AFE58JD32EVM: LMK clock issue

Sergey Kachura

Part Number: AFE58JD32EVM
Other Parts Discussed in Thread: TSW14J50EVM, , CDCM1802, LMK04821

Tool/software:

Hello,

I have AFE58JD32EVM and TSW14J50EVM. I can get data, but sample rate is always the same ~15MHz. Changing fsamp in AFE58JD32EVM GUI has no effects. According slou487.pdf I use Configuration 3 for ADC Clock Source.

I see 125MHz clock on TP44 and 125/4 = 31.25MHz on R47 (after CDCM1802RGTR). It looks like LMK 04821NKDR couldn't be controlled from GUI.

How can I fix it?

7 months ago

0 Sachin H K 6 months ago

TI__Expert 7725 points

Hi,

Changing fsamp wont change clock frequency . You need to configure in external clock mode .

0 Sergey Kachura 6 months ago in reply to Sachin H K

Prodigy 10 points

It is very strange evaluation board.
If I understand correctly I should apply 320MHz external source clock to get 80MHz(after CDCM1802) at ADC clock input to get 40MHz sample rate of all ADCs.

Is it possible to use LMK04821 for this purpose?

0 Sachin H K 6 months ago in reply to Sergey Kachura

TI__Expert 7725 points

Hi,

Device sampling clock is half of the ADC_CLK given to the AFE . To generate JESD reference clocks higher freq source is required as LMK on the board will divide and give the clocks accordingly .

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AFE58JD32EVM: LMK clock issue