I'm going to design a system to start/stop and control from remote the charge process for my eBike battery.
I am stuck on the current sense circuit as, due to chip shortage, I have not found a suitable current sense amplifier with a high common mode voltage from my PCB supplier.
I changed my design in order to go with low-side measurement and ended designing this circuit.
The sensing resistor is 4 mOhm and since the max current is 5 Amps the max voltage across the shunt will be 20mV.
I used a precision opAmp with a low input offset voltage (typ. 2uV). The resistor values give a gain of around 110 and add an offset of 0.2V to the output since my ADC is linear between 0.15 and 2.45V and any voltage below 0.15V is sampled as 0.
The charging process is controlled with a pair of Mosfets (to avoid reverse current through the Mosfet body diode).
The circuit is not isolated and the ground is common also with the MCU (an ESP32 board).
I'm not a very big seasoned expert and I'm not entirely sure if this circuit will fit and what the drawbacks might be when measuring the current from the low side.
Any comment or suggestion is really appreciated.
Thanks
I am stuck on the current sense circuit as, due to chip shortage, I have not found a suitable current sense amplifier with a high common mode voltage from my PCB supplier.
I changed my design in order to go with low-side measurement and ended designing this circuit.
The sensing resistor is 4 mOhm and since the max current is 5 Amps the max voltage across the shunt will be 20mV.
I used a precision opAmp with a low input offset voltage (typ. 2uV). The resistor values give a gain of around 110 and add an offset of 0.2V to the output since my ADC is linear between 0.15 and 2.45V and any voltage below 0.15V is sampled as 0.
The charging process is controlled with a pair of Mosfets (to avoid reverse current through the Mosfet body diode).
The circuit is not isolated and the ground is common also with the MCU (an ESP32 board).
I'm not a very big seasoned expert and I'm not entirely sure if this circuit will fit and what the drawbacks might be when measuring the current from the low side.
Any comment or suggestion is really appreciated.
Thanks