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
http://www.olimex.com/dev/DUINO/OLIMEXI … -STM32.pdf
http://www.olimex.com/dev/DUINO/OLIMEXI … _Rev_B.pdf
This board has 3 power supply options. I need only two of them.
I also have iNEMO v2 Board from ST Microelectronics : http://www.st.com/internet/evalboard/product/250367.jsp
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:
Below I colored Part of the circuit in black which i do not need.( If the image is not visible properly, please save & see or copy image, paste into a microsoft paint program or similar).
Last edited by harinath (2012-06-02 07:24:24)