ADT70

a FEATURES PRTD Temperature Measurement Range Typical IC Measurement Error ؎ 1؇C Includes Two Matched Current Sources Rail-to-Rail Output Instrumentation Amp Uncommitted, Rail-to-Rail Output Op Amp On-Board ؉ 2.5 V Reference Temperature Coefficient ؎ 25 ppm/؇C ؉ 5 V or ؎ 5 V Operation Supply Current 4 mA Max 10 ␮ A Max in Shutdown APPLICATIONS Temperature Controllers Portable Instrumentation Temperature Acquisition Cards GENERAL DESCRIPTION PRTD Conditioning Circuit and Temperature Controller ADT70* FUNCTIONAL BLOCK DIAGRAM NULLA NULLB BIAS 2.5VREFOUT ADT70 +VS OUTOA IOUTA IOUTB MATCHED CURRENT SOURCES 2.5V REF +INOA ؊INOA +INIA ؊INIA INST AMP SHUTDOWN SHUTDOWN RGA RGB GND SENSE OUTIA AGND ؊VS DGND The ADT70 provides excitation and signal conditioning for resistance-temperature devices (RTDs). It is ideally suited for 1 kΩ Platinum RTDs (PRTDs), allowing a very wide range of temperature measurement. It can also easily interface to 100 Ω PRTDs. Using a remote, low cost thin-film PRTD, the ADT70 can measure temperature in the range of –50°C to +500°C. With high performance platinum elements, the temperature change can be extended to 1000°C. Accuracy of the ADT70 and PRTD system over a –200°C to +1000°C temperature range heavily depends on the quality of the PRTD. Typically the ADT70 will introduce an error of only ± 1°C over the transducer's temperature range, and the error may be trimmed to zero at a single calibration point. The ADT70 consists of two matched 1 m...