OMAP4470_15 Datasheet, PDF (192/450 Pages) Texas Instruments – Multimedia Device Engineering Sample ES1.0

OMAP4470
Public Version
SWPS048A – AUGUST 2012 – REVISED JANUARY 2013
5 Timing Requirements and Switching Characteristics
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5.1 Timing Test Conditions
All timing requirements and switching characteristics are valid over the recommended operating conditions
unless otherwise specified.
5.2 Interface Clock Specifications
5.2.1 Interface Clock Terminology
The interface clock is used at the system level to sequence the data and/or to control transfers accordingly
with the interface protocol.
5.2.2 Interface Clock Frequency
The two interface clock characteristics are:
• The maximum clock frequency
• The maximum operating frequency
The interface clock frequency documented in this document is the maximum clock frequency, which
corresponds to the maximum frequency programmable on this output clock. This frequency defines the
maximum limit supported by the device IC and doesn’t take into account any system consideration (PCB,
Peripherals).
The system designer will have to consider these system considerations and the device IC timing
characteristics as well to define properly the maximum operating frequency that corresponds to the
maximum frequency supported to transfer the data on this interface.
5.2.3 Clock Jitter Specifications
Jitter is a phase noise, which may alter different characteristics of a clock signal. The jitter specified in this
document is the time difference between the typical cycle period and the actual cycle period affected by
noise sources on the clock. The cycle (or period) jitter terminology will be used to identify this type of jitter.
t_n–1
t_n
t_n+1
Figure 5-1. Cycle (or Period) Jitter
SWPS039-010
Jitter values are defined as follows:
• Ideal clock period = t_p
• Maximum Cycle/Period Jitter = Max (|t_i – t_p|), with i = n – 1, n, n + 1, …
• Minimum Cycle/Period Jitter = Min (|t_i – t_p|)
• Jitter Standard Deviation (or RMS Jitter) = Standard Deviation (|t_i – t_p|)
Unless otherswise specified, the jitter probability density can be approximated by a Gaussian function
and peak-to-peak jitter is defined over a ±7 sigma distribution of this function.
192 Timing Requirements and Switching Characteristics
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