ACS709 Current Sensor math to do 3.3V Vcc

Support Sensors
1

I am using a ACS709 Current Sensor at 3.3V Vcc and i want to make sure my is correct to get the correct output.

For Vcc = 5V your page says:
VIOUT = (0.028 V/A * i + 2.5 V) * VCC / 5 V

By that logic, my formula should be
VIOUT = (0.09 V/A * i + 1.65 V) * VCC / 3.3 V
Because the sensitivity is 90 mV/A.

Is this correct?

2

Hi,

With the exception of your output sensitivity, your formula is mostly correct. As we state at the top of the “Overview” section of the sensors product page, the output sensitivity should be 18.5 mV/A when Vcc is 3.3 V, so your formula should be:

V_{IOUT} = \left(\frac{0.0185V}{A}i + 1.65 V\right)\frac{V_{CC}}{3.3 V}

-Dan

3

Thanks! I am not sure why that isn’t mentioned in the datasheet.