Accessory, power management IC, and communication system

Communication systems including a case and an accessory are disclosed. In one example, the case supplies electric power. The accessory is connectable to the case with a charging line and a GND line. The charging line transmits and receives a charging signal. The GND line is set to a reference voltage. The accessory includes a requested-operation determination circuit that, based on a voltage level of the charging signal and on a duration time of the voltage level, determines one operation requested of the accessory. In another example, a power management IC is included in the accessory and connected to the case with a charging line and a GND line. The power management IC includes a requested-operation determination circuit that, based on a voltage level of the charging signal and on a duration time of the voltage level, determines one operation requested of the accessory.

TECHNICAL FIELD

The present disclosure relates to an accessory for transmitting and receiving signals to and from a case, a power management IC included in the accessory, and a communication system including the accessory.

BACKGROUND ART

Charging and communication operations are performed between a case (e.g., a docking station) and an accessory such as a pair of wireless earphones. A configuration in which two connection lines (a charging line and a GND line) are used for connection is used as a configuration for connecting the case to the accessory.

A system disclosed, for example, in PTL 1 exercises on-off control over an enable signal outputted from a driver of a case with respect to a power supply terminal of an accessory that is connected to the case with two connection lines, and establishes communication depending on whether or not the enable signal is superimposed on an outputted communication signal.

CITATION LIST

Patent Literature

SUMMARY

Technical Problem

However, the technology disclosed in PTL 1 requires the use of a separation circuit for separating the enable signal from the communication signal on which the enable signal is superimposed. Therefore, the technology disclosed in PTL 1 has a problem where circuitry is complicated.

In order to address the above problem, the present technology has an objective to provide an accessory, a power management IC, and a communication system that are capable of allowing the use of simplified circuitry.

Solution to Problem

An accessory according to an aspect of the present technology is connectable to a case with a charging line and a GRD line. The charging line transmits and receives a charging signal. The GSD line is set to a reference voltage. The accessory includes a requested-operation determination circuit. Based on a voltage level of the charging signal and on a duration time of the voltage level, the requested-operation determination circuit determines one operation requested of the accessory.

A power management IC according to another aspect of the present technology is included in an accessory, connected to a case with a charging line and a GND line, and provided with a requested-operation determination circuit. The accessory operates on electric power. The case is capable of supplying the electric power. The charging line transmits and receives a charging signal. The GND line is set to a reference voltage. Based on a voltage level of the charging signal and on a duration time of the voltage level, the requested-operation determination circuit determines one operation requested of the accessory.

A communication system according to still another aspect of the present technology includes a case and an accessory. The case is capable of supplying electric Power. The accessory is connectable to the case with a charging line and a GND line. The charging line transmits and receives a charging signal. The GND line is set to a reference voltage. The accessory includes a requested-operation determination circuit. Based on a voltage level of the charging signal and on a duration time of the voltage level, the requested-operation determination circuit determines one operation requested of the accessory.

A communication system according to yet another aspect of the present technology includes a case, an accessory, and a power management IC. The case is capable of supplying electric power. The accessory operates on electric power. The power management IC is included in the accessory and connected to the case with a charging line and a GND line. The charging line transmits and receives a charging signal. The GND line is set to a reference voltage. Further, the power management IC includes a requested-operation determination circuit. Based on a voltage level of the charging signal and on a duration time of the voltage level, the requested-operation determination circuit determines one operation requested of the accessory.

DESCRIPTION OF EMBODIMENTS

Embodiments of the present technology will now be described with reference to the accompanying drawings. Identical or similar portions in the accompanying drawings are designated by identical or similar reference signs and will not be redundantly described. The accompanying drawings are schematic and may depict a situation different from reality. The embodiments described below illustrate equipment and methods for embodying the technical idea of the present technology. The technical idea of the present technology is not specifically limited to the equipment and methods illustrated in conjunction with the embodiments described below. The technical idea of the present technology may be modified variously within the technical scope described in the appended claims.

First Embodiment

As depicted inFIG.1, a communication system1includes an accessory2and a case4. The accessory2operates on electric power. The case4is capable of supplying the electric power.

The accessory2and the case4are connected with two connection lines (a charging line6and a GND line8).

The charging line6is formed by bringing terminals (charging terminals (Vin)) individually formed on the accessory2and the case4into contact, and used to transmit and receive a charging signal.

The GND line8is formed by bringing terminals (GND terminals (GND)) individually formed on the accessory2and the case4into contact, as is the case with the charging line6, and set to a reference voltage (e.g., 0 V).

Configuration of Accessory

The accessory2includes a power management unit (PMU)10, an accessory battery20, and a signal processing circuit30.

