I made a minimal change to a product in production for 3 years. 3 out of 5 my prototype boards do not calibrate. Calibration depends on the slew rate and settling time of the OPA336U op amps in the circuit.
The OPA336U ICs in my prototypes look different from previous components. The lead frame is not the same and the TI label is different. Previous parts have bright white markings. Markings on the new OPA336U ICs are dull. Did T.I. change the marking? Is it possible that slew rate and settling time also changed?