variable output buck converter design

[weeb0]

Hello,

I was using a GS-R400V in one of my design. This part is now obsolete and unable to find anymore.

I plan to design a replacement for this part. I already found buck controller ( LM2678 ) but there is a little something that scare me. Let me explain my needs :

Input : 24V
Output : 0.5V - 23V ( I don't think it is possible to get 0.5V so I will need to use 5V - 23V )
Current : 1A - 6A

A microcontroller will control the output voltage with a digipot. I am scared of the output voltage when I will change the voltage. With the GS-R400V I had to ramp the voltage requested to have a nice output but with another controller I don't know what will be the behavior.

any hint given here will be highly appreciated.

Thank you

 

[mtwieg]

The preferable way to vary output voltage is with a variable reference, but most control ICs don't allow this because the reference is built in. Some do however, look for "tracking" type controllers. I know linear tech makes several.

 

[FvM]

Variable output down to zero can be usually achieved with standard regulators (linear or switched mode) by superimpozing a control voltage to the feedback network.