ꢀ ꢁꢂ ꢃ ꢄ ꢅ ꢆꢇ ꢈ ꢉꢈ ꢀꢊ ꢀ ꢁꢂ ꢃ ꢄ ꢅ ꢆꢇ ꢈ ꢉꢋ ꢀꢊ ꢀ ꢁꢂ ꢃ ꢄꢅ ꢆꢇ ꢈꢉ ꢇꢀ
ꢖ
ꢌ
ꢍ
ꢎ
ꢏ
ꢐ
ꢑ
ꢒ
ꢓ
ꢍ
ꢔ
ꢀ
ꢐ
ꢍ
ꢕ
ꢍ
ꢀꢖ
ꢗ
ꢂ
ꢍ
ꢕ
ꢔ
ꢗ
ꢒ
ꢘ
ꢓ
ꢆꢏ
ꢂ
ꢂꢓ
ꢘ
ꢂ
SPRS226H − NOVEMBER 2003 − REVISED AUGUST 2005
I/O Supply
DV
CV
DD
Schottky
Diode
C6000
DSP
Core Supply
DD
V
SS
GND
Figure 11. Schottky Diode Diagram
Core and I/O supply voltage regulators should be located close to the DSP (or DSP array) to minimize
inductance and resistance in the power delivery path. Additionally, when designing for high-performance
applications utilizing the C6000 platform of DSPs, the PC board should include separate power planes for
core, I/O, and ground, all bypassed with high-quality low-ESL/ESR capacitors.
power-supply decoupling
In order to properly decouple the supply planes from system noise, place as many capacitors (caps) as possible
close to the DSP. Assuming 0603 caps, the user should be able to fit a total of 60 caps, 30 for the core supply
and 30 for the I/O supply. These caps need to be close to the DSP power pins, no more than 1.25 cm maximum
distance to be effective. Physically smaller caps, such as 0402, are better because of their lower parasitic
inductance. Proper capacitance values are also important. Small bypass caps (near 560 pF) should be closest
to the power pins. Medium bypass caps (220 nF or as large as can be obtained in a small package) should be
next closest. TI recommends no less than 8 small and 8 medium caps per supply (32 total) be placed
immediately next to the BGA vias, using the “interior” BGA space and at least the corners of the “exterior”.
Eight larger caps (4 for each supply) can be placed further away for bulk decoupling. Large bulk caps (on the
order of 100 µF) should be furthest away (but still as close as possible). No less than 4 large caps per supply
(8 total) should be placed outside of the BGA.
Any cap selection needs to be evaluated from a yield/manufacturing point-of-view. As with the selection of any
component, verification of capacitor availability over the product’s production lifetime should be considered.
73
POST OFFICE BOX 1443 • HOUSTON, TEXAS 77251−1443
TI [ TEXAS INSTRUMENTS ]