The first embodiment is described below with reference to a case where the accessory2is, for example, a pair of wireless earphones that acquires audio data (sound data) from, for instance, music reproduction equipment through Bluetooth (registered trademark) or other wireless communication, and outputs a sound based on the sound data.

The PMU10includes a regulator11, a reception path12, a transmission path13, a register14, and a requested-operation determination circuit15.

The regulator11receives a command signal inputted from the requested-operation determination circuit15, and outputs the command signal to the signal processing circuit30. Further, the regulator11includes a DC-DC converter and an LDO (Low Drop Out).

The DC-DC converter is a circuit that switches input power with a switching element at a relatively high speed, and rectifies and smooths the switched input power to obtain DC power having a desired voltage. Further, the DC-DC converter has a wider input voltage variation range than the LDO.

The LDO is a series regulator that controls the amount of voltage drop in a transistor element to obtain DC power having a desired voltage. Further, the LDO has a narrower input voltage variation range than the DC-DC converter, and provides highly efficient voltage conversion in a case where an input voltage is slightly higher than an output voltage.

The reception path12is connected to the signal processing circuit30and to the charging terminal that is connected to the charging line6.

Further, when a reception route connection signal (RxON signal) is inputted from the requested-operation determination circuit15, the reception path12connects a signal transmission route from the charging terminal to the signal processing circuit30. The reception route connection signal is a command signal that connects the signal transmission route from the charging terminal to the signal processing circuit30.

Further, when a reception route blocking signal (RxOFF signal) is inputted from the requested-operation determination circuit15, the reception path12blocks the signal transmission route from the charging terminal to the signal processing circuit30. The reception route blocking signal is a command signal that blocks the signal transmission route from the charging terminal to the signal processing circuit30.

The transmission path13is connected to the charging terminal and the signal processing circuit30. The transmission path13and the signal processing circuit30are connected by using, for example, a UART (Universal Asynchronous Receiver Transmitter).

Further, when a transmission route connection signal (TxON signal) is inputted from the signal processing circuit30, the transmission path13connects a signal transmission route from the signal processing circuit30to the charging terminal. The transmission route connection signal is a command signal that connects the signal transmission route from the signal processing circuit30to the charging terminal.

Further, when a transmission route blocking signal (TxOFF signal) is inputted from the signal processing circuit30, the transmission path13blocks the signal transmission route from the signal processing circuit30to the charging terminal. The reception route blocking signal is a command signal that blocks the signal transmission route from the signal processing circuit30to the charging terminal.

The register14is connected to the signal processing circuit30by using, for example, an I2C (Inter-Integrated Circuit).

Further, based on the command signal inputted from the requested-operation determination circuit15, the register14inputs, to the signal processing circuit30, the transmission route connection signal or the transmission route blocking signal to be inputted to the transmission path13.

Based on the voltage level of the charging signal inputted from the case4through the charging line6and on the duration time of the voltage level of the charging signal, the requested-operation determination circuit15determines (identifies) one operation requested of the accessory2.

Operations that can be requested of the accessory2include a recovery operation and a communication operation. The recovery operation recovers the signal processing circuit30from a sleep state. The communication operation provides one-way communication from the case4to the requested-operation determination circuit15and two-way communication (one-way communication and two-way communication) between the signal processing circuit30and the case4. Further, the operations that can be requested of the accessory2include a charging operation, an initialization operation, and a sleep operation. The charging operation charges the accessory battery20. The initialization operation initializes (resets) the system of the accessory2. The sleep operation switches the running signal processing circuit30into the sleep state.

It should be noted that the communication between the accessory2and the case4may include, for example, a communication for indicating the remaining capacity (remaining battery level) of a later-described case battery40by using a blinking or steadily glowing LED.

The requested-operation determination circuit15may be configured as depicted, for example, inFIG.2.

The configuration depicted inFIG.2indicates, as an example, that the requested-operation determination circuit15includes a first determination section15a, a first counter processing section15b, a second determination section15c, a second counter processing section15d, a third determination section15e, and a third counter processing section15f.

Upon receiving an input of the charging signal, the first determination section15adetermines whether the voltage level of the inputted charging signal is higher than the reference voltage and lower than a preset first threshold voltage. In a case where the voltage level of the inputted charging signal is higher than the reference voltage and lower than a preset first threshold voltage, the first determination section15aoutputs the charging signal to the first counter processing section15b. Meanwhile, in a case where the voltage level of the inputted charging signal is higher than the reference voltage and not lower than the first threshold voltage, the first determination section15aallows the charging signal to flow to a ground terminal.

