FAN5090

www.fairchildsemi.com

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www.fairchildsemi.com

FAN5090
Two Phase Interleaved Synchronous Buck Converter for VRM 9.x Applications
Features
Programmable output from 1.10V to 1.85V in 25mV steps using an integrated 5-bit DAC Two interleaved synchronous phases for maximum performance 100nsec transient response time Built-in current sharing between phases Remote sense Programmable Active Droop (Voltage Positioning) Programmable switching frequency from 100KHz to 300KHz per phase Adaptive delay gate switching Integrated high-current gate drivers Integrated Power Good, OV, UV, Enable/Soft Start functions Drives N-channel MOSFETs Operation optimized for 12V operation Overcurrent protection using MOSFET sensing 24 pin TSSOP package

Description
The FAN5090 is a synchronous two-phase DC-DC controller IC which provides a highly accurate, programmable output voltage for VRM 9.x processors. Two interleaved synchronous buck regulator phases with built-in current sharing operate 180 out of phase to provide the fast transient response needed to satisfy high current applications while minimizing external components. The FAN5090 features Programmable Active Droop for transient response with minimum output capacitance. It has integrated high-current gate drivers, with adaptive delay gate switching, eliminating the need for external drive devices. The FAN5090 uses a 5-bit D/A converter to program the output voltage from 1.10V to 1.85V in 25mV steps with an accuracy of 1%. The FAN5090 uses a high level of integration to deliver load currents in excess of 50A from a 12V source with minimal external circuitry. The FAN5090 also offers integrated functions including Power Good, Output Enable/Soft Start, under-voltage lockout, over-voltage protection, and adjustab
le current limiting with independent current sense on each phase. It is available in a 24 pin TSSOP package.

Applications
Power supply for Pentium IV Power supply for Athlon VRM for Pentium IV processor Programmable step-down power supply

Block Diagram
BYPASS 6 23 RT 12V 18 5V Reg UVL O BOOT A 13 12V

OSC

Digital Control

15 12V 17 16 BOOT B VO 12V

GNDA

Current Limit

12 11

Digital Control

10 12V 8 9

5-Bit DAC
1 2 3 4 5 VID0 VID2 VID4 VID1 VID3 24

Power Good
19 PWRGD 21 7 22 ENABLE/SS 20 ILIM

DROOP/E AGND

Pentium is a registered trademark of Intel Corporation. Athlon is a registered trademark of AMD. Programmable Active Droop is a trademark of Fairchild Semiconductor.

REV. 1.0.1 9/16/03