Boone, N.C. TT electronics IRC Wirewound and Film Technologies Division has developed a "tight-pitch" version of its open air, metal element current sense resistor (OAR series) with ratings as high as 3 watts (W) in a reduced PC-board footprint. These new OAR-TP series devices are designed to save board space in densely-packed power supply designs.
The new OAR-TP through-hole resistors offer a high current, flameproof alternative to conventional axial devices and flat chips for current-sense circuits, particularly in applications where space is at a premium. The resistor’s footprint is reduced by extending the height of the device above the board, thus keeping the resistor element’s “hot spot” safely off the PC-board while providing for increased air circulation under it, resulting in increased heat dissipation and cooler operation, explained the company.
The OAR-TP series resistors offer identical specifications to the OAR devices. These resistors are rated for 1 W or 3 W at 85°C, with resistance values from 0.1Ω to 0.005Ω, with tolerances down to ±1%. They feature temperature coefficient of resistance (TCR) values as low as ±20 ppm/°C and inductance values in the single-digit nanoHenry range. The operating temperature range is -40°C to 125°C.
A lead-free, RoHS-compliant version is available, as is a low inductance version for high-frequency applications. Custom specifications are also available.
The flameproof OAR-TP 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%, said the company.
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 has mounting centers of 5 mm or 7 mm, depending on resistance, resulting in a potential reduction of more than 50% for the OAR-1 device and 60% for the OAR-3.
The OAR-1TP measures .275 (width) x .300 in. (height) (7.0 x 7.8 mm), while the OAR-3TP offers a footprint of .275 x 1.25 in. (7.0 x 32.0 mm) and .197 x 1.25 in (5.0 x 32.0mm), depending on resistance value. Click here for a complete list of physical dimensions.
Typical pricing for the OAR-TP series resistors ranges from $0.18 to $0.20 in quantities of 25,000. Delivery is from stock to 10 weeks.
TT electronics IRC Wirewound and Film Technologies Division, 1-828-264-8861,www.irctt.com