Why does the NRF52 need such a large inductor?

[MSDEV]

The NRF52840 specifies a 20%, 10uH inductor for the integrated DCDC convertor. Why is the inductor value so large? This switcher runs at 8MHz, which usually means something like 2.2uH for the inductor. I've got TI parts on the bench that run ~2MHz, use a smaller value inductor and have ten times the current rating! 

[psychogenic]

I'd have to guess it's all about ripple... everything else being equal, I think you'd get about 5 times less with a 10u rather than your 2u.  Don't know if the IC absolutely needs such, curious to hear what Nordic's priorities on this selection were.

In any event, a more complete description of the selection process from TI is Choosing Inductors and Capacitors for DC/DC Converters.

HTH,

PatD