• State TI Thinks Resolved
  • Locked Locked
  • Replies 4 replies
  • Answers 2 answers
  • Subscribers 21 subscribers
  • Views 155 views
  • Users 0 members are here
Support feedback
Options
Options
Similar topics

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

Original question:

LMX2820: Software patch that must be inserted when using Instant Cal.

LMX2820: Software Patch that must be inserted when using instant cal

bob miller
Prodigy 40 points
Part Number: LMX2820

Tool/software:

The patch to fix the Instant Cal VCO 3 to VCO 4 transitions requires 20 writes to register 0x6A.  Is it sufficient to write the 20 registers in sequence or must Register 0 be written in between each 0x6A write to latch the the data into the chip?

Another way of phasing this question:  Is 0x6A double buffered?

  • 0
    Prodigy 40 points

    I should of written "Is it sufficient to write the 20 values to Register 0x6A in sequence or must Register 0 be written in between each 0x6A write to latch the data into the chip?"

  • 0 in reply to bob miller
    TI__Guru* 95190 points

    Hi Bob,

    0x6A are not double buffered, they will be latched to the chip right after they are written to to chip.

    Attached here the procedure of setup Instcal, FYI.

    Initialization register setting
    1. Set DBLBUF_PLL_EN, DBLBUF_CHDIV_EN, DBLBUF_OUTBUF_EN, DBLBUF_OUTMUX_EN = 1
    2. Set DBLR_CAL_EN = 0; INSTCAL_SKIP_ACAL = 0
    3. If VCO doubler is required, set INSTCAL_DBLR_EN = 1, otherwise set this bit to 0
    4. Set INSTCAL_DLY = T x fosc (in MHz) / 2^CAL_CLK_DIV, where T = 2.5 x CBIASVCO / 0.47µF. CBIASVCO is the bypass capacitor at pin 3
    5. Configure other registers to lock to 5.65GHz without any calibration assist
    6. Set INSTCAL_PLL_NUM = 2^32 x (PLL_NUM / PLL_DEN)
    Programming
    7. Vcc power up LMX2820
    8. Program all the registers, LMX2820 should lock to 5.65GHz
    InstCal calibration
    9. Program INSTCAL_EN = 1
    9.5 run Index routine
    10. Program R0 (with FCAL = 1), calibration will begin
    11. Wait 100ms
    12. Program R0 (with FCAL = 0) to complete the calibration
    13. If LD pin did not turn HIGH, program RESET = 1 to reset LMX2820. After LMX2820 is reset, repeat Step 8 to 12
    Changing VCO frequency
    14. Program INSTCAL_PLL_NUM, PLL_N, PLL_NUM and PLL_DEN (if their value have change)
    15. Program R0 (with FCAL = 0) to change VCO frequency

    9.5 Index routine
    1. Program R106[10] = 1 (0X6A 0400)
    2. Program R107[5:0] = 0 (0x6B 0000)
    3. Program R108 = 0 (0x6C 0000)
    4. Program R109 = 0 (0x6D 0000)
    5. Program R106[9:0] = 514 (0x6A 0602)
    6. Program R106[11] = 1 (0x6A 0E02)
    7. Program R106[11] = 0 (0x6A 0602)
    8. Repeat step 5 to 7 for R106[9:0] = 515 to 519
    9. Program R106[10] = 0 (0x6A 0000)

  • 0 in reply to Noel Fung
    Prodigy 40 points

    Thx Noel,

    I want to make sure I get this right.  Line 5 of the index routine lists 514 (decimal assumed).  0x0602 is 1538 decimal though.  Am I missing something here?  Should I use the hex values you provided in the patch?

    Rgds,

    Bob

  • 0 in reply to bob miller
    TI__Guru* 95190 points

    Hi Bob,

    R106[15:0] = 0x602 = 0110 0000 0010

    R106[9:0] = 514d = 10 0000 0010

    they are matched.