Riedon targets low cost current sensing applications with low ohmic value resistors

November 05, 2013 // By Paul Buckley
Targeting the demanding requirements of current sensing and shunt applications Riedon's portfolio of low ohmic value resistors provide AEC-Q200 compliance for use in harsh automotive environments.

The resistor portfolio ranges from Riedon's economical bare metal element MSR series through to the company's CLSA series chip resistors.

Utilizing various technologies, Riedon offers ±1% tolerance resistances from 0.5 milliohms up to 1 ohm in various package formats with TCRs as low as ±20 ppm/°C and power ratings up to 5 W. For tolerances down to ±0.1%, Riedon is also able to supply four terminal versions of its axial lead low ohm power resistor.

Riedon’s MSR series uses a bare metal element in an all-welded construction for through-hole circuit board mounting to provide resistance values from 5 mΩ to 100 mΩ, while also achieving low inductance (<10 nH) and low TCR (±20 ppm/°C). MSR resistors are available in 1, 3 and 5-Watt power ratings with tolerances of ±1% or ±5%.

For surface mount applications, Riedon has several chip resistor solutions: the company's MNRS chip shunt resistors offer excellent long-term stability and low inductance with 4- and 6-Watt ratings and resistances from 1 mΩ to 4 mΩ; the CSR family of ultra low ohm metal strip chip resistors come in three sizes (1206 / 2010 / 2512) for power ratings from 1 to 3 Watts, with standard and customized resistance values from 0.5 mΩ to 15 mΩ; and featuring an alumina substrate for high power dissipation the CLS/CLSA series of chip resistors operate over -55°C to +155°C, with the CLSA parts meeting the Automotive Engineering Council’s AEC-Q200 stress test qualification.

“Current sensing applications  insert a low ohmic precision resistor in series with the load current, creating a small voltage drop that can be readily measured and used to calculate the current flowing through the resistor”, explained Phil Ebbert, Riedon’s VP of Engineering, “Resistance values of just a few milliohms allow currents of several Amps, even tens of Amps, to be handled with device power ratings up to 5 Watts. Riedon’s capability to produce such low ohmic values, with well defined