JP3039265B2 - Voltage / current generator - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a voltage / current generator having a limiter function.

[0002]

2. Description of the Related Art FIG. 3 shows an example of a conventional voltage generator. In the figure, 10 is an output setting unit, 20 is an output limiting unit, 30 is a load connected to the output terminals 30a and 30b,
Rc is a resistance element. In the output setting unit 10, 11
Is a setting signal generator that outputs a signal for setting the magnitude of the generated voltage, 12 is a buffer amplifier to which the output of the setting signal generator is added, 13 is an integrator that integrates the output of the buffer amplifier 12, and 14 is an integration circuit. It is an amplifier that amplifies the output of the device 13. The output terminal of the amplifier 14 is connected to the output terminal 30a and fed back to the buffer amplifier 12, whereby a stable output according to the set value is obtained.
You can get more. A non-inverting input terminal of the integrator 13 and one end of the resistor Rc are connected to a potential point COM serving as a voltage reference, and the other end of the resistor Rc is connected to an amplifier 14.
Are connected to the common potential point COMa.

In the output limiting section 20, reference numeral 21 denotes a limiter setting signal generator, reference numerals 22 and 23 denote amplifiers, and reference numerals 22a and 23a.
Are switches, 24 is an amplifier, 25 is a diode, 2
Reference numeral 6 denotes a comparator, and 27 denotes a field-effect transistor (hereinafter referred to as FET). The FET 27 is connected to the output terminal of the buffer amplifier 12 constituting the output setting unit 10 and the input terminal of the amplifier 24 constituting the output limiting unit 20. The input terminal of the amplifier 22 is connected to the other end of the resistance element Rc, and the input terminal of the amplifier 23 is connected to the output terminals 30a, 30a.
b. The output terminals of the amplifiers 22 and 23 are connected to the input terminal of the amplifier 24 together with the output terminal of the limiter setting signal generator 21 via switches 22a and 23a, respectively. The output terminal of the amplifier 24 is connected to the input terminal of the buffer amplifier 12 in the output setting unit 10 via a diode 25 and the FET 27 via a comparator 26.
Connected to the gate.

[0004] The operation of the apparatus having such a configuration will be described as follows. In this case, the switch 22a is turned on and the switch 23a is turned off. The value is set by the setting signal generator 11 in the output setting unit 10 so that a desired output voltage is obtained. This setting signal is supplied to the buffer amplifier 12,
It is added to the integrator 13 and the amplifier 14. Amplifier 14
Is taken out from the terminals 30a and 30b as an output generation voltage and supplied to the load 30. With the voltage supplied to the load 30, the resistance element Rc
, A current corresponding to the value of the load flows, and a voltage drop generated in the resistance element is input to an amplifier 24 via an amplifier 22 and a switch 22 a constituting an output limiting unit 20. In the amplifier 24, the output voltage of the amplifier 22 is added (compared) to the output of the limiter setting signal generator 21. in this case,
The output (positive) of the amplifier 22 is the limiter setting signal generator 21
When the absolute value is smaller than the value (negative) set in the above, the output of the amplifier 24 becomes negative and the diode 25 is turned off, and the output of the comparator 26 becomes L level. As a result, the FET 27 is turned off. It has become.

Conversely, when the output voltage of the amplifier 22 is larger in absolute value than the output of the limiter setting signal generator 21, the output of the amplifier 24 becomes positive and the diode 25
Is turned on, the output of the comparator 26 becomes H level, and the FET 27 is turned on. as a result,
A feedback loop including the diode 25, the buffer amplifier 12, and the FET 27 is formed in the amplifier 24.

As described above, when the voltage corresponding to the voltage supplied to the load 30 becomes larger than the limiter voltage set by the limiter generator 21, the diode 25 and the FET 27 conduct, and the amplifier 2 is turned on by the feedback loop formed as a result.
4 is controlled so that the output of the buffer amplifier 12 corresponds to the output of the limiter setting signal generator 21. As a result, the voltage obtained from the amplifier 14 of the output setting unit 10 is subjected to a limiter corresponding to the value set by the limiter setting signal generator 21. In this way, a limiter is applied in the case of voltage output, which limits the magnitude of the output voltage.

[0007] Such a voltage generator with an output limiter has been conventionally used.
Since the limiter is applied by turning on / off the ET 27, the level at which the FET 27 is turned on / off is about −0.4 V in the case of the junction type FET. As a result, the comparator 26 is driven by the comparator 26 to drive this FET. Will be needed. The necessity of a comparator to operate the FET switch causes economical loss, delays the limiter operation, and when the limiter function is activated, a current or voltage exceeding the limit current is supplied to the load. As a result, there is a problem that the load is adversely affected while having the limiter function.

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems, and to realize a low-cost, high-responsive voltage / current generator with an output limiter. It is in.

