amplificatore kamaz
This IC is rated at 85C. That's why I also think that there is a problem with my circuit/ op-amp spec.
The temperature is measured by a temperature IC with I2C interface going back to the same PIC. The temp IC and the op-amp are about 15cm away from each other, but all the equipment is in the same heat chamber with controllable ambient temperature. The actual temperature of the op-amp could be higher than 55C when the problem starts, but it cannot be higher than 75C as this is the ambient temp inside the chamber.
The ADC datasheet says that the input source impedance should be less than 2.5K for the convertion accuracy to be within the spec of +-0.5LSB. I will have to use an op amp because I need the signal to be phase shifted. This is why I used this amplifier in an inverting configuration.
Could this problem happen because of input bias current, offset voltage drift and/or open loop gain variation? What parameters would be most critical in the datasheet?