The **AD8642ARMZ-R2** is a high-precision, low-power, dual-channel JFET input operational amplifier (op-amp) manufactured by Analog Devices. It is widely used in applications requiring low bias current and high input impedance. --- ### 1. Key Technical Specifications | Parameter | Specification | | :--- | :--- | | **Number of Channels** | Dual (2) | | **Input Type** | JFET (High Impedance) | | **Supply Voltage (Max)** | ±13 V or 26 V | | **Supply Voltage (Min)** | ±2.5 V or 5 V | | **Input Bias Current** | 1 pA (typical) | | **Gain Bandwidth Product** | 3.5 MHz | | **Slew Rate** | 3 V/µs | | **Package Type** | MSOP-8 (ARMZ suffix) | | **Operating Temperature** | -40°C to +125°C | --- ### 2. Functional Features * **Low Input Bias Current:** Because it uses JFET technology, the input current is extremely low (pico-ampere range). This makes it ideal for interfacing with high-impedance sensors like photodiodes. * **Rail-to-Rail Output:** The output voltage can swing almost to the full range of the power supply rails, maximizing the dynamic range. * **Low Noise:** It offers low voltage noise and low current noise, which is critical for precision instrumentation. * **Settling Time:** It features a fast settling time, making it suitable for data acquisition systems. --- ### 3. Pin Configuration (MSOP-8) | Pin Number | Symbol | Function | | :---: | :--- | :--- | | 1 | OUT A | Output of Channel A | | 2 | -IN A | Inverting Input of Channel A | | 3 | +IN A | Non-inverting Input of Channel A | | 4 | V- | Negative Power Supply | | 5 | +IN B | Non-inverting Input of Channel B | | 6 | -IN B | Inverting Input of Channel B | | 7 | OUT B | Output of Channel B | | 8 | V+ | Positive Power Supply | --- ### 4. Typical Applications The AD8642 is commonly found in the following circuits: 1. **Photodiode Transimpedance Amplifiers:** Converting light-generated current into voltage. 2. **Precision Filters:** Active low-pass or high-pass filters where component loading must be minimized. 3. **Medical Instrumentation:** High-impedance electrode monitoring (e.g., ECG/EEG). 4. **Data Acquisition:** Buffering high-resolution Analog-to-Digital Converters (ADCs). --- ### 5. Part Number Breakdown * **AD8642:** The base model number. * **ARMZ:** Indicates the package (MSOP-8) and RoHS compliance. * **R2:** Specifies the tape and reel size (usually a 7-inch reel with 250 units).