JPH089071A - Power supply circuit for communication equipment - Google Patents

Abstract

PURPOSE:To simplify the design, development and management or the like of a power supply circuit in the communication equipment whose system power supply voltage differs from the system and to prevent the operation of a DC/DC converter from being unstable. CONSTITUTION:A -48VDC is adopted for a large capacity system and a -24VDC is adopted for a small capacity system as a system power voltage from a main power supply 11. An input voltage detection circuit 2 detects whether a voltage applied to a power input terminal 1 is -24VDC or -48VDC and a power supply control circuit 3 activates a DC/DC converter main body 4 in the case of -24VDC and does not activate it in the case of -48VDC. The DC/DC converter main body 4 boosts the input voltage of -24VDC into -48VDC in its operation and provides an output to a power supply output terminal 5 but provides the input voltage as an output to the power supply output terminal 5 in its inoperativeness. The power supply voltage of -48VDC is applied to circuits such as a trunk circuit.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power supply circuit used for communication equipment such as a PBX (Private Branch Exchange),
In particular, the present invention relates to a power supply circuit used in a communication device in which a system power supply voltage varies depending on the system.

[0002]

2. Description of the Related Art Generally, in a communication device, a system power supply voltage (power supply voltage of a main power supply) is often different between a large capacity system and a small capacity system. Taking the PBX as an example, the system power supply voltage is −48V in the large capacity system and −24V in the small capacity system. However, since the power supply voltage of -48V is used in the PBX, for example, in the trunk line trunk regardless of the large capacity or the small capacity system, in the large capacity system for the trunk line trunk, the system power supply voltage of -48V is unchanged (or stable). However, in a small capacity system, the system power supply voltage of -24V must be boosted to -48V.

[0003]

However, in a communication device in which the system power supply voltage varies depending on the system as described above, if the power supply circuit is individually designed / developed, manufactured, stock controlled, serviced, etc. There is a problem that it does not become. Further, in order to simplify this trouble, it is conceivable that the printed circuit board of the power supply circuit is shared at the time of design / development and the mounted components are changed according to the power supply voltage at the time of manufacturing, but the trouble of management etc. does not change. Furthermore, in the case of the PBX, if a -24V power supply circuit of a small capacity system is diverted for a large capacity system, a suitable DC / DC converter cannot be obtained or the operation of the DC / DC converter becomes unstable. There is a problem.

In view of the above-mentioned conventional problems, the present invention can simplify design, development, management, etc. in a communication device in which the system power supply voltage varies depending on the system, and D
An object of the present invention is to provide a power supply circuit of a communication device capable of preventing the operation of the C / DC converter from becoming unstable.

[0005]

In order to achieve the above object, the invention according to claim 1 converts a system power supply voltage from a main power supply into a predetermined voltage during operation and uses it as a power supply voltage, and when not operating, the power supply voltage as it is. , A DC / DC converter for outputting to a necessary circuit of a communication device, a voltage detection means for detecting a system power supply voltage from a main power supply, and the DC / DC converter when the voltage detected by the voltage detection means is not the predetermined voltage. And a control circuit for operating the DC converter and controlling the DC / DC converter not to operate when the predetermined voltage is applied.

According to a second aspect of the present invention, the DC / DC converter operates when a system power supply voltage from a main power supply is applied, boosts the voltage to a predetermined voltage, and outputs the power supply voltage to a necessary circuit of a communication device. At the same time, the control circuit operates the DC / DC converter when the system power supply voltage from the main power supply is equal to or lower than the predetermined voltage, and when the system power supply voltage from the power supply is the predetermined voltage, the control circuit directly outputs the power supply voltage. It is characterized by having a switch for outputting to a necessary circuit of a communication device.

According to a third aspect of the present invention, the DC / DC converter does not operate when the system power supply voltage from the main power supply is relatively high, and outputs the power supply voltage as it is, and when it is relatively low, operates. It is characterized in that the predetermined high voltage is output.

