**AD7793BRU: A Comprehensive Guide to the Low Noise, Low Power 24-Bit Sigma-Delta ADC**
In the world of precision measurement, the ability to accurately capture small analog signals is paramount. The **AD7793BRU from Analog Devices** stands as a cornerstone in this domain, a highly integrated, low-noise, complete analog front end for low-frequency measurement applications. This 24-bit sigma-delta (Σ-Δ) ADC combines exceptional performance with remarkably low power consumption, making it an ideal solution for a vast array of demanding industrial, instrumentation, and sensor interface applications.
**Architecture and Key Features**
At its core, the AD7793BRU utilizes a **sigma-delta modulation technique** to achieve its high resolution. This architecture oversamples the input signal and uses noise shaping to push quantization noise out of the baseband, resulting in extremely high effective resolution within the target frequency range. The device includes a proprietary programmable gain amplifier (PGA) with gains from 1 to 128, allowing it to directly interface with low-level signals from transducers like thermocouples, RTDs, and strain gauges without requiring extensive external signal conditioning.
One of its most celebrated features is its **ultra-low noise performance**, with a typical noise level of only 40 nV RMS at a gain of 128 and a update rate of 4.17 Hz. This enables the resolution of the smallest signal changes, which is critical for precision applications. Furthermore, it operates on a **remarkably low power supply current**, typically consuming just 65 µA in normal mode and dropping to a mere 1 µA in power-down mode. This makes it perfectly suited for battery-powered or portable equipment where longevity is key.
The AD7793BRU is a complete data acquisition solution. It integrates an on-chip, low-noise instrumentation amplifier, a precision reference voltage source, and the clock oscillator, minimizing the need for external components and simplifying board design.
**Application Highlights**
The combination of high precision and low power consumption opens doors to numerous applications:
* **Portable Weigh Scales and Strain Gauge Transducers:** Its low noise and high resolution ensure accurate weight measurement.
* **Temperature Measurement with RTDs and Thermocouples:** The integrated excitation current sources for RTDs and the high PGA gains simplify temperature sensing designs.
* **Gas and Pressure Monitoring:** Effectively interfaces with various low-output sensors.
* **Industrial Process Control:** Its robustness and precision are ideal for factory automation and control systems.
* **Medical Instrumentation:** The low noise is critical for capturing bio-signals like ECG and EEG in portable medical devices.
**Getting Started with Design**
Designing with the AD7793BRU is streamlined by its **simple 3-wire serial interface** (compatible with SPI, QSPI, MICROWIRE, and DSP protocols), which communicates with a host microcontroller. Key configuration settings, including output data rate (which can be set from 4.17 Hz to 470 Hz), gain, and channel selection, are managed through its internal registers. For optimal performance, careful attention to PCB layout is advised. This includes using a solid ground plane, decoupling the power supply and reference pins with ceramic capacitors placed close to the device, and shielding analog input lines to minimize noise pickup.
**ICGOODFIND Summary**
The AD7793BRU is a premier choice for designers seeking a **high-resolution, low-noise, and power-efficient analog-to-digital conversion solution**. Its high level of integration reduces system complexity and component count, while its exceptional performance metrics make it a reliable workhorse for the most demanding precision sensor measurement tasks.
**Keywords**
1. **Sigma-Delta ADC**
2. **Low Noise**
3. **Low Power**
4. **24-Bit Resolution**
5. **Precision Measurement**