Upon receiving an input of the charging signal, the first counter processing section15bdetermines whether or not the voltage level of the charging signal has remained higher than the reference voltage and lower than the first threshold voltage for a preset first threshold period (e.g., several milliseconds). If it is not determined that the voltage level of the charging signal has remained higher than the reference voltage and lower than the first threshold voltage for the first threshold period, the first determination section15aconcludes that the one operation requested of the accessory2is the recovery operation. Meanwhile, if it is determined that the voltage level of the charging signal has remained higher than the reference voltage and lower than the first threshold voltage for the first threshold period, the first determination section15aconcludes that the one operation requested of the accessory2is the communication operation.

Further, if the voltage level of the inputted charging signal, which has been higher than the reference voltage, lowers to the reference voltage, the first determination section15adetermines that the one operation requested of the accessory2is the sleep operation.

Upon receiving an input of the charging signal, the second determination section15cdetermines whether the voltage level of the inputted charging signal is not lower than the first threshold voltage and is lower than a second threshold voltage that is preset to be higher than the first threshold voltage. In a case where the voltage level of the inputted charging signal is not lower than the first threshold voltage and is lower than the second threshold voltage, the second determination section15coutputs the charging signal to the second counter processing section15d. Meanwhile, in a case where the voltage level of the inputted charging signal is not lower than the second threshold voltage, the second determination section15callows the charging signal to flow to the ground terminal.

Upon receiving an input of the charging signal, the second counter processing section15ddetermines whether or not the voltage level of the charging signal has remained higher than the first threshold voltage and lower than the second threshold voltage for a preset second threshold period (e.g., several milliseconds). It should be noted that the second threshold period may be equal to the first threshold period. If it is not determined that the voltage level of the charging signal has remained higher than the first threshold voltage and lower than the second threshold voltage for the second threshold period, the second determination section15ccontinues with determination. Meanwhile, if it is determined that the voltage level of the charging signal has remained higher than the first threshold voltage and lower than the second threshold voltage for the second threshold period, the second determination section15cconcludes that the one operation requested of the accessory2is the charging operation.

Upon receiving an input of the charging signal, the third determination section15edetermines whether the voltage level of the inputted charging signal is not lower than the second threshold voltage. In a case where the voltage level of the inputted charging signal is not lower than the second threshold voltage, the third determination section15eoutputs the charging signal to the third counter processing section15f.

Upon receiving an input of the charging signal, the third counter processing section15fdetermines whether or not the voltage level of the charging signal has remained higher than the second threshold voltage for a preset third threshold period (e.g., several milliseconds). It should be noted that the third threshold period may be equal, for example, to the first threshold period. If it is not determined that the voltage level of the charging signal has remained higher than the second threshold voltage for the third threshold period, the third determination section15econtinues with determination. Meanwhile, if it is determined that the voltage level of the charging signal has remained higher than the second threshold voltage for the third threshold period, the third determination section15econcludes that the one operation requested of the accessory2is initialization operation.

Consequently, when determining the one operation requested of the accessory2, the requested-operation determination circuit15performs processes (I) to (V) below.

Upon detecting that the voltage level of the charging signal higher than the reference voltage and lower than the first threshold voltage, the requested-operation determination circuit15determines that the one operation requested of the accessory2is the recovery operation.

When it is determined that the one operation requested of the accessory2is the recovery operation, the requested-operation determination circuit15outputs a command signal (system recovery signal) for causing the signal processing circuit30to switch into a standby state. Additionally, the requested-operation determination circuit15outputs a command signal (power ON signal) to the regulator11in order to supply electric power to the signal processing circuit30.

In a case where the voltage level of the charging signal has remained higher than the reference voltage and lower than the first threshold voltage for the first threshold period, the requested-operation determination circuit15determines that the one operation requested of the accessory2is the communication operation.

When it is determined that the one operation requested of the accessory2is the communication operation, the requested-operation determination circuit15outputs the reception route connection signal to the reception path12.

Thereafter, when the charging signal is inputted to the signal processing circuit30, the requested-operation determination circuit15outputs the reception route blocking signal to the reception path12. Additionally, the requested-operation determination circuit15outputs a command signal to the register14in order to input the transmission route connection signal to the signal processing circuit30.

Further, when a communication signal outputted from the signal processing circuit30is inputted to the case4, the requested-operation determination circuit15outputs a command signal to the register14in order to input the transmission route blocking signal to the signal processing circuit30.

In a case where the voltage level of the charging signal has remained not lower than the first threshold voltage for the second threshold period, the requested-operation determination circuit15determines that the one operation requested of the accessory2is the charging operation.

