Query on choosing the inductor value at the output of the buck converter TPS542941

Vasanthan Nagarajan

Hi,

As you know, we are using the TPS542941PWPR buck converter in our design.

We have 4 different voltage rails in our design.

We are using the circuit based on the design from webench tool in which each voltage rail has different inductor value parts.

Please let us know whether it is feasible to have same value inductor (say 2.2uH) for all the voltage rails and also share the calculations behind this inductor values for different voltage rails if available.

Thanks,

Vasanthan N

over 10 years ago

0 JohnTucker over 10 years ago

TI__Guru**** 191445 points

The datasheet Table 1 on page 14 list the recommended inductor values. You can use 2.2uH for output voltages between 1V and 3.3V. There is no equation for it. For DCAP2, the inductor and output capacitor is chosen for reasons of loop crossover. For traditional voltage or current mode control, the inductor is sized so the ripple current is a percentage (usually 20 to 40%) of the load current.

0 Vasanthan Nagarajan over 10 years ago in reply to JohnTucker

Intellectual 260 points

Thank you for your input, John Tucker.

Actually i'm already having the design for the rails with the different inductor values based on the design from WEBENCH tool.

In that design, the output capacitor values for all the rails is 22uF.

Now If i change the inductor values to 2.2uH for all the rails, do i need to change the capacitor values or 22uF capacitor is OK for these inductors also

Thanks,

Vasanthan N

0 JohnTucker over 10 years ago in reply to Vasanthan Nagarajan

TI__Guru**** 191445 points

Can you post your schematic? Then I can check it.

Power management

Power management forum

Query on choosing the inductor value at the output of the buck converter TPS542941