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DAC38RF82EVM: On-Board VCXO Clock Mode (CMODE4)

Dan Sellers
Prodigy 20 points

Part Number: DAC38RF82EVM
Other Parts Discussed in Thread: DAC38RF82

Hello, 

I am trying to get this eval kit up and running but am not getting to far. So far software recognizes the devices but I am unsuccessful in configuring this into CMODE4 listed in the user guide. The user guide doesn't have an example using this mode, however I want to evaluate the device with the on board circuitry without using any external sources. 

I have the boards connected to a 5V supply with 5A current limit (should be more than enough).

 

On the EVM jumpers I have the following set-up:

 

JP1 = shunt on 2-3; take DAC out of sleep mode

JP2 = shunt on 1-2; enable DAC output

JP3 = closed; enable power to 122.88MHz VCXO

JP8 = open; enable VDDIG1 supply

JP9 = open; enable VEE18N supply

JP10 = open; enable on-chip pll clock mode

 

Those descriptions are per page 3 from user guide.

 

I think the GUI is where I am running into some troubles with the setup. Is there a quick test setup to output a RF signal I can use to make sure my hardware setup is correct?

  • 0
    TI__Expert 4880 points

    Hey Dan,

    Instructions for how to operate the DAC38RF82 in CMODE4 are actually located on the main page of the DAC GUI. Look to the second paragraph in the right panel. 

    Yusuf

  • 0 in reply to Yusuf%20Agoro
    Prodigy 20 points

    Hi Yusuf, 

    I have seen/read the instructions in the GUI, however there was still some issues with getting my eval board to operate with the 122.88MHz VCXO. I think I was more looking for an example setup/procedure to go about in setting the device to output a tone in VCXO mode if something like that exists. 

    As a side note, I have been able to get the device to work in CMODE3, with an external reference clock. Since the two modes are very similar I feel there may be something small I may be missing like desoldering/resoldering a capacitor. Not sure if this is true I have yet to look at the eval board schematic if that is available. 

    I did double check my jumper connections too.  

    thanks, 

    Dan sellers

  • 0 in reply to Dan Sellers
    TI__Guru* 91947 points

    8741.6144MSPS_8x_10M_ref_LMF_841.cfgDAC38RF82_6144M_PLL_3072M.pptxDan,

    Give this start up sequence a try. You will need the attached config file as well. This will allow you to operate the DAC with the on-board 122.88MHz VCXO. The 10MHz input is optionally. The setup will work with or without it. 

    Regards,

    Jim