JP3897524B2 - Power supply monitoring apparatus, power supply monitoring method, information processing apparatus, and optical disc apparatus - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a power supply monitoring apparatus that monitors the voltage of a communication cable that supplies power in data communication conforming to a communication interface that can supply power through a communication cable. The present invention also relates to an information processing apparatus and an optical disc apparatus that use the power supply monitoring apparatus.
[0002]
[Prior art]
The IEEE 1394 standard defines a four-wire interface consisting of two signal line pairs and a six-wire interface consisting of four signal lines consisting of two signal line pairs plus a power line and a ground line. ing. As for the communication cable, a 4-pin cable is used in the case of a 4-wire interface, and a 6-pin cable is used in the case of a 6-wire interface. Whether to use a 4-pin cable or a 6-pin cable can be selected at the stage of system design.
[0003]
When a 6-pin cable is used, for example, the following advantages can be cited.
1) If power is supplied via a communication cable, it is not necessary to have a line for supplying power independently, and the system can be integrated.
2) When supplying power via a communication cable, the power consumption of the entire system constructed via the communication cable can be managed.
[0004]
When power is supplied via a communication cable, it is necessary to maintain the supplied power supply voltage at a predetermined voltage necessary for operating the system that receives the power. The IEEE 1394 standard defines the minimum output voltage as 8 V as a requirement for the power supply source of the cable. The maximum output voltage is defined as 30V. Normally, the state of the power supply is monitored by an integrated circuit for an interface (hereinafter referred to as “physical layer IC”) that controls communication conforming to the interface in the physical layer.
[0005]
FIG. 6 shows a conventional configuration of a monitoring circuit 11 of a power supply (hereinafter referred to as “cable power supply”) supplied by a cable in a system (physical layer IC) 10 using a 6-pin cable. Since the cable power Vdd to be monitored is supplied with a high voltage of 8V or more and 30V or less, it is directly connected to the cable power monitoring terminal 21 (hereinafter referred to as “CPS terminal”; CPS: Cable Power State) of the physical layer IC 10. If connected, the physical layer IC 10 will be destroyed. Therefore, the power supply voltage is divided by the resistors R1 and R2 to a low voltage that does not destroy the physical layer IC10, and then input to the physical layer IC10. The voltage input to the physical layer IC 10 is compared with the reference voltage Vref by the comparator 15 and the comparison result is output as a binary digital signal consisting of “1” and “0”. The comparison result is transmitted to a register 13 (hereinafter referred to as “PS register”; PS: Power Status) reflecting the state of the cable power supply in the dedicated physical layer register area. Here, the PS register is a register defined by the IEEE 1394 standard. When the cable power supply Vdd maintains the minimum output voltage or higher, “1” indicating that the power supply Vdd of the cable is normal is set in the PS register 13. When the voltage is below the minimum output voltage, “0” indicating that the power supply Vdd of the cable is abnormal is set in the PS register 13.
[0006]
When the system shown in FIG. 6 is configured, the resistor R2 used for voltage division of the cable power supply Vdd is generated inside the physical layer IC11. Generating the resistor R2 inside the physical layer IC11 is advantageous in terms of manufacturing cost and mounting area as compared with the case where the resistor R2 is configured outside the physical layer IC11.
[0007]
FIG. 7 is a diagram illustrating a configuration of a monitoring device for a cable power supply in a cable peripheral portion of a system using a 4-pin cable. In the case of a 4-pin cable, since the cable power source is not used, the CPS terminal 21 of the physical layer IC 10 is directly connected to the power source Vdd that operates the physical layer IC 10. Since it is directly connected to the power supply Vdd, the comparison result of the comparator 15 in the physical layer IC 10 is always “1”. As a result, the value of the PS register 13 is always “1”, indicating that there is no abnormality.
[0008]
The physical layer IC 10 used in the system shown in FIG. 6 is the same as the physical layer IC 10 used in the system shown in FIG. That is, as described above, the physical layer IC 10 is used in the manner shown in FIG. 6 when incorporated in a system using a 6-pin cable, and when incorporated in a system using a 4-pin cable. It is used in a manner as shown in FIG.
