Hi!

I have problems with my project. I need to ensure baterry backup supply for my 89c52 without reseting uC while switching power supply.

I used 7806 with 1n4001 diode on the output (I have 5.5V to uC and batteries). Then I connected Ni-MH cell 4.8V thru 3.3ohm (current limiting) resistor. Regular power goes thru 7806 and diode to uC. I also added 1000uF cap. in parallel with uC. When power fails, my uC reset due to undervoltage (I use TC1232 brown out detector and wd timer). I tried to put 1uF cap. (there is also 1000u on same line) to the brown out detector, but it still resets.

I would appreciate some proven schematics that work.

I've run out of ideas. Got some?


regards, Damjan