Electronic – Source selection Circuit


I am doing a project, in which there are two dc source a) 48V_ DC b) 48V_Reg to power the board.

If either of two is present, that power source will power the board.

If two power source is also present then it should select 48V_DC

Please let me know any IC or circuit in where I can implement above features.

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Best Answer

This is a common requirement on telephone or wide area network equipment and servers.

The most straightforward way is just with a pair of diodes. No active devices required.

Solutions such as relays have the problem that there will be a power drop-out while switching over.

IC vendors such as Analog Devices have more sophisticated solutions that also support hot-plugging and avoid the voltage drop of diodes.