JP2003215165A - Power source circuit - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To effectively avoid the generation of a surge voltage due to switching of ranges, for example, when applied to a power source circuit for measurement where output voltage is changed over a wide range. <P>SOLUTION: An impressed voltage V is held temporarily when the switching between the voltage ranges S3, S4 is conducted. <P>COPYRIGHT: (C)2003,JPO

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,
For example, the present invention can be applied to a power supply circuit for a measuring instrument that can change the output voltage in a wide range. The present invention, by temporarily holding the applied voltage when switching the voltage range,
It is possible to effectively avoid generation of surge voltage due to switching of voltage range.

[0002]

2. Description of the Related Art Conventionally, in a power supply circuit used for various measurements, a variable range (that is, a voltage range) of an applied voltage applied to a drive target is set by setting a voltage range, and a digital-analog conversion circuit The applied voltage can be varied within a variable range by adjusting the set value.

That is, FIG. 4 is a block diagram showing a power supply circuit of this type. In the power supply circuit 1, a voltage setting DAC (Digital to Analog Converter) 2 is a voltage data indicating an applied voltage V by a controller controlling the operation of the power supply circuit 1 and further by setting a switch by a user operation. In response to this, this voltage data is digital-analog converted. This allows the power supply circuit 1
Generates a reference voltage which is a control reference for the applied voltage V.

The voltage range switching circuit 3 switches the resistance value of the voltage / current conversion resistor by, for example, controller control or user operation, and converts the reference voltage output from the voltage setting DAC 2 into voltage / current and outputs the reference voltage. As a result, with respect to the reference voltage generated by the voltage setting DAC2,
The voltage range of the applied voltage V is set.

The sense amplifier (sense AMP) 4 constitutes a voltage detection circuit for detecting the applied voltage V by voltage-current converting the applied voltage V supplied to the load 5 and outputting it.

The subtraction circuit 6 subtracts the output current of the sense amplifier 4 from the output current of the voltage range switching circuit 3,
As a result, the error voltage between the reference voltage and the applied voltage is detected by converting the current. As a result, the subtraction circuit 6 constitutes an error detection circuit that detects an error value between the reference voltage and the applied voltage.

The error amplification circuit 7 amplifies and outputs the output value of the subtraction circuit 6, and the power amplification circuit 8 supplies electric power corresponding to the output value of the error amplification circuit 7 via the current detection circuit 9. Output to load 5. The current detection circuit 9 detects the current of the load 5 and outputs the detection result, and based on the detection result, the control circuit (not shown) limits the power supply by the power amplification circuit 8.

Thus, in the power supply circuit 1, a feedback loop is formed to control the applied voltage V so that the applied voltage V of the load 5 corresponds to the current value based on the reference voltage input to the subtraction circuit 6. In this control, the applied voltage V is finely adjusted by the voltage data set in the voltage setting DAC 2, and the voltage range switching circuit 3
The variable range of the applied voltage V can be set by the setting of.

[0009]

By the way, in the power supply circuit 1 having the configuration shown in FIG. 4, the applied voltage V may be varied continuously and in a large range. In this case, in the power supply circuit 1, the setting of the voltage range switching circuit 3 is also switched while switching the voltage data set in the voltage setting DAC 2.

In the conventional power supply circuit 1, the voltage data of the voltage setting DAC 2 and the voltage range switching circuit 3 are as described above.
There is a case where the output current of the subtraction circuit 6 instantaneously changes when switching between the setting and the setting, and the applied voltage V instantaneously becomes an abnormally high voltage (hereinafter, such an abnormal voltage is surged. Called voltage). If it is possible to prevent the occurrence of such a surge voltage, it is possible to provide a voltage source with much higher quality than in the past.

The present invention has been made in consideration of the above points, and an object thereof is to propose a power supply circuit capable of effectively avoiding generation of this kind of surge voltage.

[0012]

In order to solve such a problem, in the invention of claim 1, the applied voltage applied to the driven object is detected, and the applied voltage is compared with the reference voltage.
It is applied to a power supply circuit that supplies power to an object to be driven with an applied voltage, the applied voltage is changed by changing the reference voltage, and the change range of the applied voltage relative to the change range of the reference voltage is changed by switching the voltage range of the applied voltage. A hold circuit for temporarily holding the applied voltage when switching and switching the voltage range of the applied voltage is provided.

