Other Parts Discussed in Thread: LM324A
My customer using op amp as integrator for gain & adding bias to analog signal (please see the illustration below), Op Amp V+ = 3.3V, V- = 0V
The usage is that want to shift audio analog signal up 1.65V to get it into MCU ADC to process (MCU ADC input range 0~3.3V)
For both LMV641 & LM324A, the spec for abs. min input pin voltage should no lower than -0.3V:
Is this due to protection diode on the input pin?
LMV641’s spec has no internal block diagram so not sure.
LMV641 was permanently damaged after gave vin- analog sine tone signals over 500mVrms (over 700mV ~ -700mV), though LM324A had no issue with 2Vrms input
- Is the absolute min & max voltage add/minus 0.3V from the supply voltage due to protection diode? Or is there other concerns?
- If using LM324A for this application (Vin- can range from 2.8V ~ -2.8V) seems no problem so far, though is there any long term concern? Or we really need op amp which has negative voltage supply on V- for this application?