CN204761416U - AD converting circuit for test system is moved to microbit - Google Patents

Abstract

The utility model discloses an AD conversion circuit for a micro-displacement test system, which comprises a first capacitor, a reference voltage source chip, a polar capacitor, a second capacitor, a third capacitor and an AD conversion chip, wherein the reference voltage source chip includes four Pins, that is, the first to fourth pins, wherein the first pin and the second pin are connected through the first capacitor, the third pin is connected to the positive pole of the polar capacitor, and the negative pole of the polar capacitor is connected to the analog ground; The AD conversion chip includes ten pins, that is, the fifth to the fourteenth pins, wherein the fifth pin is connected to the positive pole of the polar capacitor, the eighth pin is connected to the analog ground, and the sixth pin is connected to the eighth pin Connected through the second capacitor, the fourteenth pin and the eighth pin are connected through the third capacitor, the tenth to the thirteenth pins are connected to the host computer, and the ninth pin is connected to the power ground. The technical effect is: it can Improve the measurement accuracy of micro-displacement, reduce power consumption, reduce noise, reduce output voltage hysteresis and long-term output voltage drift.

Description

An AD conversion circuit for a micro-displacement test system

technical field

The utility model relates to an AD conversion circuit, in particular to an AD conversion circuit for a micro-displacement test system.

Background technique

The AD conversion circuit is used to convert the analog quantity into a digital quantity through a certain circuit, and the AD conversion circuit only needs to complete the conversion of the analog DC voltage to the digital quantity. Generally, single-chip microcomputers include AD conversion circuits, because the number of conversion bits of the AD conversion circuit inside the single-chip microcomputer is usually not high. Ordinary single-chip microcomputers are generally 8-bit AD conversion circuits. For example, STC12C5630AD also has AD conversion functions. It is 10 bits, and the number of AD conversion bits directly determines the measurement accuracy of the system. In order to achieve high micro-displacement measurement accuracy, a separate high-resolution AD conversion circuit must be specially set.

Utility model content

The purpose of this utility model is to overcome the defects of the prior art and provide an AD conversion circuit for a micro-displacement test system, which can improve the measurement accuracy of micro-displacement, reduce power consumption, reduce noise, reduce output voltage hysteresis and long-term output voltage drift.

A technical solution to achieve the above object is: an AD conversion circuit for a micro-displacement test system, including a first capacitor, a reference voltage source chip, a polar capacitor, a second capacitor, a third capacitor, and an AD conversion chip, wherein:

The reference voltage source chip includes four pins, a first pin, a second pin, a third pin and a fourth pin, wherein the two ends of the first capacitor correspond to the first pin and the The second pin is connected, the third pin is connected to the positive pole of the polar capacitor, and the negative pole of the polar capacitor is connected to analog ground;

The AD conversion chip includes ten pins, the fifth pin, the sixth pin, the seventh pin, the eighth pin, the ninth pin, the tenth pin, the eleventh pin, the twelfth pin pin, the thirteenth pin and the fourteenth pin, wherein the fifth pin is connected to the positive pole of the polarity capacitor, the eighth pin is connected to the analog ground, and the two pins of the second capacitor terminal is correspondingly connected to the sixth pin and the eighth pin, the two ends of the third capacitor are correspondingly connected to the eighth pin and the fourteenth pin, and the tenth pin, the The eleventh pin, the twelfth pin and the thirteenth pin are connected to the host computer, and the ninth pin is connected to the power ground.

Further, the reference voltage source chip is ADR4550 chip of Arnold Company.

Further, the AD conversion chip is the AD7988 chip of Arnold Company.

A technical scheme of an AD conversion circuit for a micro-displacement test system of the present invention is adopted, including a first capacitor, a reference voltage source chip, a polar capacitor, a second capacitor, a third capacitor and an AD conversion chip, wherein the reference The voltage source chip includes four pins, namely first to fourth pins, wherein the first pin and the second pin are connected through a first capacitor, and the third pin is connected to the polar capacitor The positive pole of the polar capacitor is connected to the analog ground; the AD conversion chip includes ten pins, namely the fifth to fourteenth pins, wherein the fifth pin is connected to the polar capacitor The positive connection of the eighth pin is connected to the analog ground, the sixth pin is connected to the eighth pin through the second capacitor, the fourteenth pin is connected to the eighth pin Through the connection of the third capacitor, the tenth to the thirteenth pins are connected to the host computer, and the ninth pin is connected to the power ground. Its technical effect is: it can improve the measurement accuracy of micro-displacement, reduce power consumption, reduce noise, reduce output voltage hysteresis and long-term output voltage drift.

Description of drawings

FIG. 1 is a schematic diagram of an AD conversion circuit for a micro-displacement testing system of the present invention.

Detailed ways

In order to enable those skilled in the art to better understand the technical solution of the present utility model, its specific implementation will be described in detail below in conjunction with the accompanying drawings:

Please refer to Fig. 1, an AD conversion circuit for a micro-displacement test system of the present invention, including a first capacitor 3, a reference voltage source chip 1, a polar capacitor 4, a second capacitor 5, a third capacitor 6, and an AD conversion chip 2, of which:

The reference voltage source chip 1 includes four pins, the first pin 11, the second pin 12, the third pin 13 and the fourth pin 14, wherein the two ends of the first capacitor 3 correspond to the first pin 11 is connected to the second pin 12, the third pin 13 is connected to the positive pole of the polarity capacitor 4, and the negative pole of the polarity capacitor 4 is connected to the analog ground.

