AD9546SLASHPCBZ datasheet(66/205 Pages) AD

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AD9546

Data Sheet

Rev. 0 | Page 66 of 205

UTS CHANNEL TIME STAMP SOURCE

Each UTS channel has independent access to the various time

stamp sources within the AD9546. The user assigns a specific

time stamp source via Bits[4:0] of Register 0x0E01, or more

generally, for UTS x (where x = 0 to 8, integer), add x × 0x0005

to the register addresses given for UTS 0.

The decimal value of the five source bits relates to the time

stamp source per Table 42.

Table 42. Time Stamp Source Assignment Codes

Source Bit Field Value (Decimal)

Time Stamp Source

REFA (default)

REFAA

REFB

REFBB

DPLL0 feedback

DPLL1 feedback

Auxiliary REF0

Auxiliary REF1

Auxiliary NCO 0

Auxiliary NCO 1

Reserved

Auxiliary REF2

Auxiliary REF3

IUTS 0

IUTS 1

15 to 31

Reserved

The recommendation is to use the same time stamp source

while a UTS channel remains enabled. However, the user can

enable a UTS channel and assign a time stamp source

simultaneously with no negative implications.

UTS CHANNEL TIME OFFSET

The user has the option of having a UTS channel apply a time

offset to time stamps processed by the channel, with the time

offset being relative to the common time scale in units of

2−48 sec. Time offset is via Bits[23:0] (signed) in Register 0x0E02

to Register 0x0E04 for UTS 0, or more generally, for UTS x

(where x = 0 to 8, integer), add x × 0x0005 to the register

addresses given for UTS 0.

For example, to program a time offset of −25 ns (−25 × 10−9 sec),

first convert to the appropriate units and round the result to the

nearest integer as follows:

−25 × 10−9 × 248 = −7,036,874

This value in 24-bit hexadecimal format is: 0x 94 A036.

UTS CHANNEL TAG

The user can have a UTS channel selectively process only

tagged time stamps (see the Tagged Time Stamps section) from

the specified time stamp source (rather than every time stamp

from that source). Tagged time stamp selection is via Bit 5 in

x = 0 to 8, integer), add x × 0x0005 to the register addresses

given for UTS 0. Logic 1 selects tagged time stamp processing,

whereas Logic 0 (default) causes the UTS channel to process all

time stamps from the specified time stamp source.

UTS CHANNEL TIME FORMAT

The user can select the output time format of each UTS channel

independently via a format bit. Format selection is via Bit 1 in

x = 0 to 8, integer), add x × 0x0005 to the register address given

for UTS 0. Logic 0 (default) selects fractional seconds format,

and Logic 1 selects PTP format.

See the Synchronization Time subsection of the Common

Clock Synchronizer (CCS) section for details on fractional

seconds format and PTP format.

UTS CHANNEL STATUS FLAG ASSIGNMENT

Whenever a UTS channel converts an input time stamp to a

time code and delivers it to the FIFO, the UTS channel also

includes a 3-bit status value as part of the time code.

The 3-bit status value is an encoding of the following five

available status conditions:

•

Invalid (common clock reference invalid)

•

Fault (common clock reference fault)

•

Unlocked (common clock DPLL unlocked)

•

Tag (state of the tag bit associated with the UTS channel

that processed the time stamp)

•

Format (state of the format bit associated with the UTS

channel that processed the time stamp)

The user can choose one of seven predefined 3-bit encoded

status patterns (see Table 43). The selection is via the 3-bit flags

bit field in Bits[4:2] of Register 0x0E00 for UTS 0, or more

generally, for UTS x (where x = 0 to 8, integer), add x × 0x0005

to the register address given for UTS 0.

Each bit of the flags bit field encodes to a unique status bit (or

logical combination of status bits). That is, each bit of the 3-bit

flags bit field encodes to a specific status bit pattern based on

the value of the 3-bit flags bit field.

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