The **AD8422ARZ-R7** is a high-precision, low-power instrumentation amplifier manufactured by **Analog Devices**. It is designed to extract small differential signals in the presence of large common-mode noise. --- ### 1. Key Technical Specifications The following table summarizes the primary electrical characteristics of the AD8422ARZ-R7: | Parameter | Specification | | :--- | :--- | | **Architecture** | 3-Op Amp Instrumentation Amplifier | | **Gain Range** | 1 to 1000 (Set by a single resistor $R_G$) | | **Quiescent Current** | 330 $\mu$A (Max) | | **Input Offset Voltage** | 60 $\mu$V (Max) | | **CMRR** | 94 dB (Min at $G=1$) | | **Bandwidth** | 2.2 MHz ($G=1$) | | **Voltage Supply** | Dual: $\pm 2.3$V to $\pm 18$V; Single: 4.6V to 36V | | **Package** | 8-Lead SOIC (R7 suffix denotes 7-inch Tape and Reel) | --- ### 2. Core Features & Benefits * **Ultra-Low Noise:** It features very low voltage noise ($8 \text{ nV}/\sqrt{\text{Hz}}$), making it ideal for weighing scales and medical sensors. * **Power Efficiency:** Despite its high performance, it consumes very little power, which is critical for battery-operated industrial handhelds. * **Input Protection:** The device includes robust input protection, allowing the inputs to withstand voltages up to 40V from the opposite supply rail without damage. * **High CMRR:** Its high Common-Mode Rejection Ratio (CMRR) ensures that electromagnetic interference (EMI) and line noise are filtered out from the desired signal. --- ### 3. Pin Configuration For the 8-lead SOIC package, the pins are typically assigned as follows: | Pin Number | Mnemonic | Description | | :---: | :--- | :--- | | 1 | **-IN** | Inverting Input | | 2, 3 | **RG** | Gain Setting Resistor Terminals | | 4 | **+IN** | Non-Inverting Input | | 5 | **-Vs** | Negative Supply | | 6 | **REF** | Reference Terminal (Sets Output Offset) | | 7 | **Vout** | Output Terminal | | 8 | **+Vs** | Positive Supply | --- ### 4. Typical Applications * **Medical Instrumentation:** ECG and non-invasive blood pressure monitors. * **Industrial Process Control:** Bridge amplifiers for pressure and temperature sensors. * **Precision Data Acquisition:** Front-end for high-resolution ADCs. * **Portable Instrumentation:** Handheld multimeters and environmental sensors. --- ### 5. Gain Calculation Formula The gain ($G$) of the AD8422 is programmed by connecting an external resistor ($R_G$) between Pins 2 and 3: ```math G = 1 + \frac{19.8 \text{ k}\Omega}{R_G} ``` ---