WM8352 datasheet(329/336 Pages) WOLFSON

329 / 336 page

Production Data

WM8352

PD, February 2011, Rev 4.4

329

When selecting a suitable output inductor, the inductance value and the saturation current must be

compatible with the operating conditions of the converter.

The magnitude of the inductor current ripple is dependent on the inductor value and can be

determined by the following equation:

VOUT -VIN

L . FSW

IL =

IL = Inductor ripple current

= Output voltage

= Input voltage

= Inductance

= Switching frequency (1MHz)

VOUT

VIN

FSW

The inductor current is also a function of the DC-DC Converter maximum input current, which can be

determined by the following equation:

As a minimum requirement, the DC current rating should be equal to the maximum input current plus

one half of the inductor current ripple.

To be suitable for the application, the chosen inductor must have a saturation current that is higher

than the peak inductor current given by the above equation. To maximise the converter efficiency,

the inductor should also have a low DC Resistance (DCR), resulting in minimum conduction losses.

Care should also be taken to ensure that the inductor is effective at the applicable operating

temperature.

See Section 29.4.4 for recommended inductor, capacitor and FET component details.

WM8352 Datasheet(PDF) 329 Page - Wolfson Microelectronics plc