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TPS71733 with Lithium accumulator

Maxim Galkin
Intellectual 460 points
Other Parts Discussed in Thread: CC2530

Hello!

I create a portable device with CC2530. I want to use lithium accumulator with LDO TPS71733. The output voltage of accumulator is in range from 3 to 3,7 V. I have a question, how LDO TPS71733 will be work when input voltage range equal or below 3,3 V? What kind of dropout voltage will be (peak current consumption 100 mA, average is 2 mA) on linear regulator? How will be increased quiescent current of TPS71733 (and ground pin current) and noise level? How will be decreased PSRR?

5353.PowerFlow.pdf

P.S. Is this a good idea to use LDO with accumulator in non-regulating mode?

With best regards, Maxim Galkin.

  • 0
    TI__Guru 55940 points

    Hi Maxim,

    Dropout can be seen using Figure 8 in the datasheet.  

    For TPS71733 you should expect IGND to be typically 163uA while in dropout.  We do not specify noise in dropout because during dropout the LDO effectively does not have any PSRR and any noise on the supply would pass through.  Any filtering would be attributed to the input and output capacitors.

    Due to the fact that a typical LDO would have increased ground current while in dropout, it is typically not recommended to use an LDO with an accumulator while in dropout.

    Very Respectfully,

    Ryan

  • 0 in reply to Ryan Eslinger
    Intellectual 460 points

    Hello, Ryan.

    Thanks for reply!
    With best regards, Maxim Galkin.