I have a 50 Amps 75mV current shunt (in a 12V line) with an ADS1115 amplifier hooked up to an arduino.
I now fried two ADS1115 boards (smoke visible...).
First time I had VDD connected to 5V and read somewhere it should be 3,3. Changed it (and without A0 and A1 connected) it worked. When I connected A0 and A1 it again immediately fried the chip...
vorstendom:
I have a 50 Amps 75mV current shunt (in a 12V line) with an ADS1115 amplifier hooked up to an arduino.
I now fried two ADS1115 boards (smoke visible...).
You have just discovered that shunt voltage has to stay withing the supply extremes of the A/D converter.
Even with the shunt in the ground line, and a differential hookup, you can only measure positive voltages.
Maybe you should use an INA219 breakout board (Adafruit/ebay).
Voltage, high-side bi-directional current, PGA, and 12-bit A/D, all in one.
Just connect the onboard 0.1ohm shunt (current inputs) to the external shunt.
Leo..
Yes I know 16 bit is not 16V I am just a bit of an electronic noob
But I now do understand why it fried hooking up more than .3+VDD.
@MarkT, I did look at boards like you linked to but I am going to use it in a camper and using a 750W 12V DC to 220AC converter I can get up to 60 amps or so and even though for some of those breakout boards it is within specs I trust a shunt more than such a small breakout board with those kind of amps.
@Wawa, Thx for the INA219 tip. I will order one and see how it works. It has more functionality but it is also more expensive and I do not understand what exactly are the benefits if I only would measure the amps through a shunt.
later I will also hook up a solar panel (with a converter) to charge the battery. I thought that would give me negative differential voltage so that I can measure what is used but also what is charged. Is this not correct?
Yes. The INA219 bi-directional. Charging and discharging.
The advantage of measuring high-side (in the + line) is that you don't have to break ground (with a shunt).
A shunt in the ground wire could give all sorts of problems.
Leo..
and I thought I was measuring a differential signal ( so max 75 mV over the shunt...).
I added a link to a quick sketch of the connections. (it seems an image link to a dropbox does not work...)
Taking any input outside the supply range of a chip fries it , the anti-static diodes must have
vaporized instantly in your setup as you had many amps available! That probably saved your Arduino
from being destroyed too.