Any difference powering the board through VIN vs 3V3?

I’m using an ESP8266 NodeMCU and I’m curious about power. I typically power the board with a 5V wall plug source through the 3V3 pin. This is because I’ve read that powering via the VIN pin and USB at the same time could fry my USB port, and I often have it plugged into the computer to update code. The board has voltage converters so I’m not worried about that, but I’m curious if there’s any difference between powering through VIN vs 3V3?

The reason I ask is I’m trying to make a sound reactive project, but have a considerable amount of noise on the A0 analog reading. I know power is one source of noise, so I wanted to clarify this. Thanks!

You will have to find a schematic of the specific nodemcu. But it sounds extremely unhealthy to put 5V into the 3.3V pin.

I have no experience with ESP, so I do not know if an ESP12 is the same as an ESP8266. I found this schematic for the ESP12:

If you have 3.3v you should use the 3.3v input if you have 5-12v use the vIn , but if your voltage is above 5v don't use the usb at the same time. ESP12 has a regulator to provide 3.3v to the board from the 5vUSB or the vIn pin. Why would you want to connect power from USB and a wall socket at the same time ?

Deva_Rishi:
if you have 5-12v use the vIn...

NodeMCU boards are designed for 5volt USB supply.
A significantly higher voltage on the 5volt pin will eventually fry the tiny 3.3volt voltage regulator.

Powering the board with 5volt on the 3.3volt pin is a sure way of frying the ESP WiFi module.
You should power the module with a 5volt cellphone charger on the USB socket.
Or with/through a powebank, connected to the USB socket.
Leo..

nodeMUC power pins the vIn takes anything upto 20v wow that's more than i thought !

I think you (and Henry) are confused with absolute max ratings and normal operating conditions.
The NodeMCU uses AFAIK a 5-pin SPX3819 regulator. 20volt/800mA absolute max.
Don't assume you can do both at the same time.

With 6volt on V-in, voltage across the regulator is 6-3.3= 2.7volt.
The average ~100mA a NodeMCU draws generates about 0.27watt of heat in that ant-sized regulator.
About the maximum at which it will shut down from overheating.
Leo..

It is in fact, the same story as the Arduino (UNO).

Yes, it has a regulator, and a "Vin" pin. Yes, the regulator is specified up to 20 V.

So you can power it with a "higher" voltage, unless you want to transmit. :grinning:

Paul__B:
So you can power it with a "higher" voltage, unless you want to transmit. :grinning:

Wawa:
Powering the board with 5volt on the 3.3volt pin is a sure way of frying the ESP WiFi module.
You should power the module with a 5volt cellphone charger on the USB socket.
Or with/through a powebank, connected to the USB socket.
Leo..

So if I understand correctly, I may see some issues with the WiFi module powering the board with 5V through the 3v3 input? I'm currently powering it through the 3v3 with no issues, but I'm trying to get a final design nailed down and would like to minimize issues.

It's a pain to have to unplug the power every time I want to connect to USB using VIN. And it makes troubleshooting some parts of the program problematic, such as the excess noise a mic pics up if powered via USB. Is there any way I can put power into VIN but still keep the USB connected?

It shouldn't be a problem to power the NodeMCU with 5volt on the V-in pin, while connected to USB (for uploading).
The NodeMCU has a diode between V-in and USB power, to protect the PC from harm (assuming you haven't fried that already with your experiments).
If this is for your wearable project, then consider powering the NodeMCU with a powerbank, connected to the USB socket.
Leo..

dlovinger:
So if I understand correctly, I may see some issues with the WiFi module powering the board with 5V through the 3v3 input? I'm currently powering it through the 3v3 with no issues,

Yes, but i thought you were powering it with 3.3v on the 3.3v pin !? only 3.3v should power the 3.3v pin !!!
If you're powering with a higher voltage only use the vIn !
When you start to power the vIn pin with voltages much higher then 5v the unit may still work, but then the heat that the regulator needs to dissipate may be more than it's capable of, causing an overheat shut-down, which causes a reset.
If you have your own 3.3v regulator (connected to the 3.3v pin) you could put a heatsink. or you could put a 5v regulator and connect it to the vIn.

dlovinger:
I'm using an ESP8266 NodeMCU and I'm curious about power. I typically power the board with a 5V wall plug source through the 3V3 pin.

Supplying 5V at the 3V3 pin presents 5V to the ESP8266 component which is well above its voltage rating. Stop doing this.

This is because I've read that powering via the VIN pin and USB at the same time could fry my USB port

The NodeMCU boards that I've used (LoLin "V3" and WeMOS) have a protection diode such that 5 V presented at VIN can not back feed into the USB port. This is why it's important that you identify the specific NodeMCU board that you're using as there are several versions that have adopted this name.

MrMark:
Supplying 5V at the 3V3 pin presents 5V to the ESP8266 component which is well above its voltage rating. Stop doing this.
The NodeMCU boards that I've used (LoLin "V3" and WeMOS) have a protection diode such that 5 V presented at VIN can not back feed into the USB port. This is why it's important that you identify the specific NodeMCU board that you're using as there are several versions that have adopted this name.

Alright, got it. I'm using the ESP8266 ESP-12E NodeMCU (Amazon.com: HiLetgo 1PC ESP8266 NodeMCU CP2102 ESP-12E Development Board Open Source Serial Module Works Great for Arduino IDE/Micropython (Small) : Electronics). I've read all sorts of conflicting things online about whether or not I'll fry a USB port, but it seems the consensus here is that there's protection against that and I can safely use VIN and connect to USB at the same time. I'll start doing this. Thanks for the help everyone.

We remain curious as to whether you were truly feeding 5 V into its 3.3 V rail?

Paul__B:
We remain curious as to whether you were truly feeding 5 V into its 3.3 V rail?

I was, which I now realize is not the best idea. But it has actually worked just fine for ~5 months, with as much as 10A going in at times.

If the 10A was actually going into the 3.3v pin the board would be on fire (that's 50 watts, it would start smoking within seconds)

I've heard of people powering ESP8266's at 5v, not realizing you're not supposed to do that - those cheapo ESP8266 chips are tough as nails. You really shouldn't do that though.

How do you know there was 10 amp going through it. It would release the magical smoke at much less than that.

DrAzzy:
those cheapo ESP8266 chips are tough as nails.

That is not my experience..

Deva_Rishi:
That is not my experience…

How did you manage to trash one?

I frequently hear stories of people running them at 5v long term not realizing they are 3.3v devices, and I haven’t managed to damage any of mine.

I've managed to trash many, although i mainly blame my high power switching power supply i have always fed them through a 3.3v regulator. I have 2 main ways of connecting them 1 is to the a softSerial on an Arduino which ever since i am using opto-couplers in between has been safe (hwSerial has never been an issue) and the other way is by connecting 1 pin(gpio0) to a 7400 TTL input (5v) and even that has been causing fried chips my suspicion is that an ESP pin in output mode is rather sensitive to anything over 3.3v applied to it, and strange peaks in the power supply can also problems.

dlovinger:
I was, which I now realize is not the best idea. But it has actually worked just fine for ~5 months, with as much as 10A going in at times.

10A is hard to believe.