JPS6040046B2 - Stabilized power supply circuit - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a stabilized power supply circuit, and more particularly to a stabilized power supply circuit in which the temperature coefficient of the output voltage or current can be set.

FIG. 1 shows the principle of a conventional stabilized power supply circuit. In the figure, 1 is a control circuit, 2 is a differential amplifier, and a reference voltage V2 is applied to the positive input terminal of the differential amplifier 2. V3 is the power supply voltage.

Further, the output voltage V, is divided by the resistors R^ and R8 and applied to the negative input terminal of the differential amplifier 2, and V3 is the power supply voltage. These positive and negative input terminal voltages are compared by a differential amplifier 2, and an output proportional to the difference is output from a control circuit 1.
In addition, negative feedback is applied. If the gains of the control circuit 1 and the differential amplifier 2 are set so that the loop gain of this negative feedback is sufficiently high, the output voltage V is stabilized to a voltage expressed by the following equation m. V. =V2 (・Tosagi)
-------- [1' In the above-mentioned subordinate voltage stabilizing power supply circuit, the reference voltage V2 does not change with changes in ambient temperature, so the output voltage V, does not change with changes in ambient temperature.

Therefore, it has a drawback that the temperature change amount of the output voltage cannot be set to an arbitrary value. SUMMARY OF THE INVENTION In order to solve the above-mentioned drawbacks, an object of the present invention is to provide a temperature-compensated stabilized power supply circuit that can adjust the temperature change characteristics of a stabilized output voltage or a stabilized output current. .

The present invention comprises a bridge circuit including one or more temperature change elements and a variable resistor placed on the output side, and one input terminal having a voltage divider circuit or a current voltage divider placed on the output side of a stabilized power supply circuit. A differential amplifier to which the output of the shunt circuit is supplied and the output from the variable resistor of the bridge circuit is supplied to the other input terminal, and the output of this differential amplifier is applied to send out a stabilized voltage or stabilized current. A temperature-compensated stabilized power supply circuit, characterized in that the temperature-compensated stabilized power supply circuit comprises a control circuit for adjusting the variable resistance of the bridge circuit to adjust the temperature change characteristics of the stabilized output voltage or the stabilized output current. It is about providing. Next, embodiments of the present invention will be described with reference to the drawings.

FIG. 2 shows an embodiment of the stabilized power supply circuit according to the present invention, and the same or corresponding parts as in FIG. 1 are denoted by the same reference numerals.

In the figure, 3 is a control circuit, and 4 is a differential amplifier.
The output voltage V, is divided by resistors RA and RB and applied to the negative input terminal of the differential amplifier 4. Further, the positive input terminal of the differential amplifier 4 is connected to the sliding terminal of the variable resistor R5, and the fixed terminals at both ends of the variable resistor R5 are connected to the connection point between the resistors R and R2 and the connection point between the resistors R3 and R4, respectively. Connected to the dots. Further, the other ends of the resistors R and R3 are commonly connected, and a reference voltage V4 whose one end is grounded is connected to this connection point, and the other ends of the resistors R2 and R4 are grounded. In this way, the positive input terminal of the differential amplifier 4 is connected to a bridge circuit consisting of resistors R, -R5 and a reference voltage power supply N4. In addition, the input terminal voltage supplied to the positive and negative input states of the reed amplifier 4 is the differential amplifier 4.
An output proportional to the difference is applied to the control circuit 3 to provide negative feedback.

Here, a negative feedback circuit is constituted by the differential amplifier 4, the control circuit, and a voltage dividing circuit made up of resistors R^ and RB.The control circuit 3
It is assumed that the gain of the differential amplifier 4 and the gain of the differential amplifier 4 have been set.
The resistor R2 is an element whose resistance value changes depending on the temperature (hereinafter referred to as a temperature change element), such as a thermistor.If the resistance value at room temperature is Ro, and the coefficient of change due to temperature is M, then the following equation is obtained. There is a relationship of the formula.

R2;M old〇……(
2l FIG. 3 is a characteristic diagram showing an example of the temperature coefficient M of the temperature change element, in which the vertical axis represents the temperature coefficient M of the temperature change element, and the axis represents the ambient temperature T (°C).

In FIG. 2, since the above-mentioned relationship of equation {1} holds true in the same way as in the circuit of FIG. 1, the output voltage V, is proportional to the voltage V2 at the positive input terminal of the differential amplifier 4.

Further, V2 is determined by the reference voltage V4 and the resistors R, to R5. Further, since R2 is a temperature changing element, the voltage V2 changes with changes in ambient temperature, and the output voltage V, changes with changes in ambient temperature. Let V be the value of the output voltage y at room temperature. Then, the amount of change in the output voltage with respect to the value at room temperature V, /V,o is the resistance value R. , Ro, and R3 to R5, it can be expressed as the following equation [3}. Note that here, in order to represent the position of the sliding terminal of the variable resistor R5, the variable resistor R5 is
The resistance value between one fixed terminal and the sliding terminal of No. 5 is expressed as XR5 as shown in the figure. Further, at room temperature, it is assumed that R, , Ro, R3, and R4 are adjusted in advance to balance the bridge circuit.

Here, OSX≦1, R. R4=R3R.

