Maxim > Design Support > Technical Documents > Subsystem Boards > APP 5561 Keywords: Santa Fe, MAXREFDES5 , subsystem reference design, analog front end, AFE, industrial sensors, isolated power and data, industrial automation, PLC, medical, MAXREFDESS , MAXREFDE55 , MAXREFDESS, MAXREFDE55, isolation SUBSYSTEM BOARD 5561 Santa Fe (MAXREFDES5 ): 16-Bit High Accuracy Multi-Input Isolated Analog Front End (AFE) Jan 11, 2013 Abstract: This document explains how the Santa Fe (MAXREFDES5 ) subsystem reference design meets the higher resolution, higher voltage, and isolation needs of industrial control and industrial automation applications. Hardware and firmware design files as well as FFTs and histograms from lab measurements are provided. On February 28, 2014, the name of MAXREFDES5 was changed from Cupertino to Santa Fe. Maxim made this change in an effort to distinctly identify MAXREFDES5 as a design focused on industrial applications. Other than the name change, the design remains the same, with similar high performance analog functionality. Introduction Today s field programmable gate arrays (FPGAs) and microcontrollers with internal analog-to-digital converters (ADCs) are capable of low- resolution and low-voltage analog More detailed image (JPG) inputs. However, they fall short on being able to meet the needs of industrial control and industrial automation applications, where isolation, higher resolutions, and higher voltage system solutions are often needed. The Santa Fe (MAXREFDES5 ) subsystem reference design is a 16-bit high- accuracy industrial analog front end (AFE) that accepts -10V to +10V, 0 to 10V, and 420mA current loop signals with isolated power and data integrated into a small form factor. The Santa Fe design integrates low-noise high- impedance analog buffers (MAX9632) a highly accurate ADC with innovative on-chip attenuation (MAX1301) an ultra-high precision 4.096V voltage reference (MAX6126) 600V data isolation (MAX14850) and RMS isolated/regulated +12V, -12V, and 5V power rails (MAX256/MAX1659). 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. Page 1 of 12Figure 1. The Santa Fe subsystem design block diagram. Features Applications High accuracy 10V, 0 to 10V, and 420mA Inputs Industrial sensors Isolated power and data Process control Small printed circuit board (PCB) area Industrial automation Device drivers PLCs Example C source code Medical Pmod -compatible form factor Detailed Description of Hardware The Pmod specification allows for both 3.3V and 5V modules as well as various pin assignments. This module is designed only for a supply voltage of 3.3V and uses the SPI pin assignments as illustrated on the right. The power requirements are shown in Table 1. The currently supported platforms and ports are shown in Table 2. Page 2 of 12