JPH02263217A - Load increasing circuit for voltage variable shunt regulator ic - Google Patents

Abstract

PURPOSE:To attain the highly accurate and stable supply of the constant voltage by absorbing the fluctuation of a load radio wave with a control amplifier, thereby preventing the change of the operating current of a voltage variable shunt regulator IC. CONSTITUTION:A voltage variable shunt regulator IC 10 is connected in series to an operating current detecting resistance R3 which detects the operating current of the IC 10. Then these IC 10 and the R3 are connected in parallel to a load RL. A pair of boosting resistors R1 and R2 are connected in series and then connected in parallel to the RL. Simultaneously, the junction of both resistors R1 and R2 is connected to a reference voltage output terminal of the IC 10. Then both-terminal voltage of the R3 are compared with the set voltage level, and a control amplifier 11 where the deviation of both voltage levels is suppressed down to zero is inserted in a power circuit. Thus the fluctuation of a load current is absorbed by the amplifier 11. Consequently, the load of the IC 10 has substantially no change and the IC 10 can supply the stable constant voltage to the load.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a load expansion circuit, and in particular, a voltage variable circuit suitable for expanding the load of a voltage variable shunt regulator without impairing the characteristics of the voltage variable shunt regulator IC. This relates to a load expansion circuit for a shunt regulator IC.

[Conventional technology]

Conventionally, circuits of this type shown in FIGS. 4 and 5 are known.

In the case of the circuit shown in FIG. 4, there is a resistor R+ that boosts the output voltage of the voltage variable shunt regulator ICl0.
Since the load RL is connected to both ends of Rt, a constant voltage can be supplied to the load RL from the voltage variable shunt regulator ICl0 with respect to the large pulled-down load RL or the variable load Rt.

On the other hand, in the case of the circuit shown in FIG. 5, the load RL is connected to the emitter of the transistor T, and ICl0 is connected to the current source 1 via the diode D1, so the large load RL that is pulled up A constant voltage can be supplied from ICl0 to.

[Problem to be solved by the invention]

However, in the case of the one shown in FIG. 4, variations may occur in the load voltage vL due to variations in the base-emitter voltages v and f of the transistor T.

On the other hand, the one shown in FIG. 5 has a problem in that the variation in the load voltage vL increases due to the variation in the base-emitter voltage V□ of the transistor T1 and the forward voltage V of the diode D.

Further, there is a problem in that the difference in temperature characteristics between the voltages VIE and (1) and the temperature difference between the transistor T, and the diode D1 adversely affect the temperature fluctuation of the load voltage vL.

An object of the present invention is to provide a load expansion circuit for a voltage variable shunt regulator IC that can supply a stable constant voltage to a load without impairing the characteristics of the voltage variable shunt regulator IC even when the load fluctuates. .

[Means to solve the problem]

In order to achieve the above object, the present invention connects a voltage variable shunt regulator IC and an operating current detection resistor for detecting the operation of this IC in series and in parallel with the load, and connects a pair of boosting resistors to the load. are connected in series and in parallel with the load, and the connection point of these step-up resistors is connected to the reference voltage output terminal of the IC, and the voltage across the operating current detection resistor is compared with the set voltage to determine the deviation between the two. A load expansion circuit for a variable voltage shunt regulator IC is constructed by inserting a control amplifier into a power supply circuit to suppress the voltage to zero.

[Effect]

By adopting the above-mentioned means, the control amplifier absorbs the load current fluctuation when the load fluctuates, and the operating current of the shunt regulator IC hardly changes. It becomes possible to supply voltage.

〔Example〕

Hereinafter, one embodiment of the present invention will be described based on the drawings.

In FIG. 1, an error detection control amplifier (amplifier) 11 is inserted into the power supply circuit that supplies power to the load RL, and the output side of the control amplifier 11 includes the load RL, boosting resistors R, R1, and IK. Variable pressure shunt regulator ICl01
A resistor R3 is connected.

The boosting resistors Rr and Rz are connected in series to both ends of the load RL, and the connection point of these resistors is connected to the reference voltage output terminal R of the voltage variable shunt regulator ICl0.

