JPS6249525A - Voltage setting circuit - Google Patents

Abstract

PURPOSE:To set the output voltage simply and accurately by using a constant voltage power supply device in a remote sensing mode and at the same time connecting with switching a resistance between a sense input terminal and a power supply terminal of the load. CONSTITUTION:A constant voltage power supply device 1 set in a remote sensing mode compares the voltage supplied to a sense input terminal 3 with the reference voltage level. The voltage drop of the connection line set between a power supply terminal 9 of the load 8 and the terminal 3 can be neglected. Thus the voltage applied to the terminal 9 can be kept at a fixed level even in case the voltage drop of a feeder 4 cannot be ignored. While the ratio of the output voltage to be compared with the reference voltage can be changed by connecting with switching a resistance 6 between both terminals 9 and 3. In such a way, the output voltage can be set at a desired level simply and accurately.

Description

[Detailed Description of the Invention] [Summary] A constant voltage power supply device is used in remote sensing mode, and a switch for switching and connecting a resistor is provided between the power supply terminal of the load and the sense input terminal. This is to accurately set the output voltage of the voltage device.

[Industrial application field]

The present invention relates to a voltage setting circuit that can accurately and quickly set the output voltage of a constant voltage power supply.

Constant-voltage power supplies can obtain a constant output voltage even when the load changes, and are often used as power supplies for operating various electronic devices. It is also used as a power source for temperature testing of various electronic devices.

[Conventional technology]

A constant voltage power supply device compares the output voltage with a reference voltage,
A common configuration is to control the on/off time ratio of switching, smooth the switching output and supply it to the load, and keep the output voltage constant even when the load changes. Therefore, by changing either the output voltage or the reference voltage using a variable resistor or the like and comparing them, the output voltage can be set arbitrarily.

FIG. 5 shows a block diagram of the constant voltage power supply device, in which 31 is a primary rectifying and smoothing circuit that rectifies and smoothes the AC input voltage;
2 is an inverter section that is composed of switching elements such as transistors and outputs a switching output via a transformer; 33 is a secondary rectifying and smoothing circuit that rectifies and smoothes the output of the inverter section 32; and 34 is an output voltage and a reference voltage. 35 is an error amplifier that amplifies the comparison output of the comparison circuit 34, 36 is a time ratio control circuit that controls the on/off time ratio in the inverter section 32, 37 is a reference voltage, R, , R2 is a resistor, RV is a variable resistor, TI,
T4 is a sense input terminal, T2.73 is an output terminal, and 12 is a load.

The AC input applied to the constant voltage power supply 11 is converted into DC by the primary rectifying and smoothing circuit 31 and then sent to the inverter section 32.
added to. The inverter section 32 is a time ratio control circuit 36
The on/off time ratio is controlled by the switching output terminal T2. The direct current is supplied to the load 12 from T3.

Sense input terminal T1, output terminal T2, sense input terminal T
A local sensing mode in which output terminals T2.4 and output terminal T3 are directly connected, respectively, is common.
The output voltage output from T3 is connected to the resistor RI and variable resistor Rv.
, a voltage applied to a series circuit of resistors R2 and adjusted by a variable resistor Rv is applied to a comparator circuit 34 for comparison with a reference voltage 37. That is, a voltage proportional to the output voltage and the reference voltage 37 are compared. The output of the comparison circuit 34 is amplified by an error amplifier 35 and applied to a time ratio control circuit 36. This time ratio control circuit 36 sets the on/off time ratio so that when the output voltage is above a reference value, the on time is shortened, and when the output voltage is below the reference value, the on time is lengthened. Set the on/off time ratio to
Controls the inverter section 32. Thereby, the output voltage is made constant.

Also, output terminal T2. If the voltage drop in the power supply line connecting between T3 and load 12 cannot be ignored, the sense input terminal T
This is a remote sensing mode in which I and T4 are connected to the power supply terminal of the load 12. That is, since the voltage directly applied to the load 12 is input to the sense input terminals TI and T4, the output voltage compensates for the voltage drop in the power supply line, and a constant voltage can be applied to the load 12. becomes possible.