[0009]
[Problems to be solved by the invention]
In the embodiment shown in FIG. 7, the resistor R2 consumes power even though it does not contribute to the cable power supply voltage monitoring operation. That is, in the system shown in FIG. 7, a current always flows in a path connected to the power source Vdd, the CPS terminal 21, the resistor R2, and the ground, and power is consumed by the resistor R2.
[0010]
In general, in an electronic device incorporating an IEEE 1394 interface, in a battery-driven application such as a portable personal computer or a digital camera, an interface circuit (physical layer IC) is usually used during data transfer in order to reduce power consumption. ) Is set to low power consumption mode. In this low power consumption mode, in the physical layer IC, a circuit other than the minimum circuit necessary for guaranteeing a plug and play function that can be used immediately after a peripheral device is connected with a cable is placed in a standby state.
[0011]
In the system shown in FIG. 7, during normal operation in which data transfer is performed, power consumed in the above path including the resistor R <b> 2 is very small compared to power consumed by the entire physical layer IC 10. In the power consumption mode, the power consumed in the path occupies a considerable proportion of the power consumed by the entire physical layer IC 10, and suppression of power consumption at that time becomes a problem.
[0012]
In order to solve such a problem, it is desirable to suppress the power consumed by the resistor R2. For this reason, a method of increasing the resistance value of the resistor R2 can be considered. However, although the method of increasing the resistance value of the resistor R2 can reduce power consumption, there is a problem that the area occupied by the resistor R2 in the physical layer IC 10 increases and the manufacturing cost of the circuit increases.
[0013]
Further, a method of externally attaching the resistor R2 without incorporating it into the physical layer IC 10 is conceivable. However, in the system shown in FIG. 7, the power consumed by the above path is eliminated, but in the system shown in FIG. 6, since the resistor R2 is externally attached, the number of components mounted on the system increases. There's a problem.
[0014]
The present invention has been made to solve the above-described problems, and in a device for monitoring a power supply voltage of a communication cable in data communication conforming to a communication interface that can be supplied with power by the communication cable, a component on the system is mounted. An object of the present invention is to provide a power supply monitoring apparatus that suppresses power consumption without increasing the number. It is another object of the present invention to provide an information processing apparatus and an optical disc apparatus using the power monitoring apparatus.
[0015]
[Means for Solving the Problems]
The power supply monitoring apparatus according to the present invention is a power supply monitoring apparatus that monitors the voltage of a cable that supplies power in data communication conforming to a communication interface that can supply power through a communication cable. The power supply monitoring device compares a monitoring voltage input terminal for inputting a voltage to be monitored, a voltage dividing resistor connected between the voltage input terminal and the ground, and a voltage input from the voltage input terminal and a reference voltage. Comparing means, an output register for storing a comparison result from the comparing means, and a sleep means for inputting a sleep signal for controlling the power supply monitoring device to a sleep state in which the operation is stopped. When the sleep signal from the sleep means is active, the output of the output register is fixed to a predetermined value regardless of the voltage input to the monitoring voltage input terminal. By providing the sleep means, the power supply monitoring device can be controlled to a sleep state in which its monitoring function is stopped as necessary, and power consumption can be reduced.
[0016]
Preferably, the monitoring voltage input terminal is connected to the ground when the power monitoring device is used in the sleep state, and is connected to a communication cable that supplies power when the power monitoring device is not used in the sleep state. . In this way, by connecting the monitoring voltage input terminal to the ground in the sleep state, no current flows through the voltage dividing resistor, so that power consumption can be suppressed.
[0017]
Preferably, when the sleep signal is active, the output of the output register is fixed to “1”. That is, preferably, in the sleep state, a value “1” indicating that the power supply monitoring signal is normal is always output.
[0018]
The sleep means may be a terminal for inputting a sleep signal or a register for storing the sleep signal. This increases the freedom in designing the sleep means.
[0019]
The power monitoring apparatus further includes monitoring signal input means for inputting a monitoring signal for the power supply voltage of the communication cable from outside, and selection means for selecting and outputting the output of the output register and the output from the monitoring signal input terminal. You may prepare. At this time, the selection means selects the output of the output register when the sleep signal is not active, and selects and outputs the output from the monitoring signal input means when the sleep signal is active.
