Hi,
I'm designing a circuit to measure AC current flow based on the Allegro ACS714 (Hall effect current sensor -> 100mV/Amp). I want to catch a small current, few 10s to few 100s of mA. Setting 100mA as the design goal => and input signal 10mV. ACS714 output is small signal AC at a 2.5V reference.
I have four goals with my measured signal
1. I would like to gain my signal for effective ADC sampling
2. I would like to rectify the signal for ADC
3. I would like to shift the reference to 0V
4. Reduce amplifier bandwidth to reduce high frequency noise
I though this was pretty simple... I AC coupled my signal into an inverting opamp (LMV321 powered with 0-5V) precision rectifier starting with a modest gain of 100. I put a bandwidth reducing cap in the feedback path. I attach a sketch of the circuit.
I built the circuit and my amp output is driving to the positive rail and becomming hot. Am I missing something silly? Ive checked for shorts, diode polarity etc.
I'm designing a circuit to measure AC current flow based on the Allegro ACS714 (Hall effect current sensor -> 100mV/Amp). I want to catch a small current, few 10s to few 100s of mA. Setting 100mA as the design goal => and input signal 10mV. ACS714 output is small signal AC at a 2.5V reference.
I have four goals with my measured signal
1. I would like to gain my signal for effective ADC sampling
2. I would like to rectify the signal for ADC
3. I would like to shift the reference to 0V
4. Reduce amplifier bandwidth to reduce high frequency noise
I though this was pretty simple... I AC coupled my signal into an inverting opamp (LMV321 powered with 0-5V) precision rectifier starting with a modest gain of 100. I put a bandwidth reducing cap in the feedback path. I attach a sketch of the circuit.
I built the circuit and my amp output is driving to the positive rail and becomming hot. Am I missing something silly? Ive checked for shorts, diode polarity etc.