i am using omnibus fc and individual esc.so i am planning to make one at home. I searched for pdb schamatic but i didn't find any.

i have two options to build the pdb.
1. 7805 but which is not efficient
2. switch mode power supply. i saw many pdb has common IC. i didn't find the ic name. i can use lm2576 but again this ic has little bigger package.

anyone has schamatic of the pdb with regulator for reference.

what are the current requirements for 5v and 3.3v respectively ?

for 5v for regulator approx. 2A is sufficient.

And 3.3 volts?

Have you tried MP1584 buck module?
It is small as compared to LM2596 and also it is able to supply upto 3A(advertised).
And also it is variable so you can use same type for multiple output requirements.

MP1584  looks perfect. and for 3.3V i don't think we need more than 200mA if i am not wrong.

see if LM1117-3.3v/800ma LDO works and what is the maximum input voltage you are planning to apply (3S ot 6S) ?

i am planning to use 4S battery. for 3.3v  regulation i will be using LM1117-3.3v only.

Don't hook 3.3V regulator directly to 4S battery if your power consumption is 200ma. Since 1117 is linear regulator you may fry the chip if the current draw is high current.

Better to hook input of 3.3v to 5V out of buck regulator onboard. You will have good efficiency. 

Quote from: Balakrishna Reddy on August 16, 2020, 12:49:17 PM
Don't hook 3.3V regulator directly to 4S battery if your power consumption is 200ma. Since 1117 is linear regulator you may fry the chip if the current draw is high current.

Better to hook input of 3.3v to 5V out of buck regulator onboard. You will have good efficiency.  

irrespective of current load, LM1117-3.3v will fry if connected to 4S pack, as absolute maximum input is 15vdc, So it can take up to 3S (4.2x3s=12.6v) pack directly.

Yea using 5v output of the regulator as input to LM1117-3.3 works but make sure that overall current requirements are take care by the 5V regulator (3amp + 0.2amp).

yes you got me right. i will be using smps ic for 5 volt (here i can connect battery directly) which will given to 5v ic which need 5v .
then i will give 5v input to 3.3v regulator to regulate and after getting 3.3v i will supply MCU and other IC. and yes 3.3v consumption won't go beyond 200-300mAmps as per my understanding (mcu will not consume this much and again one or two ic).