Other Parts Discussed in Thread: TMCS1100
Hi,
I have read through the forum but have been unable to find the answers to my questions. I am hoping I can find some help by posting here.
I am trying to achieve inline current sensing of a BLDC motor. I am planning to use a 0.82mOhm shunt resistor (9W & 70*C TCR). My motor/power source is 12V. I will supply the INA240 with 5V. I have wired it for Vs/2 voltage reference with ref1 to 5v and ref2 to ground, yielding 2.5V. The output of the INA240 is going to an ADC (analog) pin on the ATMega328p. I will be sensing between 0A to 30A. From my calculations I have got Vdiff = 25mV and PrSense = 0.747W. IN- is connected to the motor phases and IN+ is connected to the mosfets (sources (high-side)/drains(low-side)), either side of the shunt resistors.
I have read through the datasheet but I have a few questions.
- Is one shunt resistor on each motor phase, each connected to the one INA240 a correct configuration? (3 shunt resistors & 1 INA240 total) Or do I need 3 INA240's?
- I was originally planning to use the INA240A4 with 200V gain, but I am since questioning that perhaps that is too much of a gain? I am a little confused about the gain. Could you advice me on a suitable gain for my project?
I hope you have all the information you need, I look forward to replies! Thank you in advance.