• State Resolved
  • Locked Locked
  • Replies 1 reply
  • Subscribers 47 subscribers
  • Views 773 views
  • Users 0 members are here
Support feedback
Options
Options
Related

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

INA226: Measuring High Currents

Praveen GD
Guru 57737 points

Part Number: INA226
Other Parts Discussed in Thread: INA190, INA240, DRV425

Hi,

One of our customer is considering INA226/0 for a high current requirement. Can you let us know the best suitable part? Below are the details of requirement.

1. High Side sensing with a Battery of 12V (28V Max).

2. Current Range 200A to 2000A. (Not mA)

3. Bidirectional Sensing required

4. +/- 1% Accuracy required.

With such a requirement, what do you think is the best solution?

If we use INA226, we are worried about Sense resistor value and its Power dissipation.

Regards,

Praveen

  • 0
    TI__Mastermind 26335 points

    Hello Praveen,

    Thanks for reaching out on the forum.  Your requirements are quite challenging to meet for any single current shunt monitor.  To measure up to 2000A with the INA226, you would need a 41uohm resistor, which you would probably need to create through multiple parallel 200u shunts or have one custom manufactured.  I get this value by taking the INA226's max shunt value (81.92mV) and dividing by 2000A.  For this size shunt, board layout also becomes extremely critical.   Aside from this, the INA226 will not get you the level of accuracy you desire.  41uohm * 200A = 8.2mV.  The input offset of the part can be as high as 7.5mV.  Thus your error near 200A would be 91.6% (vos/(I*rshunt)).  Also as you noted, the power dissipation could be quite substantial (163.8W) even with a 41uohm shunt.

    Alternative parts you could use include the INA190 and INA240.  The max errors for these parts over your operating range should be about 1.26% and 1.04 % respectively, neglecting error from shunt tolerance.  The shunts for these parts would be 90uohm and 110uohm.  So their power dissipation will be even larger.

    Alternatively you might consider using a fluxgate sensor, a hall sensor, or an isolation amplifier.   As for using a fluxgate sensor, I would recommend the DRV425.  To understand what is entailed in designing with DRV425, I would read the following: Bus Bar Design Considerations and Bus Bar Theory of Operation.  We also have a TI Design EVM that you can purchase, test, and adapt for your application here.  To assist with the design, I would recommend using the DRV425 System Parameter Calculator found here.