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.

INA234: Power calculation issue

Part Number: INA234


Hello,

I am having trouble with calculating the right power via INA234's power register (0x03). The datasheet provides the following equation:

Power [W] = 32 x CURRENT_LSB x POWER

If I were to use it, I would obtain enormous numbers. My test case is the following:

CURRENT_LSB = 8,

Voltage = 23.756 V,

Current = 0.280 A

The above values are read via INA234 IC, but also verified with a multimeter. The power register reading I get at this time is around 418. If I were to use the given equation to get the power:

Power [W] = 32 x 8 x 418 = 107008

The expected power is 23.756 * 0.280 = 6.65168 W

I have noticed that similar power I can get if I divide the power register value by 64:

Power [W] = 418 / 64 = 6.53125

But this is just me guessing.

I would appreciate all feedback on whether the power equation from the datasheet is correct or not, or whether I am doing something wrong...

  • Hi,

    This has to do with the fact that current register is treated as 12-bit (right shift by 4) instead of as 16-bit, yet the power register is 16-bit.

    To calculate the correct power value, we should divide the current LSB (of the 12-bit case) by 16, and use it as the new current LSB in the power equation. In other words, the power should be 32 x (8/16) x 418=6.688W

    Regards, Guang