AD5560 Grounding Question

I would like to confirm AD5560 layout for DGND pin and AGND pins. In datasheet, “Analog and digital sections are separated and confined to certain areas of the board”. 

However, we study MT-031 (Grounding Data Converters and Solving the Mystery of "AGND" and "DGND"). 

MT-031 in Page 8 advise mixed-signal IC should tie DGND pin and AGND pins together with minimum lead lengths 

If not, according to MT-031, “connecting DGND to the digital ground plane applies VNOISE across the AGND and DGND” 

Datasheet and MT-031 statement is different. Should we connect both GND pin in AD5560 layout? 

Besides, our application will require multiple AD5560. 

In datasheet, “multiple devices require an AGND-to-DGND connection, the connection should be made at one point only” 

If AGND and DGND pin tie together, could you advise how to connect all GND? Is it like a star following?

 

  • 0
    •  Analog Employees 
    on May 6, 2021 8:51 AM

    Hi ,

    You are correct that the AGND and DGND are best connected on a star ground connection. This is usually done in such manner that the the star ground connection must be as close as possible to the power supplies and as far away from the part as possible to lessen ground transients. We also do this standard procedure on our evaluation boards. Also, please note that we do not recommend copying our evaluation board design apart from star ground connection as mentioned earlier. The eval board is meant to showcase part performance only and it is not meant to be used as a reference design for a system design.


    Best Regards,
    DJ