TPS54233: Adjustible Vout by digital potentiometer

Hi Patrick,

What is the input voltage?

In theory, it is feasible, but if you adjust the output voltage, the system may be unstable. So, you need to select the appropriate compensation values to cover the range of Vout. And I think Vout=24V is a little large.

Shawn

Hello Shawn,

The input voltage is 24V.

I want to use it as a ajustable power supply with much better efficenty than with a power OPV.

The system is normally set on Vout = 4V. But it should have a Vout which I can change with my µC from 2,3 to 24V.

How do I get the system more stable? 

Best regards,

Patrick

Hi TI-Team,

I found the TPS54240.

This device offers a varriable switching frequency from 0,1MHz to 2,5MHz.

With the combination of sensing the current with a shunt, define the Vout with the digital potentiometer and change the switching frequency it should work?

Or are there other issues I miss.

Thank you,

Patrick

Hi Patrick,

Why do you want to change the switching frequency? It will make the compensation more complicated, I think you can use Webench to do the simulation.

https://webench.ti.com/power-designer/switching-regulator/customize/152?AppType=None&Flavor=None&O1I=2.5&O1V=3.3&Topology=BUCK&VinMax=13.20&VinMin=10.80&VoltageOption=None&base_pn=TPS54240&flavor=None&lang_chosen=en_US&op_TA=30&optfactor=3&origin=pf_panel&refpage=https:%2F%2Fwww.ti.com%2Fproduct%2FTPS54240

Shawn

Hello Shawn,

I want to change the switching frequency, because of the calculation of the coil.

The wide range of load current (0,1-1A) and the wide Vout range (2,3-24V) are causing a Ciol from 80µH down to 1,28µH.

When I change the switching frequcy I can get the euqation 28 to the same coil. I know this is for L min but I also guess that the coil should not be 60 times bigger than L min in the "worst case".

thanks,

Patrick 

Equation 28