According to a fourth aspect of the present invention, input voltages for stable operation are different, and different system power supply voltages from the main power supply are converted into predetermined voltages during operation, and are output to necessary circuits of communication equipment as power supply voltages. A plurality of DC / DC converters, a voltage detection means for detecting a system power supply voltage from a main power supply, and a stable operation among the plurality of DC / DC converters according to the voltage detected by the voltage detection means. And a control circuit for selectively operating one of them.

According to a fifth aspect of the present invention, the plurality of DC /
The output voltage of the DC converter is different.

[0010]

According to the present invention, when the system power supply voltage from the main power supply is not a predetermined voltage, DC / DC
Since the converter operates and the DC / DC converter does not operate when the voltage is a predetermined voltage, one type of power supply circuit can be used even when the system power supply voltage varies depending on the system. Therefore, design, development and management are possible. Etc. can be simplified. In addition, since the DC / DC converter operates or does not operate, the DC / DC converter can operate even when the system power supply voltage varies depending on the system.
It is possible to prevent the operation of the converter from becoming unstable.

Further, according to the inventions of claims 4 and 5, one of the plurality of DC / DC converters which operates stably is selectively operated, so that even when the system power supply voltage differs depending on the system. One type of power supply circuit can be used, and therefore, design, development, management, etc. can be simplified. Also, since the DC / DC converter operates or does not operate, it is possible to prevent the operation of the DC / DC converter from becoming unstable even when the system power supply voltage varies depending on the system. You can

[0012]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing a power supply circuit of a PBX as an embodiment of a power supply circuit of a communication device according to the present invention. In the PBX, the power supply circuit 10 includes DC-24 from the main power supply 11.
A system power supply voltage of V or -48V is supplied. The main power supply 11 is supplied with a commercial power supply 12 of AC100V or 200V and generates a power supply voltage of DC-48V in a large capacity system, and is used in a small capacity system.
A generator that generates a power supply voltage of -24V is used. The power supply circuit 10 of the present embodiment supplies a power supply voltage of DC-48V to the trunk circuit, for example, regardless of the large capacity or small capacity system, by the system power supply voltage from the main power supply 11.

In FIG. 1, a power supply voltage from a main power supply 11 is applied to a power supply input terminal 1 (1a, 1b), and an input voltage detection circuit 2, a power supply control circuit 3 and a DC / DC converter are connected via the power supply input terminal 1. It is applied to the DC converter body 4. Here, the DC / DC converter main body 4 is operated by the DC-24.
Power supply output terminal 5 by boosting V input voltage to DC-48V
It is configured to output to (5a, 5b) and output the input voltage as it is to the power supply output terminal 5 when it is not operating.

The input voltage detection circuit 2 detects whether the voltage applied to the power supply input terminal 1 is -24V or -48V and applies the detection signal to the power supply control circuit 3.
The DC / DC converter main body 4 is controlled so as to operate by applying the input voltage as a power supply voltage in the case of -24V, while the DC / DC converter main body 4 is prevented from operating in the case of -48V. That is, the output voltage is controlled to output -48V as it is.

FIG. 2 shows the input voltage detection circuit 2 and the power supply control circuit 3 in detail. GND of power input terminal 1
The (0V) terminal 1b has a voltage dividing resistor R1 and a Zener diode Z.
1 is connected to the negative terminal 1a of the power input terminal 1 through a series circuit of 1, and the connection point of the resistor R1 and the Zener diode Z1 is connected to the base of the PNP transistor Tr1 via the base resistor R2. The Zener diode Z1 has a Zener voltage VZ1 in the range of -24V>VZ1> -48V.

