RS Components has introduced Isabellenhütte's portfolio of high-precision, low-ohmic value resistors for use as current sensors. Created using two different proprietary manufacturing technologies such as ISA-Plan and ISA-Weld, Isabellenhütte current sensing resistors meet stringent criteria for thermoelectric voltage, long-term stability and inductance that enable designers to optimise the use of power on PCBs more efficiently. RS is the first distributor in the EMEA and Asia Pacific regions to offer Isabellenhütte products, including over 200 variants of SMD power resistors.
Isabellenhütte power resistors are widely used in automotive applications such as battery management in electric, hybrid and conventional vehicles, ABS (anti-lock braking systems), ASR (anti-skid control), 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, high-precision resistor elements are etched onto a homogeneous film of one of Isabellenhütte's resistance alloys - either Manganin or Zeranin - which have a low resistance temperature coefficient (TCR). They are electrically insulated, mounted on a metal substrate with good thermal conductivity and packaged as small SMDs. The resistor material is thermoelectric, well coupled to copper, and reduces the thermoelectric voltage to practically zero. Heat conduction in the substrate allows excellent pulse power. While ISA-Plan resistors are available with resistance values from 1 mΩ to 4.7 Ω, with a tolerance of 0.5 %, 1 % or 5 %, and with power ratings from 0.5 W to 7 W and TCRs up to 20 ppm/ °C.
ISA-Weld power resistors consist of an electron-beam welded copper composite and a resistive alloy: Manganin, Zeranin, Noventin, ISAOHM or Aluchrom. These materials, in particular, are flexible enough to be adapted to a variety of geometries and applications, and ensure uniform current density and heat distribution within the resistor. ISA-Weld resistors offer resistance values from 0.1 to 6.8 mΩ, with a tolerance of 1 % or 5 %, power ratings up to 15 W and TCRs up to 20 ppm/°C.