According to the invention of claim 2, claim 1
In the configuration, the digital-analog conversion circuit that performs the digital-analog conversion process on the voltage data that indicates the applied voltage to generate the reference voltage, the voltage range switching circuit that switches the voltage range, and the error value between the reference voltage and the applied voltage. An error detection circuit that detects an error value, an error amplification circuit that amplifies an error value, a power amplification circuit that outputs power according to the output value of the error amplification circuit to a drive target, and a voltage detection circuit that detects an applied voltage. The hold circuit temporarily holds the applied voltage by holding the input value of the power amplifier circuit.

According to the invention of claim 3, claim 2
In the configuration, the switch circuit that stops the output of the output value of the error amplification circuit to the power amplification circuit in conjunction with the hold operation by the hold circuit, and the output value of the error amplification circuit is output by the corresponding output of the voltage detection circuit. A conversion circuit for converting the error value between the reference voltage and the applied voltage in the error detection circuit and a switch circuit for switching the detection of the error value between the reference voltage and the output value of the conversion circuit in the error detection circuit. To have.

According to the invention of claim 4, claim 1
In the configuration described above, the digital-analog conversion circuit that generates the reference voltage by performing the digital-analog conversion process on the voltage data that indicates the applied voltage, the voltage range switching circuit that switches the voltage range, and the error between the reference voltage and the applied voltage. Depending on the output value of the error detection circuit that detects the value, the error amplification circuit that amplifies the error value, the current detection circuit that detects the current supplied to the drive target, and the current detection circuit. A power amplifier circuit that outputs power to a drive target,
And a voltage detection circuit for detecting an applied voltage, wherein the hold circuit holds the output voltage of the power amplification circuit, and supplies the power to the current detection circuit instead of the power amplification circuit by the held voltage. , Temporarily hold the applied voltage.

According to the invention of claim 5, claim 4
In the configuration described above, a conversion circuit that converts the output voltage of the power amplification circuit into a corresponding output value by the voltage detection circuit in conjunction with the hold operation by the hold circuit, and the reference voltage and the applied voltage in the error detection circuit And a switch circuit for switching detection of an error value between the reference voltage and the output value of the conversion circuit.

According to the structure of claim 1, the applied voltage applied to the driving target is detected, and the applied voltage is compared with the reference voltage to apply the power supply voltage to the driving target. , The applied voltage is changed by changing the reference voltage, and the change range of the applied voltage with respect to the change range of the reference voltage is changed by changing the voltage range of the applied voltage,
By having a hold circuit that temporarily holds the applied voltage when switching the voltage range of the applied voltage, even if the applied voltage changes temporarily by switching the voltage range of the applied voltage, this voltage change is held. It is possible to prevent the generation of the surge voltage effectively.

According to the structure of claim 2, in the structure of claim 1, the voltage range for switching the voltage range and the digital-analog conversion circuit for performing the digital-analog conversion processing of the voltage data indicating the applied voltage to generate the reference voltage. A voltage range switching circuit, an error detection circuit that detects the error value between the reference voltage and the applied voltage, an error amplification circuit that amplifies the error value, and outputs power according to the output value of the error amplification circuit to the drive target. And a voltage detection circuit for detecting the applied voltage. The hold circuit holds the input value of the power amplifier circuit to temporarily hold the applied voltage. By holding the value, the applied voltage can be temporarily held to effectively avoid generation of a surge voltage.

According to the configuration of claim 3, in the configuration of claim 2, a switch circuit for stopping the output of the output value of the error amplification circuit to the power amplification circuit in association with the hold operation by the hold circuit. , The output value of the error amplification circuit,
A conversion circuit for converting the output value corresponding to the voltage detection circuit,
The error detection circuit has a switch circuit that switches the detection of the error value between the reference voltage and the applied voltage to the detection of the error value between the reference voltage and the output value of the conversion circuit. When holding and temporarily stopping the control by the feedback loop, a feedback loop is formed that applies the applied voltage to the load in a uniform manner, and the fluctuation of the error value due to the switching of the voltage range is changed in a short time. Can be converged. Therefore, by that much, it is possible to return to the original state in a short time and complete the switching of the voltage range.

