First time poster, I'm working on a custom PCB with the NORA-W106-00B found on the Arduino Nano ESP32. There is a 2nH inductor on the 3.3V line next to the controller, this is the only part that did not arrive.
Is this component necessary? What are the implications of not including it on the board? Could I just put a big solder blob on top of it and call it a day?
Will most probably work without...
But may cause stability issues if other things are fed from the same supply or disturb other things fed from the same supply.
Make your own! Wind a single layer of fine insulated wire on a 1/4 or less resistor and solder the ends to the resistor leads. Install your 2nH inductor onto your board.
I didn't even think of doing that, would a ballpark estimate be super good enough for this application? Thank you!
I think it's 2mH
Your PCB traces probably have more than 2nH inductance
I think you are correct. That would either take a LOT of wire winding or use a ferrite slug with wire wound around it. Probably in the schematic for a real purpose, not decoration.
It's a little odd the schematic im following is here L2 is the inductor
If it's not a huge concern then ill just throw a 0ohm resistor or a solder blob down and call it a day
Make sure you read the disclamer.
2nH really makes no sense. A PCB trace 10 mils wide and 100mils long will probably be near 2nH
Let me make sure I understand correctly --> 2nH might be a misprint on the schematic and it might be a different value like 2uH or 2mH?
I think so. Like I said even short PCB traces that are thin can have that much inductance. Did you look at any of the NORA reference designs or app notes.
Is that for the IC or a module?
I'm not sure if I entirely understand your question but it is for the power pin on the ESP32-S3 and appears again on the power pin of the NORA-W106-00B schematic
Based on the notes, the inductor is there to prevent OTHER devices from having problems generated by the microprocessor. If your other devices will not be bothered, then no need for the inductor.
It's part of HF filtering on the power supply.
I think usually you'd see a ferrite bead there (although FB inductances are much higher, AFAIK.)
To which schematic are you referring?
You can certainly buy 2.0nH inductors: https://www.mouser.ch/ProductDetail/TE-Connectivity-Sigma-Inductors/36550603S2N0T?qs=i8QVZAFTkqS%2FhQNfo8IajA%3D%3D for a few cents each.
Although I would not like to have to hand solder the 0402 package version.
I put the data (100nF/2nH) into an LC filter calculator LC Filter Calculator and got a cutoff frequency of 11.25kHz
The schematic you show for the ESP32 is for the IC and that should be of no concern for your design since you do not have direct access to the IC in the NORA module and you have no idea what is already inside the module
Here is somethoing else to consider, the NORA datasheet shows VDD_SPI as an output NOT a power input. So I again question the validity of those schematics.
I also do not see the use of a inductor in any of the NORA documentation.
I think it is 11 MHz...
Thank you for your help, I'm going to be building the board this morning. If everything works first try (I hope so) ill see if I have trouble with other devices.
The only other items on the board are a SPI TFT LCD Display, flash memory, LIPO charging circuit, and a microphone. I'll check if there's any issues with that...
I would maybe assume given all of the above that it was just copied into the Arduino design simply because it existed in the Espressif docs. But who am I to say that, I'll leave an update later today.
