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VPG debuts sealed Z-Foil power current sensing resistors

Posted: 15 Jul 2013 ?? ?Print Version ?Bookmark and Share

Keywords:Vishay Precision Group? resistors? heat sink? power?

Vishay Precision Group (VPG) recently revealed that its Vishay Foil Resistors brand (VFR) has released two new ultra-high-precision hermetically sealed Z-Foil power current sensing resistors with low TCR of 0.2ppm/C (from -55C to 125C, 25C ref.), PCR (R due to self-heating) of 4ppm/W typical, and tolerances to 0.01 per cent.

Designed to provide optimal performance when mounted on a chassis or cooled heat sink, the hermetically sealed VHP4Z and VPR247Z offer power ratings of 10W (heat sink) and 3W (free air), and a four-terminal Kelvin configuration for increased accuracy in high-power applications.

The devices offer a welded construction and a screw-mount for direct attachment to a metal heat sink. Hermetic sealing and a nitrogen back-fill for the VPR247Z provide maximum protection against environmental stresses to ensure long-term stability.

Ideal for applications such as test and measurement where rapid R stabilisation and resistance stability under transient power conditions are required, the devices offer excellent load-life stability down to 0.005 per cent typical (50ppm) at 3W (heat sink) at 25C for 2,000 hours. While the VHP4Z's copper leads provide low thermal EMF, the VPR247Z provides a significantly reduced size and weight and features gold-plated copper leads for higher stability.

The VHP4Z and VPR247Z offer a thermal stabilisation time of "The VHP4Z and VPR247Z are based on our expertise in stress analysis and proprietary methods of manufacturing precision 4-terminal resistors," said Yuval Hernik, Senior Director of Application Engineering for VFR. "Their use of Z-Foil technology allows them to achieve a very low TCR and PCR over a very wide temperature range. And since this important specification is also influenced by the application's assembly methods, anticipated current fluctuations, and accuracy and response time requirements, we are available to collaborate with our customers on their designs for the most efficient design process.

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