Boone, N.C. Capable of handling high current loads for current sensing applications, TT electronics IRC Wirewound and Film Technologies Division has developed an ultra-low resistance (<2 mΩ), metal strip resistor rated for 45 amps at 1 watt (W) with low inductance and low temperature coefficient of resistance (TCRs).
Designated the CSS Series, the surface-mount, metal strip resistor is offered in a two-terminal and a four-terminal Kelvin design. Rated for a full 1 W at 70°C, the CSS resistors offer a resistance value range of 0.0005Ω to .003Ω with tolerances of 1%, 3% and 5% and TCRs as low as ±20 ppm/°C. They are rated for operation from -40°C to 125°C.
The series also features low inductance values of <0.1 nH at 100 KHz and 300 KHz. Continued stability beyond 300 MHz makes the CSS series suitable for high-speed computer power supply applications. For more detailed specs, please visit IRC's web site to view the CSS series datasheet.
The CSS series chips fit within the industry-standard 2512 footprint, with a board-mounted profile of 0.030-in. (0.76 mm). They are used extensively in applications requiring precision current sensing and power management circuits in computers, power supplies and motor control circuitry where current-sense devices are used.
According to David Winkler, product manager at IRC's Wirewound & Film Technologies Division, "The CSS Series resistors are used in voltage regulation modules (VRMs) to sense the current on multiple phases to help balance the overall load. Design engineers seeking to balance current between the multiple phases (traces) required to supply the 60+ amps for today's microprocessors require a simple linear method of current sensing that is both stable and reliable over a broad temperature range. Other current sense methods, such as RDSon or inductor (RL) sensing, are not as accurate over temperature."
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