Welcome to our site! Electro Tech is an online community (with over 170,000 members) who enjoy talking about and building electronic circuits, projects and gadgets. To participate you need to register. Registration is free. Click here to register now.
This appears to be a supply switchover circuit. The correct circuit has to be Fig. A. Assuming the 5V is capable of delivering more than a couple hundred milliamps, Fig. B will burn out D5, and then proceed to damage the battery through the body diode.