JP2006107295A - Regulator - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a regulator capable of controlling output voltage at high speed and feeding a heavy-current to a load without using an OP amplifier of high current feed capability. <P>SOLUTION: Voltage control is gained at high speed in performing stabilizing control of the output voltage by the OP amplifier 1 and, even when the heavy-current is fed to the load, excessive current feed capability as the OP amplifier 1 is unnecessary. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a regulator that can operate at high speed during output voltage stabilization control and can supply a large current to a load.

  Conventionally, in order to stably operate an electronic device, a constant voltage power source (regulator) capable of supplying a constant voltage by stabilizing the output voltage is used as the power source. In this case, when a stabilized output voltage is supplied from a regulator to a load such as an electronic device, a voltage control circuit using an operational amplifier (OP amplifier) is used as a circuit configuration of the regulator, and an output signal obtained from the output voltage is used. There is a method of performing stable voltage control by applying feedback to the OP amplifier.

  However, when voltage control is performed at a high current supply and at a high speed, in order to improve the current supply capability of a regulator with a single OP amp, not only simply increasing the current flowing through each element, but also adding a new circuit. As a result, the parasitic capacitance component (capacitor component) increases, and it is difficult to operate at high speed.

  Therefore, a configuration has been proposed in which an output voltage control transistor is connected to the output of the OP amplifier, and voltage control of the output voltage control transistor is performed by the OP amplifier, thereby supplying a large current to a device that is a load.

A conventional regulator as described above (for example, see Patent Document 1) will be described below.
FIG. 4 is a block diagram showing the configuration of a conventional regulator. As shown in FIG. 4, this regulator provides an OP amplifier 1 for controlling the output voltage control transistor 4, a load 5 connected to the output signal 7, and a feedback to the OP amplifier 1 based on the output signal 7. When the feedback signal 8 is obtained, it is composed of feedback function means 6 having a feedback function for determining the feedback amount. The OP amplifier 1 compares the control voltage 9 and the feedback signal 8 with the same. By controlling the output voltage so that the output signal 7 becomes a desired constant voltage, the output voltage 7 is controlled to be stabilized.

In such a regulator, since a large current flows only in the output voltage control transistor 4 according to the load current, an OP amplifier having a low current supply capability may be used as the OP amplifier 1 for stabilization control. This enables high-speed voltage control with high accuracy.
WO 00/39935

  However, in the conventional regulator as described above, when there is a possibility that the impedance of the load 5 becomes low and the control needs to be performed near the power supply voltage with a large current during the voltage supply, the voltage control In this case, a power loss due to the parasitic resistance component of the output voltage control transistor 4 becomes a problem, and in order to suppress the loss, a control element having a low parasitic resistance component and a very large power capacity is required as the output voltage control transistor 4. Accordingly, the parasitic capacitance (capacitor component) of the output voltage control transistor 4 increases.

  As a result, in order to operate the output voltage control in the regulator at high speed, that is, to increase the cutoff frequency of the entire regulator, the voltage control of the output voltage control transistor must be performed at high speed. Therefore, in order to perform output voltage control at high speed under the parasitic capacitance, a large current is required as a control current for driving the output voltage control transistor.

  Accordingly, an OP amplifier that drives and controls the output voltage control transistor also requires an element having a large current supply capability. In order to make the OP amplifier operate at high speed and have a large current supply capability, such an OP amplifier is required. The amplifier design becomes complicated.

  The present invention solves the above-described conventional problems, and provides a regulator capable of controlling an output voltage at high speed and supplying a large current to a load without using an OP amplifier having a high current supply capability.

  In order to solve the above-mentioned problem, a regulator according to claim 1 of the present invention is a regulator that controls an output voltage control transistor based on a control signal to stabilize an output voltage to a load. A current mirror that drives and controls the output voltage control transistor, a current control unit that controls a drive current of the current mirror, a feedback function unit that determines a feedback signal based on an output signal output from the output voltage control transistor, and An OP amplifier that controls the current control unit based on a control signal and the feedback signal is provided.

  The regulator according to claim 2 of the present invention is the regulator according to claim 1, wherein a multiple output type is used as the current mirror, and the current flowing to the multiple output side of the current mirror is converted into a voltage. A resistor for conversion is provided, and the current on the multiple output side is monitored based on the voltage converted by the resistor.

