LMK00338EVM: No output after startup

HAL

Part Number: LMK00338EVM

Hi,

We're using the LMK00338EVM with a differential input. We are able to see a clean output when using the internally generated clk, but we are not able to see an output after startup when using our input signal.

We are using ClkIn0+/- for the input and ClkoutA0+/- for the output. We removed R24 and populated R30 and R23 with 50Ohm resistors.

Here is a zoomed out view:

Zoomed in:

Here is our input clk:

over 3 years ago

0 Aaron Black over 3 years ago

TI__Expert 5040 points

Hello Heather,

In the changes done on the board I can see that you've changed the input type from LVDS to HCSL. These are both differential input types, could you advise why the change was necessary?

Previously it was also mentioned that you've had a working input using the "internally generated clock", I think you mean to say the onboard crystal of 25 MHz, is that correct?

The input signal you've provided also only shows 1 end of a differential signal, please provide an image of the differential signal as these signals do not seem to be in phase as we can see from the output signal.

If you have changed from the Input selection from OSCin to CLKin please note that the correct bits needed to be programmed as well. Please find Table 2: Input Selection to confirm this is programmed correctly.

0 Aaron Black over 3 years ago in reply to Aaron Black

TI__Expert 5040 points

Hello Heather,

Please see previous response for some general guidance and prior questions about setup.

If additional information is required please feel free to respond or start another question on E2E.

Clock & timing

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LMK00338EVM: No output after startup