JPH06309071A - Power saving circuit - Google Patents

Abstract

PURPOSE:To provide the power saving circuit which can stop supplying electric power to an interface circuit external equipment is not connected. CONSTITUTION:In the power saving circuit of a device which is used while the interface circuit of a host machine and external equipment are connected by a cable 5, the power source terminal of the interface circuit is connected to a power supply line (Vcc) through a short-circuit line 8 provided in the connector 4 of the cable 5. When the host machine and external equipment are not connected, the connector 4 of the cable 5 is disconnected from the host machine, so the power source terminal of the interface circuit and the power supply line are disconnected and no electric power is supplied to the interface circuit, so the power consumption becomes zero at this time.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power save circuit for reducing power consumption of office automation equipment such as a notebook computer, and more particularly, it is configured to eliminate waste of power consumption in an interface circuit with external equipment. It is a thing.

[0002]

2. Description of the Related Art In recent years, miniaturization of workstations, DTPs, personal computers and the like has progressed, and OA devices such as portable notebook personal computers that can be easily carried around have become widespread. In this portable device, in order to extend the usage time as much as possible, it is necessary to increase the battery capacity, but it is necessary to avoid increasing the weight that hinders carrying. In order to meet these conflicting requirements, it is necessary for portable devices to achieve low power consumption and to be configured to operate as long as possible within a specified battery capacity. There is.

[0003]

However, an external device (FDD,
In a device that is used by connecting with a CD-ROM or the like), power is supplied to the driver and the receiver circuit of the interface circuit with the external device of the host machine even when the external device is not connected, and many devices are used. Power is being consumed.

The present invention solves these conventional problems and provides a power save circuit capable of stopping the supply of power to the interface circuit with an external device when the external device is not connected. The purpose is to do.

[0005]

Therefore, in the present invention, in a power save circuit of an apparatus in which an interface circuit of a host machine and an external device are connected by a cable, a power save terminal of the interface circuit and a power supply line are connected. ,
It is configured to be connected via a short-circuit wire provided in the connector of the cable.

Further, in a power save circuit of an apparatus in which an interface circuit of a host machine and an external device are connected by a cable, a host machine and an external device are connected between a power supply terminal of the interface circuit and a power supply line. A switch means is provided which is turned on when connected and is turned off when not connected.

[0007]

Therefore, when the host machine and the external device are not connected, the connector of the cable is disconnected from the host machine, so that the power supply terminal of the interface circuit is disconnected from the power supply line. Therefore, no power is supplied to the interface circuit, and the power consumption at this time becomes zero.

The same applies to the case where the switch means is provided, and when the external device is not connected, the power supply to the interface circuit is cut off and the power consumption becomes zero.

[0009]

【Example】

(First Embodiment) In the power save circuit of the first embodiment, the driver and receiver of the interface circuit are connected unless the connector of the cable connecting the host machine and the external device is coupled to the connector of the interface circuit of the host machine. It is configured so that power is not supplied to the circuit.

FIG. 1 shows a state in which an interface circuit of the host machine and an external device interface circuit are connected by a cable 5, and the connector 3 of the host machine is shown.
And the connector 4 of the cable 5 are coupled, and the other connector 6 of the cable 5 and the connector 7 of the external device are coupled.

The interface circuit of the host machine comprises a driver circuit 1 for converting and sending out signals A to D, and a receiver circuit 2 for outputting received signals E to H.

The host-side connector 4 of the cable 5 for connecting the host machine and the external device is provided with a jumper wire 8 for connecting two independent pin groups (the number of pins in the group is arbitrary) to each other. ing.

Driver circuit 1 and receiver circuit 2
A power supply line for supplying power (Vcc) to the connector 3
Further, after passing through the pin of the connector 4, the jumper wire 8, and the other pin of the connector 4, the power source terminals of the driver circuit 1 and the receiver circuit 2 are connected again via the connector 3.