The AD conversion chip 2 includes ten pins, the fifth pin 21, the sixth pin 22, the seventh pin 23, the eighth pin 24, the ninth pin 25, the tenth pin 26, the eleventh pin pin 27 , twelfth pin 28 , thirteenth pin 29 , and fourteenth pin 210 .

Wherein the fifth pin 21 is connected to the anode of the polarity capacitor 4, so that the AD conversion chip 2 obtains a reference input voltage.

The eighth pin 24 is connected to analog ground.

Both ends of the second capacitor 5 are correspondingly connected to the sixth pin 22 and the eighth pin 24 , and the sixth pin 22 is used as the input power of the AD conversion chip 2 .

The two ends of the third capacitor 6 are correspondingly connected to the fourteenth pin 210 and the eighth pin 24, and the third capacitor 6 is used as the input power supply of the input/output interface of the AD conversion chip 2;

The tenth pin 26, the eleventh pin 27, the twelfth pin 28 and the thirteenth pin 29 are connected with the host computer 7, wherein the tenth pin 26 is an AD conversion input interface; the eleventh pin 27 It is a serial output interface, and the result of AD conversion is output through the eleventh pin 27; the twelfth pin 28 is a serial clock input interface; the thirteenth pin 29 is a serial input interface.

The ninth pin 25 is connected to the power ground.

When the AD conversion circuit for a micro-displacement test system of the utility model is used, the ADR4550 chip of Arnold Company is used as the reference voltage source chip 1. ADR4550 is a high-precision, low power consumption, low-noise reference voltage source, and the maximum initial Error is ±0.02%, with excellent temperature stability and low output noise. The ADR4550 chip has good precision and temperature stability, good anti-noise performance, low output voltage hysteresis, and low long-term output voltage drift, which improves the accuracy of the AD conversion circuit used in the micro-displacement test system of the utility model within the life and temperature range. The first pin 11 of the reference voltage source chip 1 is connected to the +6V power supply, the second pin 12 is grounded, and the third pin 13 is connected to the fifth pin 21 of the AD conversion chip 2 to provide high precision for the AD conversion chip 2. The reference voltage.

The AD conversion chip 2 adopts Arnold's 16-bit analog-to-digital converter AD7988, and its fifth pin 21 receives the high-precision reference voltage provided by the AD conversion chip 2. The fifth pin 21 is decoupled by a 10 μF polar capacitor 4 Connect to analog ground.

Its sixth pin 22 is connected to a +2.5V DC power supply to supply power for the AD conversion chip 2 .

Its seventh pin 23 is an analog input pin for receiving analog input signals.

The thirteenth pin 29 is a serial input pin, if the thirteenth pin 29 is at low level during the rising edge of the tenth pin 26, the chain mode is selected. In this mode, the thirteenth pin 29 is input, and the analog-to-digital conversion result is transmitted to the eleventh pin 27 in a daisy chain; if the thirteenth pin 29 is high during the rising edge of the tenth pin 26 level, select CS mode. In this mode, the eleventh pin 27 can serially output signals when the eleventh pin 27 or the thirteenth pin 29 is at low level.

In the signal collection stage, the AD conversion chip 2 collects the analog signals input from the seventh pin 23 and the eighth pin 24 .

When the acquisition phase is complete and the tenth pin 26 goes high, the conversion phase is entered. In the conversion stage, an output code is generated after comparison by a comparator inside the AD conversion chip 2 . If the chain mode is selected at this time, the digital signal is output to the host computer 7 through the eleventh pin 27; if the CS mode is selected at this time, the digital signal is jointly transmitted through the eleventh pin 27 and the thirteenth pin Output to the host computer 7.

In summary, the AD conversion circuit for a micro-displacement test system of the present invention can improve the measurement accuracy of micro-displacement, reduce power consumption, reduce noise, and reduce output voltage hysteresis and long-term output voltage drift.

Those of ordinary skill in the art should recognize that the above embodiments are only used to illustrate the utility model, rather than as a limitation to the utility model, as long as within the spirit of the utility model, the above-mentioned The changes and modifications of the embodiments will all fall within the scope of the claims of the present utility model.

Claims (3)

1. a micrometric displacement test macro A/D convertor circuit, comprises the first electric capacity, reference voltage source chip, polar capacitor, the second electric capacity, the 3rd electric capacity, AD conversion chip, it is characterized in that:

Described reference voltage source chip comprises four pins, first pin, the second pin, the 3rd pin and the 4th pin, the two ends correspondence of wherein said first electric capacity is connected with described first pin and described second pin, described 3rd pin is connected with the positive pole of described polar capacitor, the negative pole of described polar capacitor be connected in analog;

Described AD conversion chip comprises ten pins, 5th pin, 6th pin, 7th pin, 8th pin, 9th pin, tenth pin, 11 pin, 12 pin, 13 pin and the 14 pin, wherein said 5th pin is connected with the positive pole of described polar capacitor, described 8th pin be connected in analog, the two ends correspondence of described second electric capacity connects described 6th pin and described 8th pin, the two ends correspondence of described 3rd electric capacity connects described 8th pin and described 14 pin, described tenth pin, described 11 pin, described 12 pin is connected with host computer with described 13 pin, be connected described 9th pin and power supply.

2. a kind of micrometric displacement test macro A/D convertor circuit according to claim 1, is characterized in that: described reference voltage source chip is the ADR4550 chip of Ya Nuode company.

3. a kind of micrometric displacement test macro A/D convertor circuit according to claim 1, is characterized in that: described AD conversion chip is the AD7988 chip of Ya Nuode company.