JP3178785B2 - Clock supply circuit - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an OCU in a digital line station (hereinafter referred to as "OCU").
The present invention relates to a clock supply circuit for reducing power consumption caused by a clock supplied to a digital circuit in the device.

[0002]

2. Description of the Related Art FIG. 4 shows a configuration of a communication system including an OCU. In the figure, OCU1 installed on the station side,
A digital line home connection device (hereinafter, referred to as “DSU”) 3 installed at the user home side is connected by a two-line metallic line (hereinafter, referred to as “subscriber line”) 2. Each one of the subscriber lines 2 is indicated as L1, L2. A terminal device 5 is connected to the DSU 3 via the user / network interface line 4.
Is connected. The OCU 1 is connected via a signal line 6 inside the station.
A user information signal and an OCU control signal are exchanged with the exchange.

[0003] For example, in a communication system providing an ISDN basic interface, the interconnection condition between the DSU 3 and the terminal device 5 is determined by ITU-T Recommendation I.430 or TTC.
Complies with standard JT-I430-a, DSU3 and OCU1
The interconnection conditions with ITU-T Recommendation G.961 or T.
It conforms to TC standard JT-G961. FIG. 5 shows a configuration example of a communication system at the time of remote accommodation. Here, a configuration when a communication system is constructed in a user building or the like is shown.

In the figure, a plurality of OCUs 1 are accommodated in a remote multiplexing device 7 installed in a user building or the like, and a plurality of intra-station signal lines 6 are time-division multiplexed by a multiplexing device 9 to perform multiplex transmission. It is connected to the exchange at the central office via the line 8. The remote multiplexing device 7 is usually backed up by a battery 10 to maintain communication at the time of a 100 V AC power failure. Therefore, reduction of power consumption in the OCU 1 is a major issue.

FIG. 6 shows a configuration example of a conventional OCU. In the figure, a station inside signal line 6 has a user information / OCU control signal 11 exchanged with an exchange and an externally supplied clock 12 necessary for the operation of the OCU 1. The intra-office interface circuit block 13 is a digital circuit that operates using the externally supplied clock 12 as a main clock, detects an OCU control signal in the user information / OCU control signal 11, and executes control such as starting and stopping the OCU 1. The user information signal in the user information / OCU control signal 11 is connected to the transmission line termination circuit block 14 without being processed by the intra-office interface circuit block 13.

The transmission line termination circuit block 14 is usually
Pulse transmission and intra-station interface circuit block 1
3 is configured to operate using the externally supplied clock 12 as a main clock for receiving and transmitting a signal, and to receive a pulse, using the internally supplied clock 21 from the crystal oscillator 20 as a main clock. It is also possible to adopt a configuration in which the externally supplied clock 12 is used as the main clock instead of the internally supplied clock 21 to perform pulse reception.

In order to operate the transmission line termination circuit block 14, it is necessary to detect a communication start request signal and to instruct the transmission line termination circuit block 14 to start transmission / reception of pulses, start power supply to the DSU 3, and the like. A call request (communication request from the user side) input from the subscriber line 2 is detected by a call request detection circuit block 18 and the detection result is transmitted by a call start signal 19 to a transmission line termination circuit block 14.
Will be notified. A direct current flowing on the subscriber line 2 is normally used for a call request from the user side. On the other hand, the incoming call request signal (communication request signal from the exchange side) is included in the OCU control signal in the user information / OCU control signal 11, and the incoming call request signal 16 output from the intra-office interface circuit block 13. Is the incoming call request detection circuit block 1
5, and the result of the detection is notified to the transmission line termination circuit block 14 by an incoming call activation signal 17.

When the call start signal 19 or the call start signal 17 is turned on (communication start request), the transmission line termination circuit block 14 starts transmission / reception of a pulse and starts power supply to the DSU 3. If the call start signal 19 or the call start signal 17 is turned off (communication stop request),
The transmission and reception of the pulse and the power supply to the DSU 3 are stopped.

[0009]

2. Description of the Related Art It is known that a digital circuit consumes power due to a current flowing in a transient process such as a switching operation due to an input of a clock or the like even when an element current does not flow in a steady state. ing. Conventional O
In the CU1, since the external supply clock 12 and the internal supply clock 21 are always supplied to the transmission line termination circuit block 14, even in the stop state where communication is not required,
Useless power is consumed by the switching operation of the digital circuit by the clock. For example, even if all or a part of the circuit of the transmission line terminating circuit block 14 is composed of a low power consumption CMOS-LSI, the operation clock is supplied to charge and discharge the parasitic capacitance of the gate element in the CMOS-LSI. And the power consumption increases as the clock frequency increases.

On the other hand, in order to reduce the power consumption of the transmission line terminating circuit block 14, there is a method of using a power switch to stop the power supply for operation when the transmission line termination circuit block 14 is stopped.
However, this method has a problem that the power consumption at the time of the start-up operation is increased by the power loss due to the on-resistance of the power switch. The present invention does not increase the power consumption during the start-up operation in the OCU, and the transmission line termination circuit block in a stopped state.
Clock that can reduce the power consumption in the click
The purpose of the present invention is to provide a power supply circuit .

[0011]

A clock supply circuit according to the present invention is provided.
The communication path uses a communication start / stop request signal to the transmission line termination circuit block of the OCU, and a clock ( externally supplied clock,
Block input clock is blocked. As a result, the digital circuit of the transmission line termination circuit block enters the hold state, and power consumption can be reduced. In particular, in the case of a digital circuit constituted by a CMOS-LSI that consumes power to charge and discharge the parasitic capacitance of the gate element, the effect of reducing power consumption is great.

