New DC-DC Conversion Chip Set for Advanced Processors Boosts Efficiency
May 5, 2004 - International Rectifier, IR® introduced a control and synchronous switching chip set for high-frequency DC-DC converters powering next-generation Intel® and AMD processors in high-end advanced servers and desktop computers. Other applications include point-of-load (POL) DC-DC conversion in telecom and datacom systems.The chip set pair delivers 84.5% efficiency at 90A in a four-phase 1U (1.75-in. height) VRM outline system switching at 750kHz per phase and 87% efficiency at 150A in an eight-phase embedded VRD10.2 design switching at 400kHz per phase.
The first device is the monolithic IRF6691 DirectFETKYTM, which integrates a Schottky diode and synchronous MOSFET into a single package to enable an efficiency improvement of 1.1% at 1MHz per phase at full load compared to other existing highest-performing 20V synchronous FETs on the market when using the same control FET. The IRF6691 also features a typical RDS(on) of 1.2 mOhm at 10VGS (1.8 mOhm at 4.5VGS ) and a typical Qrr of 26nC, providing the best thermal performance with lower reverse recovery losses and reduced overall part count.
The second device is the IRF6617 DirectFETTM HEXFET® Control MOSFET. Specifically tailored for control FET switching, the IRF6617 features a very low total gate charge (Qg of 11nC), delivering a 33% reduction in on-resistance times gate charge product of 87mOhm-nC at 4.5VGS compared to previous 30V devices.
Patented DirectFETTM Packaging Technology
Both devices feature International Rectifier's patented DirectFET packaging technology that presents a whole new set of design advantages not previously delivered by standard plastic discrete packages. By deploying a new dual-side cooling design, the DirectFET power MOSFET family effectively doubles the current handling capacity of high frequency DC-DC buck converters powering advanced processors.
| Part Number | Package | BVDSS | RDS(on) max. @10V | RDS(on) max. @4.5V | VGS | ID @ Tc=25єC | QG typ | Qrr typ |
| (V) | (mOhm) | (mOhm) | (V) | (A) | (nC) | (nC) | ||
| IRF6617 DirectFETTM MOSFET |
DirectFET | 30 | 8.1 | 10.3 | 20 | 55 | 11 | 7.2 |
| IRF6691 DirectFETKYTM MOSFET and Schottky Diode |
DirectFET | 20 | 1.8 | 2.5 | 12 | 180 | 47 | 26 |
Availability and Pricing
Both devices are available immediately. The IRF6691 DirectFETKY device is US $1.49 each and the IRF6617 DirectFET MOSFET is US $0.87 each; pricing for both devices is in 10,000-unit quantities.
