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My customer is to monitor input power and report via I2C.
Input is 54V nominal, 60V max. Load is 100% resistive and there is no hotswap. The highest power board is 2500W.
I’m thinking of using INA226-Q1 with low side sensing, and with the input divided by ½, so the max voltage the chip will see is 30V. I think it should be easy enough to multiply this power number by 2 upstream.
Any concerns with this approach? I think it can be done, but I’m not sure what effective resistance I need to maximize the current sensing range. I’m sure I’ll need quite a few in parallel, since it’s ~46A at the highest load at nominal Vo.
Hi Amy,
As long as you use low side sensing you can use this approach. For Bus voltage divider resistors you can refer to Page 6 and 7 of TIDA-00528. Note the INA226 has an input impedance of about 830K Ω between VBUS pin and it’s ground pin.
For the shunt resistor, you don't need resistors in parallel. In fact this is not recommended to avoid accuracy errors due to extra traces. There are shunt resistors with very small values as 1mohm.
With a 46A, 82mV full range of the Rshunt voltage a 1mOhm resistor should be good. You can fins some in this DigiKey link.
Regards,