[0020]
The monitoring signal input means may be a terminal for inputting a monitoring signal or a register for storing the monitoring signal.
[0021]
Preferably, the operation of the comparator is stopped when the sleep signal is active. Thereby, the power consumption in the sleep state can be further suppressed.
[0022]
The power supply monitoring method according to the present invention is a power supply monitoring method in a power supply monitoring apparatus that monitors the voltage of a cable that supplies power in data communication conforming to a communication interface that can supply power through a communication cable. The method inputs a voltage to be monitored, compares the input voltage with a reference voltage, stores the comparison result in a register, and outputs the value stored in the register as a voltage monitoring result. When a sleep signal for controlling the sleep state, which is a state in which the operation of the monitoring device is stopped, is input and the input sleep signal is active, the output of the register is set regardless of the input monitor voltage. The value is fixed to a predetermined value.
[0023]
An information processing apparatus according to the present invention is an information processing apparatus that performs information processing based on a predetermined program, and performs data communication with an external device, in accordance with a communication interface that can be powered by a communication cable. Communication control means for controlling is provided. The communication control means monitors the voltage of the communication cable that supplies power using the power supply monitoring device.
[0024]
An optical disc apparatus according to the present invention is an optical disc apparatus that reads and writes data from and to an optical disc, and is data communication with an external device, and data communication conforming to a communication interface capable of supplying power via a communication cable. Communication control means for controlling The communication control means monitors the voltage of the communication cable that supplies power using the power supply monitoring device.
[0025]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.
[0026]
(Embodiment 1)
FIG. 1 shows a part of the configuration of an interface IC including a power supply monitoring unit according to the present invention. The interface IC 10a controls data communication in accordance with the IEEE 1394 protocol, and is used by being incorporated in an information processing apparatus such as a personal computer or other electronic devices. In particular, since the interface IC 10a shown in FIG. 1 is for controlling the physical layer of the interface protocol, it is hereinafter referred to as “physical layer IC”.
[0027]
The physical layer IC 10a includes a power supply monitoring unit 11a. As described in the prior art, power can be supplied through a communication cable in the IEEE 1394 protocol, and the power supply monitoring unit 11a is supplied through an information processing apparatus that performs data communication and a communication cable that connects them between electronic devices. The power supply voltage is monitored, and the monitored result is output as a binary signal. The power monitoring unit 11a includes a PS register 13, a comparator 15, a reference voltage generation circuit 17 that generates a reference voltage Vref, and a resistor R2. The power supply monitoring unit 11a further includes a CPS terminal 21 for inputting a cable power supply voltage to be monitored. The physical layer IC 10a also inputs a sleep signal (CPS-SLEEP signal) for controlling to a “sleep state” (details will be described later) in which the power monitoring function of the power monitoring unit 11a is stopped. Is provided. The sleep terminal 23 is connected to the comparator 15, the reference voltage generator 17, and the PS register 13 (set terminal of the PS register 13).
[0028]
The physical layer IC 10a configured as described above has two operation states: an active state in which power supply monitoring is performed and a sleep state in which the power supply monitoring function is stopped. These states are switched by a sleep signal input to the sleep terminal. In the active state, the power supply monitoring unit 11a monitors the power supply voltage of the communication cable connected to the CPS terminal 21 and outputs a monitoring signal based on the voltage. In the sleep state, the power supply monitoring unit 11a stops its power supply monitoring function, that is, does not monitor the power supply voltage of the communication cable, and always outputs a value “1” indicating “normal” as a monitoring signal.
[0029]
The physical layer IC 10a is used by being incorporated in an electronic device, and the connection mode at that time is a system in which the electronic device uses a communication cable power supply (system using a 6-pin cable) or a system that does not use ( The system depends on whether the system uses a 4-pin cable. That is, when incorporated in a system using a cable power supply (a system using a 6-pin cable), the power supply monitoring unit 11a is operated in an active state for monitoring the cable power supply voltage, while the system does not use the interface cable power supply. This is because when incorporated in a (system using a 4-pin cable), it is necessary to operate the power supply monitoring unit 11a in a sleep state in which the monitoring function is stopped. More specifically, it is as follows.
