Fairchild FAN5091 Specifications manual
Summary
This advanced two-slice synchronous buck converter controller provides precise, high-efficiency power regulation for demanding applications. Featuring a highly programmable output voltage and built-in current sharing, it delivers exceptional transient response crucial for modern high-performance processors like CPUs. The manual details its integration of remote sensing, various protection modes, and adaptability to complex power supply designs, making it essential for hardware engineers building stable Voltage Regulator Modules (VRMs) requiring microvolt accuracy and reliable load handling up to 50A.
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www.fairchildsemi.com
FAN5091 Two Slice Interleaved Synchronous Buck Converter
Features Description Programmable output from 1.10V to 1.85V in 25m V steps The FAN5091 is a synchronous multi-slice DC-DC controller using an integrated 5-bit DAC IC which provides a highly accurate, programmable output Two interleaved synchronous slices for maximum voltage for all high-performance processors. Two interleaved performance synchronous buck regulator slices with built-in current shar- 100nsec response time ing operate 180° out of phase to provide the fast transient Built-in current sharing between slices response needed to satisfy high current applications while Remote sense minimizing external components. The FAN5091 features
Programmable Active Droop (Voltage Positioning) remote voltage sensing and Programmable Active Droop
Programmable frequency from 200KHz to 2MHz for 100nsec converter transient response with minimum out- Adaptive delay gate switching put capacitance. It has integrated high-current gate drivers, Integrated high-current gate drivers with adaptive delay gate switching, eliminating the need for Integrated Power Good, OV, UV, Enable/Soft Start external drive devices. The FAN5091 uses a 5-bit D/A con- functions verter to program the output voltage from 1.10V to 1.85V in Drives N-channel MOSFETs 25m V steps with an accuracy of 1%. The FAN5091 uses a Operation optimized for 5V operation high level of integration to deliver load currents in excess of High efficiency mode (E*) at light load 50A from a 5V source with minimal external circuitry. The Overcurrent protection using MOSFET sensing FAN5091 also offers integrated functions including Power 24 pin TSSOP package Good, Output Enable/Soft Start, under- voltage lockout,
over-voltage protection, and adjustable current limiting with independent current sense on each slice. It is available in a
Applications
24 pin TSSOP package.
Power supply for Pentium IV Power supply for Athlon VRM for Pentium IV processor Programmable step-down power supply
Block Diagram
Bypass +12V
5V Reg
Digital
Control
Digital
Control
5-Bit Power DAC Good
2 3 VID0 VID2 VID4
PWRGD DROOP/E* GNDA ENABLE/SS ILIM
VID1 VID3
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. 1.0.0 5/10/01
Page Summary Contents For Fairchild FAN5091 Specifications manual
Manual Details
| Brand | Fairchild |
|---|---|
| Pages | 21 |
| File Size | 193.41 KB |
| Published | July 16, 2026 |
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Frequently Asked Questions
How is the output voltage programmed and monitored?
The voltage can be set from 1.10V to 1.85V in 25mV steps using the five VID pins, and the status is monitored via the PWRGD pin.
What connections are necessary for safe system ground?
AGND (Pin 7) should connect to a low impedance system ground plane, while PGNDA (Pin 16) must connect directly to the low-side MOSFET source.
How does the device handle high current loads?
It features two interleaved synchronous slices with built-in current sharing, maximizing voltage for high-performance processors and supporting load currents in excess of 50A.
What is the transient response time?
With a programmed frequency range of 200KHz to 2MHz, the controller achieves a fast 100nsec converter transient response.