**AD7858BRZ: A Comprehensive Technical Overview of Analog Devices' 12-Bit Pseudo Differential SAR ADC**
The AD7858BRZ from Analog Devices represents a high-performance, 12-bit analog-to-digital converter (ADC) that leverages the Successive Approximation Register (SAR) architecture. Designed for a wide array of precision measurement applications, this ADC integrates key features that make it a compelling choice for system designers seeking a balance of speed, accuracy, and power efficiency.
At its core, the **AD7858BRZ is a 12-bit resolution ADC** capable of delivering **up to 200 kSPS (kilo Samples Per Second)** throughput. This sampling rate makes it suitable for medium-speed data acquisition systems found in industrial process control, instrumentation, and medical devices. The converter utilizes a **pseudo differential analog input** structure. This configuration is a significant feature, offering a practical compromise between the noise immunity of a fully differential input and the simplicity of a single-ended one. It employs two input pins: a primary input (VIN+) and a secondary reference input (VIN-). The ADC measures the voltage difference between these two pins (VIN+ - VIN-), which allows it to reject common-mode noise to a considerable degree. This is particularly advantageous in electrically noisy environments where ground potentials may vary.
The device is built on a robust SAR architecture, renowned for its **deterministic latency and precise control over sampling instants**. Unlike delta-sigma (ΔΣ) ADCs that require filter settling time, a SAR ADC provides a conversion result after a fixed number of clock cycles. This characteristic is critical for multiplexed applications where multiple channels must be sampled at specific, well-defined times.
Power management is a standout feature of the AD7858BRZ. It operates from a single **2.7 V to 5.25 V supply**, making it compatible with both 3 V and 5 V systems. Furthermore, it incorporates sophisticated power-down modes. When not converting, the device can be placed into a standby mode, drastically reducing its power consumption to microampere levels. This **low-power operation is ideal for battery-powered and portable equipment**, extending operational life without sacrificing performance.
The interface is serial (SPI®/QSPI™/MICROWIRE™/DSP compatible), which minimizes the number of microcontroller I/O pins required for communication. This serial interface facilitates easy isolation and connection to modern digital processors. The AD7858BRZ also includes an on-chip **precision 2.5 V reference**, which can be used for the conversion process or bypassed if an external reference is preferred for higher accuracy or different voltage scaling. The device is offered in a compact SOIC package, ensuring a small footprint on printed circuit boards.
In summary, the AD7858BRZ delivers a combination of **medium-speed conversion, excellent DC accuracy, and remarkable power efficiency**. Its pseudo differential input provides enhanced noise rejection compared to single-ended ADCs, making it a versatile solution for challenging industrial environments.
**ICGOODFIND:** The AD7858BRZ is a highly integrated and efficient 12-bit SAR ADC, offering designers an optimal blend of speed, **pseudo differential noise rejection**, low power consumption, and a simple serial interface for a multitude of precision sensing and data acquisition applications.
**Keywords:** SAR ADC, Pseudo Differential, 12-Bit Resolution, Low Power, Serial Interface
