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LiPO battery to power ARM M at 3.3 volts

Harry
Expert 2920 points
Other Parts Discussed in Thread: TPS63020

I want to power a ARm M using a LIPO battery.

two option I have currently

one is to use a LDR (linear regulator) that would reduce the 3.7 till it becomes 3.4 volts and then my arm wont work

the other solution is to use a IC like TPS63020
http://www.ti.com/product/tps63020#samplebuy
this after doing the LDO automatically switches to boost mode and drains the battery till 2.7V which is not harmful to the battery and boosting will stop there after to stop damaging the batttery


Can somone pls tell me which is the best solution? Does this TPS63020 do a good linear regulation? is there any other Ic I could use?

or should I first let a LDR do its job and manually detect the voltage and then manually switch to boost one the voltage of LIPO reaches 3.3 and stop at 2.7?

which method would be better?

my last question is should I make the TPS63020 output 3.3 and directly provide it to the ARM? Would it be smooth enough?

thank you so much for all your replies

  • 0
    TI__Guru**** 150790 points

    Yes, the TPS630xx family is a great option to provide a regulated output voltage with an input voltage that goes both above and below the desired output voltage.  They never operate in LDO mode, but are either buck or boost converters depending on the level of Vin.  They achieve very high efficiencies that way.

    I suggest you order the EVM and connect it to your ARM device to evaluate how it performs.  You can likely just directly connect them in your system and testing the EVM will confirm this.

  • 0 in reply to Chris Glaser
    Expert 2920 points

    Dear Chris Glaser,

    I intend to use a LIPO as you already know. So I was wondering from the region 4.2volts to 3.4 volts is it more efficient to use a 0.1V drop out linear regulator ? or the TPS63021 which automatically switches to boost mode when voltage of the battery reaches <3.3

    it would be easy for me to use the TPS63021 only but which is more effective? 

    are there any 3.3V 0.1V drop out regulators you know? or could you kindly tell me which option is the path for high efficiency? Im really worried about power.

    I opened this therad as well explaining my whole problem. please put in any ideas if you feel free to share with me

    http://e2e.ti.com/support/power_management/non-isolated_dcdc/f/196/t/243483.aspx

  • 0 in reply to Harry
    TI__Guru**** 150790 points

    As a student, it is important for you to do the math to answer your question.  There are efficiency curves in the TPS63020 datasheet, while the LDO's efficiency is the same for any LDO under the same operating conditions.  Note that it does not depend on the dropout.

  • 0 in reply to Chris Glaser
    Expert 2920 points

    Dear Crhis Glaser,

    thanks for the great advice.

    its true what you say.. I understand. And I had been doing it non stop for around 4 days . Its just that im new to this topology because for everything we are used to doing linear and linear and linear :-(

    im tring my best to learn.

    I find data sheets hard to grab the data from initially since im new. I am going throgh some videos on TI.com teaching how to actually chose the right IC. it explains a lot about USB OTG, power path, efficiency etc.

    it says Switch mode is way better than Linear always in terms on efficiency. it just that it has lots of components.. but i think om going to selltle down for a switch mode power path Lipo 

    for such a regulator, If im charging one LIPO cell, what would be the best Solar input voltage & current? 

    Do you suggest there would be a drop on the solar cells voltage once connected across the Vin? 

    Your answer with regard to this would be so much appreciated