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Power management circuit for STM32F103

Question asked by Reddy.Harinadha on Jun 1, 2012
Latest reply on Sep 17, 2015 by Clive One
Dear all,
I need to design a board based on STM32F103RE.
My board need to be powered in two ways, USB & Li-Ion 3.7V battery. In addition i need to design a IN-BUILT battery charging circuit( USB to Li-Ion battery) for the board. When I attach battery, it should be automatically charged and kept in this state until the other power source (USB or external adapter) is removed and it should AUTOMATICALLY power the board - no jumpers, no switches!

I found the exact functional power_supply section in the following board schematics:
OLIMEXINO-STM32 MAPLE / ARDUINO LIKE DEVELOPMENT BOARD
Board details
Board Schematics
This  board has 3 power supply options. I need only two of them.

I also have iNEMO v2 Board from ST Microelectronics : iNEMO v2
It has two power supply options, but a switch is used to select one of them. Moreover, it needs 5V DC supply if USB power not used. 
In my case i want to use 3.7 Li-Ion/Li-Po battery when USB not used. I did not like the switch to select power source.
I liked auto switching power source of  OLIMEXINO-STM32 

If it is possible to just remove the DC-DC power supply(power input voltage from 9 to 30V DC) part of OLIMEXINO-STM32 it really suits me.
But i need to use SMD components to make my board as small as possible, like iNEMO v2.

I would like to request if you have any suggestions for me or 
If you think you can solve my problem in few minutes & send circuit diagram, i will be very thankful.
Below are the power management circuits of two boards i mentioned:
OLIMEXINO board Power management circuit
iNEMO board Power management circuit
Thank you.

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