The GND terminal 1b of the power supply input terminal 1 is also connected to the emitter of the transistor Tr1 and the cathode of the Zener diode Z2, and the collector of the transistor Tr1 and the anode of the Zener diode Z2 are connected via a resistor R3.
It is connected to the terminal 1a and is a PNP transistor Tr.
2 and the collector of the transistor Tr2 is connected to the-terminal 1a via the resistor R4. Zener diode Z2 has a Zener voltage VZ2 of -24V.
The following are used:

One of the power supply terminals 4a of the DC / DC converter main body 4 has a GN of a power supply input terminal 1 and a power supply output terminal 5.
The D terminals 1b and 5b are connected, and the other power supply terminal 4b is connected to the emitter of the transistor Tr2. The terminal 4c is connected to the negative terminal 1a of the power supply input terminal 1, and the terminal 4d is connected to the negative terminal 1a of the power supply output terminal 5. A diode 6 is connected between the terminals 4c and 4d with a reverse polarity.

The DC / DC converter body 4 is -24V in operation according to the power supply voltage between the power supply terminals 4a and 4b.
Input voltage is boosted to -48V and output to the power supply output terminals 5a and 5b via the terminals 4a and 4d. On the other hand, when not operating, the -48V input voltage is output as it is via the terminals 4a and 4c and the diode 6. Is configured to. In such a configuration, the transistor Tr1 in the input voltage detection circuit 2 is off when the voltage applied to the power supply input terminal 1 is -24V and is on when it is -48V.
Therefore, in the case of -24V, the transistor Tr1 is off, so that the transistor Tr in the power supply control circuit 3 is
2 is turned on and the DC / DC converter main body 4 is in the operating state, and the input voltage of -24V is boosted to -48V and output to the terminals 4a and 4d.

On the other hand, the voltage applied to the power input terminal 1 is -48.
In the case of V, since the transistor Tr1 is on, the voltage across the Zener diode Z2 in the power supply circuit 3 is almost zero.
It becomes V, the transistor Tr2 is turned off, and DC / D
The C converter body 4 receives the input voltage of −48 V as it is through the terminals 4 a and 4 c and the diode 6 and the power output terminal 5
Output to a and 5b.

Therefore, according to the above embodiment, when the voltage applied to the power input terminal 1 is -24V, the DC / DC converter main body 4 operates and the input voltage of -24V is -48V.
If the voltage applied to the power input terminal 1 is -48V after boosting to V, the DC / DC converter main body 4 does not operate and becomes -4.
Since the input voltage of 8V is output as it is, it is possible to simplify the same design, development, management and the like in the PBX of the large capacity system with the system power supply voltage of -48V and the small capacity system of -24V. Further, since the DC / DC converter main body 4 operates or does not operate according to the system, it is possible to prevent the operation from becoming unstable.

In the example shown in FIG. 2, the Zener diode Z2 may be omitted, but in this case, since the input voltage of the DC / DC converter body 4 fluctuates and its output voltage fluctuates, DC / DC This problem can be solved by providing the DC converter body 4 with a circuit in which the fluctuation of the input voltage does not affect the output voltage.

Next, a modification of the above embodiment will be described with reference to FIG. In this example, the input voltage detection circuit 2 is connected to the power input terminals 1a and 1b, and the GND terminal 1
b is DC / D via a switch 7 such as a transistor
It is connected to all power supply terminals of the C converter body 4. Furthermore, the GND terminal 1b of the power input terminal 1 and the power output terminal 5
A diode 6 is connected between the GND terminals 5b so that it does not turn on when the power supply voltage is -24V but turns on when the power supply voltage is -48V.

In this configuration, when the applied voltage to the power supply input terminals 1a and 1b is -24V, the switch 7 is turned on by the control of the input voltage detection circuit 2 and the power supply voltage is DC / D.
The DC / DC converter main body 4 is operated by being supplied to the C converter main body 4, and the input voltage of -24V is -48V.
To the power supply output terminals 5a and 5b.