[0012]

Figure 1 DETAILED DESCRIPTION OF THE INVENTION shows an embodiment of the OCU including a clock supply circuit according to claim 1. In the figure, the basic configuration of the OCU 1 is the same as that of the conventional OCU 1 shown in FIG.
Is the same as The feature of the present embodiment is that an AND gate 24 as a switch element for disconnecting the externally supplied clock 12 supplied to the transmission line terminating circuit block 14,
An OR gate 22 is provided for performing on / off control of an AND gate 24 by a start signal 23 which is a logical sum of an incoming call start signal 17 and a call start signal 19.

Here, the incoming call activating signal 17 and the calling activating signal 19 are defined to be at a high level when a communication start request is made and to be at a low level when a communication stop request is made.
That is, when the communication start request is issued, the activation signal 23 goes high, and the externally supplied clock 1
2 is supplied to the transmission line termination circuit block 14. on the other hand,
At the time of the communication stop request, the activation signal 23 becomes low level, the external supply clock 12 is blocked by the AND gate 24, and the supply to the transmission line termination circuit block 14 is stopped.

FIG. 2 shows an embodiment of an OCU including a part of the clock supply circuit of the present invention . In the figure, OCU1
Is similar to that of the conventional OCU 1 shown in FIG. The feature of this embodiment is that the transmission line termination circuit block 1
And an AND gate 25 as a switch element for disconnecting the internal supply clock 21 supplied to the C.4, and a start signal 2 obtained by ORing the call start signal 17 and the call start signal 19
3 is provided with a logical sum gate 22 for performing on / off control of a logical product gate 24.

Here, the incoming call activating signal 17 and the calling activating signal 19 are defined to be at a high level when a communication start request is made and at a low level when a communication stop request is made.
That is, when the communication start request is issued, the activation signal 23 becomes high level, and the internal supply clock 2
1 is supplied to the transmission line termination circuit block 14. on the other hand,
At the time of the communication stop request, the start signal 23 becomes low level, the internal supply clock 21 is blocked by the AND gate 25, and the supply to the transmission line termination circuit block 14 is stopped.

FIG. 3 shows an embodiment of an OCU including the clock supply circuit according to the second aspect. In the present embodiment, FIG.
2 is combined with each embodiment shown in FIG. 2, and has a configuration in which disconnection control is performed on the externally supplied clock 12 and the internally supplied clock 21 supplied to the transmission line termination circuit block 14.

[0017]

As described above, according to the clock of the present invention,
The supply circuit can prevent the operation clock supplied to the transmission line termination circuit block when the communication is stopped by adding the switch means by the gate circuit. This allows
The power consumption of the transmission line termination circuit block at the time of communication stop is summarized in the power consumption in the gate circuit of the switch means,
The power consumption of the OCU can be significantly reduced. In particular, the operation time during the battery backup operation in the remote multiplexing device can be extended. In addition, since the battery capacity can be reduced, a small battery can be employed.

[Brief description of the drawings]

FIG. 1 shows an OC including a clock supply circuit according to claim 1 .
The figure which shows Embodiment of U.

FIG. 2 shows an OCU including a part of the clock supply circuit of the present invention .
FIG.

FIG. 3 shows an OC including the clock supply circuit according to claim 2;
The figure which shows Embodiment of U.

FIG. 4 is a diagram showing a configuration of a communication system including an OCU.

FIG. 5 is a diagram showing a configuration example of a communication system at the time of remote accommodation.

FIG. 6 is a diagram showing a configuration example of a conventional OCU.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Digital line terminal unit (OCU) 2 2-line metallic line (subscriber line) 3 Digital line home terminal unit (DSU) 4 User / network interface line 5 Terminal device 6 Internal signal line 7 Remote multiplexer 8 Multiplexing Transmission line 9 Multiplexer 10 Battery 11 User information / OCU control signal 12 External supply clock 13 Local interface circuit block 14 Transmission line termination circuit block 15 Call request detection circuit block 16 Call request signal 17 Call start signal 18 Call Request detection circuit block 19 Call start signal 20 Crystal oscillator 21 Internal supply clock 22 OR gate 23 Start signal 24, 25 AND gate

Continuation of front page (58) Field surveyed (Int.Cl. ⁷ , DB name) H04M 19/00

Claims (2)

(57) [Claims] And 1. A means for detecting the communication start-stop request signal is started by the communication start request signal, and a transmission line termination circuit block stops operation by the communication stop request signal <br/>, transmission line termination the clock supply circuit of the digital line station terminator is configured to operation clock of the circuit blocks are supplied from the outside, the heat transfer of the externally supplied clock by the communication start request signal
Clock supply circuit, characterized in that it comprises a switch means for stopping the supply of the external clock supplied to the feed supplied to the line termination circuit block, said transmission line terminating circuit block by the communication stop request signal. 2. A means for detecting the communication start-stop request signal is started by the communication start request signal, and a transmission line termination circuit block stops operation by the communication stop request signal <br/>, transmission line termination In a clock supply circuit of a terminal unit in a digital line station, wherein an operation clock of a circuit block is supplied from an external and an internal oscillator, an external supply clock and an internal supply clock are supplied to the transmission line termination circuit block by the communication start request signal. And the transmission line termination circuit according to the communication stop request signal.
A clock supply circuit comprising switch means for stopping supply of an external supply clock and an internal supply clock to a block .