ADS42LB69: Using LMK04832 to synchronise two ADS42LB69(4 ADCs)

Sudipto Patra

Part Number: ADS42LB69
Other Parts Discussed in Thread: LMK04832

In our design we are using two numbers of ADC (ADS42LB69) and Clock will be fed to these ADCs from the clock distribution IC LMK04832. The LMC04832 IC having SYNC/SYSREF_REQ signal. How to connect this signal to ADCs Please suggest.

Reference Design

over 4 years ago

0 jim s over 4 years ago

TI__Guru* 91947 points

Sudipto,

I would follow the example shown in the attached schematic. Using the circuit that is shown connected to DCLKout2_3 pins of the LMK device will allow you the option to drive the ADC input clock and SYNC as either LVPECL or LVDS. It will also allow plenty of adjustment to meet the SYNC input setup and hold time requirements. Duplicate this circuit to drive both of your ADC's.

Regards,

Jim

ADS54J20_ADS54J40_ADS54J42_ADS54J60_ADS54J69-SCH_E.pdf

0 Sudipto Patra over 4 years ago in reply to jim s

Prodigy 30 points

Hi Jim,

Question is whether the clocks for the ADC chip is to be generated from different output ports of LMK device or single output. Similarly the SYNC for ADC chips to be generated from different outputs of the LMK device or single output.

Also I understand that clock divider in the ADC chip o be used for sync to work properly. Divide by 1 will not have any effect.

0 jim s over 4 years ago in reply to Sudipto Patra

TI__Guru* 91947 points

Sudipto,

Yes, use different outputs of the LMK so only one output is connected to one input of the ADC's. By design, all outputs of the LMK will have the same delay.

If you are not using the internal clock divider (divide by 1 mode), the only way to synchronize the outputs is to provide clocks with the same amount of delay by routing them the same length from the LMK device.

Regards,

Jim

0 Sudipto Patra over 4 years ago in reply to jim s

Prodigy 30 points

Hi Jim,

PFA scheme for connection. Let me know your feedback.LMK_ADC.pdf

+1 jim s over 4 years ago in reply to Sudipto Patra

TI__Guru* 91947 points

Sudipto,

Block diagram looks fine.

Regards,

Jim

0 Sudipto Patra over 4 years ago in reply to jim s

Prodigy 30 points

Thanks Jim

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ADS42LB69: Using LMK04832 to synchronise two ADS42LB69(4 ADCs)