El Segundo, Calif.—International Rectifier's IR3094 is a three-phase PWM control IC with integrated drivers suited for 80-amp DC/DC converter applications. This chip, used with the company's DirectFET MOSFET output stage power devices, cuts real-estate requirements by up to 40 percent.
A typical 80-amp, synchronous buck solution for DDR memory in rack servers and point-of-load (POL) modules for high-density data systems would require 13 devices (one controller, three stages to drive external MOSFETs, and three MOSFETs per phase). A chip set made with the IR3094 controller and the IRF6637 and IRF6678 DirectFET MOSFETs reduces the silicon component count to seven for the same output current. The power MOSFETs (three pairs) can be placed directly next to the IR3094 to minimize parasitics from PCB traces. The total solution takes less than two square inches of board space.
The IR3094 delivers up to 3 amps at 0.85 to 5.1 volts for driving the power MOSFET stages. Features include a high-accuracy (1 percent) reference voltage, adaptive voltage positioning, and programmable switching frequency up to 540 kHz. The IR3094 provides system protection with programmable soft start, hiccup over-current protection, over-voltage protection, and a "power good" indicator.
Suitable output stages include the IRF6678 synchronous MOSFET, which features a typical on-resistance of 1.7 milliohms at Vgs = 10 and 2.3 milliohms at Vgs = 4.5. Similarly, the company's IRF6637 control MOSFET has a Miller charge of just 4 nC and a typical on-resistance of 5.7 milliohms, and 8.2 milliohms, respectively. Both MOSFETs are housed in the medium can DirectFET package, occupying the same board area as a SO-8 with a low (0.7 mm) profile, and provide improved thermal performance through double-sided cooling.
Click here for the product datasheet. The IR3094MPbF PWM controller, in a 7-by-7 mm, 48-lead MLQP package, and its companion DirectFET MOSFETs are available immediately. Pricing is $2.34 each for the IR3094; the IRF6678 is $1.25 each and the IRF6637 is 91 cents each. All pricing is in 10k-unit quantities, and is subject to change. The IR3094 and the DirectFET MOSFETs are RoHS compliant.
International Rectifier, 1-310-252-7105, www.irf.com