timer Compliant Controller project （3）--bom and sch

After optimization of structural solution ， I  must prepare the bom and  drawing circuit diagram as soon as possible.

1 selection the suitable components.

At first，The power circuits  core component is LNk 306 and LDO, I must find the datasheet and typical circuit. and  compare the components lib of our company.as shown in the following  figure.  input  100-250V AC power (wide voltage input) , The diode is protect  the circuit， The output is 12V @ 200mA （ test the voltage was stable ）

In addition ，Mcu power is 3.3V ，so  we need a DC-DC  buck  IC ，I choice  LDO ，becase  it‘s  very affordable and useful，as we know，In traditional design，we also  use 7805 and 7803， But our products are powered by batteries for 3.3V，and we use a ups circuits to  switching power supply  automatic.the LDO output power drop is superior to 7805。

2 Drawing   circuits

I use the Altium designer ， as we know ， Set up  the schematic library ，here will not carefully described。