## Technical Overview of the AD7674AST The **AD7674AST** is a high-performance, 18-bit, 800 kSPS, Charge Redistribution SAR (Successive Approximation Register) Analog-to-Digital Converter (ADC). It is manufactured by Analog Devices and belongs to the **PulSAR®** family. ### 1. Key Technical Specifications | Parameter | Specification | | :--- | :--- | | **Resolution** | 18-Bit | | **Throughput Rate** | 800 kSPS (Sampling Mode) | | **Interface** | Parallel and Serial (SPI/QSPI/MICROWIRE/DSP compatible) | | **Input Type** | Differential | | **Signal-to-Noise Ratio (SNR)** | 100 dB typical | | **Total Harmonic Distortion (THD)** | -110 dB | | **Power Consumption** | 120 mW @ 800 kSPS | | **Package** | 48-Lead LQFP (Low-profile Quad Flat Pack) | --- ### 2. Functional Architecture The AD7674 is designed with a specific architecture to ensure high precision and high speed: * **SAR Core:** Uses a capacitive DAC to determine the digital output, eliminating the pipeline delay found in other ADC types. * **Internal Clock:** It features an onboard conversion clock, so the timing of the conversion process is handled internally once triggered. * **Reference Buffer:** While it requires an external reference (typically 2.5V or 5V), it includes a buffer to minimize the impact on the driving circuitry. * **Digital Interface:** The `AST` suffix denotes the package type. The device supports a versatile interface that can operate at 3.3V or 5V logic levels. --- ### 3. Pin Configuration Categories The 48 pins of the AD7674AST are categorized into four main functional blocks: 1. **Analog Inputs:** `IN+` and `IN-` pins for differential signal acquisition. 2. **Power Supply:** * `AVDD`: Analog Supply (+5V). * `DVDD`: Digital Supply (+5V). * `OVDD`: Digital Output Driver Supply (2.7V to 5.25V). 3. **Control Pins:** * `CNVST`: Convert Start (Initiates the sampling process). * `BUSY`: Output indicating a conversion is in progress. * `SER/PAR`: Selects between Serial or Parallel interface. 4. **Data Pins:** `D[17:0]` for parallel data output or `SDOUT` for serial data. --- ### 4. Typical Applications Due to its high bit depth (18-bit) and speed, the AD7674AST is commonly used in: * **Medical Imaging:** MRI and CT scan data acquisition. * **High-Speed Data Acquisition:** Industrial process control and automation. * **Instrumentation:** Spectrum analyzers and high-end multimeters. * **Digital Beamforming:** Advanced radar and communication systems. ---