The **AD8209WBRMZ-R7** is a high-precision, high-voltage, bidirectional current sense amplifier designed primarily for automotive and industrial applications. It is manufactured by Analog Devices and is engineered to extract small differential voltages in the presence of high common-mode voltages. --- ### 1. Key Technical Specifications | Parameter | Specification | | :--- | :--- | | **Common-Mode Voltage** | -2V to +45V (Continuous), up to 65V (Survival) | | **Fixed Gain** | 14 V/V | | **Input Offset Voltage** | ±1 mV (Maximum) | | **Operating Temperature** | -40°C to +125°C (Automotive Grade) | | **Package** | 8-Lead MSOP (Micro Small Outline Package) | | **Supply Voltage** | 4.5V to 5.5V | | **Bandwidth** | 80 kHz | --- ### 2. Core Functional Blocks The device architecture consists of two main stages: 1. **Differential Amplifier (Pre-Amp):** This stage features high input impedance and handles the high common-mode voltage. It converts the differential input (from a shunt resistor) into a ground-referenced signal. 2. **Output Buffer:** This stage provides a low-impedance output and allows for additional filtering or level shifting. 3. **Reference Input (VREF):** This pin allows the user to offset the output voltage, enabling the measurement of **bidirectional** currents (current flowing in both directions through the shunt). --- ### 3. Part Number Breakdown: AD8209WBRMZ-R7 | Suffix | Meaning | | :--- | :--- | | **AD8209** | Base Model Number | | **W** | Automotive Qualified (AEC-Q100) | | **B** | Performance Grade (Offset/Drift characteristics) | | **RM** | Package Code (MSOP) | | **Z** | RoHS Compliant (Lead-Free) | | **R7** | 7-inch Tape and Reel (Quantity 1,000) | --- ### 4. Typical Application Circuit The AD8209 is typically used with a low-value shunt resistor ($R_{shunt}$). ```arduino +Line ----[ R_shunt ]---- To Load | | IN- <--- ---> IN+ __________________________ | AD8209 | | | | OUT = (Gain * V_diff) | |__________________________| | To Microcontroller (ADC) ``` --- ### 5. Notable Features * **High Rejection:** It has an excellent Common-Mode Rejection Ratio (CMRR), which means it ignores the high voltage on the lines and only measures the tiny voltage drop across the resistor. * **Zero-Drift Architecture:** The internal design minimizes changes in accuracy due to temperature fluctuations, which is critical for engine compartment electronics. * **Bidirectional Sensing:** By applying half of the supply voltage to the $V_{REF}$ pin, the output sits at 2.5V when there is zero current, allowing it to swing up for positive current and down for negative current.