### AD8475BRMZ-R7: Precision Fully Differential Funnel Amplifier The **AD8475BRMZ-R7** is a precision, selectable-gain, fully differential amplifier manufactured by Analog Devices. It is primarily designed as a "funnel" amplifier—meaning it takes high-voltage signals and attenuates them to levels suitable for high-speed, low-voltage Analog-to-Digital Converters (ADCs). --- ### 1. Key Technical Specifications | Parameter | Specification | | :--- | :--- | | **Function** | Differential Funnel Amplifier / ADC Driver | | **Gain Settings** | 0.4x and 0.8x (User selectable) | | **Input Voltage Range** | Up to ±12.5V (on a single 5V supply) | | **Output Type** | Fully Differential | | **Bandwidth (-3dB)** | 85 MHz | | **Slew Rate** | 50 V/µs | | **Operating Supply** | +3V to +10V (Single) or ±1.5V to ±5V (Dual) | | **Package** | 8-lead MSOP (Mini Small Outline Package) | --- ### 2. Core Functional Features * **Precision Attenuation:** Unlike most amplifiers that increase signal amplitude, the AD8475 is optimized to reduce (attenuate) signal levels. This allows industrial-level signals (like ±10V) to interface with 5V or 3V ADCs. * **Integrated Resistors:** The gain-setting resistors are laser-trimmed and integrated onto the chip. This ensures excellent gain accuracy and high Common-Mode Rejection Ratio (CMRR). * **Rail-to-Rail Output:** The output can swing very close to the supply rails, maximizing the dynamic range for the ADC. * **VOCM Pin:** Includes a common-mode voltage pin that allows the user to set the output common-mode voltage independently, ensuring the signal is centered perfectly for the ADC's input range. --- ### 3. Pinout and Internal Logic The device is housed in an 8-lead MSOP package. Below is the functional breakdown of the pins: | Pin | Name | Description | | :--- | :--- | :--- | | 1 | **VOCM** | Output common-mode voltage set point. | | 2 | **VIP** | Positive Input. | | 3 | **VIN** | Negative Input. | | 4 | **V-** | Negative Power Supply. | | 5 | **VOUT-** | Negative Differential Output. | | 6 | **VOUT+** | Positive Differential Output. | | 7 | **V+** | Positive Power Supply. | | 8 | **GAIN** | Gain selection pin (Connect to V+ for 0.4x, V- for 0.8x). | --- ### 4. Typical Application Circuit The AD8475 is commonly used in **Data Acquisition Systems (DAQ)**. ```c // Signal Flow Example [High Voltage Sensor ±10V] | v [AD8475 (Gain = 0.4)] --> Attenuates ±10V to ±4V | v [Precision SAR ADC] --> 16-bit or 18-bit Digital Output ``` --- ### 5. Packaging Suffix Breakdown: "BRMZ-R7" * **B:** Performance Grade (Industrial temp range -40°C to +105°C). * **RM:** MSOP (Mini Small Outline Package). * **Z:** RoHS Compliant / Lead-Free. * **R7:** Tape and Reel packaging (7-inch reel, typically 1,000 units).