LMX2594: Fcal_en status after lock high or low?

It's int mode

Hi Anye,

As long you follow the suggested programming sequence, you should not have problem in switching the VCO frequency.

If you are not using any VCO assist mode, then FCAL_EN should be =1 all the time.

The following bits will affect the VCO calibration process, ensure you have them set properly.

Thank you I will verify our spi

Meanwhile just to emphasize we use sync and also sometimes force mode. 

Does your answer stays thrle same? 

Are there situations where you may work with Fcal_en=0

Is yes what are they?

Did you had such situations as in my video

Is this familiar phenomena? 

Hi Arye,

In SYNC mode, there is an additional divider called IncludedDivide, which will affect the N-divider value, make sure you have the correct N-divider set properly in SYNC mode. Please check the datasheet for the details. A quicker way to determine the IncludedDivide and N-divider value is use TICS Pro.

If you use full assist with FCAL_EN = 0, there will be no VCO Calibration. However, if you use SYNC and full assist together, FCAL_EN needs to be equal to 1 as SYNC requires FCAL_EN=1. 

Thank you,

I use TICs Pro with EVB.

I think that the includedDivide is given there automaticly according to my settngs on the GUI, it also seems that the Fcal_EN give the above issue only on my board while on the EVB with same settings it don't make any issue.

is it possible to do the sync and than disable the Fcal_en, or they always need to be on together? if they always need to be on together and i have this issue it might be that i'm not operating it in the right way and that i will need to verify the suquence (on monday) according to your first reposne.

but if its ok that the Fcal_en will be on only during the sync for one moment and than turn it off, it my ease my solution if the seuquce is ok and the problem will continue ... because of Fcal_EN.

if it continue may i send you our spi hex commands for review?

hope you also see in the video that at the last seond after Fcal_en=0 it becomes stable, it hard to see because the video stops but it stays stable as it seen in the last frame.

Hi Arye,

After SYNC, I believe we can make FCAL_EN = 0. 

If you are doing the same thing to EVM and your board but got no issue on the EVM, then try to slow down your programming speed on your board. FYI, GUI speed is 125kHz.