nRF54LM20A-PAAA Reference circuit - bulk capacitor

[HW72]

Hello,

According to the reference circuit (https://docs.nordicsemi.com/r/bundle/ps_nrf54lm20a/page/chapters/ref_circuitry.html-concept_refcircuit_config_1), a bulk capacitor C4 with a value of 10 µF / 6.3 V in a 0402 package is used. If a 3.3 V MCU supply voltage is used, the effective capacitance is approximately 4 µF in the 0402 package.

Is this expected to be the minimum effective capacitance, or is a lower capacitance acceptable?

I am asking because I need to save space on the PCB, so I would like to know whether this minimum capacitance is actually acceptable.

Thank you.

C4

10 µF

Capacitor, X6S, 6.3 V, ±20%

0402

[Ressa]

Hi,

The bulk capacitor you are mentioning is the biggest cap on VDD and its main tasks is to prevent voltage drop during high current activities. So depending on the quality of ground plane/ traces / maximum current consumption in your application, cap value can be changed. If you are using 3.3 V supply and having a good quality supply source (low internal resistance) and the connection between supply source and VDD pins are solid (like having dedicated power plane undeath SoC), so I personally think the value can be changed (reduced). But it is not something that has been validated by Nordic, so you need to verify/validate it on your prototype over several samples. 

Br,
Ressa