I have a very simple Lead-Acid battery charger with slow (1kHz) PWM regulator.
I would like to add current and voltage measurement (with PIC18F ADC - 200kSPS).
I have no problem with voltage measurement, but I'm not sure about my shunt and current measurement.
2SK2554 transistor is logic-level, opens completely at Vgs = 4V, it has Id over 30A at Vgs 2.5V.
Maximum voltage on shunt will be no more than 1V.
I don't expect more than 10A current (this is powered from 100W power supply with 10A fuse).
PWM signal is 5V level.
Can I avoid high-side current sensing and place shunt at transistor source like this?
At 10A current voltage on shunt will be 1V so Vgs will be 4V. At 25A current there should be still 2.5V on gate, so transistor will not blow up and everything else will be fine, right?
Can I avoid "hardware" filter at ADC inputs and filter measurements "digitally" in microcontroller software (maybe by calculating average from 20-100k samples taken at 100kSPS)?