JP2000092251A - Power supply system for isdn terminal - Google Patents

Abstract

PROBLEM TO BE SOLVED: To extend an application scope of an ISDN terminal by providing a means that charges power to a battery circuit and a means or the like that supplies power from the charged battery circuit to the ISDN terminal so as to avoid supply of AC 100 V to the ISDN terminal. SOLUTION: This system is provided with an ISDN terminal connected to an ISDN network terminator, a battery circuit placed to the ISDN terminal, a means that charges power via an interface from the ISDN network terminator to the battery circuit, and a means that feeds power to the ISDN terminal from the charged battery circuit. A switch (m) of the battery circuit 24 disconnects a charging path from a T terminal interface in this system and the battery circuit 24 supplies power to a feeding terminal Vcc 28 of a load (terminal 21) via a switch (n). On the other hand, the switch (n) of the battery circuit 25 disconnects a load feeding path and the battery circuit 25 closes the switch (m) to charge a secondary battery of the battery circuit 25 via a DC/DC converter 23 from a T terminal interface wiring 2.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power supply system for an ISDN terminal device such as a digital telephone, a terminal adapter, and a digital telemetering device connected to an ISDN line.

[0002]

2. Description of the Related Art Conventionally, power supply systems for ISDN terminal devices such as digital telephones, terminal adapters, and digital telemetering devices connected to ISDN lines are ITU-
T Recommendation I. 430, the power from the T point interface specified in ITU-T I.430 is converted to a voltage (DC /
(DC converter) to directly supply power to the load.

FIG. 4 shows a power supply system of a conventional ISDN terminal device. In the figure, 1 is an ISDN network terminator, 2 is T
Multi-bus wiring for point interface, 3 for terminating resistor, 4
Is an ISDN terminal device, 5 is a terminal circuit, 6 is a DC / DC converter, 7 is a power adapter, 8 is an AC100V power cord, 9 is a switch for specifying whether to operate with station power or to supply power from the power adapter, and 10 is A power supply terminal of the ISDN terminal device, 51 is a control unit, and PT3 and PT4 are pulse transformers.

That is, the network terminating device 1 supplies power to a plurality of terminal devices 4 connected to the T-point interface wiring 2, and the maximum output of the power supply of the network terminating device 1 is 420 mW. On the other hand, the input power of the terminal device 4 connected to the T point interface wiring 2 is 380 mW at the maximum in the entire T point interface.

[0005] Point / multipoint connection (P / M
In P), in order to notify the incoming call to all terminal devices 4 at the time of an incoming call,
All terminal devices 4 connected to the T point interface wiring 2 are activated. In the case of a digital telephone, the power consumption during operation is about 250 mW. When a plurality of digital telephones are connected, only one of them is designated as a designated terminal and the switch (K) 9 is set to the station power supply mode, The terminal device 4 is operated by the output of the DC / DC converter 6. On the other hand, the other terminal devices 4 set the changeover switch (K) 9 on the power supply adapter 7 side, and supply power from the AC power supply 100 from the adapter power supply 7.

Here, the operation of the DC / DC converter 6 will be described. The DC / DC converter 6 has X (-), Y connected to the middle point of the pulse transformers PT3 and PT4.
The power on the T point interface wiring 2 is 42 at the (+) terminal.
V to 32 V, and receives the operating voltage of the terminal circuit 5 (for example, 5
V), and the power is supplied to the power supply terminal (Vcc) 10 of the terminal device 4 from the output point P. The load power consumed by the terminal circuit 5 is supplied directly from the X and Y terminals from the T point interface. Therefore, when a plurality of terminal devices 4 operate simultaneously, the power output of the network terminating device 1 drops and the drooping characteristic is obtained when the terminal output exceeds a certain value. Since the power is not normally supplied, the terminal device 4 cannot operate.

[0007]

SUMMARY OF THE INVENTION ITU-T Recommendation I.T. 4
30, the maximum output power of the network termination device on the T-point interface specified in Recommendation I.430 is 42 maximum.
0 mW, and in the case of a digital telephone as a terminal device, for example, approximately 250 mW of power is consumed during operation. Therefore, in order to suppress the power consumed by simultaneous activation on the T-point interface when an incoming call is received, one terminal (designated terminal) Can be operated only with station power supply, and other terminal devices
An adapter power supply with 100V input had to be used.

For this reason, when trying to connect the second terminal device at the point T, there is a problem that if the power supply tap of AC100V is not nearby, it cannot be installed or is difficult to install.

The present invention has been made in view of the above circumstances, and can eliminate the AC100V power supply of an ISDN terminal device and can be installed only with a communication line, so that the ISDN terminal device can be used in a wider range. An object of the present invention is to provide a power supply system for a device.

[0010]

In order to achieve the above object, an ISDN terminal power supply system according to the present invention comprises an ISDN terminal equipment connected to an ISDN terminal equipment via an interface.
A terminal device, a battery circuit provided in the ISDN terminal device, charging means for charging the battery circuit with power supplied from the ISDN network termination device via an interface, and a battery charged by the charging means From the circuit
Power supply means for supplying power to the DN terminal device.

