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[ LMX2582 ] Lock Time

Other Parts Discussed in Thread: LMX2582, LMX2592

[ LMX2582 ] Lock Time

Hi,

The  datasheet describes an example of Lock Time with somewhere around <100uS order.


However my customer has reported that the lock time on their system is longer than 10mS.
Can you help to make sure whether this is expected or something wrong on register settings?
I have ask customer to change ACAL_FAST and FCAL_FAST.

The register setting and tcs file are attached.

Thank you for your support in advance.
Please let me know, if you need further information.

Thanks,
Ken

[SETUP]
ADDRESS=888
CLOCK=8
DATA=4
LE=2
PART=LMX2582
ADDRESS_I2C=0x0

[PINS]
PINNAME00=CE
LOCATION00=7
PINVALUE00=True

[MODES]
NAME00=R64
VALUE00=4195247
NAME01=R62
VALUE01=4063232
NAME02=R61
VALUE02=3997697
NAME03=R59
VALUE03=3866624
NAME04=R48
VALUE04=3146748
NAME05=R47
VALUE05=3080384
NAME06=R46
VALUE06=3017379
NAME07=R45
VALUE07=2949220
NAME08=R44
VALUE08=2883584
NAME09=R43
VALUE09=2818048
NAME10=R42
VALUE10=2752512
NAME11=R41
VALUE11=2687376
NAME12=R40
VALUE12=2621440
NAME13=R39
VALUE13=2589188
NAME14=R38
VALUE14=2490490
NAME15=R37
VALUE15=2441216
NAME16=R36
VALUE16=2360337
NAME17=R35
VALUE17=2294299
NAME18=R34
VALUE18=2278394
NAME19=R33
VALUE19=2173450
NAME20=R32
VALUE20=2105610
NAME21=R31
VALUE21=2033153
NAME22=R30
VALUE22=1966132
NAME23=R29
VALUE23=1900676
NAME24=R28
VALUE24=1845540
NAME25=R25
VALUE25=1638400
NAME26=R24
VALUE26=1574153
NAME27=R23
VALUE27=1542210
NAME28=R22
VALUE28=1450752
NAME29=R20
VALUE29=1310820
NAME30=R19
VALUE30=1247589
NAME31=R14
VALUE31=921599
NAME32=R13
VALUE32=868352
NAME33=R12
VALUE33=815105
NAME34=R11
VALUE34=720920
NAME35=R10
VALUE35=659672
NAME36=R9
VALUE36=592642
NAME37=R8
VALUE37=528516
NAME38=R7
VALUE38=469170
NAME39=R4
VALUE39=268611
NAME40=R2
VALUE40=132352
NAME41=R1
VALUE41=67592
NAME42=R0
VALUE42=8732

[FLEX]
CalculatedCPG=24.21875
CalculatedKvco=34.2
CalculatedTotalDivide=2
Fosc_FREQ=20
FoutA_FREQ=2450
FoutB_FREQ=2450
Fpd_FREQ=40
Fvco_FREQ=4900
VCO_MULTIPLIED_FREQ=4900
btn_LoadRegisters=Load Registers
btn_SimplifyFraction=Simplify Fraction





  • Hi Ken,

    As you see in the example we used the 200MHz OSCin with CAL_CLK_DIV=0 which gives a calibration clock of 200MHz, this is a dominant factor in the amplitude calibration time. Basically if you have OSCin of 100MHz, your total calibration time is about two times as long. So with 20MHz, you are somewhere around 10 times as long as the example. One option you have is just turn off the amplitude calibration, by setting ACAL_EN=0, then you should see much faster calibration times by skipping this function. You can then set the amplitude manually by doing VCO_IDAC_OVR=1 and then setting VCO_IDAC (around 350 - 400 you should see the best VCO phase noise) to manually optimize the VCO amplitude.

    Regards,

    Brian Wang

  • Hi Brian,

    Thank you for sharing information, it should help my customer to reduce the lock time.
    However, some registers, you mentioned, not being opened on datasheet.
    (SNAS680A –DECEMBER 2015–REVISED DECEMBER 2015)

    I can see similar descriptions and more information on LMX2592 datasheet, though.

    Can you check or share the latest register details with me?

    Thanks,
    Ken
  • Ken,

    I see, please refer to the LMX2592 datasheet for those updated register information. Those exact same ones are being copied over into the LMX2582 datasheet, it is in progress right now.

    Regards,

    Brian

  • Hi Brian,

    "ACAL_EN" is not described in the latest LMX2592 datasheet.
    You can see some terms "ACAL_EN", but not listed in register mapping.

    Can you check?
    Thanks,
    Ken

  • Hi Ken,

    ACAL_EN is R0[4], it got missed out on the last update. We'll have that added into the datasheet register map and description in this upcoming revision. In the meantime the programming software (TICS Pro) has the register available to use already.

    Regards,

    Brian Wang

  • Thanks for checking, Brian!

    I will share this information with my customer and ask them to try to make sure whether Lock Time can be shortened.
    Also looking forward to having updated datasheet.

    Thanks,
    Ken