JPH0287866A - Power consuming circuit - Google Patents

Abstract

PURPOSE:To limit the power consumption of a call IC, etc., to within an allowable value by providing a clamping means for generating a current corresponding to a DC component of a line voltage generated by a line current applied from a telephone circuit, and keeping the line voltage constant even if the line current is varied by controlling a voltage/current converting means. CONSTITUTION:The DC output voltage of a voltage generating means 50 corresponding to the DC component of a line voltage generated by a line current applied from the telephone circuit 6 is converted to a current by the voltage/ current converting means 60. In this state, when the line voltage is boosted, the DC voltage is also boosted, therefore, the output current of a clamping means 70 is increased, and the output current of the voltage/current converting means 60 is increased and works in the direction for lowering the line voltage. As a result, the boosting of the line voltage is negated, and it is held in a constant voltage. In such a manner, the power consumption of the inside of an IC can be limited to an allowable value or below.

Description

[Detailed Description of the Invention] [Field of Industrial Application] This invention sets the voltage supplied from a telephone line to a telephone IC used in a telephone set to a constant value, thereby reducing the power consumption of the telephone IC, etc. within an allowable value. The present invention relates to a power consumption circuit used when limiting power consumption.

[Conventional technology]

Conventionally, call ICs are driven by line voltage sent from an exchange at a telephone office through a telephone line, but the voltage and current applied to the call IC through the telephone line vary greatly depending on the line distance from the telephone office. For this reason,
For example, a power consumption circuit shown in FIG. 5 is used to cause an external resistor to consume surplus power so that the power consumption inside the IC is limited within an allowable value. This power consumption circuit is equipped with a main circuit section 2 composed of IC as an internal circuit as well as a telephone communication circuit, and its line input terminal 4
A telephone line 6 is connected to , and a line voltage V is applied between the line input terminal 4 and the ground terminal 8 .

is added. The main circuit section 2 is provided with other circuits 10 such as a communication circuit that receives the line voltage V.

And in this power consuming circuit, the line voltage ■.

A current corresponding to the current flows to ground through the resistor 12, the diode 14, 16, and the diode-connected transistor 22. The capacitor 20 connected to the terminal 18 is
The capacitor 20 functions as a bypass for AC components such as audio signals weighed against the line voltage 1, and only DC components are supplied to the transistor 22 by the capacitor 20. The current flowing through the diodes 14 and 16 flows into the diode-connected transistor 22 forming a current mirror circuit, and a current corresponding to the area ratio of the transistors 22 and 24 is sucked into the transistor 24 side. A surplus of the line current It flows into the collector side of the transistor 24 through a resistor 30 externally connected between terminals 26 and 28, and this current becomes the power consumption current IFD.

Therefore, in this power consumption circuit, a diode voltage of 3Vr is set at the terminal 18 by the diode 14.16 and the base-collector voltage of the diode-connected transistor 22, and when the line voltage exceeds 3V, the power consumption is reduced. The circuit starts operating, and unnecessary power consumption current IPD is discharged to the ground side through transistor 24.

[Problems to be Solved by the Invention] By the way, when a telephone using such a power consumption circuit is connected to a telephone line, the line voltage VL and line current with respect to the distance of the telephone line 6! , as shown in Figure 6,
At point A, which is far from the telephone office, the line voltage VLI and line current rt+ are low, and at point B, which is close to the telephone office, the line voltage VL2 and line current IL2 are high. Since the line voltage V is loaded with AC signals such as voice signals, it must be set higher than the voltage that can ensure the dynamic range of the AC signals. If you adjust the power consumption current IFD and set the line voltage to a high value so that the line voltage VLI at point A becomes the optimum voltage, then at point B, which is close to the telephone office,
The line voltage VL2 at the point increases. Therefore, at point B, the IC is required to have a high breakdown voltage, and there are drawbacks such as increased power consumption within the tC package.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a power consumption circuit that does not increase power consumption in a large current range of line current and can maintain a sufficient dynamic range even in a low current range.

