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LMX2582: Lock time & RF output

shivakant dwivedi
Intellectual 960 points
Part Number: LMX2582
Other Parts Discussed in Thread: LMX2594

Hi,

I am using LMX2582 in one of my designs at the initial level.

I want to know whether for Both output ie channel A & B has the same output power level for the same frequency & settings?

Whether both outputs are synchronized?

I want to achieve fast lock time 20uS so what is the drawback to achieving this?

Can LMX2594 is able to provide fast locking time up to 20uS?

If yes then what are settings & limitations to achieve this?

  • 0
    TI__Guru** 106770 points

    Hi Shivakant,

    both output are synchronized because they came from the same source. With the same output power setting, their output power may not be exactly the same but is very close to each other. This is because the buffers are identical in design. 

    In order to achieve 20µs fast lock time, you need to provide a 200MHz reference clock. Furthermore, you need to program couples of additional registers that are mentioned in the data to let the VCO calibration runs faster. In other words, you have more registers to write and may need a faster SPI rate. 

    in LMX2594, you can use the full assist mode to achieve fast lock. Before you can use full assist mode, you need to do auto-calibration first to find out the three key VCO parameters (VCO_SEL, VCO_CAPCTRL and VCO_DACISET). We are going to release an application note regarding the calibration and assist mode operation in this month. Please check back.