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university:courses:electronics:electronics-lab-8a [25 Jun 2020 22:07] – external edit university:courses:electronics:electronics-lab-8a [20 Jul 2022 20:35] (current) – [Objective:] Doug Mercer
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 ====== Activity: A Floating (two terminal) Current Source / Sink ====== ====== Activity: A Floating (two terminal) Current Source / Sink ======
  
-===== Objective: =====+=====Objective:=====
  
 The objective of this activity is to investigate the ΔV<sub>BE</sub> concept to produce an output current which is stabilized (less sensitive) to variations of the input voltage level. Feedback is used to build a circuit which produces a constant or regulated output current over a range of supply voltages The objective of this activity is to investigate the ΔV<sub>BE</sub> concept to produce an output current which is stabilized (less sensitive) to variations of the input voltage level. Feedback is used to build a circuit which produces a constant or regulated output current over a range of supply voltages
  
 +=====Background:=====
 +
 +The [[adi>media/en/technical-documentation/data-sheets/AD590.pdf|AD590]] is a 2-terminal integrated circuit temperature transducer that produces an output current proportional to absolute temperature. The schematic diagram of this floating current source is shown in figure 7 of the AD590 datasheet. The a simplified and less accurate version of this concept is used as the experimental circuit in this activity.
 +
 +The AD590 uses a fundamental property of silicon BJT transistors to realize its temperature proportional characteristic. If two identical transistors are operated at a constant ratio of collector current densities, r, then the difference in their base-emitter voltage is (kT/q)(In r). Because both k (Boltzman’s constant) and q (the charge of an electron) are constant, the resulting voltage is directly proportional to absolute temperature (PTAT). For more details please refer to the datasheet.
 ===== Materials: ===== ===== Materials: =====
 ADALM2000 Active Learning Module\\ ADALM2000 Active Learning Module\\
university/courses/electronics/electronics-lab-8a.txt · Last modified: 20 Jul 2022 20:35 by Doug Mercer

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