[Means to solve the problem]

The power consumption circuit of the present invention includes a voltage generating means for generating a DC voltage output corresponding to a DC component of a line voltage generated by a line current applied from a telephone line, and a voltage proportional to the DC voltage output. a voltage converting means, a voltage-current converting means having an external resistor at an external terminal for consuming surplus power, adding the voltage output of the voltage converting means and outputting a current; clamping means generates a current corresponding to the DC voltage when the DC voltage becomes large, and controls the voltage-current converting means to keep the line voltage constant even if the line current changes.

[For production]

With this configuration, the DC voltage corresponding to the DC component of the line voltage generated by the line current applied from the telephone line is converted into a current by the voltage-current conversion means. Therefore, when the line voltage rises, the DC voltage also rises, so the output current of the clamp means increases, which increases the output current of the voltage-current conversion means and acts in the direction of lowering the line voltage.

As a result, the increase in line voltage is canceled out and the voltage is kept constant.

Note that an external resistor for consuming surplus power is provided at the external terminal included in the voltage-current conversion means, and most of the power supplied from the telephone line is consumed by this external resistor, thereby allowing the power consumption inside the IC to be reduced. Limit below value.

〔Example〕 FIG. 1 shows an embodiment of the power consumption circuit of the invention.

A main circuit section 2 is constituted by an IC together with a telephone circuit, etc., and a line voltage ■ is applied between a line input terminal 4 and a ground terminal 8 of this main circuit section 2 through a telephone line 6, and a line current rL is applied. Supplied.

This main circuit section 2 is provided with other circuits 10 such as a communication circuit receiving line voltage (1).

Then, between the line input terminal 4 and the terminal 18 of the main circuit section 2, a DC voltage VCC corresponding to the DC component of the line voltage ■ generated by the line current ■ applied from the telephone line 6 is generated. A resistor 40 is connected as a voltage generating means, and a capacitor 20 is connected to the terminal 18, forming a bypass path for discharging an alternating current signal such as an audio signal superimposed on a direct current to the ground side. Therefore, at the terminal 18,
DC voltage VC that has a proportional relationship with the DC component of line voltage
C occurs.

A voltage conversion circuit 50 is installed at the input section of the main circuit section 2 as a voltage conversion means for generating a voltage proportional to the DC voltage VCC generated at the terminal 18.

That is, a resistor 51 is connected in series to the resistor 40 through the terminal 18, and the current flowing through the resistor 51 is equal to the DC voltage VC.
C, and flows to the ground side through the diode-connected transistor 52 in the current mirror circuit. A current proportional to the current flowing through the transistor 52 flows through the transistor 53 due to the current mirror effect.
flows to

The current of this transistor 53 is supplied from the line input terminal 4 through a diode-connected transistor 54 forming a current mirror circuit. A current proportional to the current flowing through the transistor 54 flows through the transistor 55 due to the current mirror effect. Therefore, a current that is proportional to the current flowing through the resistor 51 flows through the transistor 55, and this current flows through the resistor 56 connected to the collector side of the transistor 55. Therefore, a current proportional to the current flowing through the resistor 51 flows through the resistor 56, so that a voltage (2) proportional to the DC voltage VCC at the terminal 18 is generated. occurs.

Voltage generated across resistor 56■. is added to a voltage-current conversion circuit 60 installed as voltage-current conversion means.

This voltage-current conversion circuit 60 is provided with a resistor 62 connected to the outside through a current discharge terminal 61 of the main circuit section 2 . The voltage generated across the resistor 56 is applied to the positive input terminal (+) of the operational amplifier 64 via the resistor 63, the base of the transistor 65 is connected to the output side of the operational amplifier 64, and the emitter of the transistor 65 and the operational amplifier 64 are connected to each other. The negative input terminal (−) of 64 is connected through a resistor 66 . That is, in this voltage-current conversion circuit 60, the resistor 5
Voltage generated at 6■. and the voltage V of the current release terminal 61,
The operational amplifier 64 operates so that the base potential of the transistor 65 is adjusted so that the current discharge terminal 61
The power consumption current IFD output from the resistor 6 is determined.
2 and a current IP equal to the collector current of transistor 65.
D flows. That is, this current IPD corresponds to the voltage 6 generated in the resistor 56 of the voltage conversion circuit 50.

