## AD8476ACPZ-R7: Technical Overview The **AD8476ACPZ-R7** is a low-power, fully differential precision amplifier and ADC driver manufactured by Analog Devices. It is specifically designed to simplify the conversion of single-ended signals to differential signals to drive high-precision Analog-to-Digital Converters (ADCs). --- ### Key Specifications | Parameter | Specification | | :--- | :--- | | **Type** | Differential Amplifier / ADC Driver | | **Gain** | Fixed Unity Gain (G=1) | | **Supply Voltage** | 2.3 V to 18 V (Single) / ±1.15 V to ±9 V (Dual) | | **Supply Current** | 330 μA (Typical) | | **Bandwidth (-3dB)** | 5 MHz | | **Input Offset Voltage** | 200 μV (Max) | | **Package** | 16-Lead LFCSP (3mm x 3mm) | | **Slew Rate** | 10 V/μs | --- ### Core Functional Components 1. **Integrated Precision Resistors:** The device includes laser-trimmed internal resistors that set the gain to exactly 1. This eliminates the need for external components, saving PCB space and ensuring excellent gain accuracy and low drift over temperature. 2. **Differential Output Stage:** It converts a single-ended input signal into a balanced differential output. This is critical for modern SAR and Pipeline ADCs which require differential inputs to maximize dynamic range and reject common-mode noise. 3. **VOCM Pin (Output Common-Mode Control):** This pin allows the user to set the output common-mode voltage independently of the input. By applying a voltage to this pin, you can level-shift the output signal to match the optimal input range of the downstream ADC. 4. **Rail-to-Rail Output:** The outputs can swing very close to the supply rails, providing maximum signal headroom. --- ### Application Example: Simple ADC Interface Below is a conceptual representation of how the AD8476 is typically used in a signal chain. ```c [Single-Ended Sensor] ---> [AD8476 In+] --- [AD8476 Out+] ---> [ADC Diff In+] [AD8476 In-] --- [AD8476 Out-] ---> [ADC Diff In-] ^ ^ | | [Ground/Vref/2] [VCM from ADC] ``` ### Advantages for Design * **Ease of Use:** No external gain-setting resistors are required, reducing the error budget associated with resistor tolerances. * **Low Power:** At only 330 μA, it is ideal for battery-powered or portable instrumentation. * **Versatility:** It can handle relatively high supply voltages (up to 18V) while maintaining high precision. ---