Sense resistor handles more current

An IRC Wirewound and Film Technologies product story

Edited by the Electronicstalk editorial team Mar 10, 2006

The OARS-XP Series of current sense resistors has a novel form factor that provides compliant terminations to better handle TCE mismatch between the device and the PC board.

Providing design engineers with a higher current rating in a proven surface mount package, TT electronics IRC Wirewound and Film Technologies Division has developed a surface mount current sense resistor with extended power ratings.

Designated the OARS-XP Series, the open-air, flameproof device has a unique form factor that provides compliant terminations to better handle TCE (thermal coefficient of expansion) mismatch between the device and the PC board.

According to David Winkler, Product Manager at IRC's Wirewound and Film Technologies Division, the XP designation on the product name refers to the wider metal element that enables the device to handle higher current.

"The unique design of this device provides superior thermal expansion cycling", said Winkler.

"Like the standard OARS Series resistors, the compliant leads on the resistor allow for thermal expansion, making the device ideal for a number of applications that require repeated thermal cycling".

Applications for the resistors include surge and pulse circuits, AC power applications, current sensing and feedback, Winkler continued.

Winkler explained that the actual in-circuit power rating of the OARS-XP Series devices will depend on several design factors, including substrate material; trace width and thickness; airflow in the enclosure, as well as heat-generating components (such as FETs).

"Our benchmark testing proves that the OARS-XP Series device can achieve power ratings of 3W using 2oz of copper in a 0.25in-wide trace on standard FR-4 circuit board", Winkler continued.

Resistance value for the resistor ranges from 2 to 50mohm, with tolerances down to +/-1%.

Inductance values are less than 10nH, with operating temperature ranging from -40 to +125C.

IRC will also produce devices outside these specifications to meet customer requirements.

Lead-free RoHS-compliant and zero ohm jumper versions are also available.

Typical pricing for the OARS-XP Series resistors is $0.40 each in 1500-piece per reel quantities.