The Microchip 24FC04T-I/MUY is a 4-Kbit serial EEPROM organized as 256 x 8 x 2 banks, communicating over an I²C bus at up to 1 MHz. The 450 ns access time is the read-cycle window the master sees; at 1 MHz SCL, each bit is 1 µs wide, so 450 ns leaves comfortable setup-and-hold margin on the bus. The 5 ms page/word write cycle time is the period the EEPROM holds SCL low during a write — firmware needs to account for that delay before starting the next transaction.
Surface-mount only — no through-hole variant in this order code.