## AD8429BRZ-R7: Technical Overview The **AD8429BRZ-R7** is an ultra-low noise instrumentation amplifier (In-Amp) designed by Analog Devices. It is specifically engineered to measure small signals in the presence of large common-mode voltages, making it a high-performance choice for precision data acquisition. --- ### 1. Key Technical Specifications | Parameter | Specification | |:---|:---| | **Gain Range** | 1 to 10,000 (Set by a single resistor $R_G$) | | **Ultra-Low Noise** | 1 nV/√Hz input voltage noise | | **High CMRR** | 126 dB min (G = 1000) | | **Bandwidth** | 1.2 MHz (G = 100) | | **Slew Rate** | 22 V/µs | | **Supply Voltage** | ±4.5 V to ±18 V | | **Package** | 8-Lead SOIC_N | --- ### 2. Functional Characteristics #### A. Gain Configuration The gain of the AD8429 is programmed using a single external resistor ($R_G$). The formula to calculate the gain is: $$G = 1 + \frac{6 \text{ k}\Omega}{R_G}$$ * **Precision:** Because it uses a classic 3-op-amp architecture, it maintains high performance even at high gains. #### B. Noise Performance The most significant feature of this part is its **1 nV/√Hz** noise density. This allows it to detect microvolt-level signals without the amplifier's own internal noise masking the data. This is critical for medical imaging (EEG/ECG) and high-end sensors. #### C. High Common-Mode Rejection Ratio (CMRR) It excels at rejecting "noise" that appears on both input lines (such as 50/60Hz power line interference). With a CMRR of 126 dB, it can extract a tiny differential signal while ignoring volts of common-mode interference. --- ### 3. Pinout and Internal Structure | Pin Number | Name | Description | |:---:|:---|:---| | 1, 8 | -IN, +IN | Differential Inputs | | 2, 3 | RG | Gain Setting Resistor Pins | | 4, 7 | -Vs, +Vs | Negative and Positive Power Supplies | | 5 | REF | Reference Pin (sets output offset) | | 6 | VOUT | Output Signal | --- ### 4. Typical Applications * **Medical Instrumentation:** EEG, ECG, and patient monitoring. * **Industrial Sensors:** Strain gauges, pressure sensors, and load cells. * **Precision Data Acquisition:** High-resolution Analog-to-Digital Converter (ADC) drivers. * **Audio Research:** Low-noise pre-amplification for high-end microphones. --- ### 5. Part Number Suffix Breakdown * **AD8429:** Base part number. * **B:** Grade (Higher precision/lower offset than 'A' grade). * **R:** Package type (SOIC). * **Z:** RoHS compliant (Lead-free). * **R7:** Tape and Reel packaging (7-inch reel).