We have 3 different batches (27E317T, 74ATTHT & 71A19FT). Among them 74ATTHT batch is the best. 27E317T is 70%+ and 71A19FT is 50% failures rate at bench test. All 3 chips logo format are different. I've assumed it was manufactured from different factory. I like to know how to read those batch code and why 74ATTHT is working better than the other 27E317T & 71A19FT.
