INA226 for sensing Motor current

Hello Eason,

You described the application as low side sensing in your post, but the picture you attached shows a high side shunt.  If your application is similar to Figure 23 in the INA226 datasheet then it is considered high side sensing.

We need more information to be able to assist.  Can you provide a schematic of your circuit?  Information about what the INA226 is connected to would be helpful.

I can see no reason why a load current of 15A through a 3mΩ would cause any issues for the INA226, so any damage to the chip may have come from your setup.  Do you have any pictures of your setup?

Best regards,

Kareem Moulana

Dear  Kareem Moulana,

you are right , this is high side current sensing. our design circuit is as below, Thanks.

Hello Eason,

If you could create another setup of the INA226 with your circuit, I would like to see scope shots of your common mode voltage and your supply voltage. As you monitor them, cross reference the values you see with the limits we establish in the Absolute Maximum Ratings section of the datasheet. Even transients can be damaging to the chip.

Out of curiosity, is it correct to assume your Vbus pin connected to the Vin- pin in your circuit as implied by your first picture?

What motor are you using in your circuit?

Best regards,
Kareem Moulana

Dear Kareem Moulana,
Having double checked the Vbus pin, it is definitely connected to Vin+. In our experiment, we use DC electronic load (~10A) to test the sensing function, then it seems work very well without any problem, but once we connected to our DC motor equipment of car, it blow up after running few times.
I am not sure if we should add some protection components.
please give me some suggestion, Thanks.

Hello Eason,

I believe you may be experiencing transient spikes on your supply voltage and/or common voltage pins. Please obtain oscilloscope screenshots measuring your supply voltage and common voltage on power-up with your setup.

If you are experiencing large spikes on your supply, you may consider employing a (3V-5V) zener diode between supply and ground to afford you some protection.

For a good resource dealing with transient protection, please reference the current shunt monitor FAQ.  Specifically the TI design TIDA-00302, which is focused on transient robustness.

Regards,
-Kareem

Hi, Kareem,

I am the system designer. Eason is our agent FAE. This system is installed in car to control electric window motors, INA226 is designed to sense current through motors to do electric windows prevent clamping.

The simplified system diagram is as below,

When motor starts working(current is about 2A), INA226 is working well. When motor stalls(current is about 12A), INA226 burns out.

Please advice why this system cannot work while motor stalls. Thanks in advance.

Regards,

roy

 

Dear Sir,

We have some problem need to be clarification in our application. In our Motor current sensing, we use both High side current sensing at Motor forward and Low side current sensing at Motor reverse. I learned INA226 is a Bi-Directional current sensor, is this workable for our application?

Moreover, When the motor starts working(current is about 2A), INA226 is working well. When the motor stalls(current is about 12A), INA226 burns out (we tried to measure the  pin impedance of the fail unit  , we found both VIN+/VIN- are damaged.

Do you think it will be damaged by over current? or over voltage spike?

Please kindly help on this issue and I am looking forward to having your comment , Thanks.

Dear Kareem,

this is the layout file below , please let me know your thoughts, Thanks.

Eason,

Thank you for the information.  There are a few points of concern with what I'm seeing.

Your shunt resistor's appearance is concerning.  Is the resistor damaged or blown?  To prevent your resistor from blowing, make sure to size its power rating with a healthy safety margin taking into account the maximum stall current.  There appears to be bubbling/excess flux and solder on the shunt, which do not bode well.  Solder and flux add resistance, which combined with a large stall current could cause an unexpectedly large differential voltage across your shunt resistor.  Please measure what the effective shunt resistance is on the board.

During a stall current the power supply will sag, and when it is relieved the supply can rebound higher than its nominal value.  Please attach scope shots of the common mode voltage as well as the power supply for the INA226 during normal conditions and during the stall event.

Best regards,

Kareem Moulana