Page 351 of the datasheet tells us ATmega168-20PI is the standard DIP, ATmega168-20PU is the unleaded version. I'd buy whichever is cheaper.
-20 for 20MHz version, P for DIP, I for industrial temp range, U for unleaded (RoHS).
-j
Page 351 of the datasheet tells us ATmega168-20PI is the standard DIP, ATmega168-20PU is the unleaded version. I'd buy whichever is cheaper.
-20 for 20MHz version, P for DIP, I for industrial temp range, U for unleaded (RoHS).
-j