Electrical Specifications (Continued)
6.2 ELECTRICAL CONNECTIONS
6.2.1 Power/Ground Connections and Decoupling
Testing and operating the GXLV processor requires the
use of standard high frequency techniques to reduce par-
asitic effects. These effects can be minimized by filtering
the DC power leads with low-inductance decoupling
capacitors, using low-impedance wiring, and by connect-
ing all VCC2 and VCC3 pins to the appropriate voltage lev-
els.
6.2.1.1 Power Planes
Figure 6-1 shows layout recommendations for splitting the
power plane between VCC2 (core: 2.2V, 2.5V, 2.9V) and
VCC3 (I/O: 3.3V) volts in the BGA package. The illustration
assumes there is one power plane, and no components
on the back of the board.
Figure 6-2 shows layout recommendations for splitting the
power plane between VCC2 (core: 2.2V, 2.5V, 2.9V) and
VCC3 (I/O: 3.3V) volts in the SPGA package.
3.3V Plane
(V
)
CC3
26
A
1
A
2.2V, 2.5V, or 2.9V Plane
(V
)
CC2
Geode™ GXLV
Processor
3.3V Plane
(V
3.3V Plane
(V
)
)
CC3
CC3
352 BGA - Top View
2.2V, 2.5V, or 2.9V Plane
(V
)
CC2
AF
AF
1
26
3.3V Plane
(V
)
CC3
Legend
= High frequency capacitor
= 220 µF, low ESR capacitor
= 3.3V connection
Note: Where signals cross plane splits, it is recommended to include
= 2.2V, 2.5V, or 2.9V connection
AC decoupling between planes with 47 pF capacitors.
Figure 6-1. BGA Recommended Split Power Plane and Decoupling
Revision 1.1
185
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