Further, according to the present invention, in the power supply system of the ISDN terminal device, a plurality of battery circuits are provided in the ISDN terminal device, one of the battery circuits cuts a charging path to supply power to the ISDN terminal device, and the other battery circuit. Cuts the power supply path and
It is characterized by charging power supplied from the SDN network terminating device via an interface.

Further, according to the present invention, in the power supply system of the ISDN terminal device, when the power supply voltage of one of the battery circuits falls below a predetermined value, one of the battery circuits cuts off the power supply path, and the power supply path of the one of the battery circuits is cut off.
Switching the power supply path and the charging path of a plurality of battery circuits so that the power supplied from the SDN network terminator through the interface is charged and the other battery circuit cuts the charging path and supplies power to the ISDN terminal device. It is characterized by the following.

Further, the present invention is characterized in that, in the power supply system of the ISDN terminal device, the battery circuit is constituted by a secondary battery or a large-capacity capacitor.

According to the present invention, a circuit for receiving power from the T point interface and a circuit for supplying power to the load side are separated from each other without taking the form of DC / DC converting the power supply of the T point interface and directly supplying power to the load. It was decided to use a secondary battery or a large capacity capacitor. Therefore, even if a plurality of terminal devices connected to the T point interface operate simultaneously, the power supply output of the network termination device is excessive because the power supply circuit of the T point interface is disconnected from the load circuit of the terminal device. The load can be always suppressed to a specified maximum value of 420 mW or less without a load.

The application of the present invention depends on the utilization rate and the power conversion efficiency for the maximum input power of 380 mW of the terminal device connected to the T point interface. For example, if the total usage rate is 0.2 and the conversion efficiency is 0.8, the conversion efficiency exceeds the usage rate, so that charging of the secondary battery or the large-capacity capacitor is sufficiently possible.

[0016]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below in detail with reference to the drawings.

FIG. 1 is a structural explanatory view showing an embodiment of the present invention. In the figure, 1 is an ISDN network termination device, 2
Is the T-point interface multi-bus wiring, 3 is the terminating resistor,
21 is an ISDN terminal device, 22 is a terminal circuit, 23 is DC
/ DC converter, 24 is a battery circuit connected to the load power supply side, 25 is a battery circuit connected to the charging side, 26 and 27 are switching drivers for switching switches (contacts) m and n when the battery voltage drops, 28 is a terminal device Power supply terminal (Vcc),
29 is a control unit, PT1 and PT2 are pulse transformers, S
1, S2 is a signal, m is a charging switch (contact), n is a load power supply switch (contact), and switches (contacts) m and n are both switches (contacts) m and n simultaneously to prevent momentary interruption. This is an early make switch (contact) having a period in which it is turned on. D1 and D2 are backflow prevention diodes, which prevent backflow of current when both the switches m and n are on.

FIG. 2 is a block diagram of the battery circuit shown in FIG. In the figure, 41 is an overcharge prevention circuit, 42 is an overdischarge prevention circuit, CP1 is a first comparator, CP2 is a second comparator, and B is a secondary battery.

FIG. 3 is a characteristic diagram for explaining the operation of the overcharge prevention circuit of FIG.

Next, referring to FIG. 1, the IS of this embodiment will be described.
The power supply system of the DN terminal device will be described.

In FIG. 1, the network terminating device 1 supplies power to a plurality of terminal devices 21 connected to the T point interface wiring 2, and the maximum output power is 420 mW.

The difference from FIG. 4 is that battery circuits 24 and 25 including secondary batteries are used without using an AC 100 V adapter power supply.

First, the function of the DC / DC converter 23 in the power supply system of this embodiment will be described. The DC / DC converter 23 can operate in the input voltage range of 42 to 32 V, but the power supply stop voltage to the battery circuits 24 and 25 is set to around 35 V to prevent the load power from being exceeded. DC /
The power supply to the load is automatically stopped in the DC converter 23. The DC / DC converter 23 has three types of output terminals: a power output terminal Q serving as an input to the battery circuits 24 and 25, a lower reference voltage L of the secondary battery B, and an upper reference voltage H of the secondary battery B. The battery circuits 24 and 25 are switches m and n
Use to switch the connection destination. That is, the battery circuit 24
Switch off the charging path from the point interface with switch m,
Power is supplied to the power supply terminal (Vcc) 28 of the load (terminal device 21) via the switch n. On the other hand, the battery circuit 25 disconnects the load power supply path with the switch n, closes the switch m, and connects the DC / DC converter 2
3, the secondary battery B of the battery circuit 25 is charged.
Here, 26 and 27 are secondary batteries B of the battery circuits 24 and 25.
Is a driver M for switching the switches m and n when the power supply voltage falls below the lower-limit reference voltage L.