Then, when the line current ■ is large and the DC voltage VCC increases, a current corresponding to the DC voltage VCC is generated on the negative input terminal (-) side of the operational amplifier 64 of the voltage-current conversion circuit 60. A clamp circuit 70 is connected which controls the current conversion circuit 60 and keeps the line voltage (2) constant even if the line current IL changes. A series circuit of a constant voltage element 71 and a resistor 72 that generates a constant voltage V REF by DC voltage VCC is installed in the human power section of the clamp circuit 70 , and the voltage V REF is generated at the connection point between the constant voltage element 71 and the resistor 72 . The voltage comparator 73 uses the voltage ■ and lEF as the reference voltage.
is applied to the negative input terminal (-) of Also, DC voltage ■. A series circuit of resistors 74.75 is installed to divide and take out the voltage, and the voltage ■, corresponding to the DC voltage VCC generated at the connection point of the resistors 74.75, is connected to the positive input terminal (+) of the voltage comparator 73. ) has been added. Then, the comparison output of the voltage comparator 73 is connected to the negative input terminal (-) of the operational amplifier 64.
has been added to.

Here, the resistance value of resistor 74.75 is R74, R? When S is assumed, the voltage ■ generated at the connection point of the resistors 74 and 75 is as follows, and is proportional to the DC voltage VCC. When this voltage (6) exceeds the voltage V REF, an output current IC is generated in the voltage comparator 73, which flows to the negative input terminal (-) of the operational amplifier 64.

Therefore, in the operating characteristics shown in FIG. 2, the line current It
Considering the case where increases from ■ to ■1□, the line current! , the line voltage VL also increases. and,
When the line voltage V increases, the DC voltage VCC at the terminals also increases. When the DC voltage VCC rises, the voltage 2 also rises proportionally, but since the voltage across the constant voltage element 71 is fixed at the voltage V IIP:F, the voltage 2 becomes larger than the voltage V REF. , an output current I representing the comparison result flows through the voltage comparator 73. Output current ■ to voltage comparator 73.

When the current flows, the potential of the negative input terminal (-) of the operational amplifier 64 decreases, and the base potential of the transistor 65 increases.

When the base potential of the transistor 65 rises, the voltage at the current discharge terminal 61 increases, and the current I flowing through the resistor 62 increases.
PD increases. As the current IPD increases, the line voltage ■
, acts to lower the As a result, the line current ■, becomes I
Even if the line voltage (2) increases from Ll to ttz and the line voltage (2) attempts to rise, negative DC feedback is applied through the path, and the line voltage (2) L is maintained at a constant value.

Therefore, in Fig. 2, A is far from the telephone office and the telephone line 6 is long, and B is close to the telephone office and the telephone line 6 is short.As is clear from these operating characteristics, the line voltage In the section D1 where , is increasing, the DC voltage VCC is rising in accordance with the line voltage VL, and in the section D2 where the stabilizing operation of the clamp circuit 70 is working,
A constant DC voltage VCC is obtained regardless of the magnitude of the line current. It can be seen that Vt becomes constant.

Next, FIG. 3 shows a specific example of the circuit configuration of the power consumption circuit of the present invention, and this power consumption circuit is configured inside a telephone IC (not shown).

The voltage conversion circuit 50 is constructed in the same manner as the embodiment shown in FIG.

