LMX2594: Fail to trigger the manual ramp

Adrian Liu

Intellectual 1200 points

Part Number: LMX2594

Hi Team,

Customer used the attached config to evaluate the lmx2594.

But the VCO freq did not change after sending the RampClk rising edge.

Could you help check the attached .tcs file, and help provide a usable configuration version？

Summarized customer's use case here:

Init VCO frequency = 8000M

Init RF out=1000M

VCO change range: 400M to 8500M

Ramp step: ≥3kHz，≤10MHz

manual mode ramp

400-8.5G.tcs

Adrian

7 months ago

+1 vicente flores prado 7 months ago

TI__Mastermind 18921 points

Hello Adrian,
It appears that customer divider value is incorrect after having loaded the .tcs file you attached.

Please note customer will need to recalibrate VCO due to how wide this ramp will be.

Ask customer to try the following config file - they will just need to press the 'Clock Ramp' button in the GUI.

8875.400-8.5G.tcs

Regards

Vicente

0 Qiang Ren 6 months ago in reply to vicente flores prado

TI__Intellectual 1475 points

Vincente,

I'm in the same project with Adrian. We used your tcs registers, but still fail to ramp the frequency Sequence is as below:

Set ramp_en bit=0, didn't give ramp_clk signal to device, read 0x6e=0x428, MUX_OUT reports PLL lock. Output signal didn't ramp.
Set ramp_en bit=1, give ramp_clk signal to device, 0x6e=0x538, MUX_OUT reports PLL unlock. Output signal didn't ramp.

Since the only difference between your bench and the customer bench is the ramp signal, is there a register to read the ramp_clk status? Or is there a reg to override the ramp_clk function?

Thanks.

Qiang

0 vicente flores prado 6 months ago in reply to Qiang Ren

TI__Mastermind 18921 points

Hi Qiang,
I went to the bench and managed to create a +/- 3kHz ramp with the following configuration.

Please note at some point, you will need to manually take care of the divider values for smaller output frequencies.

400-8.5G (1).tcs

Regards,

Vicente

0 Qiang Ren 6 months ago in reply to vicente flores prado

TI__Intellectual 1475 points

Vicente,

We are a bit confused, at which small frequency, should we marginally take care of divider values?
thanks.

Regards,

Qiang

0 vicente flores prado 6 months ago in reply to Qiang Ren

TI__Mastermind 18921 points

Hi Qiang,

any output frequency lower than 7500 MHz (VCO min) will require either manually changing output divider.

regards,

vicente

0 Qiang Ren 6 months ago in reply to vicente flores prado

TI__Intellectual 1475 points

Vicente,

But how do we do the ramping by the ramp_clk pin trigger, when output less than 7500M? Do you mean that when we the output ramp from 400M, VCO is 8000M, so we change the output divider to 20 by registers?

Regards,

Vicente

0 vicente flores prado 6 months ago in reply to Qiang Ren

TI__Mastermind 18921 points

That is correct

regards,

vicente

0 Qiang Ren 6 months ago in reply to vicente flores prado

TI__Intellectual 1475 points

Vicente,

So in summary, when we want to ramp the frequency lower than 7500MHz, we can't use the ramp_clk pin to control the ramp. We can only ramp the frequency by changing the output divider one step by one step?

Regards,

Qiang

0 vicente flores prado 6 months ago in reply to Qiang Ren

TI__Mastermind 18921 points

Correct

you would need to set the VCO frequency you need for that specific RFout and then use the output integer divider to divide down VCO frequency

regards,

vicente

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LMX2594: Fail to trigger the manual ramp