High-end current-sense devices optimise power use on PCBs

RS Components has introduced the Isabellenhütte portfolio of high-precision, low-ohmic current-sense resistors. Created using two different proprietary manufacturing technologies known as ISA-Plan and ISA-Weld, the company current-sense resistors satisfy stringent criteria about thermoelectric voltage, long-term stability and inductance that enable electronics designers to optimise power use on PCBs more efficiently than otherwise possible.

The company's power resistors are extensively employed in automotive such as battery management in electric, hybrid and conventional vehicles, ABS, ASR, cruise control, power steering, fuel injection and traction control systems. They are also found in power supplies, as shunts for energy meters and IGBT power modules, and in various industrial, telecommunications and consumer applications.

In ISA-Plan devices, highly precise resistor elements are etched onto a homogenous film of one of the company's resistance alloys — either Manganin or Zeranin — which exhibit a very low-temperature coefficient of resistance. They are electrically insulated, mounted on a metal substrate with good thermal conductivity, and packaged as small SMDs. The resistor material is thermoelectrically well matched to copper, decreasing thermoelectric voltage to practically zero. Heat conduction into the substrate permits excellent pulse power ratings. These resistors are offered with resistance values from 1mOhm to 4.7Ohm, tolerances of 0.5%, 1% or 5%, power ratings from 0.5W to 7W, and TCR down to 20ppm/C.

ISA-Weld power resistors comprise of an electron-beam-welded composite of copper and a resistance alloy: Manganin, Zeranin, Noventin, ISAOHM or Aluchrom. These materials are sufficiently flexible to be adapted to a range of geometries and applications and provide uniform current density and heat distribution within the resistor. ISA-Weld resistors offer resistance values from 0.1mOhm to 6.8mOhm, tolerances of 1% or 5%, power ratings up to 15W, and TCR down to 20ppm/C.