Production Data
WM8352
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:
IL = Inductor ripple current
VOUT = Output voltage
VOUT - VIN
VIN = Input voltage
IL =
L . FSW
L
= Inductance
FSW = Switching frequency (1MHz)
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.
PD, February 2011, Rev 4.4
329
w
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