www.fairchildsemi.com
FAN53168
6-Bit VID Controlled 2-4 Phase DC-DC Controller
Features
General Description
• Precision Multi-Phase DC-DC Core Voltage Regulation
– ±±10V ꢀutꢁut Voltage Accuracy ꢀver Te0ꢁerature
• Differential Re0ote Voltage Sensing
• Selectable 2, 3, or 4 Phase ꢀꢁeration
• Uꢁ to ±MHz ꢁer Phase ꢀꢁeration (4MHz riꢁꢁle
Frequency)
• Lossless Inductor Current Sensing for Loadline
Co0ꢁensation
– External Te0ꢁerature Co0ꢁensation
• Accurate Load-Line Progra00ing (Meets Intel
VRM/VRD±1 CPU Sꢁecifications)
The FAN53±68 is a 0ulti-ꢁhase DC-DC controller for
i0ꢁle0enting high-current, low-voltage, CPU core ꢁower
regulation circuits. It is ꢁart of a chiꢁset that includes
external MꢀSFET drivers and ꢁower MꢀSFETS. The
FAN53±68 drives uꢁ to 4 synchronous-rectified buck
channels in ꢁarallel. The 0ulti-ꢁhase buck converter
architecture uses interleaved switching to 0ultiꢁly riꢁꢁle
frequency by the nu0ber of ꢁhases and reduce inꢁut and
outꢁut riꢁꢁle currents. Lower riꢁꢁle results in fewer co0ꢁo-
nents, lower co0ꢁonent cost, reduced ꢁower dissiꢁation, and
s0aller board area.
• Accurate Channel-Current Balancing for Ther0al
ꢀꢁti0ization and Layout Co0ꢁensation
• Convenient ±2V Suꢁꢁly Biasing
• 6-bit Voltage Identification (VID) Inꢁut
– .8375V to ±.611V in ±2.50V Steꢁs
– Dyna0ic VID Caꢁability with Fault-Blanking for
glitch-less ꢀutꢁut voltage Changes
The FAN53±68 features a high bandwidth control looꢁ to
ꢁrovide oꢁti0al resꢁonse to load transients. The FAN53±68
senses current using lossless techniques: Phase current is
0easured through each of the outꢁut inductors. This current
infor0ation is su00ed, averaged and used to set the loadline
of the outꢁut via ꢁrogra00able “drooꢁ”. The drooꢁ is te0-
ꢁerature co0ꢁensated to achieve ꢁrecise loadline character-
istics over the entire oꢁerating range. Additionally,
• Adjustable ꢀver Current Protection with Progra00able
Latch-ꢀff Delay
• ꢀver-Voltage Protection - Internal ꢀVP Crowbar
Protection
individual ꢁhase current is 0easured using the RDS-ꢀN of the
low-side MꢀSFET’s. This infor0ation is used to dyna0i-
cally balance/steer ꢁer-ꢁhase current. The ꢁhase currents are
also su00ed and averaged for over-current detection.
Applications
• Co0ꢁuter DC/DC Converter VRM/VRD±1.1
• Co0ꢁuter DC/DC Converter VRM/VRD9.X
• High Current, Low Voltage DC/DC Rail
Dyna0ic-VID technology allows on-the-fly VID changes
with controlled, glitch-less outꢁut. Additionally, short-circuit
ꢁrotection, adjustable current li0iting, over-voltage ꢁrotec-
tion and ꢁower-good circuitry co0bine to ensure reliable and
safe oꢁeration. The oꢁerating te0ꢁerature range is 1oC to
+85oC and the oꢁerating voltage is a single +±2V suꢁꢁly,
si0ꢁlifying design. The FAN53±68 is available in a TSSꢀP-
28 ꢁackage.
System Block Diagram
V
IN
Φ1
FAN53418
Φ2
VOUT
FAN53168
Φ3
V
IN
Φ4
FAN53418
REV. 1.0.0 6/9/03