TMPSNSRD-RTD2: RTD w/ 22bit ADC, USB Interface

The RTD Reference Design demonstrates how to implement a Resistive Temperature Detector (RTD) and accurately measure temperature. This solution uses the MCP3551 22-Bit Analog-to-Digital Converter (ADC) to measure voltage across the RTD. The ADC and the RTD are referenced using an on-board reference voltage, and the ADC inputs are directly connected to the RTD terminals. This provides a ratio metric temperature measurement. The solution uses a current limiting resistor to bias the RTD. It provides a reliable and accurate RTD instrumentation without the need for extensive circuit compensation and calibration routines.

This solution uses an on-board (local) surface mount RTD and an external RTD. The local and external RTDs are selected using JP2.

In addition, this reference design includes a silicon temperature sensor, MCP9804. This sensor is used for comparison only, it is not needed for the RTD instrumentation circuit. The MCP3551 and MCP9804 outputs are read using a USB PIC® MCU. This controller is also connected to a PC using USB interface. The Thermal Management software is used to plot the RTD temperature data in strip chart format.

The RTD Reference Design has the following features:

• Surface mount PT100 RTD
  
• External RTD connector (not included)
  
• Thermal Management GUI
  
• 22-Bit ADC MCP3551
  
• ±1°C Maximum accuracy temperature sensor MCP9804
  
• PIC18F2550 microcontroller
  
• USB interface to PC