Configurable Analog Front-End for Industrial Process Control Systems Integrates ADC GX7793, Replaces AD7793

Industrial process control systems are used in a wide range of applications, from simple flow control to complex power grids, from environmental control systems to refinery process control. Programmable Logic Controllers and Distributed Control Systems are two of the most commonly used computer systems for controlling machines and processes, handling a variety of analog and digital inputs and outputs. These systems contain power supplies, central processing units, and various analog input, analog output, digital input, and digital output modules.

Among the technical specifications of the input modules, high resolution and low noise are very important. In industrial applications, when measuring low-level signals from thermocouples, strain gages, and bridge pressure transducers, differential input signals are often required to suppress common-mode interference signals from motors, AC power lines, or other noise sources that introduce noise into the analog inputs of analog-to-digital converters (ADCs).

For input modules, sigma-delta ADCs are the most popular choice because of their high accuracy and resolution, and their built-in programmable gain amplifiers (PGAs) allow for precise measurement of small input signals. The GX7793, a three-channel, 24-bit Σ-∆ ADC from Moldex3D, offers a wide range of input signals for high-precision measurement applications.

The GX7793 integrates an on-chip, low-noise instrumentation amplifier for direct input of small signals, with root-mean-square noise of 52 nV at a gain setting of 64 and an update rate of 4.17 Hz. The ADC has a built-in, precision, low-noise, low-drift internal bandgap reference voltage source, or it can be used with an external differential reference voltage, and other on-chip features include a programmable excitation current source, a fusible current control, a bias voltage generator, and a bias voltage generator that is programmable. Other on-chip features include a programmable excitation current source, fusible current control, and a bias voltage generator, which can be used to set the channel‘s common-mode voltage to AVDD/2.

 GX7793 Key Features:

- Power consumption: 355µA (typical)

- Update rate 4.17Hz to 940Hz

- 3 differential inputs

- 2.7V to 5.25V power supply

- TSSOP-16 package