The Microchip 24LC00T-I/OT is a 128-bit serial EEPROM organized as 16 x 8 bits, communicating over an I²C bus at up to 400 kHz. It is a non-volatile memory intended for small configuration parameters, serial numbers, calibration constants, or unique identifiers — not firmware storage. The 3.5 µs access time is adequate for a read during a power-up sequence or a periodic poll, but it won't keep up with a streaming data log.
That is useful when the board already carries both rails — you can power the EEPROM from whichever is cleaner or more available. The write cycle time of 4 ms per word or page means the bus is tied up for that duration after a write — firmware should check the acknowledge polling or add a delay before the next I²C transaction.
Package and footprint — SOT-23-5 on the board
The 24LC00T-I/OT is supplied in a SOT-23-5 package (SC-74A, SOT-753 equivalent). The five-pin footprint is compact — about 2.9 mm x 1.6 mm — and suits space-constrained designs like sensor modules or dongles. It is a surface-mount part, so reflow soldering is the intended assembly method. The package is ROHS3 compliant per the listing.