Designing for High Frequency Operation
15-16
ADSP-2126x SHARC Processor Hardware Reference
Jitter should be kept to an absolute minimum. High frequency jitter on
the clock to the processor may result in abbreviated internal cycles.
Never share a clock buffer IC with a signal of a different clock fre-
quency. This introduces excessive jitter.
As shown in
, keep the portions of the system that operate at
different frequencies as physically separate as possible. The clock supplied
to the processor must have a rise time of 3 ns or less and must meet or
exceed a high and low voltage of 2 V and 0.4 V, respectively.
Other Recommendations and Suggestions
• Use more than one ground plane on the PCB to reduce crosstalk.
Be sure to use lots of vias between the ground planes. One V
DD
plane for each supply is sufficient. These planes should be in the
center of the PCB.
• To reduce crosstalk, keep critical signals such as clocks, strobes,
and bus requests on a signal layer next to a ground plane and away
from or layout perpendicular to other non-critical signals.
• If possible, position the processors on both sides of the board to
reduce area and distances.
• To allow better control of impedance and delay, and to reduce
crosstalk, design for lower transmission line impedances.
Figure 15-5. Reducing Clock Jitter and Ring
FREQUENCY 1
CLOCK
a
ADSP-2126x
S
Содержание ADSP-21261 SHARC
Страница 30: ...Contents xxx ADSP 2126x SHARC Processor Hardware Reference ...
Страница 40: ...Register Diagram Conventions xl ADSP 2126x SHARC Processor Hardware Reference ...
Страница 58: ...Differences From Previous SHARCs 1 18 ADSP 2126x SHARC Processor Hardware Reference ...
Страница 112: ...Secondary Processing Element PEy 2 54 ADSP 2126x SHARC Processor Hardware Reference ...
Страница 178: ...Summary 3 66 ADSP 2126x SHARC Processor Hardware Reference ...
Страница 204: ...DAG Instruction Summary 4 26 ADSP 2126x SHARC Processor Hardware Reference ...
Страница 322: ...Setting Up DMA 7 32 ADSP 2126x SHARC Processor Hardware Reference ...
Страница 436: ...SPORT Programming Examples 9 86 ADSP 2126x SHARC Processor Hardware Reference ...
Страница 521: ...ADSP 2126x SHARC Processor Hardware Reference 11 31 Input Data Port rts IDP_ISR end ...
Страница 522: ...Input Data Port Programming Example 11 32 ADSP 2126x SHARC Processor Hardware Reference ...
Страница 590: ...Timer Programming Examples 14 20 ADSP 2126x SHARC Processor Hardware Reference ...
Страница 796: ...I O Processor Registers A 174 ADSP 2126x SHARC Processor Hardware Reference ...
Страница 800: ...B 4 ADSP 2126x SHARC Processor Core Manual ...
Страница 846: ...Index I 36 ADSP 2126x SHARC Processor Hardware Reference ...