[0008]

According to the present invention, a setting signal generator is provided, and a setting signal set by the setting signal generator is applied to a buffer amplifier to generate a voltage or a current corresponding to the value of the setting signal. An output setting unit, a limiter setting signal generator, an amplifier for comparing a voltage corresponding to a voltage or a current obtained from the output setting unit with an output of the limiter setting signal generator, an input terminal of the amplifier and the buffer amplifier A switch element that is connected between the output terminal of the amplifier and a switch element that is turned on by the output of the amplifier when a voltage corresponding to the voltage or current obtained from the output setting unit becomes larger than the output of the limiter setting signal generator. And a voltage corresponding to a voltage or a current obtained from the output setting unit and connected between the input terminal of the buffer amplifier and the input terminal of the buffer amplifier becomes larger than the output of the limiter setting signal generator. In the apparatus provided with the output restriction portion made of diodes which conduct a, is obtained characterized by using a transistor as the switching element.

[0009]

According to the present invention, when the limiter is to be operated, the transistor is immediately turned on by the output of the amplifier constituting the output limiting section.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below. FIG. 1 is a block diagram showing an embodiment of the apparatus of the present invention, and this figure illustrates the case of a voltage generator. In FIG. 1, the same parts as those in FIG. 3 are denoted by the same reference numerals as those in FIG. 3, and the re-description thereof will be omitted.
The switch 22a is on and the switch 22b is off. In FIG. 1, reference numeral 40 denotes a transistor. The collector electrode of the transistor 40 is connected to the output terminal of the buffer amplifier 12 in the output setting unit 10, and the emitter electrode is connected to the output limiting unit 20.
And the base electrode is connected to the output terminal of the amplifier 24, respectively.

In the device having such a configuration, the output of the limiter setting signal generator 21 is larger than the output voltage of the amplifier 24 obtained as a result of detecting the magnitude of the voltage obtained from the output terminals 30a and 30b (the input voltage of the amplifier 24). Is positive), the transistor 40 and the diode 25 are off because the output of the amplifier 24 is pulled to the negative side. Conversely, if the output of the limiter setting signal generator 21 is smaller than the output signal of the amplifier 24 (the input of the amplifier 24 is negative), the output of the amplifier 24 tends to be positive, and as a result, the diode 25 and the transistor 40 are turned on. ,
A feedback circuit including a diode 25, a buffer amplifier 12, and a transistor 40 is formed in the amplifier 24, and the output setting unit 10 and the output limiting unit 20 are coupled to operate the limiter as described with reference to FIG.

Next, current generation will be described. FIG. 2 shows a circuit diagram in this case. In the case of current generation, switch 2
Turn off 2a and turn on 23a. In the case of voltage generation, the output terminal of the setting device 11 is connected to the output terminal of the amplifier 14, but in the case of current generation, the output terminal of the setting device 11 is connected to a resistor Rc.
Is connected to one end. The potential point COM is the amplifier 13,
14 and the other end of the resistor Rc are also at the same potential. The setting is performed by the setting unit 11 in the output setting unit 10 so that a desired output current is obtained. The setting signal is applied to the buffer amplifier 12, the integrator 13, and the amplifier 14, and a current corresponding to the setting signal is generated from the amplifier 14, and the current is supplied to the load 30. In this case, the resistance element Rc functions as a constant current element. The terminals 30a, 3
The voltage generated at 0b is applied to the amplifier 23 of the output limiting unit 20. Thereafter, the output of the amplifier 23 is compared with the output of the limiter setting signal generator 21 by the amplifier 24 in the same manner as the voltage generation.
0 is off, and if it is positive, it conducts with the diode 25. When conducting, a feedback loop is formed in the amplifier 24,
This limits the output current.

As described above, according to the present invention, in a device in which an output limiting unit is added to an output setting unit, the output of the last stage amplifier of the output limiting unit is provided as a switch element in a feedback circuit of this amplifier. Since the transistor is turned on / off, the use of the FET as in the conventional device eliminates the need for a comparator for driving the FET. As a result, it is possible to obtain a voltage / current generator that is economical and has an improved reaction speed.

[Brief description of the drawings]

FIG. 1 is a configuration diagram showing an embodiment of a voltage generator according to the present invention.

FIG. 2 is a configuration diagram showing an embodiment of the current generator of the present invention.

FIG. 3 is a configuration diagram of an example of a conventional device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Output setting part 11 Output setting part 12 Buffer amplifier 20 Output limiting part 21 Limiter setting signal generator, 22-24 Amplifier 25 Diode 30 Load 40 Transistor

Claims (1)

(57) [Claims] An output setting unit that includes a setting signal generator, and adds a setting signal set by the setting signal generator to a buffer amplifier to generate a voltage or a current according to the value of the setting signal; A generator, an amplifier for comparing a voltage corresponding to a voltage or a current obtained from the output setting unit with an output of the limiter setting signal generator, and connected between an input terminal of the amplifier and an output terminal of the buffer amplifier. When a voltage corresponding to the voltage or current obtained from the output setting unit becomes larger than the output of the limiter setting signal generator, a switch element that is turned on by the output of the amplifier, an output terminal of the amplifier, and an input terminal of the buffer amplifier. Between the output setting unit and the voltage corresponding to the voltage or current obtained from the output setting unit. A voltage-current generator, comprising: a transistor as the switch element.