When the host machine and the external device are not connected by the signal cable 5, the connector 3 and the connector 4 in FIG. 1 are not coupled, and therefore the driver circuit 1 and the receiver circuit of the host interface circuit are not connected. Two
Is disconnected from the power supply (Vcc), and the power consumption in the driver circuit 1 and the receiver circuit 2 becomes zero. That is, the power consumption of the host machine can be reduced.

At that time, the output signals E, H of the receiver circuit 2
Is made inactive by the pull-down resistor, so that it does not adversely affect the system.

When the host machine and the external device are connected by the signal cable 5, the connector 3 and the connector 4,
Further, the connector 6 and the connector 7 are connected, and power is supplied to the driver circuit 1 and the receiver circuit 2 through the jumper wire 8 in the connector 4. At this time, the driver circuit 1 and the receiver circuit 2 are activated, and all interface signals (signals A to D, signals E to H, signals a to d, etc.) between the host machine and the external device are activated.
Signals e to h) are cable 5, connector 6, connector 7
And the host machine is ready to use the external device.

(Second Embodiment) The power save circuit of the second embodiment is provided with a switch for controlling the power supply to the driver circuit and the receiver circuit of the interface circuit according to the presence or absence of the connection of the external device.

FIG. 2 shows a state in which the interface circuit of the host machine and the external equipment interface circuit are connected by a cable 5. As in the case of the first embodiment (FIG. 1), the connector 3 of the host machine is shown. And the connector 4 of the cable 5 are coupled, and the other connector 6 of the cable 5 and the connector 7 of the external device are coupled.

The power supply (Vcc) supply line is connected to the power supply terminals of the driver circuit 1 and the receiver circuit 2 via the transistor 9 which operates as a control switch, and
The base of the transistor 9 is supplied with the output of the receiver 10 for identifying whether or not the host machine is connected to the external device.

The identification signal 11 input to the receiver 10 is low level when an external device is connected to the host machine because it is grounded through the external device, and is high level when the external device is not connected. Become.

Therefore, when an external device is not connected to the host machine, the output of the receiver 10 is inverted to a low level, the transistor 9 is turned off, and the driver circuit 1 and the receiver circuit 2 are supplied with power. Be cut. Therefore, the power consumption of the driver circuit 1 and the receiver circuit 2 becomes zero, and the power consumption of the host machine can be reduced. At this time, the output signals E and H of the receiver circuit 2 are made inactive by the pull-down resistor, so that they do not adversely affect the system.

When an external device is connected to the host machine, the output of the receiver 10 becomes high level, the transistor 9 is turned on, and power is supplied to the driver circuit 1 and the receiver circuit 2. Therefore, the driver circuit 1 and the receiver circuit 2 are activated, and all interface signals (signals A to D, signals E to H, signals a to d, signals e to h) between the host machine and the external device become valid, and the host The machine is ready for external equipment.

[0023]

As is apparent from the above description of the embodiments, the power save circuit of the present invention can disconnect the power supply to the driver circuit and the receiver circuit when the cable is not connected. It is possible to reduce the power consumption of the host machine when the external device is not connected.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of a power save circuit according to a first embodiment of the present invention,

FIG. 2 is a block diagram showing a configuration of a power save circuit in a second embodiment.

[Explanation of symbols]

 1 Driver circuit 2 Receiver circuit 3, 4, 6, 7 Connector 5 Cable 8 Jumper wire 9 Transistor 10 Receiver for identification 11 Identification signal

Claims (2)

[Claims] 1. A power save circuit of an apparatus for connecting an interface circuit of a host machine and an external device by using a cable, wherein a power supply terminal and a power supply line of the interface circuit are connected,
A power save circuit configured to be connected via a short-circuit wire provided in the connector of the cable. 2. A power save circuit of an apparatus for connecting an interface circuit of a host machine and an external device by using a cable, wherein the host machine and the external device are provided between a power supply terminal of the interface circuit and a power supply line. A power save circuit having switch means which is turned on when and are connected and is turned off when not connected.