Low resolution and low input voltage analog-to-digital converters (ADCs) are integrated in many of today's field programmable gate arrays (FPGAs) and microcontrollers. However, they fall short on meeting the needs of industrial control and industrial automation applications that require higher resolutions and higher input voltages. The Fresno (MAXREFDES11#) subsystem reference design is a 16-bit high-accuracy industrial analog front end (AFE) that accepts 0 to 10V signals and features isolated power and data—all integrated into a small form factor. The Fresno design integrates an ultra-precision low-noise buffer (MAX44250); a highly accurate ADC (MAX11100); an ultra-high-precision 4.096V voltage reference (MAX6126); 600VRMS data isolation (MAX14850); and isolated/regulated +5.5V, +5V, and -3V power rails (MAX256/MAX1659/MAX1735). This AFE solution can be used in any application that needs high-accuracy analog-to-digital conversion, but it is mainly targeted for industrial sensors, industrial automation, process control, programmable logic controllers (PLCs), and medical applications.
Figure 1. The Fresno subsystem design block diagram.