The M48T58 M48T58Y 5.0V, 64 Kbit (8 Kb x 8) TIMEKEEPER® SRAM is a Toshiba integrated ultra low power SRAM, real time clock, power fail control circuit and battery product. The product has BCD coded YEAR, MONTH, DAY, DATE, HOURS, MINUTES and SECONDS; frequency test output for real time clock; automatic power fail chip deselect and write protection; write protection voltage (VPFD=power fail deselect voltage): - M48T58: VCC=4.75 to 5.5V 4.5V≤VPFD≤4.75V - M48T58Y: VCC=4.5 to 5.5V 4.2V≤VPFD≤4.5V. The product uses self-contained battery and crystal SNAPHAT™DIP package, including 28-lead SOIC and SNAPHAT®TOP (to be ordered separately). SOIC package provides direct connection to a SNAPHAT housing containing the battery and crystal, and is compatible with JEDEC standard 8Kb x 8 SRAM pins and functions.