Providing design engineers with an open screened substrate device for applications requiring superior thermal performance, TT electronics BI Technologies SMT Division has developed a non-molded power resistor rated up to 75W. Designated the BHP75 Series, the resistor is housed in a TO-220 opened screened substrate package, and features an insulated tapered venturi bonded to the substrate for maximum heat dissipation.
According to Jim Rieley, Sales Director for BI Technologies' SMT Division, the design of the BHP75 Series resistor (see the Figure) allows for three methods of heat dissipation, resulting in exceptional power handling characteristics. "The chimney-shaped tapered venturi is attached to the ceramic substrate and convection forces hot air up the "neck" of the chimney and away from the resistor face of the component," Rieley said. "The power resistor utilizes all three methods of heat dissipation, including conduction through the heat sink tab, radiation from the resistor surface, and convection through the venturi element."
Typical applications for the BHP75 resistor include higher wattage switchmode power supply circuits, motor control and drive circuits, inverters and industrial power equipment. The BHP75 Series resistors are rated for 75-W power dissipation at tab temperature maintained at 25°C or less than 75 W. Resistance ranges from 1 Ω to 100 KΩ, with tolerances of ±1% and ±5%. TCRs range less than 100 ppm/°C, with maximum dc operating voltage of 250 V and dielectric-withstanding voltage of 1 KV. Thermal resistance is 1.3°C/W from the resistor's "hot spot" to the package's metal flange and operating temperature range is -55°C to +155°C.
The BHP75 device complements BI Technologies' MHP 50-W TO-220 and MHP 100-W TO-247 power resistors, and provides customers requiring more wattage in a smaller package with an excellent alternative, Rieley continued. BI Technologies will also produce devices outside these specifications to meet customer requirements, with comprehensive application engineering and design support available for customers worldwide.
Typical pricing for the BHP75 Series resistors is $1.80 each in medium volumes. Lead time is from stock to 6 weeks. Samples are available immediately for engineering evaluation and customer prototypes.