This voltage is applied to the operational amplifier 64 of the voltage-current conversion circuit 60 through a resistor 63. The operational amplifier 64 includes transistors 601, 602, transistors 603, 604, 605, and resistors 606.605 that form a differential pair.
607 is installed. transistor 603.604
．． Reference numeral 605 constitutes a current mirror circuit with the transistor 54, and a current proportional to the current flowing through the transistor 53 flows through the transistor 54 to each transistor 60.
Flows from 3 to 605. Therefore, a current proportional to the current flowing through resistor 51 flows through the collector of each transistor 603-605.

The voltage of the resistor 56 is applied to the base of the transistor 601 of the operational amplifier 64 through the resistor 63. is applied as the input voltage. Each transistor 601.602
Transistors 608 and 609 forming a current mirror circuit and transistors 610 and 611 forming a current mirror circuit are individually installed on the collector side of the active load.
The differential current generated in each transistor 601, 602 is taken out through transistor 6091, 611, and the current flowing in transistor 611 is supplied to transistor 609 side by transistor 612, 613 that constitutes a current mirror circuit, and is synthesized on transistor 609 side. be done. This combined current is applied to the base of transistor 614, which forms part of transistor 65 as an output circuit.

A phase compensation capacitor 615 is connected between the collector of the transistor 613 and the base of the transistor 602.
It is installed with a capacitive element on C. The collector of the transistor 614 is connected to the line input terminal 4 via a resistor 616, and the transistor 617
The base is connected. A resistor 618 is connected to the collector of this transistor 617, and
The base of the final stage transistor 619 is connected, and the resistor 62 is connected to its emitter through the current emission terminal 61. That is, transistors 614, 617 .
619 and resistors 616 and 618 constitute the transistor 65 shown in FIG.

Also, the emitter of the transistor 619 and the transistor 6
A resistor 66 is connected between the base of 02 and the base of 02 as a feedback circuit.

In the clamp circuit 70, resistors 701, 702, and 703 are connected between the terminal 18 and the ground point. The base of transistor 704 is connected to the connection point of resistors 701 and 702, the emitter is connected to terminal 18, and the collector is connected to resistor 702.
703 connection points, respectively. A transistor 704 is installed as a constant voltage element 71, and its emitter-collector voltage VtC is expressed by the sum of voltage drops across resistors 701 and 702. Here, the resistor 701
．． Assuming that the resistance values of transistor 702 are R1゜1 and R9゜2, and the voltage between the base and emitter of transistor 704 is VBE, even if the DC voltage VCC of terminal 18 increases, the voltage V REF will be as follows: (2) The rise in the emitter-collector voltage Vie of the transistor 704 is limited to the voltage 1EF.

Further, resistors 74 and 75 are connected between the terminal 18 and the ground point.

The voltage comparator 73 includes transistors 705 and 70.
6 differential pairs are installed, the emitters of transistors 705 and 706 are connected in common via resistors 707 and 708, and the connection point of resistors 707 and 708 is connected to the collector of transistor 709. A constant bias voltage 8 is applied to the base of the transistor 709, forming a constant current source. The collector of transistor 705 is grounded, and the collector of transistor 706 is connected to transistor 71.
0 and the transistor 710
．． 711 constitutes a current mirror circuit, and the transistor 71
Current is output from the collector of 1. transistor 705
The base of transistor 704 is connected to the collector of transistor 704, and the base of transistor 706 is connected to the connection point of resistor 74.75.

Since AC signals such as voice signals are added to the line voltage VL and the line current (2) applied through the telephone line 6, the AC components are bypassed by the capacitor 20 connected to the terminal 18. The DC voltage VCC of the terminal 18 is equal to the line voltage of the telephone line 6, and the resistor 4'
Only the DC component of the voltage is extracted after subtracting the zero voltage drop. The emitter-collector voltage of the transistor 704 ■. is fixed at the voltage V REF.

At the connection point of the resistor 74.7゛5, a voltage shown by equation (1) is generated. When this voltage (1) exceeds the voltage V REF, a current flows through the transistor 706 of the voltage comparator 73, and an output current I, which is proportional to the collector current of the transistor 710 of the current mirror circuit, flows to the collector of the transistor 711.

