ADM3251, ADM2578, ADM3053

Hi

I am using a ADM3251, ADM2578 and a ADM3053 in my design.

I am a little short of connections out from my enclosure.  I have designed my PCB with no GND for the ADM3053 which I now realise is a mistake - I will shortly redesign this to resolve this issue.  I previously connected Analog and I was told it would be OK to connect the GNDs on the ADM3251 and the ADM2578 on the output side ie the isolated GNDs.  My question is is it OK to connect all of the isolated GNDs together on the 3 devices?  This would mean the RS232, RS422, CAN interfaces would share the same GND connection leading out from my device (is connecting the isolated GNDs together).  In my application only one interface can be used at a time ie RS232, RS422 or CAN bus.

David

  • 0
    •  Analog Employees 
    on Jan 19, 2016 9:27 AM

    Hi David,

    For the isolated GND2 bus side of the devices you should use separate GND2 references.

    The ADM2587E, ADM3053, and ADM3251E all have different input voltage ranges.

    In more extreme cases voltages that will not damage one device may affect another device.

    The ADM2587E, ADM3053, and ADM3251E all have different absolute maximum ratings on the bus pins.

    ADM2587E: -9V to +14V

    ADM3053: -36V to +36V

    ADM3251E: RIN +/-30V, TOUT +/-15V.

    Do you need to meet any specific radiated emissions targets with this PCB? If yes then please provide details.

    For the ADM2587E we have specific layout guidelines, please see;

    http://www.analog.com/media/en/technical-documentation/application-notes/AN-1349.pdf

    The guidelines can also be used to aid layout with the ADM3053.

    Regards,

    Richard

  • 0
    •  Analog Employees 
    on Jan 19, 2016 11:38 AM

    Hi David,

    Sorry, to clarify;

    1. Yes the ADM2587E, ADM3053, and ADM3251E can all share the same GND2.

    This is assuming that the PCB accepts only 1 bus input signal at any one time.

    From your comment above this is true.

    2. Using separate GND2 fills for each part will be better from a radiated emissions point of view. Do you need to meet any radiated emissions targets ?

    Regards,

    Richard

  • Hi Richard

    Many thanks for your reply.

    I'm just confused because I previously asked if ADM2578E and ADM3251E could share a ISO GND and the answer was that this would not be a problem.  Going by the logic of the recent answer then surely this would not be ok?

    Regards

    David

    13/06/2014 - ADM3251E and ADM2587E GNDs

    created by in Interface and Isolation - View the full discussion


    Hi David,

    If you refer to the part datasheets, then:

    For the ADM2587E (page 7) when you are stating GND - do you mean GND2?

    For the ADM3251E (page 8) when you are stating GND - do you mean GNDiso?

    If both parts share the same isolated ground then that is ok.

    i.e. Ground 2 and GNDiso sharing then the same ground connection.

    Regards,

    Richard

  • 0
    •  Analog Employees 
    on Aug 2, 2018 3:20 PM
    This question has been assumed as answered either offline via email or with a multi-part answer. This question has now been closed out. If you have an inquiry related to this topic please post a new question in the applicable product forum.

    Thank you,
    EZ Admin