The Renesas X28HC64SI-90 is a 64 Kbit non-volatile parallel EEPROM organized as 8K x 8 bytes, with a 90 ns access time. The parallel interface allows single-cycle byte reads or writes. The 4.5 V supply voltage places it in the 5 V logic family.
The 28-SOIC surface-mount package keeps the board profile low and is compatible with standard reflow profiles.
Write cycle timing and endurance
The write cycle time is 5 ms per word or page — a byte write ties up the bus for that duration, so the host must either poll the ready/busy status or insert a delay between writes. For bulk programming, a page-write mode (the page size is not specified in the brief, but typical parallel EEPROMs of this density use 64-byte pages) reduces the per-byte overhead.
