the power amplifier 24 and the capacitor 25. The current limiting circuit 19 limits the output current to 100 mA, and the current limiting circuit 20 limits the output current to 150 mA.

  The capacitor 25 is an electric double layer capacitor having a very large capacitance (for example, several tens of μF or more). Since the capacitor 25 has a very large capacitance, the CPU 21 and the like cannot be operated if all the supply current from the USB power input circuit 11 and the AC adapter power input circuit 12 is consumed for charging. Therefore, in order to protect various circuits of the speaker device, a current limiting circuit 19 and a current limiting circuit 20 are provided to limit the current.

  In this embodiment, since the voltage is stored in the capacitor 25, when the speaker device emits sound that instantaneously consumes about several watts, power can be supplied from the capacitor 25 to the power amplifier 24. is there. The speaker device 1 according to the present embodiment performs stable power supply while accumulating voltage in a large-capacitance capacitor 25, depending on the form of power supply from the USB power input circuit 11 and the AC adapter power input circuit 12. LDO13, HSSW14, SW15, and SW16 are switched on and off.

  FIG. 2 is a diagram illustrating a state switching list. As shown in the figure, the speaker device 1 switches six states. First, in a state where no power is supplied from the USB power input circuit 11 and the AC adapter power input circuit 12, that is, in a state where nothing is connected to the speaker device 1, the CPU 21 does not drive, and of course various switches remain off. Yes (state 1).

  When the speaker device 1 is connected to the host and a current of 100 mA is input from the USB power input circuit 11, power is supplied to the CPU 21 via the LDO 13, and as a result, the CPU 21 is activated (state 2). Here, the CPU 21 negotiates with the host. If the negotiation is not possible, the speaker device cannot be driven and the state is switched to state 1 again, and the power is turned off.

  If the negotiation is established, the CPU 21 assumes that the bus power drive with 500 mA input is possible, sets the HSSW 14 and SW 15 to ON, and sets the current input from the USB power input circuit 11 to the digital circuit 22, the analog circuit 23, And is supplied to the current limiting circuit 19 (state 3). Further, 5 V power is supplied to the front stage of the power amplifier 24 (+5 A).

  Here, the current limiting circuit 19 limits the output current to 100 mA and supplies it to the power amplifier 24. Further, the capacitor 25 is charged by this current. When the voltage of the capacitor 25 is boosted to about 2.7 V, sufficient power (current exceeding 100 mA) can be supplied to the power amplifier 24 even in the bus power drive. Actually, it may be driven after boosting to about 3 to 3.5 V in consideration of a margin.

  That is, the power amplifier 24 receives a current of 100 mA from the current limiting circuit 19 and amplifies the audio signal. However, depending on the amount of amplification, the power amplifier 24 may consume a current exceeding 100 mA. . Here, if the power amplifier 24 consumes a current exceeding 100 mA, the voltage of the capacitor 25 drops. However, since a current of 100 mA is constantly supplied from the current limiting circuit 19, charging is performed again when the current consumption of the power amplifier 24 is reduced. As a result, the speaker device 1 can instantaneously output several watts while being driven by the bus power, and can perform stable driving.

  Next, when the speaker device 1 is not connected to the host and only the AC adapter is connected, a current of about 700 mA is input from the AC adapter power input circuit 12. In this case, the SW 16 is turned on and power is supplied to the CPU 21. As a result, the CPU 21 is activated (state 4). The power line from the AC adapter power input circuit 12 to the DC-DC converter 17 is monitored by a detection circuit (not shown), and when current is supplied to the power line, the switch of the SW 16 is turned on. It has become.

  CPU21 turns off LDO13, HSSW14, and SW15 after starting. As a result, the current input from the AC adapter power input circuit 12 is supplied to the digital circuit 22, the analog circuit 23, and the current limiting circuit 20. In addition, 5 V power is supplied to the front stage of the power amplifier 24.

  Here, the current limiting circuit 20 limits the output current to 150 mA and supplies it to the power amplifier 24. Further, the capacitor 25 is charged by this current. Similarly to the above, when the voltage of the capacitor 25 is boosted to about several volts, sufficient power can be supplied to the power amplifier 24.

