LMK04828: Clock review

Keerthana U R

Part Number: LMK04828
Other Parts Discussed in Thread: LMK04832

Hi Team,

We are designing a board with Multiple RFSOC FPGA in it. To synchronize the clock to the ADC and DAC to all the 4 FPGA's ,We have referred the below attached document,

Reference.zip

The clock architecture has a master LMK04832 and 4 slave LMK04832 for each FPGA section. The below image shows the clock architecture

The below excel sheet lists out the input and output frequencies of master and slave LMK04832

CLOCK.xlsx

I have attached the schematics of the above architecture. May I request you to review the schematics. I also request you to review the terminations at the LMK04832 outputs and also the frequencies using Tics pro tool.

CLK.zip

Regards,

Keerthana

over 3 years ago

0 Noel Fung over 3 years ago

TI__Guru* 88540 points

Hi Keerthana,

We will review the schematic, will get back to you later.

0 Keerthana U R over 3 years ago in reply to Noel Fung

Intellectual 510 points

Thank you Noel

0 Noel Fung over 3 years ago in reply to Keerthana U R

TI__Guru* 88540 points

Hi Keerthana,

U312, CLKIN0 pins missing AC-coupling capacitors. Others look fine to me.

0 Keerthana U R over 3 years ago in reply to Noel Fung

Intellectual 510 points

Hii Noel,

We are planning to use CLKIN0 pin as synchronization input, we understand that sync is an edge triggered signal to reset the dividers inside the LMK04832, may I know if we need to provide AC coupling capacitor to that pin. If that is the case what should be done with the CLKIN0* pin.

Regards,

Keerthana

0 Noel Fung over 3 years ago in reply to Keerthana U R

TI__Guru* 88540 points

Hi Keerthana,

You have both _P and _N signal, so I assume it is a differential signal, AC-couple is therefore recommended.

(21) ZU1_LMK_SYNC_P
(21) ZU1_LMK_SYNC_N

0 Keerthana U R over 3 years ago in reply to Noel Fung

Intellectual 510 points

Hii Noel,

If we use CLKIN0 as a single ended is it mandatory to connect CLKin0* pin to ground through 0.1uF capacitor.

0 Noel Fung over 3 years ago in reply to Keerthana U R

TI__Guru* 88540 points

Hi Keerthana,

According to the datasheet, yes.

0 Keerthana U R over 3 years ago in reply to Noel Fung

Intellectual 510 points

Thank you Noel.

0 Keerthana U R over 3 years ago in reply to Noel Fung

Intellectual 510 points

Thank you Noel.

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LMK04828: Clock review