According to a fourth aspect of the invention, in the configuration of the first aspect, the voltage range is switched to a digital-analog conversion circuit for performing a digital-analog conversion process on the voltage data indicating the applied voltage to generate a reference voltage. A voltage range switching circuit, an error detection circuit that detects an error value between the reference voltage and the applied voltage, an error amplification circuit that amplifies the error value, a current detection circuit that detects the current supplied to the drive target, Through the current detection circuit, a power amplification circuit that outputs power according to the output value of the error amplification circuit to the drive target, and a voltage detection circuit that detects the applied voltage, and the hold circuit is the output voltage of the power amplification circuit. Is held, and the applied voltage is temporarily held by supplying electric power to the current detection circuit instead of the power amplifier circuit by the held voltage. The temporarily holding the applied voltage by holding the output voltage of the circuit, it is possible to effectively avoid the occurrence of a surge voltage.

According to the structure of claim 5, in the structure of claim 4, the output voltage of the power amplifier circuit is converted into a corresponding output value by the voltage detection circuit in conjunction with the hold operation by the hold circuit. By having a conversion circuit and a switch circuit that switches detection of an error value between the reference voltage and the applied voltage in the error detection circuit to detection of an error value between the reference voltage and the output value of the conversion circuit, It is possible to equalize and form a feedback loop in which an applied voltage is applied to the load to converge the variation of the error value due to the switching of the voltage range in a short time. Therefore, by that much, it is possible to return to the original state in a short time and complete the switching of the voltage range.

[0022]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below in detail with reference to the drawings as appropriate.

(1) First Embodiment (1-1) Configuration of the First Embodiment FIG. 1 is a block diagram showing a power supply circuit according to the first embodiment of the present invention. In the power supply circuit 11, the same configurations as those of the power supply circuit 1 described above with reference to FIG. 4 are denoted by the corresponding reference numerals, and the duplicated description will be omitted.

In the power supply circuit 11, the voltage range switching circuit 3 switches the built-in switch circuits S3 and S4 under the control of the controller 13 to change the reference voltage V1 output from the voltage setting DAC 2 to the reference voltage V1. The resistance value of the voltage-current conversion resistor for voltage-current conversion is switched, so that the voltage range of the applied voltage V by the power supply circuit 11 is switched. That is, the voltage range switching circuit 3 converts the reference voltage V1 into a voltage-current so that the output voltage V of 1 [V] at maximum can be output from the power supply circuit 11 by switching the first switch circuit S3 to the ON state, for example. On the other hand, when the switch circuit S4 is set to the ON state in place of the switch circuit S3, the reference voltage V1 is set to the voltage current so that the maximum output voltage V of 10 [V] can be output from the power supply circuit 11. It is designed to be converted.

Each of the subtraction circuits 12 is a controller 1
The output current of the conversion circuit 14 and the output current of the sense amplifier 4 are input via the switch circuits S2A and S2B that complementarily switch the on / off state under the control of 3. The subtraction circuit 12 uses these input current and voltage range switching circuits 3
The difference value from the output current of is output.

As a result, in the power supply circuit 11, the switch circuit S2A, S2 is controlled by the controller 13.
By setting B to the off state and the on state, respectively, the output voltage V is controlled by the feedback loop control so that the output voltage V applied to the load 5 corresponds to the output value of the voltage range switching circuit 3. , Voltage setting DAC
2, the voltage range switching circuit 3 by the voltage range switching circuit 3
The output voltage V can be set to a desired voltage by variously changing the current value output from the.

The hold circuit 16 holds the output value of the error amplification circuit 7 by the sample hold signal T / H output from the controller 13 and outputs it.

The switch circuits S1A and S1B complementarily switch the on / off state under the control of the controller 13, and the switch circuit S1A outputs the output value of the error amplifier circuit 7 to the power amplifier circuit 8, while the switch circuit S1.
B outputs the output value of the hold circuit 16 to the power amplification circuit 8.

As a result, in the power supply circuit 11, the switch circuits S2A and S2 are controlled by the controller 13.
By switching B to the ON state and the OFF state, respectively, instead of the output value of the error amplification circuit 7, the hold circuit 1
The output voltage V is supplied to the load 5 based on the hold value held in 6.

The subtraction circuit 17 subtracts the output value of the error amplification circuit 7 from the output value of the hold circuit 16,
The output value of the hold circuit 16 is corrected by the output value of the error amplification circuit 7 and output.

The conversion circuit 14 corrects and outputs the output value of the subtraction circuit 17 so that the output value of the hold circuit 16 corresponds to the output value of the sense amplifier 4 in the output value of the subtraction circuit 17. .

