Powering NRF52

[yulya]

Hi During schematic design, i read regarding proper powering of NRF52 (the product is battery powered 2xAAA). somehow i can't find this info now and i would like to verify that i am not wrong: "It is not recommended to connect the SOC to Booster output for example " - am i right? i am connecting it directly to the battery cell, but i do have booster with bypass in the system in order to supply correct voltage to the Motor driver and Buzzer, when battery voltage goes low (for example up to 2v). Can anyone point me to relevant document? thank you Yulya

[ovrebekk]

Hi

It is a bit hard to define exactly how much noise you can accept on the supply lines, but a rule of thumb is that the noise should be less than 100mV peak-to-peak.

The frequency of the noise is also a factor, and some frequencies will inherently be more problematic than others.

I would try to measure the noise on a scope, and see how large it is. If it is close to 100mV p-2-p then you could try adding more decoupling capacitors, or change the routing of the supply signals, to reduce it.

Best regards
Torbjørn

[ovrebekk]

Option 1 sounds like the best one by far. Then you get more isolation between the noisy sources and the Nordic device, and any power loss in the booster won't affect the nRF52 current draw.

The only thing you have to consider is if you need a buffer between the control signals going from the nRF52 to the motor driver, since they could be running at different supply voltages.

Best regards