ELECTRONICS: For power electronics design engineers looking for high current devices capable of providing current- sense and surge protection functions in high temperature environments, TT electronics IRC offers a series of open-air current sense resistors. The OARS-3 Series surface mount metal alloy strip resistors feature a flameproof open-air design that elevates the device’s “hot spot” above the PC board, where heat can be dissipated to ambient air instead of to adjacent thermally-sensitive components. The unique design also gives the resistors superior thermal temperature cycling performance.
The resistors’ ability to operate reliably under elevated temperature conditions makes them ideal for computer power supplies, high-reliability server equipment, and automotive underhood applications.
The OARS-3 Series resistor performs at 3W; however, testing conducted by IRC engineers demonstrate that the resistor is capable of handling higher power levels without forced air depending on system thermal design. Testing at 4W reveals that, although the “hot spot” temperature can reach in excess of 230C when the resistor is running at full power, the solder joint remains at 110C or below.
The OARS-3 Series resistors are nominally rated for 3W at 70C, with a resistance range from 2mΩ to 15mΩ and tolerances to ±1 percent. Inductance values are less than 10 nanohenries, with operating temperature ranging from -40 to +125C. RoHS-compliant and 0Ω jumper versions are also available. IRC will also produce devices outside these specifications to meet customer requirements.
Typical pricing for the OARS-3 Series resistors is approximately $0.86 each in minimum order quantities of 1900 pieces. Lead time is from stock to 14 weeks.
-Edited by Kelsey Anderson