As a result, in the power supply circuit 11, the switch circuits S2A and S2B are set to the off state and the on state, and the switch circuits S1A and S1B are set to the on state and the off state, thereby holding the hold circuit 16
While the output voltage V is supplied to the load 5 based on the hold value of, the error amplification circuit 7, the subtraction circuit 17, and the conversion circuit 14 equalize the output voltage V according to the reference voltage output from the voltage range switching circuit 3. An output voltage V is applied to the load 5 to form a feedback loop for feeding back the output voltage V,
By this equalization field back loop, the output voltage to the virtual load 5 is made to converge to the voltage corresponding to the output current value of the voltage range switching circuit 3.

The controller 13 is a control circuit for controlling the operation of the power supply circuit 11, and when the user gives an instruction to make a fine change in the output voltage V, the voltage output to the voltage setting DAC in response to this change. The data is changed, whereby the reference voltage is changed and the output voltage V to the load 5 is changed.

When the range of the voltage change instructed by the user accompanies the switching of the voltage range by the process of changing the output voltage V by such a user operation, the controller 13 also sets the voltage range switching circuit 3. The output voltage V is switched by changing the output current value of the voltage range switching circuit 3 output to the subtraction circuit 12 by switching.

When such a voltage range switching process is involved, the entire operation is controlled by the sequence shown in FIG. 2 to prevent the generation of surge voltage.

That is, the controller 13 selects the switch circuit S3 in the voltage range switching circuit 3 and outputs an output voltage V of 1 [V] at maximum, for example, to the power supply circuit 11.
Set the voltage range to output from the
When the applied voltage V of the maximum voltage 1 [V] is being applied to the load 5 by the AC2 and the applied voltage V is further increased (FIGS. 2F and 2G), it is necessary to switch the voltage range. Then, the sample / hold signal T / H is raised (FIG. 2A), and the output value of the error amplification circuit 7 is held. Then switch circuit S
1A and S1B are set to the ON state and the OFF state, respectively (FIGS. 2B and 2C), the hold value of the hold circuit 16 is supplied to the power amplification circuit 8, and the power amplification of the output value of the error amplification circuit 7 is performed. The output to the circuit 8 is stopped. As a result, the controller 13 temporarily holds the applied voltage V by holding the input value of the power amplifier circuit 8, and even if the output value of the error amplifier circuit 7 changes due to the voltage range switching, the applied voltage V changes in voltage. To prevent the generation of surge voltage.

Further, the controller 13 subsequently switches the switch circuits S2A and S2B to the on-state and the off-state, respectively (FIGS. 2D and 2E), whereby the output of the voltage range switching circuit 3 is equalized. An output voltage V is applied to the load 5 according to the current, and a feedback loop for feeding back the output voltage V is formed. Thereby, in the power supply circuit 11, the applied voltage applied to the virtual load 5 quickly follows the control target value input to the subtraction circuit 12 by the feedback loop formed in this way. That is, the output value of the error amplification circuit 7 is set so as to quickly converge to a regular value by regular feedback control.

When the controller 13 forms the feedback loop in this way, the voltage range switching circuit 3
2 is switched (FIG. 2 (H)), and at the same time, the voltage data output to the voltage setting DAC 2 is switched to a value corresponding to the output voltage V of 1/10. As a result, the controller 13 reduces the reference voltage V1 output from the voltage setting DAC from the full-scale voltage up to that point (indicated by the symbol FS in FIG. 2) by the amount corresponding to the expanded voltage range, thus reducing the full-scale voltage. Set the voltage to 1/10.

Subsequently, the controller 13 switches the voltage range and the reference voltage V1 in this manner, and the feedback loop from the error amplification circuit 7 through the conversion circuit 14 is sufficient to stabilize the output value of the error amplification circuit 7. After a lapse of time, the switch circuits S1A to S2B are returned to the original settings, and the hold circuit 16 releases the hold. Further, subsequently, the voltage data to the voltage setting DAC 2 is increased by the amount instructed by the user, the voltage range is switched by these, and the process of increasing the applied voltage V is completed (FIG. 2 (I)). ).

On the contrary, when the controller 13 switches the voltage range to reduce the applied voltage V, the controller 13 similarly holds the applied voltage V and then switches the voltage range and the voltage data.

