AD9545 datasheet(114/157 Pages) AD

114 / 157 page

AD9545

Data Sheet

Rev. A | Page 114 of 157

TAGGED USER TIME STAMPS

The user time stamp processor can operate on tagged time stamps

from the various time stamp sources shown in Figure 88. When the

selected time stamp source is generating tagged time stamps, the

user can program the user time stamp processor to only pay

attention to the tagged time stamps, while ignoring untagged time

stamps. To enable tagged user time stamp processing program the

appropriate Time Stamp Only Tags x bit (where x is 0 or 1) in

Bit D5 of Register 0x2A12 and Register 0x2A13 to Logic 1.

USER TIME STAMP SYSTEM CLOCK

COMPENSATION

The user time stamp processors, like the TDCs, can benefit

from the system clock compensation capability. Because the

user time stamp processors rely on the auxiliary NCOs as a time

base reference, the source of the user time stamp processor and

its assigned auxiliary NCO TDCs must use the same system

clock compensation via the following bit fields (where x is 0 or 1),:

compensate auxiliary NCO x via auxiliary DPLL, compensate

auxiliary NCO x via DPLLx, and compensate auxiliary NCO x

via coefficients (shown in Figure 104 of the System Clock

Compensation section as auxiliary NCOx compensation

destination bits). Otherwise, the results from the user time

stamp processor are in error, because the time stamp source and

auxiliary NCO are using dissimilar time bases.

AD9545 Datasheet(PDF) 114 Page - Analog Devices