AD9545 datasheet(104/157 Pages) AD

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AD9545

Data Sheet

Rev. A | Page 104 of 157

DPLLx FORCE

FREERUN = 1?

YES

DPLLx FORCE

HOLDOVER = 1?

YES

DPLLx USES

DPLLx FREERUN

TUNING WORD

HOLDOVER

DPLL MODE

SELECTION

DPLLx

TRANSLATION

PROFILE SELECT

MODE = 0?

YES

PRIORITY

SELECTION?

YES

AUTOMATIC,

PRIORITY-BASED

TRANSLATION

PROFILE SELECTION

SELECT TRANSLATION

PROFILE x.y PER DPLLx

ASSIGN TRANSLATION PROFILE

YES

MANUAL ONLY

TRANSLATION

PROFILE SELECTION1

TRANSLATION

PROFILE

x.y VALID?

YES

DPLLx USES

TRANSLATION

PROFILE x.y

YES

MANUAL TRANSLATION

PROFILE SELECTION

WITH FALLBACK TO

PRIORITY-BASED

TRANSLATION PROFILE

SELECTION

MANUAL

TRANSLATION

PROFILE SELECTION

WITH FALLBACK TO

HOLDOVER

DPLLx USES

PRIORITY SELECTED

TRANSLATION PROFILE

DPLLx

TRANSLATION

PROFILE SELECT

MODE = 3?

DPLLx

TRANSLATION

PROFILE SELECT

MODE = 2?

x = CHANNEL, y = PROFILE

1FOR DEBUG ONLY. THE DPLL USES TRANSLATION PROFILE y WITHOUT VALIDATING THE

SOURCE. THEREFORE, THE DPLL IS NOT GUARANTEED TO FUNCTION NORMALLY.

CONTACT ANALOG DEVICES FOR FOR DETAILS.

NOTES

1. ITALICS INDICATE A REGISTER MAP BITFIELD.

DPLLx

TRANSLATION

PROFILE SELECT

MODE = 1?

Figure 83. DPLL Mode Selection Flowchart

FORCED FREERUN MODE

Although the automatic reference switching capability of the

AD9545 can cause the DPLL to switch to freerun mode, the

user can force freerun mode. In freerun mode, the DPLL

operates open loop and produces a static output frequency as

dictated by the DPLLx freerun tuning word bit field (where x is

0 or 1). Refer to the Freerun Tuning Word section for details.

FORCED HOLDOVER MODE

Although the automatic reference switching capability of the

AD9545 can cause the DPLL to switch to holdover mode, the

user can force holdover mode by writing Logic 1 to the DPLLx

force holdover bit (where x is 0 or 1) in Bit D1 of Register

0x2105 and Register 0x2205. In holdover mode, like freerun

mode, the DPLL operates open loop and produces a static

output frequency. However, the DPLL uses one of three static

tuning words dictated by the tuning word history processor (see

the Tuning Word History section). A summary of the holdover

tuning word selection appears in Figure 84.

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