  As described above, even when the voltage control is performed at high speed during the stabilization control of the output voltage by the OP amplifier and a large current is supplied to the load, an excessive current supply capability as the OP amplifier can be eliminated.

  As described above, according to the present invention, an excessively high current supply capability is not required as an OP amplifier even when a voltage is controlled at high speed when an output voltage is stabilized by an OP amplifier and a large current is supplied to a load. It can be.

  Therefore, it is possible to control the output voltage at high speed and supply a large current to the load without using an OP amplifier having a high current supply capability.

Hereinafter, a regulator showing an embodiment of the present invention will be specifically described with reference to the drawings.
The basic concept of the regulator according to the embodiment of the present invention will be described below.

  FIG. 1 is a block diagram showing a schematic configuration of the regulator according to the present embodiment. As shown in FIG. 1, the regulator according to the present embodiment controls a current mirror 3 that drives and controls the output voltage control transistor 4, a current control unit 2 that controls the current of the current mirror 3, and the current control unit 2. When obtaining the OP amplifier 1, the load 5 connected to the output signal 7, and the feedback signal 8 for applying feedback to the OP amplifier 1 based on the output signal 7, a feedback function for determining the feedback amount is obtained. Basically, the OP amplifier 1 compares the control signal 9 and the feedback signal 8 and outputs them through the current control unit 2 and the current mirror 3 so that they have the same voltage. The output signal 7 is controlled by the voltage control transistor 4.

With the configuration described above, even when a large element is required for the output voltage control transistor 4 because a low impedance is connected to the load 5, the output voltage control transistor 4 is controlled by the current mirror 3. When the current flowing through the output voltage control transistor 4 is I1, the control current I2 in the current mirror 3 is the emitter (source) junction area of the output voltage control transistor 4 and the emitter of the transistor used in the current mirror 3 ( If the source) junction area is B,

I1 / I2 = A / B
I2 = B x I1 / A

Therefore, the control current I2 is determined by the area ratio of A and B.

  That is, the control current I2 in the current mirror 3 is reduced by the area ratio of the output voltage control transistor 4 and the transistor of the current mirror 3, and the current control unit 2 only needs to control a small current. An element (for example, a transistor) to be operated may be small with a small power capacity, and the OP amplifier 1 that controls the current control unit 2 does not need a large current supply capability.

Therefore, by using the regulator of the present embodiment, the drive control of the output voltage control transistor is performed by the current mirror, and the current mirror is performed by the OP amplifier, so that the regulator can be supplied without increasing the current supply capability of the OP amplifier. Large current and high-speed voltage control are possible.
(Embodiment 1)
A regulator according to Embodiment 1 of the present invention will be described.

  FIG. 2 is a block diagram showing the configuration of the regulator according to the first embodiment. As shown in FIG. 2, the regulator according to the first embodiment includes a current mirror 3 that drives and controls the output voltage control transistor 4, a transistor T2 of the current controller 2 that controls the drive current in the current mirror 3, and a current mirror. In order to determine the amount of feedback when the OP amplifier 1 that controls the transistor T2 that controls the driving current 3 and the feedback signal 8 for applying feedback to the input side of the OP amplifier 1 based on the output signal 7 are obtained. And feedback function means 6 having a feedback function of

  In the above configuration, the OP amplifier 1 compares the voltage of the control signal 9 with the voltage of the feedback signal 8 obtained by multiplying the output signal 7 by the feedback function of the feedback function means 6, and sets them to the same voltage. As described above, the output voltage control transistor 4 is driven and controlled through the current control unit 2 and the current mirror 3 so that the voltage of the output signal 7 is controlled to a desired constant voltage. In addition, positive feedback is applied to the input side of the OP amplifier 1 by the feedback signal 8 through the feedback function means 6 based on the output signal 7.

