I want to measure the current of 12V lead acid battery for charger application. So mostly, I need bidirectional current sensing.The current measurement can be done using shunt resistor or using hall effect sensors. I see the shunt current sensors comes with I2C or SPI analog output. But the ACS712 can be directly hooked up to the analog pin of MCU. Do I need to use any op amps here to maintain the current gain. Or just use ACS712 sensor hooked up directly to the battery terminals and sensor output terminals to the MCU. Please suggest me.
ACS712 has 3 different types. These are 5A, 20A and 30Ampere versions. The sensitivities are 185 mv/A , 100mv/A and 66mV/A . Actually if these values are good for your system, just hook up the VIOut pin directly to MCU ADC input pin. Be sure VDD of ACS712 is same as VADC voltage of MCU.
If you need more you can use amplifier circuit for increase the sensitivity up to 610mV/A.