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Bipolar Tracking on start-up TPS7A47 & TPS7A33

Greg Greenwood
Intellectual 290 points
Other Parts Discussed in Thread: TPS7A47, TPS7A33

I would like to use the 1A device pair for post regulation on an SMPT bipolar supply.  However I need to be sure the start-up is relatively monotonic from .5V to 2V to avoid latch-up issues in the circuitry down stream.   Is there an appnote that addresses that concern such as slaving one output to track the rise of the other?

  • 0
    TI__Expert 8905 points

    Hi Greg,


    There is an EETimes article on one implementation of a tracking supply:

    www.eetimes.com/document.asp

    Another option the below circuit. Limited testing was done with the TPS7A47/30 and showed the best tracking when the EN pins were shorted and a 10nF Cnr was used. This approach should work with the TPS7A47 and TPS7A33. A key thing to note with this technique is that an INA must be used as the NR pin is a Hi-Z node, so any significant impedance will cause the reference voltage to decrease.

    Regards,

    David