LMK04828: output issue

Ryker She

Expert 4440 points

Part Number: LMK04828
Other Parts Discussed in Thread: DAC39J84

Tool/software:

Hi team,

Customer met below issue when they evaluated LMK04828, please help to analyze:

The power is about -14dB when LMK04828 output 1.25GHz to DAC39J84. But after double interpolating the DAC39J84, the power is only -50dB when LMK04828 output 2.5GHz to DAC39J84 and DAC can't work normally, and the clock IC output LVPECL.

Best Regards,

Ryker

10 months ago

0 vicente flores prado 10 months ago

TI__Mastermind 29362 points

Hi Ryker,

Can you share a block diagram and a .tcs configuration file for LMK04828?

Best Regards,

Vicente

0 Ryker She 10 months ago in reply to vicente flores prado

TI__Expert 4440 points

Hi Vicente,

Please refer to the .tcs as below:

5707.LMK04828.TCS

And the schematic as below:

Best Regards,

Ryker

0 Ryker She 9 months ago in reply to Ryker She

TI__Expert 4440 points

Hi Expert,

Please help to reply be today. Thanks.

BR,

Ryker

0 vicente flores prado 9 months ago in reply to Ryker She

TI__Mastermind 29362 points

Hello Ryker,
I don't see anything particularly wrong with your confirmation?
i see you have lock detect routed out to LEDs - can you achieve lock with the configuration?

Ryker She said:
The power is about -14dB when LMK04828 output 1.25GHz

I am a bit confused about this statement as I see the following outputs configured..

Best Regards,

Vicente

0 Ryker She 9 months ago in reply to vicente flores prado

TI__Expert 4440 points

Hi Vicente,

For the 2.5GHz output configuration:

R&D just set the frequency divider of 2.5GHz as 1/2 frequency divider of 1.25GHz.

How to understand 'achieve lock with the configuration'?

Best Regards,

Ryker

0 vicente flores prado 9 months ago in reply to Ryker She

TI__Mastermind 29362 points

Hi Ryker,
If customer has LD routed out to an LED which appears to be the same in schematic - if the PLLs are locked the LEDs should be lit.

Best regards,

Vicente

0 Ryker She 9 months ago in reply to vicente flores prado

TI__Expert 4440 points

Hi Vicente,

Customer makes sure that the PLLs are locked and LEDs also lit. Do you have some suggestions to solve this issue? Thanks.

Best Regards,

Ryker

0 vicente flores prado 9 months ago in reply to Ryker She

TI__Mastermind 29362 points

Hello Ryker,

is customer using their EVM or custom board? The output power doesn’t seem correct - that’s why I believed device might have been unlocked.

Sorry for delay I am out of office on vacation - I will have another AE assist you from here on.

best regards,

vicente

0 Ryker She 9 months ago in reply to vicente flores prado

TI__Expert 4440 points

Hi Vincente,

Customer used their own board and they confirmed device has been locked. Do you need some proof? And please also give us some suggestion to analyze. Thanks.

Best Regards,

Ryker

0 Kadeem Samuel 9 months ago in reply to Ryker She

TI__Mastermind 22610 points

Hello,

The team is out for the US holiday - please expect a response by 1/2/26.

Thanks,

Kadeem

0 vicente flores prado 9 months ago in reply to Kadeem Samuel

TI__Mastermind 29362 points

Hi Ryker,
I believe customer is checking this output if i'm not mistaken?

Overall there's is only one thing I noticed - when customer is using divide by 1 for direct VCO output (2.5G) can customer change to DCLKOUTx_MUX to have DCC (duty cycle correction) enabled?
This is typically required when utilizing odd output values.

Best regards,

Vicente

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LMK04828: output issue