Next, the operation of the battery circuit will be described with reference to FIGS.

In the block diagram of the battery circuit shown in FIG. 2, the battery circuit 25 on the charging side receives power from an input terminal In connected to the DC / DC converter 23, and supplies the secondary battery B via an overcharge prevention circuit 41. The battery is charged with the charging current I. Here, the overcharge prevention circuit 41 controls the charging voltage and the charging current as shown in FIG. That is, the charging voltage is compared with the secondary battery upper limit reference voltage H of the output of the DC / DC converter 23 in FIG. 1 by the first comparator CP1. Set to 0. On the other hand, in the battery circuit 24 on the load power supply side, when the voltage of the secondary battery B falls below the lower limit reference voltage L by the second comparator CP2, the output OP is output, and the switching driver (M) 26 is driven to switch. m and n are switched, the load power supply path is switched to the other battery circuit 25, and the charging path is drawn into the own battery circuit 24, and the charging current I is started to flow to the secondary battery B by R.

The charging current I shown in FIG. 2 and FIG.
It depends on the receiving voltage of the DC converter 23. For example, T
Even when a plurality of terminal devices 21 are connected to the point interface wiring 2, the value of the charging current I is small when charging is completed, but when charging is performed simultaneously by the plurality of terminal devices 21 and the charging current is large, The charging current flows from the network termination device 1 within a range not exceeding 380 mW in total. At this time, when the input voltage of the DC / DC converter 23 in the terminal device 21 reaches the lower limit value (around 35 V), the output current of the DC / DC converter 23 stops at the time when charging is not completed (point S in FIG. 3). I do. Taking a certain timing after stopping, other terminal device 2
1 to perform a scan during charging to determine whether or not the terminal device 21 can be charged. When the charging of the secondary battery B of each terminal device 21 is completed, the charging current is cut off by the overcharge prevention circuit 41, so that the load current from the network termination device 1 does not flow naturally.

The over-discharge prevention circuit 42 shown in FIG.
This is for preventing the over-discharge in the event of a failure by making the operating voltage of the device 1 constant. Usually, a diode bridge is inserted in the DC / DC converter 23 so that the polarity of the interface wiring 2 at the point T matches the polarity of the voltage conversion circuit in the DC / DC converter 23.

In the above embodiment, the case where the battery circuit is constituted by a secondary battery has been described. However, the present invention is not limited to this, and the battery circuit may be constituted by a large-capacity capacitor.

[0029]

As described above, according to the present invention, the IT
U.T. Recommendation I. 430, AC of terminal equipment connected to the T point interface specified in ITU-T I.430
Since the 100 V power supply can be eliminated and can be installed only with the communication line, the use range of the ISDN terminal device can be expanded.

[Brief description of the drawings]

FIG. 1 is a configuration explanatory diagram showing an embodiment of the present invention.

FIG. 2 is a block diagram of the battery circuit shown in FIG.

FIG. 3 is a characteristic diagram illustrating an operation of the overcharge prevention circuit of FIG. 2;

FIG. 4 is a configuration explanatory view showing a power supply system of a conventional ISDN terminal device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ISDN network termination device 2 T point interface multi-bus wiring 3 Terminating resistor 21 ISDN terminal device 22 Terminal circuit 23 DC / DC converter 24 Battery circuit connected to load power supply side 25 Battery circuit connected to charging side 26 Switching driver 27 Switching Driver 28 Power supply terminal of terminal device (Vcc) 41 Overcharge prevention circuit 42 Overdischarge prevention circuit 51 Control unit

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 5K030 GA08 HC04 JA08 JT00 KA23 5K037 AA10 AB07 AC05 BA01 BA03 DA04 DA07 5K101 KK20 LL03 MM04 MM06 NN42 VV05

Claims (4)

[Claims] An ISDN terminal connected to the ISDN terminal via an interface; a battery circuit provided in the ISDN terminal; and a power supply to the battery via the interface from the ISDN terminal. A power supply system for an ISDN terminal device, comprising: charging means for charging power to be supplied; and power supply means for supplying power to the ISDN terminal device from a battery circuit charged by the charging means. 2. A plurality of battery circuits are provided in an ISDN terminal device, one of the battery circuits cuts a charging path to supply power to the ISDN terminal device, and the other battery circuit cuts a power supply path to cut IS power.
2. The ISD according to claim 1, wherein the power supplied from the DN network termination device via the interface is charged.
N terminal device power supply system. 3. When the power supply voltage of one of the battery circuits falls below a predetermined value, one of the battery circuits cuts the power supply path to
Switching the power supply path and the charging path of a plurality of battery circuits so that the power supplied from the DN network termination device via the interface is charged and the other battery circuit cuts the charging path and supplies power to the ISDN terminal device. The power supply system for an ISDN terminal device according to claim 2, wherein: 4. The power supply system for an ISDN terminal device according to claim 1, wherein the battery circuit comprises a secondary battery or a large-capacity capacitor.