IRC's power current sense resistors are expected to gain wide acceptance in the worldwide market as a result of increased thermal management capabilities.

TT electronics IRC Wire and Film Technologies Division's OAR-TP Series open air sense resistor is designed for applications requiring the transfer of heat away from circuits and solder joints. Available in 1W or 3W rating, the resistor is being specified for current sensing, feedback, low inductance, as well as surge and pulse applications. According to David Winkler, product manager for IRC's Wire and Film Technologies Division, the current sense resistor has gained worldwide acceptance because of its narrow footprint and thermal management capabilities.

'The hot spot on the OAR-TP resistor is approximately 0.2 degrees higher than on a typical metal strip chip resistor'.

'This results in an increased thermal path for the OAR-TP, reducing heat transfer into the solder joints and circuits,' said Winkler.

'Because of this, the device is ideal for thermally harsh environments, including automotive and aerospace applications, as well as enclosed, poorly ventilated circuits in applications such as laptop computers'.

The 1W OAR-TP resistor measures just .300in in height, while the 3W device has a height of 1.25in.

Because many power supply designs are already tightly packed at the PC board level, the additional height does not create any profile issues, but rather improves cooling efficiency, Winkler continued.

The OAR-TP Series resistors feature a reduced pitch, or spacing between the leads on the circuit board (with a corresponding increase in the board mounted profile), when compared to the standard OAR Series devices.

The OAR-TP Series resistors are rated for 1W or 3W at 85C, with resistance values from 0.1ohm to 0.005ohm and tolerances down to +/-1%.

The device features TCRs as low as +/-20ppm/C and inductance values in the single-digit nanoHenry range.

Operating temperature range is -40 to +125C.

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

A lead-free RoHS-compliant version is available, as is a low inductance version for high frequency applications.

The flameproof OAR-TP Series resistors are constructed of a wire resistive element with welded copper leads to prevent solder wicking, which can change the device's resistance value in the circuit by as much as 30%.