When it is determined that the one operation requested of the accessory2is the charging operation, the requested-operation determination circuit15outputs the charging signal to the accessory battery20.

In a case where the voltage level of the charging signal has remained not lower than the second threshold voltage for the third threshold period, the requested-operation determination circuit15determines that the one operation requested of the accessory2is the initialization operation.

When it is determined that the one operation requested of the accessory2is the initialization operation, the requested-operation determination circuit15outputs a command signal to the regulator11, the reception path12, the transmission path13, the register14, and the signal processing circuit30in order to initialize their states.

In a case where the voltage level of the charging signal, which has been higher than the reference voltage, lowers to the reference voltage, the requested-operation determination circuit15determines that the one operation requested of the accessory2is the sleep operation.

When it is determined that the one operation requested of the accessory2is the sleep operation, the requested-operation determination circuit15outputs a command signal (power OFF signal) to the regulator11in order to shut off the power supply to the signal processing circuit30.

The accessory battery20is, for example, a rechargeable lithium-ion battery. The charging signal is supplied to the accessory battery20through the requested-operation determination circuit15. Further, the accessory battery20supplies power to the PMU10and the signal processing circuit30.

The signal processing circuit30receives a signal input from the requested-operation determination circuit15and the regulator11. Further, the signal processing circuit30inputs and outputs signals to and from the register14.

Further, the signal processing circuit30in the sleep state receives an input of the system recovery signal from the requested-operation determination circuit15, and upon receiving power supplied from the regulator11, the signal processing circuit30switches into the standby state. Additionally, when the power supply is shut off from the regulator11, the signal processing circuit30in the standby state switches into the sleep state.

Further, upon receiving, from the register14, an input of a command signal for inputting the transmission route connection signal to the signal processing circuit30, the signal processing circuit30outputs the transmission route connection signal to the transmission path13. Additionally, upon receiving, from the register14, an input of a command signal for inputting the transmission route blocking signal to the signal processing circuit30, the signal processing circuit30outputs the transmission route blocking signal to the transmission path13.

Configuration of Case

The case4functions as a docking station capable of docking the accessory2. Further, the case4includes a case battery40and a signal control section50.

The case battery40, which is, for example, a rechargeable lithium-ion battery, outputs the charging signal to the accessory2through the charging line6. Therefore, the case4is able to supply power to the accessory2. It should be noted that the case battery40can be charged by supplying power from the outside, for example, through a common power outlet.

The signal control section50controls the voltage level of the charging signal to be outputted to the accessory2through the charging line6and the duration time of the voltage level. Control exercised over the charging signal by the signal control section50is based on the one operation requested of the accessory2.

Operations and Effects

Referring toFIGS.1and2and based onFIGS.3to16, operations performed by the communication system1and effects produced by the operations performed by the communication system1will now be described. The following description assumes that the case4and the accessory2are not connected, and that the signal processing circuit30is in the sleep state, and further that the signal transmission route from the charging terminal to the signal processing circuit30and the signal transmission route from the signal processing circuit30to the charging terminal are blocked.

It should be noted that, inFIG.3or the like, the state where the signal transmission route from the charging terminal to the signal processing circuit30is blocked and the state where the signal transmission route from the signal processing circuit30to the charging terminal is blocked may be referred to as the “OFF” state. Similarly, the state where the signal transmission route from the charging terminal to the signal processing circuit30is connected and the state where the signal transmission route from the signal processing circuit30to the charging terminal is connected may be referred to as the “ON” state.

In a case where, for example, the remaining power of the accessory battery20is low during the use of the accessory2, the accessory2and the case4are connected with the charging line6and the GND line8in order, for example, to charge the accessory battery20.

When the accessory2and the case4are connected, that is, the charging terminals and the GND terminals formed on the accessory2and the case4are brought into contact with each other, the charging signal outputted from the case4is inputted to the requested-operation determination circuit15through the charging line6as depicted inFIG.3. Tt should be noted that the charging signal outputted from the case4and inputted to the requested-operation determination circuit15is indicated by the reference sign S1inFIG.3.

Upon receiving an input of the charging signal S1, the requested-operation determination circuit15detects the voltage level of the charging signal S1and measures the duration time of the voltage level of the charging signal S1. Then, upon detecting that the voltage level of the charging signal S1is higher than the reference voltage and lower than the first threshold voltage as indicated at time “t1” inFIG.4, the requested-operation determination circuit15determines that the one operation requested of the accessory2is the recovery operation.

When it is determined that the one operation requested of the accessory2is the recovery operation, the requested-operation determination circuit15outputs the system recovery signal to the signal processing circuit30as depicted inFIG.3. Additionally, the requested-operation determination circuit15outputs the power ON signal to the regulator11as depicted inFIG.3.