In addition, in temperature tests of various electronic devices and electronic components,
Adjust the operating voltage to the standard voltage and ±5% of the standard voltage, ±10
% or ±15%, etc. to perform various measurements. Since these various voltages also need to have a predetermined accuracy, they are supplied using the aforementioned constant voltage power supply device. Therefore, a constant voltage power supply device having a means for arbitrarily setting the output voltage described above was used.

[Problem that the invention seeks to solve]

To set various output voltages using a single constant voltage power supply, you need to use a variable resistor to change the output voltage or reference voltage input to the comparator, while checking the output voltmeter. This method has the disadvantage that setting a desired voltage value is complicated, and that it takes a long time to set an accurate output voltage.

SUMMARY OF THE INVENTION An object of the present invention is to use the remote sensing mode of a constant voltage power supply to easily and accurately set the output voltage.

[Means for solving problems]

The voltage setting circuit of the present invention will be described with reference to FIG. 1. A constant voltage power supply device 1 includes an output terminal 2 and a sense input terminal 3. Terminal 9 is connected, a circuit 7 consisting of a switch 5 and a resistor 6 is connected between the power supply terminal 9 and the sense input terminal 3, and the resistor 6 is switched and connected by the switch 5, thereby changing the output voltage. This is what you set.

[Effect]

The constant voltage power supply l in the remote sensing mode compares the voltage input to the sense input terminal 3 with a reference voltage, and also compares the voltage input to the sense input terminal 3 with the connection Vt between the power supply terminal 9 of the load 8 and the sense input terminal 3. Since the voltage drop in the line can be ignored, even if the voltage drop in the feeder line 4 cannot be ignored, the voltage applied to the power supply terminal 9 of the load 8 can be made constant, and the voltage applied to the power supply terminal 9 of the load 8 can be kept constant. By selectively connecting a resistor 6 to the sense input terminal 3 of the constant voltage power supply 1,
The ratio of the output voltage for comparison with the reference voltage can be varied, thereby allowing the output voltage to be set to a desired value.

〔Example〕

Embodiments of the present invention will be described in detail below with reference to the drawings.

FIG. 2 is a circuit diagram of a main part of an embodiment of the present invention, in which output terminals T2. T3 and the power supply terminal of the load 12 are connected by a power supply line 14, and resistors rl, r2 . ...
rn and a circuit 13 consisting of switches si, s2, . . . Sn are connected, and the sense input terminal T4 and output, j, =°,
The child T3 is connected to the child T3.

All switches S', S2. ...When Sn is turned on, a normal remote sensing mode is established in which the sense input terminal T1 and the power supply terminal of the load 12 are connected.

Then, the voltage applied to the power supply terminal of the load 12 is applied to the resistance R
The voltage applied to the series circuit of I, variable resistor RV, and resistor R2 and adjusted by variable resistor Rv is applied to the comparator circuit (see Figure 5).
is added to the voltage for comparison with a reference voltage.

Resistance rl, r2. ...Let rn be r, and the input resistance between sense input terminals TI and T4 be R (=R, +Rv+R2
), and the switches Sl, S2 . . . . Output terminal T2 when all Sns are turned on. If the voltage appearing at T3 is vo, then it becomes O. Note that ΔV indicates a unit output voltage change width.

For example, a circuit 1 with Vo=4.5V, ΔV=0.25V and L, four switches S1 to S4, and resistors r1 to r4
3, the output voltage is controlled by four switches 81 to 81.
4.5v (-10%) when S4 is on, 4.75v (-5%) when three switches 82 to S4 are on, one switch S1 is off, two switches S
3. 5 when S4 is on and two switches Sl and S2 are off, OV (±O%), 5 when one switch S4 is on and three switches 81 to S3 are off.
．． It can be set to five different values: 25V (+5%) and 5.5V (+10-%) when the four switches 81 to S4 are turned off.

