Motorola TMS320C6711D - Manual (Page 66)

TMS320C6711D
FLOATINGĆPOINT DIGITAL SIGNAL PROCESSOR
SPRS292A − OCTOBER 2005 − REVISED NOVEMBER 2005
66 POST OFFICE BOX 1443
•
HOUSTON, TEXAS 77251−1443
PARAMETER MEASUREMENT INFORMATION (CONTINUED)
timing parameters and board routing analysis
The timing parameter values specified in this data sheet do not include delays by board routings. As a good
board design practice, such delays must always be taken into account. Timing values may be adjusted by
increasing/decreasing such delays. TI recommends utilizing the available I/O buffer information specification
(IBIS) models to analyze the timing characteristics correctly. To properly use IBIS models to attain accurate
timing analysis for a given system, see the Using IBIS Models for Timing Analysis application report (literature
number SPRA839). If needed, external logic hardware such as buffers may be used to compensate any timing
differences.
For inputs, timing is most impacted by the round-trip propagation delay from the DSP to the external device and
from the external device to the DSP. This round-trip delay tends to negatively impact the input setup time margin,
but also tends to improve the input hold time margins (see Table 35 and Figure 21).
Figure 21 represents a general transfer between the DSP and an external device. The figure also represents
board route delays and how they are perceived by the DSP and the external device.