Further, upon receiving an input of the power ON signal, the regulator11supplies power to the signal processing circuit30as depicted inFIG.3.

Upon receiving an input of the system recovery signal and receiving the power supplied from the regulator11, the signal processing circuit30switches from the sleep state to the standby state.

When the power is supplied to the signal processing circuit30for a predetermined period of time after the signal processing circuit30switched from the sleep state to the standby state, the signal processing circuit30achieves recovery and becomes operative.

Thereafter, when the voltage level of the charging signal S1has remained higher than the reference voltage and lower than the first threshold voltage for the first threshold period, which ends at time “t2” as indicated inFIG.5, the requested-operation determination circuit15determines that the one operation requested of the accessory2is the communication operation. It should be noted that the communication operation inFIG.5is depicted as “one-way and two-way communication.”

When it is determined that the one operation requested of the accessory2is the communication operation, the requested-operation determination circuit15outputs the reception route connection signal (RxON signal) to the reception path12as depicted inFIG.6.

Upon receiving an input of the reception route connection signal, the reception path12connects (turns ON) the signal transmission route from the charging terminal to the signal processing circuit30.

When the voltage level of the charging signal S1is higher than the reference voltage and lower than the first threshold voltage after time t2as indicated at time “t3” inFIG.7, the reception path12continuously connects the signal transmission route from the charging terminal to the signal processing circuit30. Then, as depicted inFIG.8, the charging signal S1is inputted from the case4to the signal processing circuit30.

Upon receiving an input of the charging signal S1, the signal processing circuit30performs processing based on the voltage level (e.g., an instantaneous change in the voltage level and the time of instantaneous change in the voltage level). The processing performed based on the voltage level by the signal processing circuit30is, for example, a process of indicating the remaining capacity (remaining battery level) of the accessory battery20by using a blinking or steadily glowing LED.

Further, when the charging signal S1is inputted to the signal processing circuit30, the requested-operation determination circuit15outputs the reception route blocking signal (RxOFF signal) to the reception path12as depicted inFIG.9. Upon receiving an input of the reception route blocking signal, the reception path12blocks (turns OFF) the signal transmission route from the charging terminal to the signal processing circuit30.

Additionally, the requested-operation determination circuit15outputs a command signal to the register14in order to input the transmission route connection signal to the signal processing circuit30. Upon receiving an input of the command signal, the register14outputs, to the signal processing circuit30, the transmission route connection signal to be inputted to the transmission path13. Upon receiving an input of the transmission route connection signal from the register14, the signal processing circuit30outputs the transmission route connection signal to the transmission path13.

Upon receiving an input of the transmission route connection signal, the transmission path13connects (turns ON) the signal transmission route from the signal processing circuit30to the charging terminal.

When the reception path12blocks the signal transmission route from the charging terminal to the signal processing circuit30and the transmission path13connects the signal transmission route from the signal processing circuit30to the charging terminal, the case4communicates with the requested-operation determination circuit15, and the signal processing circuit30communicates with the case4.

When the voltage level of the charging signal S1is higher than the reference voltage and lower than the first threshold voltage after time t3as indicated at time “t4” inFIG.10, the reception path12continuously blocks the signal transmission route from the charging terminal to the signal processing circuit30. Then, when the communication signal outputted from the signal processing circuit30is inputted to the case4, the requested-operation determination circuit15outputs a command signal to the register14in order to input the transmission route blocking signal to the signal processing circuit30.

Upon receiving an input of the command signal, the register14outputs the transmission route blocking signal (TxOFF signal) to the transmission path13through the signal processing circuit30.

Upon receiving an input of the transmission route blocking signal, the transmission path13blocks (turns OFF) the signal transmission route from the signal processing circuit30to the charging terminal as depicted inFIG.11.

When the voltage level of the charging signal S1lowers to the reference voltage after time t4as indicated at time “t5” inFIG.12, the requested-operation determination circuit15determines that the one operation requested of the accessory2is the sleep operation.

When it is determined that the one operation requested of the accessory2is the sleep operation, the requested-operation determination circuit15outputs the power OFF signal to the regulator11as depicted inFIG.13.

Upon receiving an input of the power OFF signal, the regulator11shuts off the power supply to the signal processing circuit30as depicted inFIG.13.

In a case where the voltage level of the charging signal S1has remained not lower than the first threshold voltage for the second threshold period after time t5as indicated at time “t6” inFIG.14, the requested-operation determination circuit15determines that the one operation requested of the accessory2is the charging operation.

