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www.fairchildsemi.com
REV. 1.0.1 9/16/03
Pentium is a registered trademark of Intel Corporation. Athlon is a registered trademark of AMD. Programmable Active Droop is a trademark of Fairchild Semiconductor.
Block Diagram
22
VID0
11
10
14
13
17
16
24
-
+
OSC
Digital
Control
Power
Good
5-Bit
DAC
VID1
VID2
VID3
VID4
1234
5
+12V
PWRGD
-
+
ENABLE/SS
VO
AGND
7
DROOP/E*
18
6
+12V
15
5V Reg
BYPASS
23
R
T
+12V
+12V
12
8
9
21
+12V
Digital
Control
-
+
-
+
-
+
19
ILIM
20
BOOT A
BOOT B
GNDA
Current
Limit
UVL
O
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
Applications
• Power supply for Pentium
IV
• Power supply for Athlon
• VRM for Pentium IV processor
• Programmable step-down power supply
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 synchro-
nous 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 integra-
tion 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 lock-
out, over-voltage protection, and adjustable current limiting
with independent current sense on each phase. It is available
in a 24 pin TSSOP package.
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