**AD7724ASTZ: A Comprehensive Technical Overview of the 16-Bit Sigma-Delta ADC**
The **AD7724ASTZ** is a complete 16-bit sigma-delta analog-to-digital converter (ADC) that integrates a significant portion of the signal conditioning circuitry on a single monolithic chip. Representing a significant achievement in mixed-signal design from Analog Devices, this converter is engineered for applications demanding high resolution and robust performance in electrically challenging environments.
At the core of the AD7724ASTZ is an advanced **second-order sigma-delta modulator**. This architecture oversamples the analog input at a high frequency, trading speed for exceptional resolution and effective noise shaping. The modulated output is then processed by an on-chip digital filter, which removes out-of-band noise and shapes the overall frequency response. The device features a default **sinc³ (sinc cubed) filter** response, optimized for applications like weigh scales and transducer interfaces, where a fast step response to input changes is not the primary concern. The output data is presented via a parallel interface, simplifying connection to microprocessors and digital signal processors.
A key differentiator of the AD7724ASTZ is its high level of integration. The device includes a programmable gain amplifier (PGA) with gains of 1, 2, 4, and 8, allowing it to interface directly with low-level signals from sensors and transducers without requiring external amplification. Furthermore, it incorporates two pairs of differential analog input channels, providing flexibility for multiple sensor measurements. The analog and digital sections are supplied from separate pins (**AVDD** and **DVDD**), enabling designers to isolate the noisy digital supply from the sensitive analog circuitry, a critical feature for maintaining data integrity. The device operates from a single +5 V analog supply and a +3 V to +5 V digital supply.
The performance specifications of the AD7724ASTZ are impressive. It delivers true 16-bit performance with no missing codes and exhibits excellent linearity, typified by a maximum ±0.0015% integral nonlinearity (INL). It achieves a typical dynamic range of 90 dB. While the output word rate is programmable up to 1.536 MHz (with a master clock of 12.288 MHz), the effective throughput is governed by the selected filter's settling time. The sinc³ filter settles to a full-accuracy 16-bit word in three output data rate cycles, making it ideal for DC and slow-moving input signals.
The combination of high resolution, integrated programmability, and on-chip signal conditioning makes the AD7724ASTZ exceptionally well-suited for a wide range of precision measurement applications. Its primary use cases include industrial and instrumentation systems such as **weigh scales, pressure transducers, temperature measurement, and strain gage amplifiers**. Its ability to handle low-level signals directly and reject noise makes it a cornerstone component in data acquisition systems requiring high accuracy.
ICGOOODFIND: The AD7724ASTZ stands as a highly integrated, precision 16-bit sigma-delta ADC. Its combination of an on-chip PGA, flexible input channels, and a dedicated digital filter provides a complete data acquisition solution, minimizing external component count and simplifying design for precision DC measurement applications.
**Keywords:** Sigma-Delta ADC, 16-Bit Resolution, Programmable Gain Amplifier (PGA), Sinc³ Filter, Data Acquisition
