I just checked my schematic and found that I used the LTC4088 together
with an RT6150A and a PAM2401.
That was the most economical solution I found. A single-chip solution
from LT would be more expensive, so I used one step-up (PAM2401) and one
buck-boost (RT6150A).


Cheers,

Isaac


On 12/03/2015 00:11, Isaac Marino Bavaresco wrote:
> That's what my circuit does, using the same button for powering-up and
> for input.
> The switch feeds the bases of two transistors with emitters to ground,
> one collector goes to the power circuit and the other collector goes to
> a MCU pin. A third transistor is operated by a GPIO of the MCU and its
> collector is tied in parallel with the other transistor that commands
> the power circuit.
>
> I use also an RC circuit coming from the external power input that
> generates a pulse and turns on the circuit when external power is first
> applied but allows the circuit to power itself off afterwards.
>
> For the buck-boost, Linear Technology has some nice battery management
> chips (with what they call "PowerPath") with battery charger and several
> boost and buck-boost circuits. I used one of them, don't remember right
> now exactly which one.
>
> Check the LTC3566.
>
>
> Cheers,
>
> Isaac
>
>
>
> On 11/03/2015 22:52, Lee Mulvogue wrote:
>> Just been going back through Isaac's thread from 23/Feb as I'm looking a=
t
>> something similar
>> http://www.piclist.com/techref/postbot.asp?by=3Dthread&id=3D%5BEE%5D+Cha=
rger+and+power+circuit+for+mobile+equipmen&w=3Dbody&tgt=3Dpost&at=3D2015012=
3104616a#104616a
>>
>> and have a couple of related questions;
>>
>> - if using a momentary button, switching to ground, to latch the power
>> supply (MCU holding it there), is it possible to re-use that button for
>> input purposes?  I currently have two buttons switching to ground used a=
s
>> inputs, but no latched power system.  I'd like to disable the buck-boost
>> on complete shutdown, but don't have room for additional switches, and
>> double-pole switches of the style I'm using/need don't seem to exist.
>>
>> - what type of diodes were D1, D2, D3?
>>
>> - if I always need both 3.3V and 5V from a li-ion when in operation, wit=
h
>> the ability to boost from a min of about 3.0V, is there much benefit to
>> using two buck-boosts, over one buck-boost to 5V and one LDO for the 3.3=
V?
>>
>> Thanks
>> Lee
>>
>
>



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