[0030]
i) When the physical layer IC 10a is incorporated in a system using a cable power supply (system using a 6-pin cable (see FIG. 6))
In this case, a communication cable for power supply (hereinafter referred to as “power cable”) is connected to the CPS terminal 21, and the power monitoring unit 11a needs to output a monitoring signal based on the power voltage of the power cable. , Controlled to active state. For this reason, the sleep terminal 23 is connected to the power supply or the ground so that the sleep signal to the sleep terminal 23 becomes inactive. The connection to the power supply or the ground is determined by whether the sleep signal is high active or low active. Further, the CPS terminal 21 is connected to the cable power source Vdd via a resistor connected to the outside (see FIG. 6). The power supply monitoring operation of the physical layer IC 10a at this time is as follows. The cable power supply voltage input to the CPS terminal 21 is compared with the reference voltage Vref from the reference voltage generator 17 by the comparator 15, and the comparison result is output to the PS register 13. The PS register 13 stores the comparison result from the comparator 15. The voltage state of the power cable can be known from the output value of the PS register 13.
[0031]
ii) When the physical layer IC 10a is incorporated in a system that does not use a cable power supply (system using a 4-pin cable (see FIG. 7))
In this case, the power supply monitoring unit 11a does not monitor the voltage of the cable power supply and needs to always output the value “1” indicating “normal” as the monitoring signal, so that it is controlled to the sleep state. Therefore, in order to control the power supply monitoring unit 11a to the sleep state, the sleep terminal 23 is connected to the ground or the power supply so that the sleep terminal 23 is forcibly activated. The connection to the power supply or the ground is determined by whether the sleep signal is high active or low active. The CPS terminal 21 is directly connected to the ground. Thus, by directly connecting the CPS terminal 21 to the ground, power consumption at the resistor R2 can be suppressed.
[0032]
The PS register 13 always outputs “1” indicating normality when the sleep signal is active, that is, when it is set by the sleep signal from the sleep terminal 23. When the sleep signal is active, the comparator 15 and the reference voltage generator 17 stop their operations. Thus, no power is consumed by the comparator 15 and the reference voltage generator 17 in the sleep state.
[0033]
By the way, if only the power consumption is suppressed only in the low power consumption mode, the sleep terminal 23 is connected to at least one of the comparator 15 or the PS register 13, and the comparator 15, the reference voltage generator 17, and the PS register 13 are connected. Of these, the low power consumption mode control signal may be connected to one to which the sleep terminal 23 is not connected. Even with such a configuration, an effect equivalent to that obtained when the sleep terminal 23 is connected to all of the comparator 15, the reference voltage generator 17, and the PS register 13 can be obtained. When the sleep terminal 23 is connected to the comparator 15, it is necessary to fix the output of the comparator 15 so that the output result of the comparator 15 becomes “1” when the sleep signal is active.
[0034]
Further, the clock signal (CLK) of the PS register 13 in FIG. 1 may be controlled according to the sleep signal from the sleep terminal 23 so that the clock signal is not input to the PS register 13 when the sleep signal is active.
[0035]
As described above, the physical layer IC of this embodiment is provided with a sleep terminal that inputs a sleep signal that is a control signal for stopping the monitoring function, and can thereby be controlled to a sleep state for stopping the monitoring function. It becomes. Therefore, when the physical layer IC is mounted and used in a system that does not use the cable power supply of the interface, the physical layer IC can be easily controlled to the sleep state using this sleep terminal. Power to be reduced.
[0036]
In the above description, the case where the communication interface is IEEE1394 has been described. However, the present invention is not limited to this, and the present invention can be applied to other interfaces as long as the interface can supply power via a communication cable.
[0037]
(Embodiment 2)
FIG. 2 shows another configuration of the interface IC. The interface IC 10b of the present embodiment includes a physical layer block 11b that controls the physical layer, a link layer block 31 that controls the link layer, and an upper layer interface block 33 that interfaces with the higher system. The PCI bus is used as an interface system with the host system. The interface IC 10b can be controlled from the host system via the PCI bus 100, and has a register area 40 including a register 41 for storing the value of the sleep signal. The register area 40 and the physical layer block 11b are separate systems at least for the control system for clock and reset.