When it is determined that the one operation requested of the accessory2is the charging operation, the requested-operation determination circuit15supplies the charging signal to the accessory battery20as depicted inFIG.15.

Upon receiving the supplied charging signal, the accessory battery20is charged based on the voltage level of the charging signal.

In a case where the voltage level of the charging signal S1has remained not lower than the second threshold voltage for the third threshold period after time t6as indicated at time “t7” inFIG.16, the requested-operation determination circuit15determines that the one operation requested of the accessory2is the initialization operation.

When it is determined that the one operation requested of the accessory2is the initialization operation, the requested-operation determination circuit15outputs a command signal to the regulator11, the reception path12, the transmission path13, the register14, and the signal processing circuit30in order to initialize their states.

As described above, the accessory2and the communication system1according to the first embodiment are able to determine the one operation requested of the accessory2according to the voltage level of the charging signal inputted from the case4and to the duration time of the voltage level. Consequently, the one operation requested of the accessory2can be determined without requiring a configuration including, for example, a separation circuit for signal separation. This allows the use of simplified circuitry. Further, as the configuration including, for example, the separation circuit for signal separation is not required, it is not necessary to operate, for example, the separation circuit. As a result, an increase in the amount of power consumption can be suppressed.

Further, as described earlier, an operation determination method used by the accessory2and the communication system1according to the first embodiment makes it possible to determine the one operation requested of the accessory2according to the voltage level of the charging signal and to the duration time of the voltage level. Consequently, the one operation requested of the accessory2can be determined without requiring the configuration including, for example, the separation circuit for signal separation. This allows the use of simplified circuitry. Further, as the configuration including, for example, the separation circuit for signal separation is not required, it is not necessary to operate, for example, the separation circuit. As a result, an increase in the amount of power consumption can be suppressed.

Modifications

The first embodiment assumes that the accessory2is a pair of wireless earphones. However, the accessory2is not limited to wireless earphones. Alternatively, the accessory2may be, for example, a wireless microphone for recording sounds or a pair of VR (Virtual Reality) goggles for outputting video images. Further, the accessory2may be, for example, a clock or a sensor for detecting biological information (pulse, heart rate, blood pressure, etc.).

Second Embodiment

A second embodiment will be described below. However, components similar to those in the first embodiment may not be redundantly described.

As depicted inFIG.17, a communication system1according to the second embodiment includes an accessory2, a case4, and a power management IC60.

Configuration of Accessory

The accessory2includes an accessory battery20and a signal processing circuit30.

The accessory battery20is, for example, a rechargeable lithium-ion battery. The charging signal is supplied to the accessory battery20through a requested-operation determination circuit15. Further, the accessory battery20supplies power to the power management IC60and the signal processing circuit30. It should be noted that the power management IC60is able to selectively use either power supplied from the accessory battery20or power supplied from the case4by the charging signal. Therefore, in a case, for example, where the accessory battery20is dead, the power management IC60is able to operate on the power supplied from the case4by the charging signal. Further, even in a state where the accessory battery20is not to be charged, the power management IC60is able to operate on the power supplied from the case4by the charging signal.

The configuration of the signal processing circuit30is similar to that of the signal processing circuit30in the first embodiment, which has been described earlier, and will not be redundantly described.

Configuration of Power Management IC

The power management IC60is included in the accessory2, and connected to the case4with a charging line6and a GND line8.

Further, the power management IC60includes a regulator11, a reception path12, a transmission path13, a register14, and the requested-operation determination circuit15.

Upon receiving a command signal inputted from the requested-operation determination circuit15, the regulator11outputs the command signal to the signal processing circuit30. Further, the regulator11includes a DC-DC converter and an LDO.

The reception path12is connected to the signal processing circuit30and to a charging terminal that is connected to the charging line6. Further, when the reception route connection signal is inputted from the requested-operation determination circuit15, the reception path12connects a signal transmission route tram the charging terminal to the signal processing circuit30. Further, when the reception route blocking signal is inputted from the requested-operation determination circuit15, the reception path12blocks the signal transmission route from the charging terminal to the signal processing circuit30.

The transmission path13is connected to the charging terminal and the signal processing circuit30. The transmission path13and the signal processing circuit30are connected by using, for example, a UART. Further, when the transmission route connection signal is inputted from the signal processing circuit30, the transmission path13connects the signal transmission route from the signal processing circuit30to the charging terminal. Further, when the transmission route blocking signal is inputted from the signal processing circuit30, the transmission path13blocks the signal transmission route from the signal processing circuit30to the charging terminal.

The register14is connected to the signal processing circuit30by using, for example, an I2C.

