Project Analog - January 2008 - (Page 5) System Integration Issues in temperature measurement Circuits An excerpt from Application Note AN929 “Temperature Measurement Circuits for Embedded Applications” View complete document here. noiSe reduction techniqueS Accurate temperature measurements require careful attention to noise reduction techniques. The high Common-Mode Rejection Ratio (CMRR) of the differential amplifier reduces noise; however, grounding, shielded cables and Electromagnetic Interference/Electro-Static Discharge (EMI/ESD) filters are also required to prevent noise from degrading the accuracy of the measurement. grounding Figure 1 shows four basic methods of grounding a sensor. A grounded source has its negative terminal connected to ground at the sensor, often by virtue of the mechanical mounting of the sensor. In contrast, a floating source connects the sen5 · projeCt analog · jan 08 linEar activE thErmistor™ dEmo board Contents Viewpoint Wireless sensor networks Temperature sensing technology The MCP9700 Temperature-to-Voltage Converter PICtail™ Demo Board demonstrates how to interface the MCP9700 to a PICmicro® microcontroller using the PICkit™ 1 Flash Starter Kit as a platform. The MCP9700 Temperature-toVoltage Converter PICtail™ Demo Board can also be used as a “stand-alone” module to quickly add thermal sensing capablity to any existing application. This basic sensor functionality is implemented on a small Printed Circuit Board (PCB) and an interface via a standard 100 mil header. This can be used by the system designer as an example of how to integrate an analog temperature sensor into systems. click here for more information. Analog news sor’s negative terminal to ground at the amplifier. The preferred grounding configuration for a remote sensor is shown in circuits B and D. These circuits provide for a two-wire differential measurement that can be implemented with either a differential or instrumentation amplifier. A differen- tial measurement requires that the common mode voltage level of the signal source does not exceed the amplifier’s maximum input voltage specification. As shown in circuit D, adding bias resistors to reference the input signal to a known voltage can solve this problem and the resistors will not affect the measurement, if they are relatively large. Microchip analog page Thermal management overview Sample center microchipDIRECT Reference designs/ app notes Technical training http://ww1.microchip.com/downloads/en/AppNotes/00929a.pdf http://www.microchip.com http://www.microchip.com/analog http://www.microchip.com/analog http://www.microchip.com/stellent/idcplg?IdcService=SS_GET_PAGE&nodeId=2543¶m=en021419&pageId=79 http://www.microchip.com/stellent/idcplg?IdcService=SS_GET_PAGE&nodeId=2543¶m=en021419&pageId=79 http://sample.microchip.com/Default.aspx?testCookies=true http://www.microchip.com/stellent/idcplg?IdcService=SS_GET_PAGE&nodeId=1406&dDocName=en023169 http://www.microchipdirect.com/catalogselection.aspx?returnURL=default.aspx http://www.microchip.com/stellent/idcplg?IdcService=SS_GET_PAGE&nodeId=1469&filter1=function&redirects=appnotes http://www.microchip.com/stellent/idcplg?IdcService=SS_GET_PAGE&nodeId=1469&filter1=function&redirects=appnotes http://www.microchip.com/stellent/idcplg?IdcService=SS_GET_PAGE&nodeId=1423
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