ADS42JB49EVM: ADS42JB49EVM

Vladimir,

You have two options:

1. Connect an external clock to the ADC and use the 10MHz reference from the back of this source (assuming it is a signal generator) and connect the 10MHz source to J21 of the EVM. This will be used to synchronize the LMK04828 output clocks with the ADC clock source, which is required.

2. Use a splitter from your clock source and send one output to the ADC and the other to J21 of the EVM. In this mode, you will be using the LMK in clock buffer mode.

In both cases, you will need to do the following to the board to get the ADC configured for external clock mode:

1. Move C164 to R61.

2. Move C165 to R62.

After you let me know what option you plan on using, I will provide the LMK configuration file. What application is this for?

Regards,

Jim

Hello Jim,

Thanks for your reply!

The application is laboratory 8-channel signal conditioning systems. 

Thanks and Best Regards,

Vladimir.

Hello, Jim,

That project is mine, it might be fruitful. Waiting for LMK configuration file. Thanks in advance!

Best regards,

Dmitry

Dmitry,

You still need to answer the following; which mode shown below would you like to use:

1. Connect an external clock to the ADC and use the 10MHz reference from the back of this source (assuming it is a signal generator) and connect the 10MHz source to J21 of the EVM. This will be used to synchronize the LMK04828 output clocks with the ADC clock source, which is required.

2. Use a splitter from your clock source and send one output to the ADC and the other to J21 of the EVM. In this mode, you will be using the LMK in clock buffer mode.

Regards,

Jim

Hello Jim,

the mode 2 is interested.

Best Regards,

Vladimir.

Vladimir,

For the second option, after moving the capacitors mentioned before, you will need to provide two synchronized clock sources, one connected to J21 and the other to J19 of the EVM. After powering up the EVM, press the ADC_RESET switch, then load the attached configuration file. You are now setup for external clock mode.

Regards,

Jim

ADS42JB69_EVM_LMF421_ext_clk.cfg

Hello Jim,

Thanks a lot!

Last question. We can't find the J21 on the board. There is it located?

Regards,

Vladimir.

Vladimir,

If you have a Rev D board, J21 is just below oscillator Y2. If you have a Rev C board, this SMA does not exist. You would need to use J14 and move the 0 Ohm resistor on SJP3 to pins 1-2. This solder jumper is located just to the left of oscillator Y1.

Regards,

Jim

Hello Jim,

the story isn't ending yet..

Looks like we have a board Rev.C. Rev.C and D have different schematics. Concerning the  next statement: 

*****

1. Move C164 to R61.

2. Move C165 to R62.

*****

there are no such parts on our board. Could you please check?

Thanks and Best Regards,

Vladimir.

Vladimir,

The Rev C board did not provide the proper clock connection to the LMK to allow the ADC to run with external clock mode. This was one of the main reasons why we released the Rev D board. The only option you have with a Rev C board is to get a an oscillator that can be used with the internal LMK VCO to generate the frequency you plan on sending to the ADC. You then would have to synchronize the ADC external clock source with the LMK.

Regards,

Jim