engr_joni_ee
Advanced Member level 3
Hi, I need to design 1mA current source for PT1000. I just have found LM 134 adjustable current source. I have some questions, if V+(+VIn) is powered up by 5 V then how do I know about VR across RSET ? see attachment. What is the value of RSET and VR do I need to put in Eq (1) that gives ISET = 1 mA ?
If I get 1 mA through LM 134 with correct values of REST and VR then I guess PT1000 should be connected with ISET and the other terminal of PT1000 has to be connected to GND, right ? At temperature 0 C, the PT1000 will have 1000 Ohm and 1 mA through the PT1000 will give 1 V across PT1000 at 0 C that will change with temperature.
If I get 1 mA through LM 134 with correct values of REST and VR then I guess PT1000 should be connected with ISET and the other terminal of PT1000 has to be connected to GND, right ? At temperature 0 C, the PT1000 will have 1000 Ohm and 1 mA through the PT1000 will give 1 V across PT1000 at 0 C that will change with temperature.
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