LM2678: LM2678 for supply that can switch between output two voltages

Hi

yes, you can choose a switch slowly change the reisistor value(using RC circuit to make it slow), you need to choose enough output cap and inductor value.  you can use wenbench to do the simulation to see any issue to share the same output capacitor and inductor. from my view,I think it should be fine.

you can also take look at LM14050 

https://www.ti.com/product/LMR14050?keyMatch=LMR14050&tisearch=search-everything&usecase=GPN

Thanks

Daniel,

Daniel,

Daniel,

Daniel.  Thanks for the quick reply.  I went to webbench and found that 12v out required the larger Cin and L, while 5v required the larger Cout.  I reran the simulation with the larger of all three values and it seems to come out ok.  My plan is to use R1 = 1k and make R2 from a 3.12k and 5.83k resistor in series.  I will interlock the change so that the regulator is disabled when it is switched and then short out the 5.83k resistor with a small relay.  Since the transition is when it is off this should not cause a problem I think.

Daniel.  Thanks for the quick reply.  I went to webbench and found that 12v out required the larger Cin and L, while 5v required the larger Cout.  I reran the simulation with the larger of all three values and it seems to come out ok.  My plan is to use R1 = 1k and make R2 from a 3.12k and 5.83k resistor in series.  I will interlock the change so that the regulator is disabled when it is switched and then short out the 5.83k resistor with a small relay.  Since the transition is when it is off this should not cause a problem I think.

Sorry for the multiple messages, I am new and keep forgetting that the enter key sends.  Bill