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LMK04803: LMK04803 Holdover question

HENRY JUNG
Expert 2030 points
Part Number: LMK04803


DEARS.

Customer used LMK04803 for develop Digital Repeater.

They are going to use LMK04803 of HOLDOVER function.

Please kindly advise HOLDOVER setting method in LMK04803EVM.

Attached file is customer Customer LMK04803 Register value and Schematic.

[Register Value]

[SETUP]
ADDRESS=888
CLOCK=4
DATA=2
LE=6
PART=LMK04803B
PINPOSITION00=1
PINPOSITION01=7
PINPOSITION02=5
PINPOSITION03=10
[MODES]
NAME00=R0 (INIT)
VALUE00=2148925696
NAME01=R0
VALUE01=1310784
NAME02=R1
VALUE02=1310785
NAME03=R2
VALUE03=1311234
NAME04=R3
VALUE04=1311235
NAME05=R4
VALUE05=1311748
NAME06=R5
VALUE06=1311749
NAME07=R6
VALUE07=17891334
NAME08=R7
VALUE08=286326791
NAME09=R8
VALUE09=483131400
NAME10=R9
VALUE10=1431655753
NAME11=R10
VALUE11=2440315146
NAME12=R11
VALUE12=66064395
NAME13=R12
VALUE13=453771372
NAME14=R13
VALUE14=587366509
NAME15=R14
VALUE15=3523215374
NAME16=R15
VALUE16=2147516431
NAME17=R16
VALUE17=3243574288
NAME18=R24
VALUE18=216
NAME19=R25
VALUE19=46777369
NAME20=R26
VALUE20=2947022874
NAME21=R27
VALUE21=469827611
NAME22=R28
VALUE22=2228252
NAME23=R29
VALUE23=25166109
NAME24=R30
VALUE24=33554718
NAME25=R31
VALUE25=2031647
OSCIN00=15.36
EXTRA_PLL_N_DIV_1_00=1
OSCIN01=122.88
EXTRA_PLL_N_DIV_1_01=1
PINS=0
[BURST]
COUNT=0

[Schematic]

  • 0
    TI__Mastermind 28590 points
    Hello,

    On Bits/Pins tab...
    Set HOLDOVER_MODE = Enable.

    Then see section 8.3.5 of datasheet discussing holdover mode, there are two modes, fixed CPout and tracked CPout. The simplest thing to do is to set Fixed CPout holdover mode by ensuring

    FORCE_HOLDOVER = 0
    DISABLE_DLD1_DET = 0 (PLL1 digital lock detect loss activates holdover).
    EN_MAN_DAC = 1 and MAN_DAC = 512 (Use fixed CPout holdover and set holdover Vcc to 1/2 Vcc).

    Holdover exit is controlled by: HOLDOVER_DLD_CNT and PLL1_WND_SIZE. Larger HOLDOVER_DLD_CNT and smaller PLL1_WND_SIZE, the more accurate reference must be to exit holdover. In general I recommend using PLL1_WND_SIZE = 40 ns.

    If EN_VTUNE_RAIL_DET is used, then use only with Fixed CPout mode. Set DAC_LOW_TRIP and DAC_HIGH_TRIP as desired by datasheet (register 0x14d/0x14e) setting 0 is closet to low or high rail respectively.

    73,
    Timothy