Hi all,

I have a buck converter , TPS54260.
My input voltage range is 8-16V and my output is 5V and 550mA.

How should I calculate my input current to the converter?

I tried using the efficiency power equation approach but unable to find.

Can you please explain me how to find the input current?

Thanks

 

hi EM,
Have you tried the WBench tool.?
I would expect the Eff% to be around 80% to 90% depending upon the circuit design and input voltage.
Why is it important to now the Eff% exactly.?
http://www.ti.com/design-tools/over...tr_en&HQS=sva-web-webdesigncntr-vanity-lp-en#

E

 

If you know the circuit efficiency, the input current would be (Vout*Iout)/(Vin*efficiency).

 

If you know the circuit efficiency, the input current would be (Vout*Iout)/(Vin*efficiency).

I tried this. But how to determine efficiency of the buck converter?

There is a graph of output current vs efficiency. But it is for different voltage condition.

 

Is your load steady? Scope the input and use caps to smooth it out as much as possible. Put a small resistor in series, maybe a 1/4 ohm and measure the voltage across the resistor. Use that to calculate the current. If the voltage is not smooth then you can use an averaging meter to get the average current, and use a scope to get the peak current. Someone please correct me if there's a better way.

 

There is a graph of output current vs efficiency. But it is for different voltage condition.

Unless you need an exact value, the efficiency of your circuit should likely be close to that shown in the graph (≈85%).