AD8476ARMZ-RL

概要

The AD8476 is a very low power, fully differential precision amplifier with integrated gain resistors for unity gain. It is an ideal choice for driving low power, high performance ADCs as a

single-ended-to-differential or differential-to-differential amplifier. It provides a precision gain of 1, common-mode level shifting, low temperature drift, and rail-to-rail outputs for maximum dynamic range.

AD8476 はまた、デュアル 5 V 電源で動作しながら、±23 V までの大 きな産業用入力電圧からの過電圧保護も提供します。シングル 5 V 電源での消費電力はわずか 1.5 mW です。

The AD8476 works well with SAR, Σ-Δ, and pipeline converters. The high current output stage of the part allows it to drive the switched capacitor front-end circuits of many ADCs with  minimal error. Unlike many differential drivers on the market, the AD8476 is  a high precision amplifier. With 200 µV maximum output offset, 39 nV/√Hz noise, and −102 dB THD + N at 10 kHz, the AD8476 pairs well with low power, high accuracy converters.  Considering its low power consumption and high precision, the slew-enhanced AD8476 has excellent speed, settling to 16-bit

250 kSPS の取り込み時間に対する精度AD8476 は、省スペースの 16 リード、3mm × 3mm の LFCSP と 8 リード MSOP パッケージで提供されます。AD8476 は、-40℃～+125℃の温度範囲で完全 に仕様化されています。

特徴

超低消費電力

330 μA 供給電流

極めて低い高調波歪み

-126 HD2 at 10 kHz

-128 HD3 at 10 kHz

完全差動またはシングルエンド入出力

高精度ADC駆動用に設計された差動出力

スイッチド・キャパシタとΣΔADCを駆動

レールツーレール出力

出力コモンモードを調整するVOCM端子

電源電圧を超えても最大18Vの過電圧に耐える

高性能

最大250kSPSの16ビット・コンバーター駆動に最適

39 nV/√Hz 出力ノイズ

1 ppm/°C ゲイン・ドリフト最大

最大出力オフセット200μV

10 V/μs スルー・レート

6 MHz帯域幅

単一電源3 V～18 V

デュアル電源：±1.5V～±9V

アプリケーション

ADCドライバー

差動計装アンプの構成ブロック

シングルエンド-差動変換器

電池式計器

アプリケーション情報

典型的な構成

The AD8476 is designed to facilitate single-ended-to-differential conversion, common-mode level shifting, and precision processing of signals so that they are compatible with low voltage ADCs. Figure 54 shows a typical connection diagram of the AD8476. SINGLE-ENDED-TO-DIFFERENTIAL CONVERSION Many industrial systems have single-ended inputs from input

sensors; however, the signals are frequently processed by high performance differential input ADCs for higher precision. The AD8476 performs the critical function of precisely converting single-ended signals to the differential inputs of precision ADCs, and it does so with no need for external components.  To convert a single-ended signal to a differential signal, connect one input to the signal source and the other input to ground (see Figure 54). Note that either input can be driven by the source with the only effect being that the outputs have reversed polarity. The AD8476 also accepts truly differential input signals in

precision systems with differential signal paths.

出力同相電圧の設定

The VOCM pin of the AD8476 is internally biased by a precision voltage divider comprising of two 1 MΩ resistors between the supplies. This divider level shifts the output to midsupply. Relying on the internal bias results in an output common-mode voltage that is within 0.05% of the expected value.  In cases where control of the output common-mode level is desired, an external source or resistor divider can be used to drive the VOCM pin. If driven directly from a source, or with a resistor divider of unequal resistor values, the resistance seen by the VOCM pin should be less than 1 kΩ. If an external voltage divider consisting of equal resistor values is used to set VOCM to midsupply, higher values can be used because the external resistors are placed in parallel with theinternal resistors. The output common-mode offset listed in the Specifications section assumes that the VOCM input is driven by a low impedance voltage source.  Because of the internal divider, the VOCM pin sources and sinks current, depending on the externally applied voltage and its associated source resistance. It is also possible to connect the VOCM input to the commonmode level output of an ADC; however, care must be taken to ensure that the output has sufficient drive capability. The input impedance of the VOCM pin is 500 kΩ. If multiple AD8476

devices share one ADC reference output, a buffer may be neces

sary to drive the parallel inputs.