We use FAN5333BSX for a LCD backlight driver; it worked well before. However, the new ICs FAN5333BSX (laser mark: 33BL, ordered from digikey) used in recent product samples are very hot, and some of them burnt in a couple of days, and some ICs do not have outputs. After I changed it with an older FAN5333BSX (laser mark: 33BK), it works great, not hot at all. I think this new batch IC with laser mark 33BL has heat dissipation issue. Could you please confirm it with the IC supplier and how can we figure out this issue? We will do mass production soon and need this GOOD IC badly.