Further, based on the command signal inputted from the requested-operation determination circuit15, the register14inputs, to the signal processing circuit30, the transmission route connection signal or the transmission route blocking signal to be inputted to the transmission path13.

Based on the voltage level of the charging signal inputted from the case4through the charging line6and on the duration time of the voltage level of the charging signal, the requested-operation determination circuit15determines (identifies) one operation requested of the accessory2.

Operations that can be requested of the accessory2and processes (I) to (V) that are performed by the requested-operation determination circuit15to determine the one operation requested of the accessory2are similar to those described in conjunction with the first embodiment and will not be redundantly described.

Configuration of Case

The case4functions as a docking station capable of docking the accessory2. Further, the case4includes a case battery40and a signal control section50.

The case battery40, which is, for example, a rechargeable lithium-ion battery, outputs the charging signal to the power management IC60through the charging line6. Therefore, the case4is able to supply power to the power management IC60.

The signal control section50controls the voltage level or the charging signal to be outputted to the power management IC60through the charging line6and the duration time of the voltage level. Control exercised over the charging signal by the signal control section50is based on the one operation requested of the accessory2.

Operations and Effects

Referring toFIGS.1to16and based onFIG.17, operations performed by the communication system1and effects produced by the operations performed by the communication system1will now be described. The following description assumes that the case4and the accessory2are not connected, and that the signal processing circuit30is in the sleep state, and further that the signal transmission route from the charging terminal to the signal processing circuit30and the signal transmission route from the signal processing circuit30to the charging terminal are blocked.

In a case where, for example, the remaining power of the accessory battery20is low during the use of the accessory2, the accessory2and the case4are connected in order, for example, to charge the accessory battery20.

When the accessory2and the case4are connected, the charging signal outputted from the case4is inputted to the requested-operation determination circuit15through the charging line6. Upon receiving an input of the charging signal, the requested-operation determination circuit15detects the voltage level of the charging signal and measures the duration time of the voltage level of the charging signal. Then, upon detecting that the voltage level of the charging signal is higher than the reference voltage and lower than the first threshold voltage, the requested-operation determination circuit15determines that the one operation requested of the accessory2is the recovery operation.

When it is determined that the one operation requested of the accessory2is the recovery operation, the requested-operation determination circuit15outputs a system recovery signal to the signal processing circuit30. Additionally, the requested-operation determination circuit15outputs a power ON signal to the regulator11.

Further, upon receiving an input of the power ON signal, the regulator11supplies power to the signal processing circuit30. Upon receiving an input of the system recovery signal and receiving the power supplied from the regulator11, the signal processing circuit30switches from the sleep state to the standby state. When the power is supplied to the signal processing circuit30for a predetermined period of time after the signal processing circuit30switched from the sleep state to the standby state, the signal processing circuit30achieves recovery and becomes operative.

Thereafter, when the voltage level of the charging signal has remained higher than the reference voltage and lower than the first threshold voltage for the first threshold period, the requested-operation determination circuit15determines that the one operation requested of the accessory2is the communication operation.

When it is determined that the one operation requested of the accessory2is the communication operation, the requested-operation determination circuit15outputs the reception route connection signal to the reception path12. Upon receiving an input of the reception route connection signal, the reception path12connects the signal transmission route from the charging terminal to the signal processing circuit30.

When the voltage level of the charging signal is higher than the reference voltage and lower than the first threshold voltage, the reception path12continuously connects the signal transmission route from the charging terminal to the signal processing circuit30. Upon receiving an input of the charging signal, the signal processing circuit30performs processing based on the voltage level.

Further, when the charging signal is inputted to the signal processing circuit30, the requested-operation determination circuit15outputs the reception route blocking signal to the reception path12. Upon receiving an input of the reception route blocking signal, the reception path12blocks the signal transmission route from the charging terminal to the signal processing circuit30. Additionally, the requested-operation determination circuit15outputs a command signal to the register14in order to input the transmission route connection signal to the signal processing circuit30. Upon receiving an input of the command signal, the register14outputs, to the signal processing circuit30, the transmission route connection signal to be inputted to the transmission path13. Upon receiving an input of the transmission route connection signal from the register14, the signal processing circuit30outputs the transmission route connection signal to the transmission path13. Upon receiving an input of the transmission route connection signal, the transmission path13connects the signal transmission route from the signal processing circuit30to the charging terminal.

When the reception path12blocks the signal transmission route from the charging terminal to the signal processing circuit30and the transmission path13connects the signal transmission route from the signal processing circuit30to the charging terminal, the case4communicates with the requested-operation determination circuit15, and the signal processing circuit30communicates with the case4.