[0038]
The physical layer block 11b basically has the same configuration as the power supply monitoring unit 11a of the physical layer IC shown in FIG. 1, but is provided in the register area 40 instead of the sleep terminal 23 for inputting a sleep signal. The register 41 for storing the sleep signal is used. The physical layer block 11 b outputs the monitoring result of the cable power supply voltage to the link layer block 31.
[0039]
As in the case of the first embodiment, when the interface IC 10b of the present embodiment is incorporated and used in a system using a cable power source, the CPS terminal 21 is connected to the cable power source Vdd via a resistor connected to the outside. In addition, the CPS terminal 21 is directly connected to the ground when used in a system that does not use a cable power supply. Thereby, the power consumption in the sleep state is suppressed as in the case of the first embodiment.
[0040]
In the initial state, the register 41 is set to “0” when the sleep signal is “1” and active (high active), and is set to “1” when the sleep signal is “0” and active (low active). The After the initial setting of the register 41, before the operation of the physical layer block 11b, preferably before the reset of the physical layer block 11b, at least before the output data of the PS register 13 becomes valid and processed, the bus 100 The register 41 needs to be set via As in the case of the first embodiment, by controlling the PS register 13, the comparator 15, and the reference voltage generator 17 based on the sleep signal stored in the register 41, power can be obtained as in the case of the first embodiment. An inhibitory effect is obtained.
[0041]
In addition, when the cable power supply is not monitored using a physical layer IC or physical layer block, but is performed using a separate element on the system, for example, a regulator IC of a power supply, the physical layer IC or physical layer block is used. This cable power supply monitoring device does not need to be used. However, the state of the cable power source needs to be reflected in the PS register 13. The reflection in the PS register 13 can be handled by directly inputting the monitoring result of the cable power source as an input signal to the CPS terminal 21 in the configuration of FIG. However, it is very wasteful from the viewpoint of power consumption.
[0042]
(Embodiment 3)
FIG. 3 shows still another example of the interface IC (physical layer IC).
The physical layer IC 10c shown in the figure includes an external monitoring signal terminal 25 and a selector 43 in addition to the circuit configuration of the physical layer IC shown in FIG. The external monitoring signal terminal 25 inputs an “external power monitoring signal” which is a monitoring result of the cable power monitored by the power monitoring device outside the physical layer IC 10c. The selector 43 receives an output from the PS register 13 and an external power supply monitoring signal input via the external monitoring signal terminal 25. The selector 43 selects and outputs either the output from the PS register 13 or the external power supply monitoring signal input via the external monitoring signal terminal 25 based on the sleep signal input via the sleep terminal 23. That is, the selector 43 selects and outputs the external power supply monitoring signal from the external monitoring signal terminal 25 when the sleep signal from the sleep terminal 23 is active, and PS when the sleep signal from the sleep terminal 23 is inactive. The output of the register 13 is selected and output.
[0043]
As described above, the physical layer IC as a whole outputs the monitoring result monitored by the external power supply monitoring device when in the sleep state, and outputs the output of the PS register 13 when in the active state. Therefore, when the power monitoring unit 11c is in the sleep state, it is possible to suppress wasteful power consumption consumed by the resistor R2 and the like and to output a monitoring result of the cable power state.
[0044]
(Embodiment 4)
FIG. 4 shows still another example of the interface IC. The interface IC 10d shown in the figure includes a physical layer block 11d, a link layer block 31, and an upper layer interface block 33, similarly to the interface IC of the second embodiment (FIG. 2).
