I am working on developing a robot that uses the Jetson Nano 2GB version as the primary computer. I have noticed that the 40 pin header has a 3.3v output pin on it. I am hoping to be able to power the 3.3v sensors that I have using this pin rather than having to buy an additional voltage converter IC. What is the maximum load that this pin can handle?
You probably figured this out by now. The +3.3V output source is from the integrated LDO regulator in the FT232R USB UART IC. This pin should be decoupled to ground using a 100nF capacitor. The main use of this pin is to provide the internal +3.3V supply to the USB transceiver cell and the internal 1.5kΩ pull up resistor on USBDP. Up to 50mA can be drawn from this pin to power external logic if required. This pin can also be used to supply the VCCIO pin. (From the FD232 data sheet)
@smith.paul74 What do you mean by different nano? I am referring to this product:
There is an Arduino Nano. I was too eager to help that I didn’t connect the NVIDA to this until after I sent the note. The Arduino Nano only has 30 pins.
If you have a schematic for the product you do have, then find the source for the 3.3V output, where it comes from. If it comes from an IC, find the datasheet for that device and see if it gives output current capability.
If not, you could do an actual load test Imperically. If you connect a meter to the 3.3 volt source you mention, and see it is close to 3.3 volts, keep the meter measuring it and connect a load resistor. If the voltage drops more than a few percent, watch for a device getting too warm. If the warmth verses load resistance works in your favor, then you may be good to go.
1 ohm would be 3.3 amps (Probably not capable of that - just a guess). 10 ohms load would be 330 mA. (Perhaps still too much). 100 ohms load 33 mA. I don’t recall what current you need. If that is too low then you may need another source for 3.3 volts.
As far as I can tell, NVIDIA has not yet released the schematics for the 2GB nano carrier board. I am looking information on the Maximum Current that the 3.3v pins on the header can supply.
That was my understanding of your question. My last response is still valid. Do a test with a meter like I said, and you will have your answer.
I worked in electronics for 40 years. The same principles apply no mater what the circuit is.
@smith.paul74 That is my backup plan. We are severely budget constrained on this project to the point where we likely cannot afford a replacement Jetson Nano, so I came to the forum hoping someone could give me an answer without me having to perform testing that could push the Jetson to its limits in any possible way.
The 3.3v converter on 2GB devkit is MP2152 which is up to 2A output. As it is powered by VDD_5V (up to 3A), the real load capability of it depends on what current the module will draw from VDD_5V. Also the 3.3v supplies camera connector, level shift x 3, ethernet port/LED and 1.8v LDO. So it’s load capability on 40 pin header is not a fixed value, you need to estimate or do a test to get the value with your own use case.
@Trumany Thank you very much. That will likely be plenty of power for my project. Do you know if/when a schematic for the Jetson Nano 2GB Carrier board will be released?
No ETA yet, it will be uploaded to DLC once available.