(2) Operation of the First Embodiment In the above configuration, in the power supply circuit 11, the voltage data from the controller 13 is digital-analog converted by the voltage setting DAC to generate the reference voltage V1. The subtraction circuit 12 detects the current conversion value of the error voltage between the reference voltage V1 and the applied voltage V detected via the sense amplifier 4. In the power supply circuit 11, the output current value of the subtraction circuit 12 causes the power amplification circuit 8 to supply power to the load 5 via the current detection circuit 9. As a result, in the power supply circuit 11, the applied voltage V is the subtraction circuit 1
The power supplied to the load 5 is controlled by the feedback loop control so as to match the reference voltage V1 input to the load 2, and thus various applied voltages can be supplied to the load 5 according to the setting of the voltage data.

Further, in the reference voltage V1 output to the subtraction circuit 12 in this manner, the resistance value used for the voltage-current conversion process is switched by the setting of the voltage range in the voltage range switching circuit 3, and the voltage / current thereof is changed. The conversion result is input to the subtraction circuit 12. Thereby, for example, the range setting in the voltage range switching circuit 3 is changed from 1/1 to 1/10.
, And the range of the variable voltage can be switched to 10 times. As a result, in the power supply circuit 11, the applied voltage V can be varied in a wide variable range by setting the voltage range switching circuit 3 and the voltage setting DAC 2, and the load 5 can be driven by the applied voltage V.

In such a voltage switching, in the power supply circuit 11, for example, when the applied voltage V is increased stepwise in a predetermined step to switch the voltage range, the hold circuit 16 causes the error amplification circuit 7 to operate.
Is held, whereby the applied voltage V to the load 5 is maintained at a constant voltage for a fixed period. Also, in this state, the setting of the voltage range switching circuit 3 is switched,
Further, the voltage data output to the voltage setting DAC is switched at the same time by the amount of the applied voltage V that changes due to this switching. As a result, in the power supply circuit 11, the setting is switched so that the voltage range is switched and the applied voltage V is output by the voltage before switching.

Here, it is difficult to completely complete the setting of the voltage range switching circuit 3 and the voltage data output to the voltage setting DAC at the same time, which causes a surge voltage. become. However, in the power supply circuit 11, such a voltage change is prevented from occurring at the applied voltage V of the load 5 by the hold circuit 16, so that the surge voltage can be prevented from being applied to the load 5.

In the power supply circuit 11, the output value is supplied from the error amplification circuit 7 to the power amplification circuit 8 by switching the switch circuit S1B until the applied voltage V is held and the voltage range is switched in this way. Is controlled to stop. In addition, by switching the settings of the switch circuits S2A and S2B, a feedback loop in which power is supplied to the load 5 and the load voltage V is fed back is provided as an error amplification circuit 7, a subtraction circuit 17, a conversion circuit 14, and a switch. It is formed by the circuit S2A. As a result, in the power supply circuit 11, a feedback loop as if the load is being driven is formed so that the fluctuation of the error voltage due to the switching of the voltage range converges in a short time. The voltage fluctuation of each part due to the switching can be converged in a short time, and the voltage range can be switched in a short time accordingly.

Further, the subtraction circuit 17 subtracts the hold value of the hold circuit 16 from the output value of the error amplification circuit 7 and inputs it to the conversion circuit 14, so that the output value of the error amplification circuit 7 is held in the power supply circuit 11. The value is corrected by the output value of the circuit 16 and fed back to the subtraction circuit 12, whereby feedback control is performed so that the output value of the error amplification circuit 7 matches the hold value by the hold circuit 16.

In this way, when the error voltage with respect to the control target is stabilized by this equivalent feedback loop, in the power supply circuit 11, each of the switch circuits S1A to S2.
After the setting of B is returned to the original state, the voltage data is updated by the amount of change in the applied voltage V, and as a result, the entire operation is controlled so that the applied voltage V is changed as before. .

At this time, in the power supply circuit 11, until then, the output value of the error amplification circuit 7 is corrected by the output value of the hold circuit 16 and fed back to the subtraction circuit 12, whereby the error value is amplified to the hold value by the hold circuit 16. Circuit 7
The feedback control is performed so that the output values of the power supply signals of 1 and 2 are coincident with each other. Therefore, when the setting is switched to such an original state, it is possible to prevent a minute fluctuation of the input value in the power amplifier circuit 8. Can also prevent the applied voltage V from varying.

