Voltage Supply to INA226

Projects General Guidance
1

I had an INA226 talking happily to a nano in a pretty complicated set up and after several months 24/7 the sketch froze and I could not get the INA226 to initialize

To trouble shoot I tried a bunch of things but was pretty sure the board was fried.

So I took a new ina226 alone (ie. out of the set up) and I connected it to nano only.

In my previously opoerating system and for the test of the new nano, i used a cheap 5v buck converter from a 12volt wall wart, setting the buck output at 5.00v. i ran the “+” out from buck into the 5v pin of the nano and the vcc pin of the ina226. I ran the “-” output of the buck to nano ground and INA226 ground. I connected SDA to A4 and SCL to A5.

I used a “data only” usb cable to the nano to avoid any powering issues.

I then uploaded a sketch to read the buss voltage (nothing else connected to INA226) and it worked perfectly …. for about an hour.

I came back to find the sketch frozen and stuck at INA.begin. I tried an I2C scanner but it hangs up. SCL and SDA or held low at 2v, even though they were running correctly near 5v when all was well. Pretty sure i fried another ina226. the nano is fine when 226 disconnected.

All i can think is bad power/ripple/spike.

Can anyone think of any other ways i might have fried an INA 226 connected only to a nano and running happily?

2

You might have answered your own question.

Why the 12volt supply.

Assuming this is a classic Nano v3...
You can power the Nano with a 5volt cellphone charger, connected to the USB socket.
The Nano should be OK with 12volt on V-in, as long as you don't draw much more from it's pins than that INA226 board.
A safe option is a buck converter set to 6 or 7volt, and connected to the Vin pin.
Leo..

3

i used 12v supply to test because my set up is on a boat with 12v supply.

i had the buck converter set at 5.00 and the nano is fine.

cant figure out how if fried the ina226

i

4

Since the limit for the ina226 is 5.5 volts, did you measure the 5 volts to see if it was still 5 volts?

5

yup. measured 5.00 before connecting and after

6

What does the INA226's supply voltage read with your meter set to AC volts?

7

Which buck converter (link please).
Did you add an electrolytic cap to it's inputs, to kill inductive spikes from the boat wiring.
Leo..

8

i measured 10 volts ac with + lead of multimeter on buck plus and -lead on buck minus. I measured 0v ac with the leads reversed. Copilot AI said it is only real ripple if it appears with both polatiies and 10 volts ripple doesnt make sense to me anyway.

9

This is the buck i used. https://www.amazon.ca/DEVMO-Step-Down-Adjustable-Converter-Voltmeter/dp/B07R7T4SLH?pd_rd_w=HcaIY&content-ide5be1e8b6578&pf_rd_r=C13YN3QBW5T0TZCBG2ZP&pd_rd_wg=cVmOu&pd_rd_r=577a85c4-f0e0-41ec-8440-7a2f5ee696ce&pd_rd_i=B07R7T4SLH&ref_=pd_basp_d_rpt_ba_s_1_cp_t&th=1

10

I had no caps on the boat when it worked for many months but will be adding them if i get this issue sorted on the bench. I had no caps on bench test sbut there is nothing present to cause spikes. I will try caps even on next bench test. I have also ordered a proper dcdc converter to take 12v to 5v for various 5v needs in my larger set up on boat and LDO to take that to 3.3 for INA226 board. That plus caps should give a pretty gentle supply for the ina226 breakout board

11

If the nano is at 5V then that makes no sense. You will probably have issue with the I2C bus.

12

thanks for that. i know it is very sketchy to trust AI, which is why i am asking real folks here. Copilot AI says of mixed voltage set up:

So in your final setup:

  • Nano VCC: 5 V

  • INA226 VCC: 3.3 V from LDO

  • Onboard pullups: 10 kΩ to 3.3 V (because VCC = 3.3 V)

  • Optional extra pullups: you can add 10 kΩ or 4.7 kΩ to 3.3 V if you want a stronger bus, but you don’t have to.

I²C then runs as a true 3.3 V bus, with the Nano just acting as a 5 V‑powered device that happily reads 3.3 V as HIGH. No 5 V ever touches SDA/SCL.

That made sense to me.

13

For I2C the LOW is just as important if not more.
With 3.3V you reduce your noise margin on the bus, making it more susceptible to noise. There is no reason not to use 5V.
Why not power the nano with 9V via Vin and use the 5V nano output to power the INA226 and pullups

14

Thanks again for that. over the 5 years or so that i have been running this set up i have probably burnt 6 INA226 boards. The cost is trivial but at least once it happened at an inopportune time. I am assuming that is from voltage fluctuations and since the ina226 chip itself is actually 3.3 volts I thought that 3.3 might be safer in long term use.

I dont want to use Vin at 9 because that means shedding heat inside a sealed bud box that seems necessary in salt air environment. The nano runs cold with 5volts into the 5v pin. I have never had to replace one. Also, at one point i was having trouble with noise in the voltage sensing function of the nano and someone suggested to me that direct feeding of a clean 5v supply (perhaps my present issue) into the 5v pin was a better path for noise reduction and it really did stabilize the voltage measurements a lot in the very noisy environment on my boat. Finally, i was seeing infrequent sags on the 5v rail when powered from a buck converter set to 9v (might have been 8v) and that sometimes seemed to cause the I2C to lock up. What is your impression of that analysis? I am guessing that you might say that 5v is the right voltage to use and that i need to get a better handle on the cleanliness and stability of the power supply rather than looking for headroom from spikes? Again thank you for your time and thoughts.

15

No it is not, it can run on any voltage between 2.7 and 5.5V with an absolute max of 6V. Someone is obviously providing you with a lot of erroneous information.

I dont want to use Vin at 9 because that means shedding heat inside a sealed bud box

The amount of heat is minuscule and it would probably keep you from burning out the INAs

16

That means the nano reset for some reason,

17

crap … you are right … should have checked the data sheet from TI.

you are also right about my sources … its a jumble of a buddy, this forum, hard knock failures, and AI. I know is dangerous but as a hobby its fun to me as long as people are so willing to be helpful.

So, I will go to a well regulated 5 volts fed to Vin, not to the +5V pin.
I will use nano’s +5v pin to power ina226.

I do have a lot on my local ground bus. shields on 4 voltage sensing wires from the battery cells, the battery negative for voltage reference, coils from six 5v relays, nano ground, ina226 ground and power supply ground. That ground bus is wired by a 8AWG cable to boat ground and no where else.

I did have it this way at one time but with a cheap buck converter from boat main bank battery, as indicated I was getting a lot of burnt INA226 boards.

I have ordered a Mean Well dc-dc converter to implement your suggestions. Will be sure to add caps at nano and at ina226.

Does that converter sound right and do you have any other suggestions to protect INA226.

Appreciate your patience

18

Vin need to be between 7V and 12V
Is the only thing conneced to the Nano the INA226?

The ground from the INA226 should connect directly to the Nano GND and then the Nano GND to the power supply ground. You don't want the signal ground from the INA to the Nano going through another ground that may carry large currents.

19

right … i knew that 9v was a good target voltage for Vin and above 5 … brain fart.

To the nano are (a) 6 digital pins driving 6 small blue box songle, relays, ina226, and future LCD with i2c backpack (not essential).

i will also wire the grounds as you suggest. thanks for that.

20

I hope you mean relay modules and not just a relay.
You can't drive relay coils directly from a Nano, you will evenually damage the Nano pins.