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ISO1050 Vcc2 Supply

Ken Anderson
Intellectual 325 points
Other Parts Discussed in Thread: ISO1050, SN6501, TPS55010

Hi, I would like to simplify the isolated power to the ISO1050 (Vcc2) by using a VBT1 (http://www.cui.com/Product/Resource/DigiKeyPDF/VBT1-SMT.pdf). The concern is that this supply is unregulated and it's output could float as high as 5.5V with low load. The recommended voltage range for Vcc2 is 4.75V to 5.25V. Now, I don't need the full 1Mbps data rate, and there are only 2 nodes on the CAN bus, less than 8 feet away. The question is, what effect would I see if Vcc2 were to drift as high as 5.5V? The maximum rating is 6V, so I don't expect any damage. Would I see a reduced data rate, and if so, by how much?

 

Thanks,

Ken.

  • 0
    TI__Mastermind 20590 points

    Hi Ken,

    I'm checking on this from a few fronts and will try to get an answer.  In the mean time you may want to also look at the SN6501, http://www.ti.com/product/sn6501 ,  transformer driver solution that was designed as a companion for the ISO1050 and other TI isolated transceivers. Application view this with the ISO1050 is outlined on page 21 of the latest revision (Jan 2013) of the ISO1050 datasheet.

    - Scott

     

  • 0 in reply to Scott Monroe
    Intellectual 325 points

    Thanks for the reply, Scott.

    I did see that TI reference design on p.21 of the ISO1050 datasheet, but would prefer a single integrated IPS for various reasons. NVE also makes an isolated CAN xcvr with the same recommended voltage tolerance on the isolated output supply (4.75 to 5.25V), and their reference design includes a VBT1 IPS (unregulated):

     
    I have found a regulated version of the IPS, but it is quite expensive so would rather not use it if I don't have to.
     
    Thanks,
    Ken.
  • 0 in reply to Ken Anderson
    Prodigy 60 points

    Has this question been answered? More than half year now, I can not find more post on this thread. What effect would be if Vcc2 voltage supply varies from 4.5V~5.5V? I have the same considereation as Ken, 5% voltage tolerance power supply cost more and very few manufacturers. I can not retro-fit my exist application with ISO1050 because the power supply problem.

    Jian

  • 0 in reply to Jian Li1
    Intellectual 325 points

    Hi, I ended up using an integrated, regulated IPS:

    VWRBS2-D5-S5-SIP

    It's expensive though.

  • 0 in reply to Ken Anderson
    TI__Mastermind 21942 points

    Hi everyone,

    Another two piece solution that TI offers is the TPS55010 with a push-pull transformer. The entire solution is the TPS55010 (with some external passives and the transformer over the isolation barrier. It is more expensive than the three device solution that Scott mentioned above (XFMR driver, XFMR and LDO). 

    I believe this solution uses current feedback on the primary side to regulate the output. I agree that if the load were to float up to 5.5 volts under light load it should not break the device. My concern is the device most likely was not characterized at that voltage and will not necessarily meet the datasheet parameters.

    Thanks,

    John