International Rectifier Introduces New XPhase^TM Control IC for AMD Opteron^TM and Athlon 64^TM Applications

International Rectifier (IR®) introduced the IR3082 multiphase Control IC for AMD Opteron^TM and Athlon64^TM processor-powered servers and workstations. The IR3082 broadens IR's XPhase^TM family of scalable multiphase ICs and, together with DirectFET^TM power MOSFETs, delivers an optimized multiphase DC-DC power solution for mid-range and high-end servers, voltage regulator modules (VRMs) and high current telecom applications.

The IR3082 Control IC works with the IR3086A Phase IC to provide a full-featured and flexible way to implement a complete Opteron or Athlon64 power solution. For example, a 12V, four-phase design using one IRF6617 control FET and one IRF6691 synchronous FET per phase provides 86% efficiency for an output of 80A.

Unlike other multiphase solutions which have a fixed number of phases, IR's XPhase architecture enables scalable multiphase designs. The IR3082 uses five-bit voltage programming and only a few external components which simplify general purpose and non-processor-specific multiphase applications.

Technical Highlights
Features of the IR3082 include a 5-bit VID with 1.0% overall system accuracy. An adaptive voltage-positioning feature maintains the output voltage tolerance while minimizing output capacitor requirements. A patented body braking circuit can reduce the output capacitance requirement by 25%, further reducing system costs. A 150kHz to 1MHz programmable oscillator gives the designer additional flexibility to optimize for system efficiency and transient response.

For system protection and reliability, the IR3082 features programmable soft-start and hiccup over-current protection. Current sensing is achieved with loss-less inductor current sensing which improves accuracy compared to sensing circuits measuring MOSFET on-resistance. Under-voltage lockout and over-voltage protection circuits ensure reliability of system voltages. A power-good output signal indicates proper operation.

About XPhase^TM
XPhase is IR's distributed multiphase architecture that consists of control ICs and phase ICs that communicate using a simple five-wire bus scheme. Phases can be added or removed without changing the fundamental design. The five-wire analog bus consists of bias voltage, phase timing, average current, error amplifier output and VID voltage. By eliminating point-to-point wiring between the control and the phase ICs, the five-wire bus shortens interconnections, and reduces parasitic inductance and noise. This simplifies PCB layout and gives a more robust design.

Availability and Pricing
The IR3082 XPhase Control IC is packaged in a thermally-enhanced 5mm x 5mm, 20L MLPQ package. The new IC is available immediately. Pricing is US $1.49 each in 10,000-piece quantities. Prices are subject to change.