Wide temperature and extreme environment electronics are crucial to future missions. These missions will not have the weight and power budget for heavy harnesses and large, inefficient warm boxes. In addition, extreme environment electronics, by their inherent nature, allow operation next to sensors in the ambient environment, reducing noise and improving precision over the warm-box-based systems employed today.

On-chip integrated circuit processes usually have absolute tolerances in excess of 10% without post-fabrication trimming. This tolerance is often insufficient in sensing applications, especially across temperature. This necessitates either a trim step (at risk and expense) or an off-chip resistor (which involves a pad, and risk of short-circuit). In high-reliability systems, the drawn current in case of a short-circuit is an important consideration.

The proposed design uses a type of current mirror whose input is dependent upon the present operating conditions. A current limit for extreme environments utilizing this methodology has not appeared in the literature at the time of this reporting.

Extreme environment electronics are valuable to a number of disciplines, including military/aerospace, automotive, scientific research applications, and energy, among others.

This work was done by Jeremy A. Yager of Caltech for NASA’s Jet Propulsion Laboratory. NPO-48522

This Brief includes a Technical Support Package (TSP).
Precision Current Input With Well-Defined Current Limiting for Extreme Environment Applications

(reference NPO48522) is currently available for download from the TSP library.

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This article first appeared in the February, 2015 issue of NASA Tech Briefs Magazine.

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