nRF52840 High Voltage Mode - Inductor requirements

[Florian Zierer]

We are designing the nrf52840 with high voltage mode and both DCDC regulators.

Where can I find the requirements for the external circuitry, like the inductors. For now I only see the reference circuitry no. 4 but I don't know how strict the requirements for the Inductors are.

We are in search for small inductors (e.g. 10µH in 0402) but we can find only one with +/-20% and the reference circuit defines +/- 10%.

Would the DCDC also work with 20% accuracy and what would be the consequence? Would it be possible to use e.g. two 5µH in row?

[ketiljo]

Using a 20% inductor for the high voltage DCDC converter may affect the efficiency, so we recommend using 10% here. You can use several inductors in series, no problem.

[Florian Zierer]

Ok, but when you say you are recommending 10% would 20% also work but not as efficient? Perhaps this is ok for us but if it not working at all that would be bad.