High-Frequency Design Considerations
25-6
ADSP-BF50x Blackfin Processor Hardware Reference
Adding termination to fix a problem on an existing board requires delays
for new artwork and new boards. A transmission line simulator is recom-
mended for critical signals. IBIS models are available from Analog Devices
Inc. that will assist signal simulation software. Some signals can be cor-
rected with a small zero or 22 ohm resistor located near the driver. The
resistor value can be adjusted after measuring the signal at all endpoints.
For details, see the reference sources in “Recommended Reading” on
page 17-13 for suggestions on transmission line termination.
Other recommendations and suggestions to promote signal integrity:
• Use more than one ground plane on the Printed Circuit Board
(PCB) to reduce crosstalk. Be sure to use lots of vias between the
ground planes.
• Keep critical signals such as clocks, strobes, and bus requests on a
signal layer next to a ground plane and away from or laid out per-
pendicular to other non-critical signals to reduce crosstalk.
• Experiment with the board and isolate crosstalk and noise issues
from reflection issues. This can be done by driving a signal wire
from a pulse generator and studying the reflections while other
components and signals are passive.
Decoupling Capacitors and Ground Planes
Ground planes must be used for the ground and power supplies. The
capacitors should be placed very close to the
VDDEXT
and
VDDINT
pins of the
package as shown in Figure 17-4. Use short and fat traces for this. The
ground end of the capacitors should be tied directly to the ground plane
inside the package footprint of the processor (underneath it, on the bot-
tom of the board), not outside the footprint. A surface-mount capacitor is
recommended because of its lower series inductance.
Содержание EZ-KIT Lite ADSP-BF506F
Страница 50: ...Contents l ADSP BF50x Blackfin Processor Hardware Reference ...
Страница 92: ...Development Tools 1 30 ADSP BF50x Blackfin Processor Hardware Reference ...
Страница 110: ...Interface Overview 3 12 ADSP BF50x Blackfin Processor Hardware Reference ...
Страница 132: ...Unique Information for the ADSP BF50x Processor 4 22 ADSP BF50x Blackfin Processor Hardware Reference ...
Страница 236: ...Internal Flash Memory Control Registers 6 92 ADSP BF50x Blackfin Processor Hardware Reference ...
Страница 342: ...Unique Information for the ADSP BF50x Processor 7 106 ADSP BF50x Blackfin Processor Hardware Reference ...
Страница 484: ...Unique Information for the ADSP BF50x Processor 10 60 ADSP BF50x Blackfin Processor Hardware Reference ...
Страница 493: ...ADSP BF50x Blackfin Processor Hardware Reference 11 9 Core Timer Unique Information for the ADSP BF50x Processor None ...
Страница 494: ...Unique Information for the ADSP BF50x Processor 11 10 ADSP BF50x Blackfin Processor Hardware Reference ...
Страница 506: ...Unique Information for the ADSP BF50x Processor 12 12 ADSP BF50x Blackfin Processor Hardware Reference ...
Страница 544: ...Unique Information for the ADSP BF50x Processor 13 38 ADSP BF50x Blackfin Processor Hardware Reference ...
Страница 650: ...Programming Examples 15 56 ADSP BF50x Blackfin Processor Hardware Reference ...
Страница 712: ...Unique Information for the ADSP BF50x Processor 16 62 ADSP BF50x Blackfin Processor Hardware Reference ...
Страница 804: ...Programming Examples 17 92 ADSP BF50x Blackfin Processor Hardware Reference ...
Страница 972: ...Unique Information for the ADSP BF50x Processor 20 38 ADSP BF50x Blackfin Processor Hardware Reference ...
Страница 1194: ...Programming Examples 24 90 ADSP BF50x Blackfin Processor Hardware Reference ...
Страница 1256: ...ACM Registers A 50 ADSP BF50x Blackfin Processor Hardware Reference ...
Страница 1264: ...Boundary Scan Architecture B 8 ADSP BF50x Blackfin Processor Hardware Reference ...