When the voltage level of the charging signal is higher than the reference voltage and lower than the first threshold voltage, the reception path12continuously blocks the signal transmission route from the charging terminal to the signal processing circuit30. Then, when the communication signal outputted from the signal processing circuit30is inputted to the case4, the requested-operation determination circuit15outputs a command signal to the register14in order to input the transmission route blocking signal to the signal processing circuit30.

Upon receiving an input of the command signal, the register14outputs the transmission route blocking signal to the transmission path13through the signal processing circuit30. Upon receiving an input of the transmission route blocking signal, the transmission path13blocks the signal transmission route from the signal processing circuit30to the charging terminal.

When the voltage level of the charging signal lowers to the reference voltage, the requested-operation determination circuit15determines that the one operation requested of the accessory2is the sleep operation.

When it is determined that the one operation requested of the accessory2is the sleep operation, the requested-operation determination circuit15outputs the power OFF signal to the regulator11. Upon receiving an input of the power OFF signal, the regulator11shuts off the power supply to the signal processing circuit30.

When the voltage level of the charging signal has remained not lower than the first threshold voltage for the second threshold period, the requested-operation determination circuit15determines that the one operation requested of the accessory2is the charging operation.

When it is determined that the one operation requested of the accessory2is the charging operation, the requested-operation determination circuit15supplies the charging signal to the accessory battery20. Upon receiving the supplied charging signal, the accessory battery20is charged based on the voltage level of the charging signal.

When the voltage level of the charging signal has remained not lower than the second threshold voltage for the third threshold period, the requested-operation determination circuit15determines that the one operation requested of the accessory2is the initialization operation.

When it is determined that the one operation requested of the accessory2is the initialization operation, the requested-operation determination circuit15outputs a command signal to the regulator11, the reception path12, the transmission path13, the register14, and the signal processing circuit30in order to initialize their states.

As described above, the power management IC60and the communication system1according to the second embodiment are able to determine the one operation requested of the accessory2according to the voltage level of the charging signal inputted from the case4and to the duration time of the voltage level. Consequently, the one operation requested of the accessory2can be determined without requiring a configuration including, for example, a separation circuit for signal separation. This allows the use of simplified circuitry. Further, as the configuration including, for example, the separation circuit for signal separation is not required, it is not necessary to operate, for example, the separation circuit. As a result, an increase is the amount of power consumption can be suppressed.

Further, as described earlier, an operation determination method used by the power management IC60and the communication system1according to the second embodiment makes it possible to determine the one operation requested of the accessory2according to the voltage level of the charging signal and to the duration time of the voltage level. Consequently, the one operation requested of the accessory2can be determined without requiring the configuration including, for example, the separation circuit for signal separation. This allows the use of simplified circuitry. Further, as the configuration including, for example, the separation circuit for signal separation is not required, it is not necessary to operate, for example, the separation circuit. As a result, an increase in the amount of power consumption can be suppressed.

Modifications

The second embodiment assumes that the accessory2and the case4are connected with the charging line6and the GND line8. However, the form of connection between the accessory2and the case4is not limited to such a configuration. More specifically, as depicted, for example, inFIG.18, a switch70may be externally attached to the middle of the charging line6. The switch70branches the charging line6into two lines for connecting to the accessory2.

When the voltage level of the charging signal is higher than the reference voltage and lower than the first threshold voltage, the switch70inputs the charging signal to the first determination section15a(seeFIG.2). Meanwhile, when the voltage level of the charging signal is higher than the first threshold voltage, the switch70inputs the charging signal to the third determination section15e(seeFIG.2).

When the configuration depicted inFIG.18is adopted, the second determination section15cand the second counter processing section15dmay be removed from the requested-operation determination circuit15. This makes it possible to simplify the configuration of the requested-operation determination circuit15.

Other Embodiments

While the embodiments of the present technology have bees described above, it is to be understood that the present technology is not limited by the statements and drawings included in the present disclosure. It will be obvious from the present disclosure that various alternative embodiments, examples, and operational technologies may be contemplated by those skilled in the art. Further, it is apparent that the present technology also includes, for example, configurations formed as appropriate by using individual components described is conjunction with the foregoing embodiments and modifications and various embodiments other than those described in this specification. Therefore, the technical scope of the present technology is defined only by matters specifying the claimed invention within the scope of the appended claims appropriate based on the above explanation.

Further, the accessory, the power management IC, and the communication system according to the present disclosure do not need to include all the components described in conjunction with the foregoing embodiments, and may conversely include some other components. It should be noted that advantages described in this specification are merely illustrative and not restrictive. The present technology can additionally provide advantages other than those described in this specification.

REFERENCE SIGNS LIST