I'm going over the nRF52820 chipset, and I'm not sure I completely understand the reference schematics in regards to the LC filters on the REG1 DCDC enabled option.
The documentation states that LC filter should be present on the DCC line when the DCDC is enabled, but the LC filter is not present when LDO is used. Naturally, the LC components are either soldered on not soldered on, and will not be removed if REG1 is configured as LDO. I assume they will not hinder the performance of the regulator when in LDO mode. Am I correct?
I also wanted to make sure that the DCC line is the one I understand it to be- line 39 on the reference circuit. This line already has 2 coils on it- L2 and L3, and capacitors C15 and C16. Are these the LC components required or do I need to add more on top of these? I ask because with the nRF52840, the coil was placed on the DCCH line, which was close to the VDD and VDDH pins. This line is not present in the nRF52820 schematic. Lastly, I noticed a second coil was added to the ANT line (L2), which was not present in the nrf52840 schematics. I also noticed it is of the same scale as the one it is in sequence to (L1). What is the reason for this coil?
The DCDC converter needs the LC filter on the DCC pin. If the regulator is configured in LDO mode, it doesn't matter of the LC filter is in place or not.
Please refer to the reference schematics, all component shown in the different configurations are needed. Component values may changes between devices.
Hi Ketiljo!Thanks for the answer.
I understand that all components shown in the different configurations are needed, ok. Can their footprints be changed? specifically I'm interested in the L1, L2, L3 and L4 components. Can I switch 0201, 0402 and 0603 footprints without issues?
You can use 0201 and 0402 more or less interchangeable but things start to happen with large sizes as 0603 so I'd avoid that. Especially for the inductors.
You'll have a hard time finding a usable inductor smaller than 0603 for the 10 µH inducutor, L3.