This two-part series presents the design of a cost-effective, portable, high-resolution data-acquisition system (DAS) based on a precision delta-sigma analog-to-digital converter (ADC). The Part 1 article reviewed the history of thermocouple technology and the principal of the operation. It described a thermocouple interface with the MAX11200 ADC evaluation (EV) kit.1
This Part 2 of the series presents a dedicated reference design (RD) in which the MAX11200 ADC interfaces with a thermocouple and platinum resistance temperature detector (PRTD) using a simple multiplexor. No additional instrumentation amplifiers, low-noise references, and optical isolation are needed for precise temperature measurement. The new RD is cost effective, compact, and low power. We also describe the high-resolution thermocouple’s DAS and the software required to achieve accuracies of ±1°C, or better, using standardized linearization calculation algorithms.
Designed, Built, Tested
Board pictured here has been fully assembled and tested. Not available for sale.
Maxim Devices (4)
|Part Number||Name||Product Family||Order||Design kits and evaluation modules|
|MAX31855||Cold-Junction Compensated Thermocouple-to-Digital Converter||Sensor Interface||Buy Now||Design Kits|
|MAXQ622||16-Bit Microcontrollers with Infrared Module and Optional USB||MCU - Microcontroller||Buy Now||Design Kits|
|MAX4782||High-Speed, Low-Voltage, 0.7Ω CMOS Analog Switches/Multiplexers||Switches and Multiplexers||Buy Now||Not Available|
|MAX11200||24-Bit, Single-Channel, Ultra-Low Power, Delta-Sigma ADCs with GPIO||Analog-to-Digital Converters||Buy Now||Design Kits|