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Maxim > Design Support > Technical Documents > Subsystem Boards > APP 5742
Keywords: Carmel, MAXREFDES18, analog output, conditioner, programmable logic controllers (PLC),
distributed control systems (DCS), industrial control and automation
SUBSYSTEM BOARD 5742
Carmel (MAXREFDES18#): High Accuracy Analog
Current/Voltage Output
Sep 23, 2013
Abstract: The Carmel (MAXREFDES18#) subsystem reference design provides a high-accuracy analog
current/voltage output in a compact, galvanically isolated form factor. This design uniquely fits
programmable logic controllers (PLC), distributed control systems (DCS), and other industrial
applications. Hardware and firmware design files and lab measurements are provided for rapid
prototyping and development. The board is also available for purchase.
Introduction
In PLC and DCS systems, analog
output currents and voltages
provide critical control and
actuation functions. The Carmel
(MAXREFDES18#) reference
design shown in Figure 1 provides
a flexible and programmable
analog output that meets industrial control requirements.
The buffered voltage output from the MAX5316 16-bit, high -accuracy digital-to-analog converter (DAC)
drives the input of the MAX15500, a programmable analog output conditioner with extensive error
reporting. The MAX6126 ultra-high - precision voltage reference provides references for the DAC and the
output conditioner. The MAX14850 galvanically isolates data communication between the subsystem and
the system controller. Optionally, the subsystem also integrates an isolated and regulated power supply
by using the MAX13253 transformer driver and the MAX1659 and MAX1735 low -dropout (LDO) linear
regulators.
The subsystem features all typical bipolar current and voltage output ranges, and appropriate subsets,
with less than 0.105% total unadjusted error (TUE). The circuit also provides short - circuit and overcurrent
protection, open circuit detection, brownout detection, overtemperature protection, all of which are critical
for industrial applications. Flexible power-up options make Carmel an ideal choice for robust industrial
control systems.