  By adopting such a configuration, even when the impedance of the load 5 is low, the output voltage control transistor 4 requires a large current, and the output voltage control is performed even when the parasitic capacitance (capacitor component) becomes large. The drive control of the transistor 4 is performed by the current mirror 3, and the current mirror 3 is controlled by the transistor T 2 of the current control unit 2. Here, the control current flowing in the current mirror 3 is determined by the emitter (source) junction area ratio between the output voltage control transistor 4 and the transistor in the current mirror 3. The control current flowing through the current mirror 3 is controlled by the transistor T2 of the current control unit 2. When the OP amplifier 1 performs control of the transistor T2 of the current control unit 2, the beta (( It is possible to control with a current of 1 / (β) (β: current amplification factor of the transistor T2).

  Therefore, when the OP amplifier 1 controls the output voltage control transistor 4 through the current control unit 2 and the current mirror 3, the current mirror ratio of the current flowing through the output voltage control transistor 4 and the transistor T2 in the current control unit 2 are controlled. The output voltage can be controlled by the output voltage control transistor 4 by controlling the current value divided by the coefficient multiplied by the beta of the output voltage.

As a result, the OP amplifier 1 requires a small control current. Even when high-speed control is required for the output voltage, the output voltage of the output voltage control transistor 4 does not require a large current supply capability. Can be controlled.
(Embodiment 2)
A regulator according to Embodiment 2 of the present invention will be described.

  FIG. 3 is a block diagram showing the configuration of the regulator according to the second embodiment. In the regulator according to the second embodiment, as shown in FIG. 3, by adding a transistor 10 in parallel to the current mirror 3, the same current as the transistor in the current mirror 3 flows through the transistor 10. Further, when a current flows through a resistor 11 provided as a monitor voltage generating load between the transistor 10 and the ground, a terminal voltage is generated at both ends of the resistor 11.

The voltage generated in the resistor 11 has a constant function with respect to the control signal 9 input to the regulator of the present embodiment. That is, the potential V1 generated across the resistor 11 is

V1 = Vin * A (x)

As described above, it can be expressed by a relational expression obtained by multiplying the input signal Vin by the control signal 9 by a certain function A (x).

  Using the above equation, a resistance value is calculated so that the voltage generated on the monitor side by the resistor 11 and the voltage by the output signal 7 controlled on the output side of the regulator are the same, and the resistance value is the value of the resistor 11. And Therefore, when the state of the load 5 changes for some reason and the voltage of the output signal 7 in the output voltage control transistor 4 shows an abnormal value, a large current flows through the load 5 and the output signal 7 is output. The voltage value of the signal 7 decreases. However, the voltage of the monitor signal 12 is hardly affected by the outside of the regulator because the resistor 11 is configured in the regulator, and is always a constant voltage value.

  As a result, when the load 5 is in an abnormal state, a potential difference occurs between the output signal 7 and the monitor signal 12. By using this potential difference, the abnormality of the output signal 7 is reduced in the input signal that is the control signal 9. Thus, it is possible to perform control such as limiting the output current or limiting the output current of the regulator.

  The regulator according to the present invention can control the output voltage at high speed and supply a large current to the load without using an OP amplifier having a high current supply capability. It can be applied to regulators and the like that require current supply.

The block diagram which shows schematic structure of the regulator of embodiment of this invention The block diagram which shows the structure of the regulator of Embodiment 1 of this invention The block diagram which shows the structure of the regulator of Embodiment 2 of this invention. Block diagram showing the configuration of a conventional regulator

Explanation of symbols

1 Operational amplifier (OP amplifier)
2 Current Control Unit 3 Current Mirror 4 Output Voltage Control Transistor 5 Load 6 Feedback Function Means 7 Output Signal 8 Feedback Signal 9 Control Signal 10 Transistor 11 Monitor Voltage Generation Load (Resistance)
12 Monitor signal T2 Current control transistor

Claims (2)

  A regulator that controls an output voltage control transistor based on a control signal to stabilize an output voltage to a load, and controls a current mirror that drives and controls the output voltage control transistor and a drive current of the current mirror A current control unit; feedback function means for determining a feedback signal based on an output signal output from the output voltage control transistor; and an OP amplifier for controlling the current control unit based on the control signal and the feedback signal. A regulator characterized by that.   2. The regulator according to claim 1, wherein a multiple output type is used as the current mirror, a resistor that converts current flowing to the multiple output side of the current mirror into a voltage is provided, and the voltage converted by the resistor is And a regulator configured to monitor the current on the multiple output side.

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