[0045]
In particular, the physical layer block 11d of the present embodiment has a configuration substantially similar to the configuration of the physical layer IC 11c shown in the third embodiment (FIG. 3), but in the register region 40b, the second embodiment (FIG. 2). Thus, the difference is that the substitute register 41 of the sleep terminal 23 is provided and the register 45 is provided as an alternative of the external monitoring terminal 25. The register 41 stores the value of the sleep signal. The register 45 stores the value of the external power supply monitoring signal input to the interface IC 10d via the PCI bus 100 from the external power supply monitoring device 55 that monitors the voltage of the cable power supply. The registers 41 and 45 can be controlled from the host system via the bus 100. The selector 43 selects either the output of the PS register 13 or the value of the external power supply monitoring signal stored in the register 45 based on the value of the sleep signal stored in the register 41, and the link layer block 31 as the power supply monitoring signal. Output to. The register area 40 and the physical layer block 11d have separate systems for clock and reset control.
[0046]
In the initial state, the register 41 is set to “0” when the sleep signal is “1” and active (high active), and is set to “1” when the sleep signal is “0” and active (low active). The After completion of the initial setting of the register 41, before the operation of the physical layer block 11d (preferably before the reset of the physical layer block 11d), at least before the output data of the PS register 13 becomes valid and processed, the register 41, Set 45.
[0047]
(Embodiment 5)
FIG. 5 is a diagram for explaining an example of use of the interface IC shown in the above embodiment. In the drawing, an information processing apparatus 200 such as a personal computer that performs predetermined data processing such as document creation, image processing, and voice synthesis, and data reading to a CD (compact disc) that is an information recording medium including an optical disc, A state in which the CD-R device 300 that performs writing is connected by a communication cable 250 is shown. It is assumed that the information processing apparatus 200 and the CD-R apparatus 300 perform data communication according to an interface such as IEEE1394.
[0048]
The information processing apparatus 200 includes a controller 201 that controls the operation of the information processing apparatus 200 by executing a predetermined program, a RAM 203 that stores programs and data executed by the controller, a ROM 205, a hard disk 207 that is auxiliary storage means, characters, A display unit 209 for displaying an image and an input operation unit 211 including a keyboard and a mouse are connected to each other via a bus 215. Furthermore, the information processing apparatus 200 includes an interface unit 213 for controlling data communication with an external information processing device. The interface unit 213 includes the interface IC 10 as described above.
[0049]
The CD-R device 300 is a data communication between the controller 301 that controls the operation of the CD-R device 300, the drive mechanism 303 that performs processing such as reading and writing data on the CD, and the information processing device 200. And an interface unit 305 for controlling. The interface unit 305 includes the interface IC 10 as described above.
[0050]
The power monitoring device shown in the above embodiment is not limited to the information processing device and the CD-R device described above, and data communication conforms to an interface capable of supplying power via a communication cable such as IEEE1394. The same applies to any electronic device that performs the above.
[0051]
【The invention's effect】
According to the power monitoring device and the monitoring method of the present invention, it is possible to control whether or not the power monitoring device is operated in the sleep state from the outside. For this reason, in data communication conforming to an interface that can supply power via a communication cable, the power supply of the communication cable power supply need not be monitored without changing the configuration of the electronic device in which it is installed. It can be easily controlled and power consumption can be reduced.
[0052]
Further, according to the information processing apparatus or the optical disc apparatus of the present invention, the power monitoring of the communication cable power supply is not required in the information processing apparatus or the optical disc apparatus capable of data communication conforming to the interface capable of supplying power via the communication cable. In this case, power consumption can be reduced.
[Brief description of the drawings]
FIG. 1 shows a main part of an interface IC including a power supply monitoring unit according to the present invention (Embodiment 1).
FIG. 2 is a diagram showing a main part of an interface IC including a power supply monitoring unit according to the present invention (Embodiment 2).
FIG. 3 is a diagram showing a main part of an interface IC including a power monitoring unit according to the present invention (Embodiment 3).
FIG. 4 is a diagram showing a main part of an interface IC including a power monitoring unit according to the present invention (Embodiment 4).
FIG. 5 is a diagram illustrating a usage mode of an interface IC including a power supply monitoring unit according to the present invention.
FIG. 6 is a diagram illustrating a configuration of a monitoring unit for a cable power supply in a conventional system that does not use a cable power supply.
FIG. 7 is a diagram illustrating a configuration of a monitoring unit for a cable power supply in a conventional system using a cable power supply.
