LMX2594: How to check pll lock.
Part Number: LMX2594
When we tested the frequency hopping time of LMX2594 and LMX2572 phase-locked loop chips, the VCO calibration used Partial assist mode, with the output frequency hopping between 1.0g and 1.1g. The frequency hopping time of LMX2594 was 68uS, which could reach 35uS according to the manual.LMX2572 test we found that the actual FM time difference is quite large compared to the manual.
What do we need to improve? Thanks!
Could you provide your LMX2572 configuration? It will be great if you can provide it in TICS Pro format.
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In reply to Noel Fung:
In reply to user6062940:
The setting is for LMX2594 or LMX2572? I think you have issue with LMX2572 only, right?
The setting is LMX2594.
so you have problem with LMX2594 or LMX2572?
I think you have issue with LMX2572, right? if this is the case, would you please provide the LMX2572 setting?
We tested the LMX2594 Demo Board of TI,
Frequency from 1.8G to 2.5G time is consistent with the manual.The time from 2.5g to 1.8g is longer than the manual.
OK, I think you want to shorten the VCO frequency switching time. Then, what is your target switching time?
Partial assist: 35uS
35µs is a very aggressive number, I am afraid it is not always possible with partial assist. You may consider to use full assist, which will bypass calibration and therefore save some switching time. However, you also need to ensure that your loop bandwidth is wide enough to support less than 35µs switching time.
Please review the following appnote to get a sense of what kind of calibration assist can help you.
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