On the other hand, when the voltage applied to the power supply input terminals 1a and 1b is -48V, the switch 7 is turned off by the control of the input voltage detection circuit 2, and the power supply voltage is supplied to the DC / DC converter main body 4. Therefore, the DC / DC converter body 4 does not operate, but the voltage applied to the power supply input terminals 1a and 1b is output to the power supply output terminals 5a and 5b through the diode 6.

Instead of using the diode 6, the configuration of the switch 7 is modified so that the applied voltage to the power supply input terminals 1a and 1b is switched to the DC / DC converter main body 4 side in the case of -24V, and is changed to -48V. Power output terminal 5
You may make it switch to the a, 5b side.

FIG. 4 shows a modification of FIG. 3, showing an example corresponding to the case where the input voltage of the power supply input terminals 1a and 1b, that is, the output voltage of the main power supply 11 shown in FIG. The plurality of input voltage detection circuits 2a, 2b, ... Detect the voltage in the range of 0 (V) to V1, the voltage in the range of V1 to V2, ... (However, V1 <V2 <...) 7b are turned on and the input voltage detection circuit 2 in the next stage is set to the non-detection state. Further, the DC / DC converter main bodies 41, 42 ... Are supplied from the respective switches 7a, 7b.
The voltage in the range of 1 and the voltage in the range of V1 to V2 are -48V.
Is configured to convert to.

The operation will be described. Power input terminals 1a, 1
When the input voltage of b is lower than the voltage V1, the input voltage detection circuit 2a at the uppermost stage turns on the switch 7a to turn on the DC / D.
While operating the C converter main body 41, the input voltage detection circuit 2b in the next stage is forcibly set to the non-detection state.
The input voltage detection circuit 2 of the previous stage forces the input voltage detection circuit 2 of the next stage to the non-detection state. After the input voltage detection circuit 2 in the non-detection state, the switch 7 is turned off and the DC / DC converter body 4 is not operated. Therefore, only the uppermost DC / DC converter main body 41 operates to convert the input voltage in the range of 0 (V) to V1 to -48V.

When the input voltage of the power supply input terminals 1a and 1b is the voltage V1 to V2, the uppermost input voltage detection circuit 2a turns off the switch 7a and does not operate the DC / DC converter main body 41. Further, the input voltage detection circuit 2b of the next stage turns on the switch 7b to operate the DC / DC converter main body 42, and the input voltage detection circuit 2c of the next stage is forcibly set to the non-detection state. The input voltage detection circuit 2 of the previous stage is the input voltage detection circuit 2 of the next stage
Is forced to the non-detection state. Therefore, the second stage D
Only the C / DC converter body 42 operates to operate V1 to V2.
The input voltage in the range of is converted to -48.

FIG. 5 shows two input voltages of opposite polarity + Vcc,
Three types of output voltage + Vout2, + Vout1,
A power supply circuit for generating -Vout is shown. DC / DC
The converter main bodies 41a and 42a each have an input voltage + V
It is configured to convert cc into output voltages + Vout2, + Vout1 and output between the GND terminal 50 and the output terminals 51, 52. The DC / DC converter main body 43a has an input voltage -Vcc.
Is converted into an output voltage -Vout and output between the GND terminal 50 and the output terminal 53.

Further, the input voltage detection circuit 21 outputs a high level signal to the AND gate 81 when the voltage between the + Vcc terminal 1c and the GND terminal 1b which are the input terminals is the voltage + Vcc.
To the GN which is an input terminal.
When the voltage between the D terminal 1a and the -Vcc terminal 1a is -Vcc, a high level signal is output to the AND gate 81.
In this case, all the switches 71 and 72 are turned on,
The DC / DC converter main bodies 41 to 43 all operate to output the voltages + Vout2, + Vout1, and -Vout, respectively.

On the other hand, when the voltages applied to the input terminals 1a to 1c are not the predetermined voltages, the signals from the input voltage detection circuits 21 and 22 to the AND gates 81 and 82 become low level, and the DC / DC converter main body. 41-4
No 3 works.

