Current Sense Resistors
Riedon is targeting the demanding requirements of current sensing and shunt applications with its comprehensive portfolio of low ohmic value resistors, ranging from the economical bare metal element MSR series through to its CLSA series chip resistors that provide AEC-Q200 compliance for use in harsh automotive environments.
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 ±20ppm/oC and power ratings up to 5 Watts. For tolerances down to ±0.1%, Riedon is also able to supply four terminal versions of its axial lead low ohm power resistor.
The MSR series uses a bare metal element in an all-welded construction for through-hole circuit board mounting to provide resistance values from 5mΩ to 100mohm, while also achieving low inductance (<10nH) and low TCR (±20ppm/C). MSR resistors are available in 1W, 3W and 5W power ratings with tolerances of ±1% or ±5%. For surface-mount applications, the company offers several chip resistor solutions: its MNRS chip shunt resistors offer exceptional long-term stability and low inductance with 4W and 6W ratings and resistances from 1mohm to 4mohm; the CSR family of ultra low ohm metal strip chip resistors come in three sizes (1206 / 2010 / 2512) for power ratings from 1W to 3W, with standard and customized resistance values from 0.5mohm to 15mohm; and featuring an alumina substrate for high power dissipation the CLS/CLSA series of chip resistors operate over -55C to +155C, with the CLSA parts meeting the Automotive Engineering Council’s AEC-Q200 stress test qualification, says the company.
“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”, explains 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 tolerances, enables it to serve a wide range of current sensing and shunt resistor applications.”