Further, the current flowing through the resistor 56 of the voltage conversion circuit 50 is proportional to the current flowing through the resistor 51, and the current flowing through the resistor 51 is proportional to the DC voltage VCC at the terminal 18. That is, the voltage 6 generated across the resistor 56 is proportional to the DC voltage cc.

The operational amplifier 64 acts so that the voltage V6 and the voltage (2) of the current emission terminal 61 become equal, and by adjusting the base potential of the transistor 619, the current IPD output from the current emission terminal 61 is determined.

Therefore, referring to Fig. 2, when the line current IL increases from ILI to IL2, the line current ■ increases, the line voltage ■L rises, and the daily DC voltage VCC at the terminal increases.
rises. When the DC voltage VCC increases, the voltage 2 increases proportionally, but the emitter of the transistor 704
Collector voltage VEC is fixed to voltage V REF.

Therefore, the voltage ■.

When exceeds the voltage VREF, an output current ■ appears at the collector of the transistor 711. flows. Output current■.

flows, the transistor 6 on the input side of the operational amplifier 64
The base potential of 02 decreases. The collector current of transistor 602 increases, causing the base potential of transistor 619 to rise through the current mirror circuit. transistor 619
When the base potential of increases, the voltage of the current release terminal 61
, increases, and the current IPD flowing through the resistor 62 increases.

As the current IPD increases, the effect of lowering the line voltage (2) is obtained as in the previous embodiment. As a result, line current IL increases from TLI to IL2, and line voltage ■.

Even if the line voltage (2) attempts to rise, negative DC feedback is applied through the path, and the line voltage (2) is maintained at a constant value. and,
In such a circuit, the line current ■.

Even if the line voltage is set to be high in order to obtain the necessary dynamic range from the low current range of
The line voltage (2) in areas with a large number of lines does not become unnecessarily high, and as a result, the power consumption and high withstand voltage of the IC are reduced even when used in areas where the line distance is short.

Note that the clamp circuit 70 may be a simplified circuit consisting of a resistor 712, diodes 713, 714, and a transistor 715, as shown in FIG. Furthermore, by connecting the terminal 717 to the negative input terminal (-) of the operational amplifier 64, lamp characteristics similar to those of the previous embodiment can be realized.

[Effects of the Invention] As explained above, according to the present invention, a necessary and sufficient dynamic range can be obtained from a low current range,
Further, it is possible to reduce the increase in power consumption at the near point that occurs when the voltage at the far point is increased, and the need to increase the withstand voltage of the IC in response to the increase in voltage.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram showing an embodiment of the power consuming circuit of the present invention, FIG. 2 is a diagram showing the operating characteristics of the power consuming circuit shown in FIG. 1, and FIG. 3 is a specific example of the power consuming circuit of the present invention. 4 is a circuit diagram showing a specific circuit configuration example of the clamp circuit in the power consuming circuit shown in FIG. 1, and FIG. 5 is a circuit diagram showing a conventional power consuming circuit. FIG. 6 is a diagram showing the operating characteristics of the power consumption circuit shown in FIG. 5. 6...Telephone line 40...Resistance (voltage generation means) 50...Voltage conversion circuit (voltage conversion means) 60...Voltage-current conversion circuit (voltage-current conversion means) 70...Clamp circuit (clamp) Means) Figure 2 Figure Figure IL Figure

Claims (1)

[Scope of Claims] Voltage generating means for generating a DC voltage corresponding to the DC component of line voltage generated by line current applied from a telephone line; Voltage converting means for outputting a voltage proportional to the DC voltage; The terminal has an external resistor for consuming excess power,
voltage-current conversion means that adds the voltage output of the voltage conversion means and outputs a current; and when the line current is large and the DC voltage becomes large, generates a current corresponding to the DC voltage, and converts the voltage and current. and clamping means for controlling the means to keep the line voltage constant even if the line current changes.