High-frequency performance marks out film power resistor design

August 08, 2013 // By Graham Prophet
Riedon has expanded its range of specialist resistive solutions with a cost-competitive power resistor design that is non-inductive and achieves superior performance in high-frequency applications and high-speed pulse circuits.

The various product series within Riedon’s PF family of TO-style resistors all use an advanced power film formed on a heat-conducting alumina substrate that is metallised and soldered to a heat-dissipating copper plate tab, providing devices that offer excellent thermal resistance in small-size, thin-profile TO-style packages for high-density applications.

The package configurations available cover power ratings from a few Watts up to 600W in both through-hole and surface mountings: These start with the PF1260 series in an epoxy-moulded TO-126 leaded package, with resistances in the range 0.01Ω to 51 kΩ, tolerances from ±1%, a temperature coefficient (TCR) from ±50ppm and provide up to 20W dissipation (with a heatsink). The PF2200 and PF2470 series offer a similar specification but with dissipation up to 50W and 140W respectively in leaded TO-220 and TO-247 packages. For the ultimate in power dissipation, the PF2270 series uses the screw-terminal TO227 style package to handle up to 300W, when attached to an appropriate heatsink and subject to temperature derating. Finally, the PFS35 series provides a solution for surface mounting, using a TO-263 housing (D-Pak) to provide 35W dissipation when used with a heatsink or 2W with a simple solder pad. The low-inductance design makes these parts suitable for high frequency applications, such as wireless communications, or in systems that need to withstand short-duration, high-energy pulses, for example, medical equipment.

Riedon’s ( www.riedon.com) full range of TO-style power resistors are available from Digi-Key ( www.digikey.com)