In this case, if the resistance r is a standard resistance value, the input terminal T
It is necessary to find the input resistance R between I and T4 depending on the resistance r, but (R, +R2+RV) is fixedly provided in the device and is difficult to change. Therefore, it is sufficient to connect the adjustment resistor R° in parallel between the input terminals T1 and 74. At this time, the adjustment resistance R° is calculated from the formula RR' (R1+R2+RV). However, the relationship is R<(R1+R2+Rv).

FIG. 3 is a main part circuit diagram of another embodiment of the present invention, and FIG.
The same reference numerals as in the figure indicate the same parts. In this example, load 1
A resistor connected in parallel between the power supply terminals of the switches Sl, S2...2 and the sense input terminals T1, T4 is connected to the switches Sl, S2...・・・Sn
R, , R3, and R4 are resistors. Since the voltage V between the input terminals TI and 74 is kept constant, the switches Sl, S2 . ...Unit change width ΔI of the current flowing through the resistor R3 due to the on/off of Sn
is ΔI=V, /R4. Therefore, in this embodiment as well, similarly to equation (1), the resistor R4 is connected to the input voltage VI
, due to the relationship between the unit output voltage change width ΔV and the resistance R6°R3.

Here, the voltage between output terminals T2 and 73 is input voltage V,
In order to make the difference between them an integral multiple of a constant value, switch Sl, 32 . . . . The resistance value between the input terminals TI and 74 when all Sns are off should be made equal to the resistance value of the resistor R4. Therefore, it becomes.

FIG. 4 is a circuit diagram of a main part of still another embodiment of the present invention,
The same reference numerals as in FIG. 2 indicate the same parts. In this embodiment, a switch S is used to connect resistors Ra* with different resistance values.
This example is based on the case where a circuit 13 is provided that switches and connects Rb + Rc + Rd, R'' between the sense input terminals TI and 74, and Rx is a series resistor. Resistors Ra, Rb, R by S
By switching and connecting c, Rd, and Re, the output voltage of the constant voltage power supply device 11 can be set.

The circuit 13, which is a combination of a resistor and a switch, connected between the power supply terminal 1 of the load 12 and the sense input terminals Tl, I of the constant voltage power supply 11 may have various connection combination configurations in addition to the above-mentioned embodiments. It is something that can be adopted.

〔Effect of the invention〕

As explained above, the present invention provides constant voltage power supply devices 1, 1
1 sense input terminal 3. A switch 5. which sets the voltage between TI, T4 and the power supply terminal 9 of the load 8.12. s
, Si, s2. ...-3n and resistance 6. rl, T
2. The circuit 7.13 consisting of...rn is connected, and a desired output voltage can be set by a switch.
Since the output voltage is stabilized by the voltage stabilization operation in step 1, a desired output voltage can be set accurately and easily. Therefore, it can be applied to voltage settings in temperature tests of electronic equipment, etc. to obtain accurate output voltage with good reproducibility.
This makes it possible to improve measurement accuracy.

[Brief explanation of the drawing]

Figure 1 is a diagram explaining the principle of the present invention, Figures 2, 3, and 4.
The figure is a circuit diagram of a main part of an embodiment of the present invention, and FIG. 5 is a block diagram of a constant voltage power supply device. 1.11 is a constant voltage power supply, 2 is an output terminal, 3 is a sense input terminal, 4 is a power supply line, 5 is a switch, 6 is a resistor, 7,
13 is a circuit, 8 and 12 are loads, 9 is a power supply terminal, T1. T
4 is a sense input terminal, T2 and T3 are output terminals, 81 to S
n, S are switches, rl to rn, R (1-R4 are resistors.

Claims (1)

[Claims] In a constant voltage power supply device (1) comprising an output terminal (2) and a sense input terminal (3), a load is connected to the output terminal (2) via a power supply line (4). Connect a power supply terminal, and connect the power supply terminal and the sense input terminal (3).
A voltage setting circuit characterized in that a circuit (7) consisting of a switch (5) for setting a voltage and a plurality of resistors (6) connected by the switch (5) is connected between the voltage setting circuit and the voltage setting circuit.