AN2586 Freescale Semiconductor / Motorola, AN2586 Datasheet - Page 7

• Manufacturer Part Number: AN2586
• Description: MPC8260 PowerQUICC II Family Power Distribution Trends
• Manufacturer: Freescale Semiconductor / Motorola

If we use a standard SMT capacitor, the series L is around 2nH, which means we need m as follows:
This result tells us that we need at least eight capacitors to maintain an adequate bypass till 50MH. Now it
is necessary to calculate the capacitance of each of these eight capacitors.
Also note that the power supply delivery plane has the following capacitance (where A is the area and d is
the separation height all in inches):
Let us say Cpower plane = 300pF. The overall circuit model, then, will resemble Figure 4.
MOTOROLA
BM6?
MPC8260 PowerQUICC II Family Power Distribution Trends: A Survey
C
=
------------------------------------------------------------------------ -
2 π m Xmax Fbypass
Freescale Semiconductor, Inc.
×
For More Information On This Product,
×
×
1
Go to: www.freescale.com
Cpowersupply
m
×
=
----------------------- -
0.2643nH
Figure 4.
2nH
=
-------------------------------------------------------
2π 8
=
≈
0.225εrA
---------------------- -
×
7.4 8
d
×
≈
0.083
1
×
2.6e6
=
0.922nF
Previous Work Study
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