ISO1212: ISO1212 || Layout guidelines

Jyoti Vaishnav

Part Number: ISO1212

Hi TI Support,
We are using the ISO1212DBQR in our design with the bridge input configuration, similar to the reference circuit shown below (BAT54SW bridge network on both input channels).
Our question is regarding the PCB layout recommendation for the FGND pins (FGND1/FGND2).
In our implementation, the field inputs are connected through the bridge rectifier network, and the FGND nets are not directly tied to the system GND.
Could you please clarify the following:

Is it recommended to create dedicated copper polygons for FGND1 and FGND2 around the ISO1212 on the PCB, even when using the bridge input configuration?
Should the FGND polygons remain electrically isolated (floating) except for their intended field-side connections, or is it acceptable to route them as traces only?
Are there any specific layout recommendations for the bridge input configuration to achieve the best EMC/ESD performance?

3 months ago

0 Varun Kumar 3 months ago

TI__Genius 17930 points

Hi Jyoti,

Thanks for reaching out providing detailed inputs

For FGND - there's no specific need to have dedicated polygons for FGND connection. They can be traces as well. You can also refer ISO1212EVM as a reference - ISO1212 Isolated Digital-Input Receiver Evaluation Module (Rev. A)

The bridge rectifier does not affect EMC/ESD performance and hence do not require any special treatment - this can be placed as normal diode connections before the SENSE pins of ISO1212.

Regards
Varun

Isolation

Isolation forum

ISO1212: ISO1212 || Layout guidelines