Hello all,

I am using a Step-Down Converter (Part Number: TPS543C20RVFT from TI) set up in a Two-Phase Master-Slave configuration on board. I feed the input of 5V and expect 0.85V at the output. During startup, the requirements are met, but after configuring the program on the board, I am facing a drop up to 0.79-0.8V at the output. Are there any methods to overcome this? Need your suggestions to find a solution to this issue. Below is the schematic design image.

Regards,
Saurabh

 

Are you saying that your output seems to be about 50 millivolts low?

If so, how much current is your load drawing?

How much if this design is new?

 

During startup, the requirements are met, but after configuring the program on the board, I am facing a drop up to 0.79-0.8V at the output.

Then logically there may be an error/problem in the configuring.
I've no experience with that IC, or master-slave configuring, but unless there is an exact match of the component values in the two channels of the converter, could there be a feedback conflict which the ICs resolve by going into limp mode?

 

Are you saying that your output seems to be about 50 millivolts low?

Yes. Once programmed, this is the output.

If so, how much current is your load drawing?
How much if this design is new?

The design is for 80Amps.

 

Then logically there may be an error/problem in the configuring.
I've no experience with that IC, or master-slave configuring, but unless there is an exact match of the component values in the two channels of the converter, could there be a feedback conflict which the ICs resolve by going into limp mode?

Well programming-wise that's the requirement, it takes a lot of resources to function fully so basically it will not be changed. As far as the design goes, I have followed the design recommendation from TI, and also picked components as per rec. Limp mode is something I've not experienced, does it come programmed or it is a general case?

 

50 millivolts divided by 80 amps…

If you are concerned about such a small voltage drop at that kind of current you have to be very careful about the resistance of wiring, routing of the output, ground loops and where you sense the output voltage.

There is some science and a lot of art required.

 

Limp mode

I was using a car analogy. Generally known as 'hiccup mode' when referring to regulated power supplies/converters, i.e the supply temporarily shuts off or reduces its output to protect itself if there's a problem.