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TPS7B7702-Q1: Ground Shift for Antenna specification

Al
Prodigy 740 points
Part Number: TPS7B7702-Q1
Other Parts Discussed in Thread: TPS7B7702

Hi,

One question: For the TPS7B7702-Q1 my customer has the specification that if their is a ground offset of +/- 1V, the Antenna supply LDO needs to work properly.

1. So does the TPS7B7702-Q1 supports a +/11V GND-Offset?

2. Does all the diagnostic features (particular the short-circuit function works properly with such an GND offset (especially for -1V)?

To my understanding, as long as the voltage potential shift (with reference to GND) does not exceed the abs. max. ratings or the recommeended operating ratings) we should be fine. Critical should only be the condition when the internal ESD structures get's triggered by getting lower then -0.3V with refernce to GND.

 

But I would like to get this double checked!

 

Thanks in advance

Al 

  • 0
    TI__Prodigy 740 points
    Hello Apps Team,
    I got some additional inputs with regards to my TPS7B7702-Q1 inquiry:

    The question is related to a possible ground shift of the Antenna/LNA module itself, and not so much of the ground plane the TPS7B7702-Q1 is sitting on!
    So if the antenna module shifts ground by +/- 1V, does the TPS7B7702 works properly?
    I guess a ground shift of +1V should not be a problem. However -1V at the LDO output could open internal structures.
    If +/-1V shift at the output is not allowed for our device, what external protection should they foresee in their application?

    Thanks
    Albert
  • 0 in reply to Al
    TI__Expert 7015 points
    Hi Albert,

    Would you be able to provide a schematic of what you are doing? I don't really see a problem as long as the output capacitor is on the same GND plane as the LDO, but would like to make sure we are thinking of the same thing.

    Also, the only protection you should need is a Schottky diode from GND to OUT and possibly one from GND to FB depending on your application.

    Best Regards,
    Mark
  • 0 in reply to Mark Sellers
    TI__Prodigy 740 points

    Hello Mark,

    thanks for coming back here.

    Unfortunately, the design is in an early stage where E.solutions/AUDI has not started the schematic drawings yet. This will happen soon, but at the moment they are selecting the products from a technical perspective to see if they fit into the design.

    So from that, all we can say so far is that the TPS7B7702 would be on the application pcb with reference to the system GND plane and the antenna module itself could have a ground reference shift of +/-1V. This is because the antennas in a car are located at different positions (e.g. roof) where the ground potentials of the chassis could vary. Since the antenna cable shield is normally hard wired on both ends to GND (as we have also on our EMV) a ground shift on one side (ANT) could  probably pull the system GND up or down.

    Therefore the question from the customer are: Does the antenna supply LDO has an issue with this condition (which is an specified requirement) and if, what do they have to foresee in application to protect against.   

     

     Thanks

    Albert

  • 0 in reply to Al
    TI__Prodigy 740 points
    Hello Team, Mark,
    since the E2E does not allow to attach oictures, please see my email I have send separately!
    Thanks
    Albert
  • 0 in reply to Al
    TI__Expert 7015 points
    Albert,

    I am going to close this thread as we are now handling it through email.

    Regards,
    Mark