ADuM3300 layout considerations

Question

Hello, 
 We are using the ADuM3300 for RS485 isolation. 
 Due to layout constraints I routed the DE, TXD and RXD at the bottom layer just beneath the ADuM3300, as it can be seen from the picture:

I guess that that this route can decrease the isolation capability. But since I need the isolation as functional isolation, against ground loops, I'm not concerned from this. 
 What I want to know is, can this route change the functionality of the ADuM3300 ? Can it cause a problem with something else? 
 And just for my knowledge, can it decrease the isolation capability? 
 
 Thanks for your help, 
 Asaf Abraham

jnaso · Accepted Answer

Hi Asaf, 
 Yes, the isolation capabilities of the application circuit will be decreased. There are essentially parallel insulator systems here. We need to consider which system would have the lowest rating... and that becomes the limit for the application. The performance of the isolator won't change, but the outside layer pcb routing is the shortening creepage and clearance on the PCB. 
 There are smaller standard digital isolator packages available. The ADuM141E is available in 16L-QSOP for example. There are also many different integrated isolated RS485 chips in ADI's portfolio that would help reduce the total solution size. 
 Regards, 
 Jason)

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ADuM3300 layout considerations