Power from two different voltage sources

[MrCravon]

Can I power an IC form both 3.3v and 5.0v using the following setup:

Given that the IC can have an input range of 3-5v ofcource. I want to ensure the IC has power regardless of if only one or both of the voltages are present. Should I add a decoupling capacitor?

 

[malli_1729]

Anyway decoupling capacitor is necessary. If IC takes voltages from 3.3V to 5V --> then it is OK

 

[KlausST]

Hi,

Your circuit will work. For sure you need to know the voltage drop in the diodes.
As said before: Capacitors are essential. Many IC manufacturers recommend a unique capacitor at each VCC pin of each IC.
Additionally a bulk capacitor will be useful.

There are special IC s for power supply applications, they switch over automatically, while avoiding the usual voltage drop of diodes.

Klaus

 

[hobbyckts]

I think your IC as 2 VCC ponits and 2 ground points that could be meant for the the automatic switch over of the supply. As suggested by klaus

 

[MrCravon]

Thanks a lot for the help!

Your circuit will work. For sure you need to know the voltage drop in the diodes.

The forward voltage drop of the MBR0520L should be less than 300mV @ 100mA and the circuit that is powered through these diodes should not consume more than 80mA.

There are special IC s for power supply applications, they switch over automatically, while avoiding the usual voltage drop of diodes.

Do you have an example? I am looking for as simple a solution as possible with minimal chance of failure.

I think your IC as 2 VCC ponits and 2 ground points that could be meant for the the automatic switch over of the supply. As suggested by klaus

VCC1 and VCC2 are just two different sides of the isolation in a CAN-transceiver, and in this case is used to separate two power-planes. I left out as much of the circuit as possible to focus on a simple solution as possible. Thanks for the suggestion though!

 

[KlausST]

Hi,

check this:
https://www.edaboard.com/threads/344520/

Klaus

 

[hobbyckts]

check this too

https://www.edaboard.com/threads/134481/

- - - Updated - - -

https://www.circuitstoday.com/automatic-changeover-circuit