FAN5018B Fairchild Semiconductor, FAN5018B Datasheet - Page 28

• Manufacturer Part Number: FAN5018B
• Description: 6-Bit VID Controller 2-4 Phase VR10.X Controller
• Manufacturer: Fairchild Semiconductor

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FAN5018B
• Whenever a power dissipating component (e.g., a power
• Route the output power path to encompass a short
• For best EMI containment, use a solid power ground
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MOSFET) is soldered to a PCB, the liberal use of vias,
both directly on the mounting pad and immediately
surrounding it, is recommended. Two important reasons
for this are: improved current rating through the vias, and
improved thermal performance from vias extended to the
opposite side of the PCB where a plane can more readily
transfer the heat to the air. To achieve the best thermal
dissipation to the air around the board, make a mirror
image of any pad being used to heatsink the MOSFETs on
the opposite side of the PCB . To further improve thermal
performance, use the largest possible pad area.
distance. The output power path is formed by the current
path through the inductor, the output capacitors, and the
load.
plane as one of the inner layers extending fully under all
the power components.
Signal Circuitry
• The output voltage is sensed and regulated between the
• Connect the feedback traces from the switch nodes as
FB pin and the FBRTN pin (which connects to the signal
ground at the load). To avoid differential mode noise
pickup in the sensed signal, the loop area should be small.
Thus the FB and FBRTN traces should be routed adjacent
to each other atop the power ground plane back to the
controller.
close as possible to the inductor. Connect the CSREF
signal to the output voltage at the nearest inductor to the
controller.
PRODUCT SPECIFICATION
REV. 1.0.0 Jul/15/05