Products that solve problems with Σ-Δ AD converters

A/D converters are used to convert analog signals from sensors etc. into digital signals. Additionally, when a high-precision, high-resolution A/D converter is required, a Σ-Δ converter is generally used. However, among high-precision A/D converters, Σ-Δ converters consume a large amount of current, which poses a major problem when used in products with limited power such as portable equipment.

We would like to introduce the AD7124 series, a Σ-Δ type A/D converter with 24-bit resolution, provided by Analog Devices, Inc., which solves this problem.

The AD7124 series has high accuracy and high resolution, as it is also used in "Soil moisture and pH measurement sensor shield - CN0398 (EVAL-CN0398-ARDZ)" introduced in Accelerate development with Arduino compatible development support platform. It is the perfect product for demanding and low consumption applications.

低消費のヒミツ

The AD7124 series is characterized by having three power modes to choose from. There are three power modes: full power, middle power, and low power, and you can easily switch between them by simply changing the setting register, so you can flexibly adapt to the required specifications.

低消費だけじゃない、すべての機能を1パッケージに

The AD7124 series includes the AD7124-4, which has 4 differential input channels, and the AD7124-8, which has 8 differential input channels. It is an A/D converter.

なんと、機能安全にも対応できる

AD7124シリーズは、機能安全のための様々な機能を内蔵しており機能安全を検討中の方にも最適な製品です。また、診断機能も持っていますので、複数の診断機能により機能安全に対応した設計が可能です。

機能だけじゃない、シミュレーションツールも充実

"Virtual Eval Tool - BETA", a simulation tool compatible with over 100 A/D converter products, is a tool that can simulate various characteristics such as noise, distortion, FFT, resolution, timing diagram, frequency response, etc. without the need for an actual device. is. The base performance data uses model data on ADI's server, so you can always obtain the latest simulation results. Of course, you can also set arbitrary parameters, so you can simulate performance before preparing an evaluation board.

Virtual Eval Tool - BETA is available free of charge by visiting the Analog Devices, Inc. website.
http://beta-tools.analog.com/virtualeval/

シミュレーションツールは本当に使えるの？

The most important thing about simulation is: Will the results be the same as the actual device? That's the point. Here, we will compare the noise results of the evaluation board and simulator.

The evaluation board used was EVAL-AD7124-8SDZ. This evaluation board can be connected to a capture board (EVAL-SDP-CB1Z) that interfaces with a PC, and by using software dedicated to the evaluation board, performance data can be transferred to the PC without an oscilloscope. You can check it on the GUI.

ノイズ測定時の設定は、いずれも下記の設定で確認しました。

設定条件

結果は・・

It can be seen that the verification results on the simulator and the actual machine are almost the same.

上の波形は評価基板での測定結果、下の波形はシミュレーション結果です。ノイズのピーク to ピークが実測定356.44μVに対し、470μV。RMSノイズは実測定72.58μVに対し、72μVでした。
　

At the end

Please consider the AD7124 series for applications that require a 24-bit Σ-Δ type A/D converter with multiple channels, low power consumption, high accuracy, and high resolution.

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