M48T08 M48T08Y, M48T18 5 V, 64 Kbit (8 Kb x 8) TIMEKEEPER SRAM Features Integrated ultra low power SRAM, real-time clock, power-fail control circuit, and battery BYTEWIDE RAM-like clock access BCD coded year, month, day, date, hours, minutes, and seconds Typical clock accuracy of 1 minute a month, at 28 25 C 1 Automatic power-fail chip deselect and WRITE protection PCDIP28 WRITE protect battery/crystal CAPHAT V = power-fail deselect voltage): PFD M48T08: V = 4.75 to 5.5 V CC 4.5 V V 4.75 V PFD M48T18/T08Y: V = 4.5 to 5.5 V CC 4.2 V V 4.5 V PFD SNAPHAT Software controlled clock calibration for high battery/crystal accuracy applications Self-contained battery and crystal in the CAPHAT DIP package Packaging includes a 28-lead SOIC and SNAPHAT top (to be ordered separately) SOIC package provides direct connection for a snaphat top which contains the battery and 28 crystal 1 Pin and function compatible with DS1643 and JEDEC standard 8 K x 8 SRAMs SOH28 RoHS compliant Lead-free second level interconnect June 2011 Doc ID 2411 Rev 11 1/31 www.st.com 1Contents M48T08, M48T08Y, M48T18 Contents 1 Description . 5 2 Operation modes 8 2.1 READ mode 9 2.2 WRITE mode 10 2.3 Data retention mode . 13 2.4 Power-fail interrupt pin . 13 3 Clock operations . 14 3.1 Reading the clock . 14 3.2 Setting the clock 14 3.3 Stopping and starting the oscillator . 15 3.4 Calibrating the clock . 15 3.5 V noise and negative going transients . 18 CC 4 Maximum ratings . 19 5 DC and AC parameters 20 6 Package mechanical data 23 7 Part numbering 27 8 Environmental information . 29 9 Revision history . 30 2/31 Doc ID 2411 Rev 11