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Which part to use for input of 1.6v/1.8 minimum with an output of +/-5v or +/-6v?

Borislau Jevic
Prodigy 205 points
Other Parts Discussed in Thread: TPS63060, TPS65130, TPS65131, TPS65133, LM2623, LM2622

Hi,
I am trying to figure out, with the least amount of components, an IC to use, that is able to operate from at least 1.6v/1.8v with up to 9v input and a regulated LDO output of preferably +/-6v or if not, then +/-5v.

Input would be a single supply voltage from either 2x NiCD/NiMH or a 1x/2x Li-Ion/Li-Pol batteries.

I remember coming across a buck/boost design with an inverter option in a single ic but I can not locate it.

It should be able to operate as low as 20 mAh / 40 mAh upto 400 mAh continuously.

Thank you.

  • 0
    Guru 22270 points

    Hello Borislau,

    There is an online tool called WeBench from TI that allows you to enter in your power requirements and it generates a list of parts. http://www.ti.com/webench

    On that same page there is a list of other tools that you can use to design power circuits.  I plugged your values in but unfortunately WeBench does not work on an iOS device.  You have to have adobe.  Try it out on your PC and select multiple loads. That should allow you to see the -ve/+ve ranges.

    Thanks,

  • 0
    TI__Guru**** 150830 points

    Your requirement to operate from multiple battery chemistries makes this difficult.  The buck-boost you were probably thinking of was TPS63060.  

    I would suggest a boost when operating from the nickel cells and then a buck-boost when operating from the lithium.  Make your 5V or 6V rail with those.  Then, use this to get the -rail: http://www.ti.com/lit/an/slva469c/slva469c.pdf 

  • 0
    TI__Guru 65340 points

    Hello Borislau,

    For a single LiIon, please check out TPS65130/TPS65131. For +/-5V you might check TPS65133 as well.

    Best regards,
    Brigitte

  • 0 in reply to Brigitte
    Prodigy 205 points

    Thank you everyone.

    It looks like I will be using for most of the variations either the TPS65133 on its own, or with a front end using the  LM2623.

    Alternatively, the other option, of which is very close to what I originally needed and still need, for when 2 Ni-MH/NiCD batteries are on their lower end, i.e. 0.8/0.9v , and fulfills my needs in a single package is the LM2622.

    Can you please advise what values to use to get +/- 6V sharp, but not more than 6.3v, since I will be limited by the capacitors in use, that are rated at 6.3v.

    I would prefer to have a single chip solution, rather than a dual chip, and due to various options (in capacity for run time), there will also be an option to select either 2 NiMH or a 1-2 Li-Ion and the design will also be used for future projects due to flexibility.

    Having a look at p15 and figure 19, I do NOT need the 3rd out, just the positive and negative. I take it that C4 - C7 and D4 - D7 will not be needed. So what values would be needed for input of 2V - 8.4V?

    Thank you.