(3) Effects of the First Embodiment According to the configuration described above, when the voltage range is switched, the applied voltage is temporarily held, so that the generation of the surge voltage due to the switching of the voltage range is effectively avoided. can do. Therefore, it is possible to prevent damages due to surge voltage on various measured products, which are loads, and it is not necessary to stop the voltage application and switch the voltage range. It can be executed continuously, and the time required for measurement can be shortened accordingly. Further, since it is not necessary to separately take measures against surge, the entire configuration can be simplified accordingly.

By holding the input value of the power amplifier circuit by the hold circuit 16 and temporarily holding the applied voltage, the applied voltage is temporarily held by holding the error value amplified by the error amplifier circuit. hand,
It is possible to effectively avoid the occurrence of surge voltage.

Further, by stopping the output of the output value of the error amplifying circuit to the power amplifying circuit and feeding it back to the subtracting circuit 12 via the converting circuit, the applied voltage is temporarily held and the control by the feedback loop is temporarily stopped. In this case, a feedback loop that applies the applied voltage to the load is formed in an equalized manner, and fluctuations due to the switching of the voltage range of the applied voltage can be converged in a short time. By this, it is possible to return to the original state and complete the switching of the voltage range.

Further, by forming a feedback loop so that the output value of such an error amplifier circuit matches the hold value of the hold circuit, it is possible to prevent the fluctuation of the applied voltage V at the time when the hold is stopped. .

Further, the subtraction circuit 17 corrects the output value of the error amplification circuit by the hold voltage to form this feedback loop, so that a part of the configuration can be shared by the two feedback loops and the overall configuration can be simplified. it can.

(4) Second Embodiment FIG. 3 is a block diagram showing a power supply circuit according to a second embodiment of the present invention. In this power supply circuit 11, FIG.
The same configurations as those of the power supply circuits 11 and 1 described above with reference to FIG. 4 are denoted by corresponding reference numerals, and redundant description will be omitted. In the power supply circuit 21, the hold circuit 26 is arranged in the subsequent stage of the power amplifier circuit 8, and the applied voltage V is temporarily held by the hold circuit 26 when the voltage range is switched.

Therefore, the hold circuit 26 holds the output voltage of the power amplifier circuit 8 in accordance with this arrangement position, and the held value holds the current detection circuit 9 instead of the power amplifier circuit 8. Except that the applied voltage V is temporarily held by supplying power to the first
The configuration is the same as that of the hold circuit 16 according to the embodiment. In the conversion circuit 24, the hold circuit 2
The conversion circuit 14 has the same configuration as that of the conversion circuit 14 according to the first embodiment except that the input / output characteristic is set so as to correspond to the hold target in 6.

As in the second embodiment, the output voltage of the power amplifier circuit is held, and the held voltage is used to supply power to the current detection circuit instead of the power amplifier circuit. Even if the output voltage of the amplifier circuit is held and the applied voltage is temporarily held, the same effect as that of the first embodiment can be obtained.

(5) Other Embodiments In the above-described embodiments, the case where the applied voltage V is held by holding the output value of the error amplifier circuit and the output voltage of the power amplifier circuit has been described. ,
The present invention is not limited to this, and the applied voltage V may be held by holding the output value of the subtraction circuit 12,
Further, in the configuration in which the voltage range is switched by switching the reference voltage side as in the above-described embodiment, by holding the output value of the voltage range switching circuit 3,
The applied voltage V may be held.

Further, in the above-described embodiment, the feedback loop for matching the values at the input and output ends of the hold circuit and the feedback loop for converging the input value of the hold circuit to the value corresponding to the reference voltage are partially common. Although the configuration has been described, the present invention is not limited to this, and the two feedback loops may be configured separately.

Further, in the above embodiment, the case where the voltage range is switched by switching the reference voltage side has been described, but the present invention is not limited to this, and the voltage range is switched by switching the detection result side of the applied voltage V. It can also be widely applied in cases.

[0060]

As described above, according to the present invention, it is possible to effectively avoid generation of a surge voltage due to switching of the voltage range by switching and holding the voltage range.

[Brief description of drawings]

FIG. 1 is a block diagram showing a power supply circuit according to a first embodiment of the present invention.

FIG. 2 is a time chart for explaining the operation of the power supply circuit of FIG.

FIG. 3 is a block diagram showing a power supply circuit according to a second embodiment of the present invention.

