January 31, 2021
1US222 / K122UN2 - dual stage audio amplifier : weekend die-shot1US222 is a dual stage audio amplifier (later renamed to K122UN2) - not an opamp. Date code is VI 1971 - so this year we can celebrate half a century since it's manufacturing. Scratches and dirt are not mine - apparently simple microchips were quite forgiving. Schematics below.
Die size 1392x1412 µm.