The anode A of this voltage variable shunt regulator ICl0 is grounded, and the cathode side is connected to the output terminal of the control amplifier 11 via a resistor R3.

Further, both ends of the resistor R1 are connected to an error comparison voltage source V built in the control amplifier 11.

The non-inverting input terminal of the control amplifier 11 is connected to the cathode of the voltage variable shunt regulator ICl0, and the inverting input terminal is connected to the output terminal of the control amplifier 11.

The control amplifier 11 includes a resistor R3 for detecting the operating current of the voltage variable shunt regulator ICl0.
It is configured to compare the voltage at both ends with a set voltage (voltage of voltage source V) and perform control to suppress the deviation between the two to zero.

In the above configuration, the resistor Rr
Rz Rs, variable voltage shunt regulator IC
When power is supplied to l0 and load RL, the voltage across resistor R1 is maintained at V by the negative feedback action of control amplifier 11, and constant current V*/Rz flows through voltage variable shunt regulator ICl0.

Therefore, even if the load Rt varies, the control amplifier 11 absorbs the variation in the load current.

As a result, a constant voltage vL is applied to the load RL, and a necessary load current VL/RL flows.

In addition, the control amplifier 1
1 functions as a damper, the operating current of the voltage variable shunt regulator ICl0 does not fluctuate,
The load voltage vL can be maintained at a constant voltage.

In the embodiment, an IC is provided on the output side of the control amplifier 11.
Although the case where l0 and the load RL are connected in a pull-down manner has been described, as shown in FIG. 2, the control amplifier 11
It is also possible to connect the variable voltage shunt regulator rc10 and the load R4 to the output side of the circuit in a pull-up manner.

In this case, the non-inverting input terminal of the control amplifier 11 is connected to the power supply ■. and the inverting input terminal is connected to the cathode of the voltage variable shunt regulator rcio.

In this embodiment, as in the previous embodiment, the voltage across the resistor R3 is always at ■ due to the negative feedback action of the amplifier 11. 1. Even if the load RL fluctuates, it is possible to always maintain the load voltage vL at a constant voltage.

Further, in the embodiment described above, the control amplifier 11 made up of an operational amplifier having an offset voltage was used, but as shown in FIG. 3, the control amplifier 11
Instead of , it is also possible to use transistors T, T, and current source A.

In this embodiment, the base-emitter voltages v and K of the transistor T2 are controlled by a voltage variable shunt regulator IC.
It is used as an internal power supply for error detection with respect to the operating current of l0, and the load of the transistor T2 is a constant current source I. Therefore, a constant current always flows through the transistor T2, and the transistor T1 functions as a control amplifier.
The voltage across the resistor R3 is always maintained at a constant voltage, and the load R
It becomes possible to suppress fluctuations in L.

Note that it is also possible to use a fixed resistor R8 as the constant current source I3.

〔Effect of the invention〕

As explained above, according to the present invention, even if the load changes, the control amplifier absorbs the fluctuation in the load current, so it is possible to prevent the operating current of the voltage variable shunt regulator IC from changing, and It has excellent effects such as being able to supply a highly accurate and stable constant voltage without impairing the characteristics of the voltage variable shunt regulator IC even when the load or load changes.

[Brief explanation of drawings]

Fig. 1 is a block diagram showing one embodiment of the present invention, Fig. 2 is a block diagram showing another embodiment using an operational amplifier as a control amplifier, and Fig. 3 is a block diagram showing an embodiment using a transistor as a control amplifier. FIG. 4 is a block diagram of a conventional example, and FIG. 5 is a block diagram of another conventional example. ■Yo...constant current source

Claims (1)

[Claims] (1) Voltage variable shunt regulator IC and this IC
An operating current detection resistor for detecting the operating current of the circuit is connected in series in parallel with the load, a pair of step-up resistors are connected in series in parallel with the load, and the connection point of these step-up resistors is connected in series with the load. A control amplifier is connected to the reference voltage output terminal of the IC and is inserted into the power supply circuit to perform control to compare the voltage across the operating current detection resistor with the set voltage and suppress the deviation between the two to zero. A load expansion circuit for a voltage variable shunt regulator IC characterized by: