AD9558 datasheet(41/104 Pages) AD

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Data Sheet

AD9558

Rev. A | Page 41 of 104

M3b DIVIDER/OUT5 PROGRAMMING IN FRAME

SYNCHRONIZATION MODE

In frame synchronization mode, the clock distribution signal path

for OUT5 is changed, as follows: the OUT5 signal goes from the RF

divider to the M0 divider, and then to the M3 and M3b dividers.

This means that in frame synchronization mode, the total divide

ratio between the RF divider and OUT5 is M0 × M3 × M3b.

The other important change is that the sync signal for the M3b

divider is no longer the standard clock distribution sync. It is

controlled by a signal derived from the input frame pulse.

OUPUT CLOCK

(OUT0)

FRAME CLOCK INPUT

(REFC/REFD)

ENABLE Fsync

(REGISTER 0x0640[0] = 1b)

FRAME SYNC ARM

(REGISTER OR SYNC PIN)

FRAME CLOCK

(OUT5)

ACTIVE SYNC

NOTES

1. AFTER THE FRAME SYNC IS ARMED, THE FRAME CLOCK OUTPUT IS SYNCHRONIZED TO THE FRAME CLOCK INPUT.

THE SKEW BETWEEN THE FRAME CLOCK INPUT AND FRAME CLOCK OUTPUT IS 15ns (NOMINAL) PLUS A DELAY OF 0.5 TO 1.5 OUTPUT CLOCK CYCLES.

Figure 41. Frame Synchronization in Level Sensitive Mode

ACTIVE SYNC

NOTES

1. AFTER THE FRAME SYNC IS ARMED, THE FRAME CLOCK OUTPUT IS SYNCHRONIZED TO THE FRAME CLOCK INPUT.

THE SKEW BETWEEN THE FRAME CLOCK INPUT AND FRAME CLOCK OUTPUT IS 15ns (NOMINAL) PLUS 0.5 TO 1.5 OUTPUT CLOCK CYCLES.

OUPUT CLOCK

(OUT0)

FRAME CLOCK INPUT

(REFC/REFD)

ENABLE Fsync

(REGISTER 0x0640[0] = 1b)

FRAME SYNC ARM

(REGISTER OR SYNC PIN)

FRAME CLOCK

(OUT5)

Figure 42. Frame Synchronization in One Shot Mode

FRAME SYNC PULSE INPUT (ON REFC OR REFD)

Fsync_arm (FROM EITHER THE SYNC PIN OR THE Arm Soft Fsync BIT IN REGISTER 0x0641[0])

DIVIDER 1

CLOCK

DISTRIBUTION

SYNC LOGIC

M3 DIVIDER

M0 DIVIDER

M3b DIVIDER

FRAME SYNC

PULSE GENERATOR

ENABLE Fsync

OUT0

OUT5

LOGIC 0

DELAY

OUTPUT

SYNC

PULSE

OUTPUT

SYNC

LEVEL

(RETIMED)

ENABLE Fsync

NOTES

1. THE ENABLE Fsync FUNCTION IN THE DIAGRAM IS CONTROLLED BY REGISTER 0x0640[0].

ENABLE

Fsync

FROM

APLL

Figure 43. Frame Synchronization Implementation

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