1、working principle： Due to the built-in power switch with a large current, 34063 can control the switch current to 1.5A. The internal circuit includes a reference voltage source oscillator, a converter, a logic control circuit, and a switching transistor. Reference voltage source is a bandgap reference with temperature compensation. The oscillation frequency of the oscillator is determined by the external timing capacitor of the 3 pin. The switching transistor is composed of a reverse input terminal of the comparator and a logic control circuit connected with the oscillator, and is provided with a ON, and is composed of a next pulse which is synchronized with the output of the oscillator to be OFF. 2、Function Description: This module is mainly to achieve DC 5V boost to DC 12V； 3、Description of each function module: ![enter image description here][1] 4、Element and PCB plate before welding ； ![enter image description here][2] 5、Physical map after welding ； ![enter image description here][3] ![enter image description here][4] ![enter image description here][5] [1]: /editor/20160320/56ee35fde6cdb.png [2]: /editor/20160320/56ee367ae6c08.png [3]: /editor/20160503/57283f916b5b5.JPG [4]: /editor/20160503/57283f96eaf3c.JPG [5]: /editor/20160503/57283ffed9d07.JPG