nRF52840 REG0 & REG1

[Nikosant03]

Hi everyone,

I need your advice regarding the regulator configuration of nRF52840

I am designing my own PCB using Raytac's module MDBT50Q-1MV2 that carries on the nRF52840 SOC.

I will supply the module from a regulated 1.8V line and thus VDDH = VDD (Normal Voltage mode). Since I will use Normal Voltage mode the REG0 regulator stage is disabled, right?

From my understanding so far and looking the chapter 5.3.1 of nRF52840 Product Specification v1.1,  the second regulator stage REG1, is used to supply the internal chip with 1.3V and there are two options, either to use the LDO or the DC/DC converter, right? In case I use the DC/DC converter an LC filter is required on the output (between DCC and DEC4 pins). Moreover, the DC/DC converter has higher efficiency from the LDO and that means power optimization.

Ok, now I have to choose whether I will use the DC/DC or the LDO since it is required very small voltage drop (I will supply with 1.8V -> 1.8-1.3 = 500mV voltage drop). 

What is your opinion? Is it make sense to use the DC/DC converter and sacrifice some board space for the LC filter? In case that the DC/DC converter is always advantageous why do you provide the option of LDO having it as the default regulator?

Thanks in advance

Nick

[Turbo J]

The L for REG1 DC/DC is already included in the module (datasheet chapter 8) - just enable this DC/DC in code.

[Nikosant03]

Hi thank for your answer, 

So I have to place only the capacitor on DEC4 pin? But the MDBT50Q-1MV2 does not provide any DEC4 pin..

[Turbo J]

There is a surprising amount of passives under the RF can of the module - including above capacitor(s).

[Nikosant03]

Thank you for your answer!! Is there any document/schematic to identify these passives?

[ketiljo]

https://infocenter.nordicsemi.com/topic/ps_nrf52840/ref_circuitry.html