LMK04828: confirm that LMK04828 can generate 10MHz clock.

Hi Noel

I am Brooke, RF engineer from Philips. I raised up this question for Bill. Thanks for your explaination.

The VCO1 output here is specified 3000MHz, so I use SDCLK divider to get 300M and 150M clocks for my ADC/DAC usage.

From your answer, can I confirm that this 10MHz clock can be used for the device clock? I want to use this 10MHz for driving other devices on the PCB board.

How can I set the SYSREF/SYNC part of the chip to use 10MHz as the device clock? Which items should I take care when I use this 10MHz for device clock in hardware?

Does this 10MHz frequency get the samilar phase noise/jitter performance like 300M and 150M above?

Thanks for your reply。

Best Regards,

Brooke

Hi Noel

Thanks for your quickly rely. 

On my hand, there is one ADC34J25 demo board with LMK04828. Here I want to use external reference clock(coming from keysight N9010A 10MHz out) for locking both PLL1 and PLL2. Here I want to use dual-loop mode for the LMK04828. This demo board has one 100MHz VCXO for the PLL1.

Please see my configuration for the PLL1, PLL2, SYSREF/SYNC and CLK output below:

From the demo board, I can see the LED D4 is green while LED D1, D2 and D3 are not open.

From my viewpoint, I think the LMK04828 is not locked now.

Could you please help me to check the configuration above about the LMK04828? Thanks for your time.

Please see the VCXO part as below for PLL1

Hi Pal

Thanks for your reply.

I think I find the root cause.

In my configuration, I only changed the register 0x15B from 0x14 to 0xD4, and hen the STATUS_LD1 (D3) is on with green color.

Could you please let me confirm this is the status for the LMK being locked now?

Please see this register 0x15B. What's the reason from the value from 0x14 to 0xD4, the LMK can locked? It's better you can give me more explaination.

With many thanks.

Hi Pal

Thanks for the detailed explanation.

Here I got one EVM- TSW14J56, which I used for connecting the other EVM-ADC34J25. When I connected these two EVMs with FMC connectors, I open the GUI for capture the data, but here I got one isse as below on the HSDC Pro.

Could you please let me know what's the issue behind? Should I need to use other connectors between these two EVMs?

With many thanks.

Hi Brooke,

I'll re-assign this thread to data converter team, who can support you on HSDC Pro tool issue/error.

Thanks!

Regards,

Ajeet Pal

Thanks Pal. I have fix the issue. Because of my current limitation on the power supply.

Thanks again.