FIG. 4 is a block diagram showing a conventional power supply circuit.

[Explanation of symbols]

1, 11, 21 ... Power supply circuit, 2 ... Voltage setting DAC,
3 ... Voltage range switching circuit, 4 ... Sense amplifier, 5 ...
... load, 6, 12 ... subtraction circuit, 7 ... error amplification circuit,
8 ... Power amplification circuit, 9 ... Current detection circuit, 14, 24
...... Conversion circuit, 16, 26 ...... Hold circuit, S1A ~
S2B ... Switch circuit

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[Procedure amendment]

[Submission date] January 25, 2002 (2002.1.2
5)

[Procedure Amendment 1]

[Document name to be amended] Statement

[Name of item to be amended] Claims

[Correction method] Change

[Correction content]

[Claims]

[Procedure Amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0013

[Correction method] Change

[Correction content]

According to the invention of claim 2, claim 1
In the configuration of the voltage data for causing application voltage by digital-to-analog conversion, the error between the digital-to-analog conversion circuit for generating a reference voltage, and the voltage range switching circuit for switching the voltage range, the reference voltage and the applied voltage An error detection circuit that detects a value, an error amplification circuit that amplifies the error value, a power amplification circuit that outputs power according to the output value of the error amplification circuit to a drive target, and a voltage detection circuit that detects an applied voltage. The holding circuit holds the input value of the power amplifier circuit to temporarily hold the applied voltage.

[Procedure 3]

[Document name to be amended] Statement

[Correction target item name] 0060

[Correction method] Change

[Correction content]

[0060]

Effects of the Invention According to the present invention as described above, when the switch the voltage range, the applied voltage by temporarily hold, it is possible to effectively avoid the occurrence of a surge voltage due to switching of the voltage range.

Claims (5)

[Claims] 1. A method for detecting an applied voltage applied to a drive target,
By comparing the applied voltage and a reference voltage, in a power supply circuit that supplies power to the drive target by the applied voltage, the applied voltage is changed by changing the reference voltage, and the voltage range of the applied voltage is switched. A power supply circuit having a hold circuit that switches a change range of the applied voltage with respect to a change range of the reference voltage and temporarily holds the applied voltage when the voltage range of the applied voltage is changed. 2. A digital-analog conversion circuit that performs digital-analog conversion processing of voltage data indicating the applied voltage to generate the reference voltage, a voltage range switching circuit that switches the voltage range, the reference voltage and the application An error detection circuit that detects an error value between a voltage and an error value, an error amplification circuit that amplifies the error value, a power amplification circuit that outputs power according to an output value of the error amplification circuit to the drive target, and the application And a voltage detection circuit for detecting a voltage, wherein the hold circuit holds an input value of the power amplification circuit,
The power supply circuit according to claim 1, wherein the applied voltage is temporarily held. 3. A switch circuit for stopping the output of the output value of the error amplification circuit to the power amplification circuit in association with the hold operation of the hold circuit; A conversion circuit that converts the output value to a corresponding output value by a detection circuit, and detection of an error value between the reference voltage and the applied voltage in the error detection circuit is performed between the reference voltage and the output value of the conversion circuit. 3. The power supply circuit according to claim 2, further comprising: a switch circuit that switches to detect the error value of. 4. A digital-analog conversion circuit for digital-analog converting the voltage data indicating the applied voltage to generate the reference voltage, a voltage range switching circuit for switching the voltage range, the reference voltage and the applied voltage. An error detection circuit that detects an error value between a voltage, an error amplification circuit that amplifies the error value, a current detection circuit that detects a current supplied to the drive target, and the current detection circuit via the current detection circuit. The power amplifier circuit includes a power amplifier circuit that outputs power according to the output value of the error amplifier circuit to the drive target, and a voltage detection circuit that detects the applied voltage.The hold circuit holds the output voltage of the power amplifier circuit. Then, the applied voltage is temporarily held by supplying power to the current detection circuit instead of the power amplification circuit by the held voltage. A power supply circuit according to claim 1, characterized in that. 5. A conversion circuit that converts an output voltage of the power amplification circuit into a corresponding output value of the voltage detection circuit in conjunction with a hold operation by the hold circuit, and the reference in the error detection circuit. 5. A switch circuit for switching detection of an error value between a voltage and the applied voltage to detection of an error value between the reference voltage and the output value of the conversion circuit. Power circuit.