stolzie
New Member
Hi guys,
I have a bit of an issue which I am not sure how to solve. What I need to do is run two DC power supplies one 12V and one 5V (coming from the USB of PC) into a single voltage regulator that will output 3.3V. As shown below
12V DC-------
|
---------LM317 -------3V3 out
|
Diode
|
5V USB ------
Both power supplies can be plugged in at the same time but my only criteria is that the 3V3 out needs to be powered when connected to usb and when the 12V is not present and vice versa.
Is the diode the simplest solution? Or is that pretty dodgey! I am a little concerned when both are plugged in about the current draws.
I was thinking about a FET solution with various turn on state (essentially an OR gate but with power supplies)
If you can help me out it would be greatly appreciated.
Thanks
Stolzie
I have a bit of an issue which I am not sure how to solve. What I need to do is run two DC power supplies one 12V and one 5V (coming from the USB of PC) into a single voltage regulator that will output 3.3V. As shown below
12V DC-------
|
---------LM317 -------3V3 out
|
Diode
|
5V USB ------
Both power supplies can be plugged in at the same time but my only criteria is that the 3V3 out needs to be powered when connected to usb and when the 12V is not present and vice versa.
Is the diode the simplest solution? Or is that pretty dodgey! I am a little concerned when both are plugged in about the current draws.
I was thinking about a FET solution with various turn on state (essentially an OR gate but with power supplies)
If you can help me out it would be greatly appreciated.
Thanks
Stolzie