  In the self-power drive, the power amplifier 24 receives a current of 150 mA from the current limiting circuit 20 and amplifies the audio signal. However, depending on the amount of amplification, a current exceeding 150 mA may be consumed. Make up for the minute. Here, when the power amplifier 24 consumes a current exceeding 150 mA, the voltage of the capacitor 25 drops. However, since a current of 150 mA is constantly supplied from the current limiting circuit 20, charging is performed again when the current consumption of the power amplifier 24 is reduced. Thereby, the speaker device 1 can perform driving more stable than bus power driving.

  Next, when the speaker device 1 is connected to the host in a self-powered state, a current of 100 mA is input from the USB power input circuit 11. In this case, the CPU 21 negotiates with the host. If the negotiation is not possible, the self-power drive is performed with the various switches as they are (state 5).

  If the negotiation is established, the CPU 21 turns on the HSSW 14 and supplies the current input from the USB power supply input circuit 11 to the current limiting circuit 19 (state 6). As a result, a current of 100 mA is supplied from the current limiting circuit 19 to the power amplifier 24, and a current of 150 mA is supplied from the current limiting circuit 20. Therefore, a current of 250 mA is supplied to the power amplifier 24 and the capacitor 25.

  When the AC adapter is connected in the bus power drive state (state 3), the CPU 21 turns on the SW16, turns off the LDO 13 and the SW15, and switches to the state 6.

  3 and 4 are flowcharts showing the above operation (switching between states 1 to 6). FIG. 3 is a flowchart showing the operation when the speaker device 1 is connected to the host, and FIG. 4 is a flowchart showing the operation when the AC adapter is connected.

  First, in FIG. 3, when the speaker device 1 is connected to the host via USB, the LDO 13 is turned on and the CPU 21 is activated (s11). Thereafter, the CPU 21 negotiates with the host (s12). If the negotiation is established, the state shifts to state 3 and bus power driving is performed (s12 → s13).

  Then, the confirmation of whether or not the AC adapter is connected (s14) and whether or not the USB is disconnected (s15) is repeated. When the AC adapter is not connected and the USB is disconnected, the state shifts to state 1 (s16), and the operation ends (the power is turned off).

  When the AC adapter is connected, the LDO 13 is turned off and the SW 16 is turned on (s17). Then, the system is reset once (s18), then the state is shifted to state 6 (s19), and it is driven by both bus power and self power.

  Thereafter, the confirmation of whether the USB is disconnected (s20) and whether the AC adapter is connected (s21) is repeated. When the USB is disconnected, the state shifts to state 4 (s20 → s22), and the operation ends (the power remains on).

  If the USB is not disconnected and the AC adapter is disconnected, the LDO 13 is turned on and the SW 16 is turned off (s23). Then, the system is temporarily reset (s24), and the state is shifted to the state 3 to perform bus power driving (s24 → s13).

  On the other hand, when the negotiation could not be performed in the process of s12, the process proceeds to the state 2 (s31), and it is determined whether or not the AC adapter is connected (s32). If the AC adapter is not connected, the process proceeds to state 1 (s33), and the operation ends (the power is turned off).

  If the AC adapter is connected, the SW16 is turned on (s34), the state 5 is entered (s35), and self-power drive is performed. Thereafter, the confirmation of whether the USB is disconnected (s36) and whether the AC adapter is connected (s37) is repeated. When the USB is disconnected, the state shifts to the state 4 (s36 → s22), and the operation is finished (the power is kept on).

  If the USB is not disconnected and the AC adapter is disconnected, the LDO 13 is turned on and the SW 16 is turned off (s38). Then, the system is reset once (s39), and the state 2 is shifted (s39 → s31).

  Next, in FIG. 4, when the AC adapter is connected, the SW 16 is turned on and the CPU 21 is activated (s51). Thereafter, it is determined whether or not the speaker device 1 is connected by USB (s52). If the USB connection is not established, the process proceeds to state 4 (s53), and it is repeatedly determined whether the AC adapter is disconnected (s54) and whether the speaker device 1 is connected to the USB (s54 → s52). When the AC adapter is disconnected, the process proceeds to state 1 (s55) and the operation is finished.

  On the other hand, if it is determined in s52 that the USB connection is established, the CPU 21 negotiates with the host (s56). If the negotiation is established, the process shifts to the state 6 and is driven by both bus power and self power (s56 → s57).