[Explanation of symbols]
10, 10a, 10b, 10c, 10d Interface IC
11a, 11c Power supply monitoring unit
11b, 11d physical layer block
13 PS register
15 comparator
17 Reference voltage generator
21 CPS terminal
23 Sleep terminal
31 Link layer block
33 Upper layer interface block
40 register area
41 Alternative registers for sleep terminals
43 selector
45 Substitute for external monitoring terminal
200 Information processing apparatus
300 CD-R device
R2 resistance

Claims (15)

A power monitoring device that monitors the voltage of a cable that supplies power in data communication conforming to a communication interface capable of supplying power via a communication cable,
A monitoring voltage input terminal for inputting a voltage to be monitored;
A resistor connected between the voltage input terminal and ground;
A comparison means for comparing the voltage input from the voltage input terminal with the reference voltage;
An output register for storing a comparison result from the comparison means;
Sleep means for inputting a sleep signal for controlling the power supply monitoring device to a sleep state in which the operation is stopped;
When the sleep signal from the sleep means is active, the output of the output register is fixed to a predetermined value regardless of the voltage input to the monitoring voltage input terminal. The monitoring voltage input terminal is connected to the ground when the power monitoring device is used in the sleep state, and is connected to a communication cable that supplies the power when the power monitoring device is not used in the sleep state. The power supply monitoring apparatus according to claim 1, wherein: 2. The power supply monitoring apparatus according to claim 1, wherein when the sleep signal is active, the output of the output register is fixed to “1”. 2. The power monitoring apparatus according to claim 1, wherein the sleep means is a terminal for inputting a sleep signal. The power monitoring apparatus according to claim 1, wherein the sleep unit is a register that stores a sleep signal. A monitoring signal input means for inputting a monitoring signal of a power supply voltage supplied by a cable from the outside; and a selection means for selecting and outputting an output of the output register and an output from the monitoring signal input terminal,
The selection means selects an output of the output register when the sleep signal is not active, and selects and outputs an output from the monitoring signal input means when the sleep signal is active. The power supply monitoring apparatus according to 1. 7. The power supply monitoring apparatus according to claim 6, wherein the monitoring signal input means is a terminal for inputting a monitoring signal. 7. The power monitoring apparatus according to claim 6, wherein the monitoring signal input means is a register for storing a monitoring signal. The power supply monitoring apparatus according to claim 1, wherein when the sleep signal is active, the operation of the comparator is stopped. In a power monitoring method in a power monitoring device that monitors the voltage of a cable that supplies power in data communication conforming to a communication interface capable of supplying power through a communication cable.
Enter the voltage to be monitored
Compare the input voltage with the reference voltage, store the comparison result in the register,
A method of outputting a value stored in the register as a voltage monitoring result,
Input a sleep signal for controlling to a sleep state in which the operation of the power monitoring device is stopped,
When the input sleep signal is active, the output value of the register is fixed to a predetermined value regardless of the input monitor voltage. When inputting the voltage monitored by the power supply monitoring device through a predetermined input terminal,
The input terminal is connected to the ground when the power monitoring device is used in the sleep state, and is connected to a communication cable that supplies power when the power monitoring device is not used in the sleep state. The power supply monitoring method according to claim 10. The power supply monitoring method according to claim 10, wherein when the sleep signal is active, the output of the register is fixed to “1”. Input the monitoring signal of the power supply voltage supplied by the cable from the outside,
11. The output of the register is selected when the sleep signal is not active, and the monitoring signal input from the outside is selected and output as a voltage monitoring result when the sleep signal is active. Power monitoring method. In an information processing apparatus that performs information processing based on a predetermined program,
Data communication with an external device, comprising a communication control means for controlling data communication conforming to a communication interface capable of supplying power via a communication cable,
10. The information processing apparatus according to claim 1, wherein the communication control means monitors a voltage of a communication cable that supplies power using the power monitoring apparatus according to any one of claims 1 to 9. In an optical disk device that reads and writes data on an optical disk,
Data communication with an external device, comprising a communication control means for controlling data communication conforming to a communication interface capable of supplying power via a communication cable,
An optical disc apparatus characterized in that the communication control means monitors the voltage of a communication cable that supplies power using the power monitoring apparatus according to any one of claims 1 to 9.

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