LM20145DESIGN-CALC: Design spreadsheet seems to be suggesting small inductor giving a very high ripple factor

Hi,

I am looking to design a 3.3V to 1.8V 0.5A max SMPSU I have been looking at the LM20145. The design spreadsheet is suggesting a 0.45uH inductor at a switching frequency of 1MHz. I was expecting an inductor size of about 4.5uH to keep the ripple current down to 40%. Is the figure of 0.45uA to be expected?

What other converters would be suggested for this application to keep the effiency as high as possible?

Thanks