Surface-Mount Resistor from Vishay in Compact 4527 Package

Like the WSR2 (2-W) and WSR3 (3-W), the new WSR5 measures just 0.455 in. by 0.275 in. [11.56 mm by 6.98 mm] with a height profile of 0.095 in. [2.41 mm], making it a compact 5-W solution for electronic controls in automotive systems, power supplies in communications base stations, and dc-to-dc converters and VRMs in high-end workstations and servers.

A proprietary processing technique allows the WSR5 to offer extremely low resistance values ranging from 1 mΩ to 300 mΩ in a standard resistance tolerance of ± 1 %. A tolerance of ± 0.5 % is available for the resistance range of 10 mΩ to 300 mΩ. The WSR5's very low inductance values range from 0.5 nH to 5 nH, and the device's temperature coefficients are ± 110 ppm/°C for the 7.5–mΩ to 9.9–mΩ range and ± 75 ppm/°C for the 10–mΩ to 300–mΩ range.

The WSR5 resistor's proprietary construction features a molded, high-temperature encapsulation with an integrated heat sink for improved thermal management. As a result, the new device maintains the superior electrical characteristics of the Power Metal Strip construction during operation in a variety of high-current applications. Low thermal EMF, a broad operating temperature range of – 65 °C to + 275 °C, and resistance to moisture, vibration, thermal and mechanical shock ensure reliable operation. The WSR5's proprietary Power Metal Strip design features all-welded construction, solderable terminations, and a solid metal alloy resistive element.

The WSR5's high-power capability in a compact package enables designers to shift away from leaded resistors to a surface-mount solution, and thus to create smaller, lower-cost, and/or higher-performing end products. When used to replace through-hole current-sensing resistors, the WSR5 reduces manufacturing placement costs while allowing for total solder reflow assembly. Per-device costs also are further reduced by the elimination of secondary operations such as lead forming and trimming.