[0032]

As described above, in the inventions according to claims 1 to 3, the DC / DC converter operates when the system power supply voltage from the main power supply is not the predetermined voltage, and when the system power supply voltage is the predetermined voltage, the DC / DC converter. Does not operate, one type of power supply circuit can cope with the case where the system power supply voltage varies depending on the system. Therefore, the design, development, management, etc. can be simplified. Also, D
Since the C / DC converter operates or does not operate, it is possible to prevent the operation of the DC / DC converter from becoming unstable even when the system power supply voltage varies depending on the system. .

Further, in the inventions as claimed in claims 4 and 5, one of the plurality of DC / DC converters which operates stably operates selectively, so that even when the system power supply voltage varies depending on the system. One type of power supply circuit can be used, and therefore, design, development, management, etc. can be simplified. Also, since the DC / DC converter operates or does not operate, it is possible to prevent the operation of the DC / DC converter from becoming unstable even when the system power supply voltage varies depending on the system. You can

[Brief description of drawings]

FIG. 1 is a block diagram showing a power supply circuit of a PBX as an embodiment of a power supply circuit of a communication device according to the present invention.

FIG. 2 is a circuit diagram showing the power supply circuit of FIG. 1 in detail.

FIG. 3 is a block diagram showing a modified example of the power supply circuit of FIG.

FIG. 4 is a block diagram showing a power supply circuit having a plurality of DC / DC converters.

5 is a block diagram showing a modification of the power supply circuit of FIG.

[Explanation of symbols]

1, 1a to 1c Power supply input terminal 2, 2a, 2b, 21, 22 Input voltage detection circuit 3 Power supply control circuit 4, 41, 42, 41a to 43a DC / DC converter main body 5, 5a, 5b, 50 to 53 Power supply output Terminal 6 Diode 7, 7a, 7b, 71, 72 Switch 81, 82 AND gate 10 Power supply circuit 11 Main power supply

Claims (5)

[Claims] 1. A DC / DC converter that converts a system power supply voltage from a main power supply into a predetermined voltage when operating and outputs it as a power supply voltage to a necessary circuit of a communication device when not operating, and a main power supply. Voltage detecting means for detecting the system power supply voltage, and operating the DC / DC converter when the voltage detected by the voltage detecting means is not the predetermined voltage, and operating the DC / DC converter when the voltage is the predetermined voltage. A power supply circuit for a communication device, which has a control circuit for controlling so as not to allow the power supply. 2. The DC / DC converter operates when a system power supply voltage from a main power supply is applied, boosts the voltage to a predetermined voltage, outputs it as a power supply voltage to a necessary circuit of a communication device, and controls the control. The circuit operates the DC / DC converter when the system power supply voltage from the main power supply is less than or equal to the predetermined voltage, and further, when the system power supply voltage from the power supply is at the predetermined voltage, the communication device requires the power supply voltage as it is. The power supply circuit for a communication device according to claim 1, further comprising a switch for outputting to the circuit. 3. The DC / DC converter does not operate when the system power supply voltage from the main power supply is relatively high, and outputs the power supply voltage as it is, and when it is relatively low, it operates the relatively high predetermined voltage. It outputs, The power supply circuit of the communication equipment of Claim 1 or 2 characterized by the above-mentioned. 4. A plurality of DC / DCs which have different input voltages for stable operation and which convert different system power supply voltages from a main power supply into predetermined voltages during operation and output as power supply voltages to necessary circuits of communication equipment. A converter, a voltage detection means for detecting a system power supply voltage from a main power supply, and one of the plurality of DC / DC converters that operates stably according to the voltage detected by the voltage detection means. A power supply circuit of a communication device having a control circuit for operating the device. 5. The power supply circuit for a communication device according to claim 4, wherein output voltages of the plurality of DC / DC converters are different from each other.