Rainbow Electronics MAX17480 - Manual (Page 47)

MAX17480
AMD 2-/3-Output Mobile Serial
VID Controller
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5) Make the DC-DC controller ground connections as
shown in the standard application circuit (Figure 2).
This diagram can be viewed as having three sepa-
rate ground planes: input/output ground, where all
the high-power components go; the power ground
plane, where the PGND, V
DD
bypass capacitor,
and driver IC ground connection go; and the con-
troller’s analog ground plane, where sensitive ana-
log components, the MAX17480’s AGND pin, and
V
CC bypass capacitor go. The controller’s analog
ground plane (AGND) must meet the power ground
plane (PGND) only at a single point directly beneath
the IC. The power ground plane should connect to
the high-power output ground with a short, thick
metal trace from PGND to the source of the low-side
MOSFETs (the middle of the star ground).
6) Connect the output power planes (V CORE , V OUT3 ,
and system ground planes) directly to the output
filter capacitor positive and negative terminals with
multiple vias. Place the entire DC-DC converter
circuit as close to the CPU as is practical.
V DDNB
V
CORE1
V
CORE0
C OUT
C OUT
INDUCTOR
POWER
GROUND
INDUCTOR
C OUT
C OUT
SPLIT CORE
CPU SOCKET
C
IN
C IN
C
IN
C IN
AGND PIN
CONNECT THE EXPOSED
PAD TO POWER GND
USING MULTIPLE VIAS
+
C VCC
C VDD
C
IN3
L3
C
OUT3
C
EQ
R NTC
R2
R1
CSP
CSN CSP
CSN
KELVIN-SENSE VIAS TO
INDUCTOR PAD
KELVIN-SENSE VIAS UNDER THE INDUCTOR
(REFER TO EVALUATION KIT)
INDUCTOR DCR SENSING
Figure 15. PCB Layout Example