In the above formula '3}, the values of R,, R3 and R5 are set to R
,. If the value of R4 is selected to be sufficiently large compared to the value of R4, the glue formula is omitted and the following '41 formula is obtained. Person 3: ・10×(M-1) ………■ In this ■ formula, if we set ×=0 or・・・．・・・．
... [6' That is, X is set from 0 to 1 depending on the setting position of variable resistor R5, and the amount of change V, 'V, o of the output voltage with respect to temperature is set from 1 (that is, no change) to M. I can do it.

Further, as mentioned above, if the values of R,, R3 and R5 cannot be selected to be sufficiently large compared to the values of Ro and R4, the above formula '3' remains as is, and the above formula '3} is used.
When X=0 or X=1, the values of V, /V, and o are expressed as shown in the following equations [61 and '71, respectively.

That is, depending on the setting position of the variable resistor R5, X is set from 0 to 1, and is set to a value expressed by the value equation ``7'' that represents the variable quantity of the output voltage with respect to the temperature (6). be able to. FIG. 4 shows an example of the temperature change characteristics of the output voltage of the stabilized power supply circuit shown in FIG.
Further, the value of M indicates the characteristics of V, /V, and o in accordance with FIG. That is, R,=R3=1.8kO R.

=R4=1800R5=5000 In FIG. 4, the shaded range is the range of temperature change that can be selected by setting X between 0 and 1.

Furthermore, in the circuit shown in FIG. 2, the output voltage V at room temperature can be set arbitrarily by appropriately selecting the values of RA and RB.

As is clear from the above description, when the stabilized power supply circuit shown in FIG. 2 is used, the value of the output voltage at room temperature and the amount of temperature change in the output voltage can be independently set to arbitrary values.

In the embodiment shown in FIG. 2 above, only one of the resistors R, -R4, for example, the resistor R2, is used as a temperature change element, but the present invention is not limited to this. Explaining with reference to FIG. 2, the same objective as described above can be achieved even if two or more of the resistors R, to R4 are used as temperature change elements.

Also, the resistance R in the embodiment of FIG. , R3 may be replaced with a constant current circuit. In this case as well, the same purpose as described above can be achieved.

That is, if the resistors R and R3 are changed to constant current circuits as shown in FIG. 5, and a high input impedance differential amplifier 5 is added in front of the variable resistor R5, R, , The values of R3 and R5 can be equivalently made sufficiently larger than the values of Ro and R4, and the characteristic of the above-mentioned formula (5-) can be realized.In addition, in the embodiment shown in FIG. R^ and RB in the R^ and RB voltage divider circuit
Although the output voltage V at room temperature can be set to any value by selecting an appropriate value of , the present invention is not limited thereto. For example, in FIG. By replacing the voltage dividing circuit of R8 with a potentiometer, the output voltage at room temperature can be continuously set to an arbitrary value. Furthermore, although the embodiments shown in FIGS. 2 and 5 have described voltage stabilizing power supply circuits in which the output voltage has temperature change characteristics, the present invention is not limited to this, and the embodiments shown in FIG. Similarly, the present invention is also applied to a current stabilized power supply circuit whose output current has temperature change characteristics.

That is, Rc in FIG. 6 is a current shunt for output current detection, and the voltage value appearing between the terminals of this current shunt Rc and the voltage of the bridge circuit are applied to the differential amplifier 4, and this differential amplifier The output of No. 4 is applied to a control circuit 3, and the output current is stabilized by this control circuit 3. In this case, the other details are the same as those described above, so the explanation will be omitted. Further, if the power supply voltage V3 is a constant voltage, the reference voltage source V4 in this embodiment is
May be used for both purposes.

As explained above, the present invention is configured so that the temperature change characteristics of the stabilized output voltage or the stabilized output current can be adjusted. This has the advantage that the amount of temperature change in the output current can be independently set to any value.

[Brief explanation of the drawing]

Fig. 1 is a circuit diagram showing the principle of a conventional stabilized power supply circuit, Fig. 2 is a circuit diagram showing an embodiment of the stabilized power supply circuit according to the present invention, and Fig. 3 is an example of the temperature coefficient of a temperature change element. FIG. 4 is a characteristic diagram showing an example of the temperature change characteristics of the output voltage of the stabilized power supply circuit according to the present invention, and FIGS.
The figures are circuit diagrams showing other embodiments of the stabilized power supply circuit according to the present invention. 3... Control circuit, 4, 5... Insert amplifier, 6, 7... Constant current circuit, R, ~R5, R^
, RB...Resistance, V. ...Output voltage, V3
...Power supply voltage, V4...Reference voltage source. Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6

Claims (1)

[Claims] 1. A bridge circuit that includes one or more temperature change elements and a variable resistor placed on the output side, and one input terminal of a voltage divider circuit or current shunt circuit placed on the output side of the stabilized power supply circuit. a differential amplifier to which an output is supplied and whose other input terminal is supplied with the output from the variable resistor of the bridge circuit; and a control circuit to which the output of the differential amplifier is applied and sends out a stabilized voltage or stabilized current. A temperature-compensated stabilized power supply circuit, comprising: adjusting a variable resistance of the bridge circuit to adjust temperature change characteristics of the stabilized output voltage or the stabilized output current.