  Then, the confirmation of whether the AC adapter is disconnected (s58) and whether the USB is disconnected (s59) is repeated. If the AC adapter is not disconnected and the USB is disconnected, the process proceeds to state 4 (s59 → s53).

  When the AC adapter is disconnected, the LDO 13 is turned on and the SW 16 is turned off (s60). Then, the system is reset once (s61), then the state is shifted to the state 3 (s62) and driven by the bus power.

  Thereafter, the confirmation of whether the USB is disconnected (s63) and whether the AC adapter is connected (s65) is repeated. When the USB is disconnected, the state shifts to the state 1 (s63 → s64), and the operation is finished (the power is turned off).

  When the AC adapter is connected, the LDO 13 is turned off and the SW 16 is turned on (s65 → s66). Then, the system is reset once (s67), and the state is shifted to the state 6 and driven by both bus power and self power (s67 → s57).

  If it is determined in s56 that the negotiation is not possible, the state shifts to state 5 and self-power driving is performed (s56 → 68). Thereafter, the confirmation of whether the AC adapter has been disconnected (s69) and whether the USB has been disconnected (s70) is repeated. If the AC adapter is not disconnected and the USB is disconnected, the process proceeds to state 4 (s70 → s53).

  When the AC adapter is disconnected, the LDO 13 is turned on and the SW 16 is turned off (s71). Then, the system is temporarily reset (s72), and the state 2 is shifted (s73). Thereafter, it is determined whether or not the USB has been disconnected (s74). If the USB has been disconnected, the process proceeds to state 1 (s74 → s64), and the operation ends (the power is turned off).

  If the USB is not disconnected, it is checked again whether the AC adapter is connected (s75). If the AC adapter is connected, the LDO 13 is turned off and the SW 16 is turned on (s76). Then, the system is once reset (s77), and the state is shifted to the state 5 to perform self-power driving (s77 → s68).

  As described above, the current supply amount to the power amplifier is ensured by switching the drive by bus power, self power, or both, and switching the current supply amount from the current limit circuit 19 and the current limit circuit 20 to the capacitor. However, stable operation can be realized.

  In the present embodiment, the speaker device is shown as an electronic device. However, the present invention can be applied to any device that performs bus power driving by USB connection and self-power driving by an AC adapter.

It is a block diagram which shows the power supply circuit structure of the speaker apparatus which concerns on this embodiment. It is a figure which shows a state switching list. It is the flowchart which showed the operation | movement at the time of connecting the speaker apparatus 1 to a host. It is the flowchart which showed the operation | movement at the time of connecting an AC adapter.

Explanation of symbols

1-speaker device 11-USB power input circuit 12-AC adapter power input circuit 13-regulator (LDO)
14-switch (HSSW)
15-switch (SW)
16-switch (SW)
17-DC-DC converter (DC-DC)
18-Regulator (LDO)
19-current limiting circuit 20-current limiting circuit 21-CPU
22-Digital circuit 23-Analog circuit 24-Power amplifier 25-Capacitor

Claims (4)

A plurality of power input sections each receiving a different amount of current,
A plurality of current limiting circuits that output the current input from the plurality of power supply input units by limiting the output values by different output values;
A main driving circuit connected to a subsequent stage of the plurality of current limiting circuits;
A power storage circuit connected between the plurality of current limiting circuits and the main drive circuit;
Based on the current supply mode of each of the plurality of power input units, a control unit that switches a connection form between the plurality of power input units and the current limiting circuit;
With electronic equipment. The plurality of power input units include a power input unit for bus power that receives power supply from a host device, and a power input unit for self power that receives power supply from an AC adapter,
The control unit, when receiving a current supply from the bus power power input unit, connects the bus power power input unit to a current limiting circuit having a small current output value among the plurality of current limiting circuits,
2. The self-power supply input unit according to claim 1, wherein when receiving a current supply from the self-power supply input unit, the self-power supply input unit is connected to a current limit circuit having a large current output value among the plurality of current limit circuits. Electronics. The bus power supply input unit comprises a USB interface,
The electronic device according to claim 2, wherein the control unit connects the bus power power input unit to a current limiting circuit having an output value of the small current when negotiation with the host device is established.   The electronic device according to claim 1, wherein the power storage circuit is an electric double layer capacitor.

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