JPS6214526A - Voltage dividing circuit - Google Patents

Abstract

PURPOSE:To obtain many divided voltages with a small number of resistance elements by providing a switch in not only the output side but also the input side of a series resistance circuit. CONSTITUTION:Switches 31-34 re inserted between terminals 11 and 12 and a series resistance circuit 19. If switches 31 and 32 in the input side are closed when a switch 24 in the output side of the circuit 19 is closed, a voltage V outputted from a power supply circuit is impressed between terminals 13 and 14. Consequently, an output voltage Vout obtained between output terminals 28 and 29 is given by VX(B+C+D)/(A+B+C+D) where A-D are values of resistance elements 15-18. If switches 31 and 34 are closed when the switch 24 is closed, the output voltage Vout is given by VX(B+C)/(A+B+C). Since the switch is provided in the input side of the circuit 19 also, more voltages are outputted in comparison with the case where the voltage V is impressed to only both ends of the circuit 19.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a voltage dividing circuit that uses resistive elements to divide a constant voltage in proportion to the resistance value.

[Technical Background of the Invention] Many types of analog voltages are required when performing operational tests on analog-to-digital conversion circuits (A/D conversion circuits or digital-to-analog conversion circuits (D/A conversion circuits)). In order to extract these analog voltages, a voltage divider circuit using a resistance element is generally used.

FIG. 5 is a circuit diagram of a conventionally used voltage divider circuit. A constant voltage V output from a power supply circuit (not shown) is applied between the terminals 11 and 12. This constant voltage (2) is applied such that, for example, the terminal 11 side has a high potential and the terminal 12 side has a low potential.

Through the terminal 11 and the switch, or through the terminal 13 directly connected to the terminal 12 and the switch,
Alternatively, for example, four resistance elements 15 to 18 are connected in series to form a series resistance circuit 19 between the terminal 14 and the directly connected terminal 14. And a series connection point 20 between the terminal 13 and the resistive elements 15 and 16. Resistance elements 16 and 1
One end of each of the switches 23 to 27 is connected to the series connection point 21 of 7, the series connection point 22 of the resistive elements 17 and 18, and the terminal 14, respectively.
The other ends of 27 to 27 are commonly connected to a divided voltage output terminal 28. Further, a terminal 29 used as a pair with the divided voltage output terminal 28 is connected to the terminal 12 on the low potential side.

In such a circuit, several analog voltages of different values can be obtained between terminals 28 and 29 by changing the combination in which switches 23 to 27 are closed.

[Problems with Background Art] As described above, a large number of analog voltages are required in the operation test of A/D conversion circuits and D/A conversion circuits. For example 8
A bit A/D conversion circuit requires a maximum of 256 analog voltages. However, conventional voltage divider circuits require a large number of resistive elements to obtain this much output voltage. Therefore, it is difficult to equalize the values of the resistance elements, and there is a problem that the output voltage cannot be set with high precision. Furthermore, since the circuit scale becomes larger, there is also the problem of higher manufacturing costs.

[Object of the Invention] This invention was made in consideration of the above-mentioned circumstances, and its purpose is to provide a voltage divider circuit that can obtain a large number of divided voltages using a small number of resistive elements. It is about providing.

[Summary of the Invention] In order to achieve the above object, the present invention applies a predetermined voltage output from a power supply circuit between the first and second terminals, and connects a plurality of resistive elements in series. A series resistance circuit is configured, and a first switch element is selectively inserted between both ends of the series resistance circuit and any series connection point of the resistance element, and each of the first and second terminals, A second switch element is inserted between each series connection point of the resistance circuit and an output terminal for taking out the divided voltage.

[Embodiments of the invention] Hereinafter, one embodiment of the present invention will be described with reference to the drawings.

FIG. 1 is a circuit diagram showing the configuration of an embodiment of a voltage divider circuit according to the present invention. The difference between this embodiment circuit and the conventional circuit shown in FIG. 5 is that the terminals 11 and 1
Instead of connecting switch 31 directly, connect switch 31 during this time.
Similarly, instead of connecting terminals 12 and 14 directly, a switch 32 is inserted between them, and a switch 33 is inserted between terminal 11 and the series connection point 20 of the resistor. The switch 34 is inserted between the terminal 12 and the series connection point 22 of the resistor.

Next, the operation of the circuit configured as described above will be explained. Let us now consider a case where the switch 24 on the output side of the series resistance circuit 19 is closed. In this state, first, when the input side switches 31 and 32 are closed, the constant voltage V output from the power supply circuit is applied between the terminals 13 and 14 to which both ends of the series resistance circuit 19 are connected via the switches 31 and 32, respectively. is applied to Therefore, the values of resistive elements 15 to 18 are A,
B, C, and D, the voltage obtained between the output terminal 28 and the terminal 29, that is, the output voltage yout, is given by the following equation.

