**AD7868BRZ: A Comprehensive Technical Overview of Analog Devices' 8-Channel, 12-Bit Simultaneous Sampling SAR ADC**

In the realm of data acquisition systems, particularly those involving multi-phase power control, sonar, and instrumentation, the ability to capture multiple analog signals at the exact same instant is paramount. The **AD7868BRZ from Analog Devices** stands as a pivotal solution in this space, integrating an 8-channel input multiplexer with a **high-speed, 12-bit successive approximation register (SAR) analog-to-digital converter (ADC)** and a simultaneous sampling architecture. This combination delivers the critical performance required for precise, time-correlated measurements across multiple channels.

**Architecture and Key Features**

At the heart of the AD7868BRZ is a single SAR ADC core. The device's standout feature is its **true simultaneous sampling capability**. This is achieved through eight dedicated track-and-hold (T/H) amplifiers, one for each input channel. All eight T/H amplifiers can acquire their respective analog input signals at the same moment, triggered by a single CONVST (Convert Start) pulse. The sampled voltages are then held, and the internal multiplexer sequentially routes each held voltage to the high-speed SAR ADC for conversion. This architecture ensures that the phase information between all input channels is perfectly preserved, a critical factor for power quality analysis and vector mathematics.

The ADC offers a fast conversion time of 1.65 µs per channel, allowing all eight channels to be read in a little over 13 µs. It operates from a single +5 V supply and features a flexible analog input range, configurable for either **±10 V or ±5 V bipolar inputs**, making it suitable for a wide array of industrial-level signals. The device provides a parallel data interface for straightforward connection to microprocessors, microcontrollers, and digital signal processors (DSPs).

**Performance Specifications and Advantages**

The AD7868BRZ is designed for accuracy and robustness. It boasts a typical integral nonlinearity (INL) of ±1 LSB, ensuring excellent differential accuracy across the entire analog input range. With a signal-to-noise ratio (SNR) typically around 72 dB, it provides clean, reliable digital outputs.

A significant advantage of its simultaneous sampling design is the **elimination of phase delay between channels**. In applications like three-phase motor control, measuring all three phase currents and voltages simultaneously is essential for accurate power calculation and control loop stability. Sequential sampling ADCs would introduce skew between measurements, leading to calculation errors, a problem the AD7868BRZ completely avoids.

Furthermore, the device includes a 2.5 V internal reference, reducing the need for external components and simplifying board design. For applications requiring higher precision, it also allows for an external reference to be used.

**Application Areas**

The technical strengths of the AD7868BRZ make it ideal for a diverse set of demanding applications:

* **Multi-Axis Motor Control and Drives:** For simultaneous current and voltage sensing in three-phase AC motors.

* **Power Protection and Monitoring Systems:** For grid synchronization, power quality analysis, and harmonic analysis.

* **Multi-Phase Power Management**

* **Data Acquisition Systems (DAQ):** Where multiple transducers (e.g., strain gauges, thermocouples) must be sampled at the same time.

* **Radar and Sonar Array Processing**

**ICGOOODFIND:** The AD7868BRZ is a highly integrated, performance-optimized ADC that solves the critical challenge of acquiring multiple analog signals with precise temporal alignment. Its combination of **eight simultaneous sample-and-holds, 12-bit resolution, fast throughput, and flexible input ranges** establishes it as a cornerstone component in complex industrial, power, and instrumentation systems where understanding the relationship between signals is as important as the signals themselves.

**Keywords:** Simultaneous Sampling SAR ADC, 12-Bit Resolution, 8-Channel Multiplexer, Data Acquisition System, Motor Control