TPS54519: Line and Load regulation

Pedaiah G

Prodigy 40 points

Part Number: TPS54519

Hi,

We designed a buck converter with TPS54519RTER details below.

Vin = 5V

Vout = 1.8V/2A

I wanted to know the load and line regulation of buck converter. In lab i tried the below experiment.

Readings as below.

Constant Current mode	Actual output reading
Load set in DC electronic load	Voltage	Current
No load	1.8V	NA
0.1	1.7752	0.099
0.2	1.7483	0.198
0.3	1.721	0.298
0.4	1.6934	0.398
0.5	1.6662	0.498
0.6	1.6385	0.598
0.7	1.6103	0.698
0.8	1.5822	0.798
0.9	1.5532	0.898
1	1.5241	0.998

1. is test set-up i made to find the regulation correct?

2. Why converter is not able to maintain a constant voltage when i vary the load?

Regards,

Pedaiah G.

over 1 year ago

0 Chris Glaser over 1 year ago

TI__Guru*** 145250 points

Hi Pedaiah,

From your data, it is most likely that you are not measuring the output voltage at the point where the IC is regulating it (where the FB resistors are connected). If you are ready the output voltage off of the load, for example, then you are adding in the IR drop across the wires between the board and load. This will decrease the load regulation.

Can you retry measuring the voltage with meters as shown in figure 5 of this app note? https://www.ti.com/lit/an/slva236a/slva236a.pdf

Thanks,

Chris

+1 Pedaiah G over 1 year ago in reply to Chris Glaser

Prodigy 40 points

Hello Chris Glaser,

Yes, you are right.

i was measuring output off of the load.so, it is adding IR drop.

when i measure across output capacitor, i got proper output voltage.

Thanks.

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TPS54519: Line and Load regulation