Furthermore, when the input side switches 31 and 34 are closed while the output side switch 24 is closed, the constant voltage V output from the Na circuit is applied to the series resistance circuit 19 via the switches 31 and 34, respectively. Terminal 13 with one end connected
and the series connection point 22 of the resistive elements. Therefore, by providing a switch on the input side of the series resistance circuit 19, the output voltage vout when It can output voltages of quite a large number of values.

FIG. 2 shows the relationship between the closed switch and the output voltage at that time in the circuit of the above embodiment, together with that of the conventional circuit. In FIG. 2, the switches 31 to 34 are indicated by an O symbol when they are closed, and an X symbol when they are open. Furthermore, the output voltage is the value when the input voltage V is set to 1.

As is clear from FIG. 2, when four resistance elements are used, the conventional circuit can only obtain five different output voltages in total, including voltages 1 and O, but the above embodiment circuit In this case, a total of 10 different output voltage values including voltages 1 and 0 can be obtained.

In addition, in the above embodiment circuit, when applying the constant voltage V output from the power supply circuit between the terminals 11 and 12, it is applied so that the terminal 11 side has a high potential and the terminal 12 side has a low potential. By reversing the polarity when applying the constant voltage V, it is possible to obtain output voltages with even greater values.

FIG. 3 is a circuit diagram showing the configuration of an applied example of the present invention.

This application example circuit is provided with terminals 51 and 52 to which a constant voltage outputted from a power supply circuit (not shown) is applied, and furthermore, between terminals 53 and 54, 3 terminals each having a resistance value of 2Ω are provided.
resistors 55 to 57.Resistors 58 each having a resistance value of 128 Ω, 15 resistors 59 to 73 each having a resistance value of 8 Ω, and 4 resistors 74 to 77 each having a resistance value of 2 Ω are connected in series. Configure a series resistance circuit,
Between the terminals 51 and 53, a series connection point 78 between the resistors 55 and 56, and a series connection point 79 between the resistors 56 and 57.
Switches 81 to 84 are inserted between the series connection point 80 of the resistors 57 and 58, respectively, and the series connection point 85 of the resistors 77 and 76 and the series connection of the resistors 76 and 75 are inserted between the terminals 52 and 54, respectively. Switches 88 to 91 are inserted between the point 86 and the series connection point 87 of the resistors 75 and 74, respectively, and the series connection points 92 to 107 of each pair of resistors connected between the resistors 58 to 74 and the output. Switches 109 to 124 are inserted between the terminal 108 and the terminal 108.

In this application example circuit, FIG. 4 summarizes the relationship between the closed switch and the output voltage at that time. In FIG. 4, switches 81 to 84 and 88
For 91 to 91, those that are closed are marked with a circle. Furthermore, the output voltage is expressed in hexadecimal as an 8-bit expected value.

Regarding polarity, a high potential can be applied to the terminal 51,
□□□5. I, 7. □Ya. The state of 1 is considered negative polarity.

Note that the switches used in the above embodiment circuit and application example circuit include bipolar transistors, MOS t
- Analog switches such as transistors can be used.

[Effects of the Invention] As described above, according to the present invention, it is possible to provide a voltage divider circuit that can obtain a large number of divided voltages using a small number of resistance elements.

[Brief explanation of drawings]

FIG. 1 is a circuit diagram of an example circuit of the present invention, FIG. 2 is a diagram summarizing the output voltages obtained by the above-mentioned example circuit, FIG. 3 is a circuit diagram of an application example circuit of this invention, and FIG. The figure shows a summary of the output voltages obtained by the above application example circuit, and FIG. 5 is a circuit diagram of a conventional circuit. 11, 12...terminals (first and second terminals), 15.
16°17, 18...Resistance (resistance element), 19...
Series resistance circuit, 23, 24.25.26.27... switch (second switch element), 28... output terminal,
31.32.33.34...Switch (first switch element). Figure 1

Claims (1)

[Claims] A first and second terminal to which a predetermined voltage output from a power supply circuit is applied, a series resistance circuit configured by connecting a plurality of resistance elements in series, and both ends of the series resistance circuit and the resistance element. and any series connection point of the first and second
a first switch element selectively inserted between each of the terminals, an output terminal for taking out the divided voltage, and at least between each series connection point of the series resistance circuit and the output terminal. A voltage divider circuit comprising a second switch element.