M48T212A

M48T212A 3.3V TIMEKEEPER® CONTROLLER PRELIMINARY DATA s CONVERTS LOW POWER SRAM into NVRAMs YEAR 2000 COMPLIANT (4-Digit Year) USES SUPER CAPACITOR or LITHIUM BATTERY (User Supplied) BATTERY LOW FLAG INTEGRATED REAL TIME CLOCK, POWER-FAIL CONTROL CIRCUIT AUTOMATIC POWER-FAIL CHIP DESELECT and WRITE PROTECTION WATCHDOG TIMER WRITE PROTECT VOLTAGES (VPFD = Power-fail Deselect Voltage): – M48T212A: 2.7V ≤ VPFD ≤ 3.0V MICROPROCESSOR POWER-ON RESET PROGRAMMABLE ALARM OUTPUT ACTIVE in the BATTERY BACKED-UP MODE 4 A0-A3 A E EX W G WDI RSTIN1 RSTIN2 X0 XI M48T212A IRQ/FT RST E1CON E2CON VCCSW VOUT s s s s 44 1 SOH44 (MH) s s s s s Figure 1. Logic Diagram VCC VCAP DESCRIPTION The M48T212A is a self-contained device that includes a real time clock (RTC), programmable alarms, a watchdog timer, and two external chip enable outputs which provide control of up to four (two in parallel) external low-power static RAMs. A built-in 32.768 kHz oscillator (external crystal controlled) is used for the clock/calendar function. Access to all TIMEKEEPER functions and the external RAM is the same as conventional byte-wide SRAM. The 16 TIMEKEEPER Registers offer Century, Year, Month, Date, Day, Hour, Minute, Second, Control, Calibration, Alarm, Watchdog, and Flags. Externally attached static RAMs are controlled by the M48T212A via the E1CON and E2CON signals (see Table 4). Automatic backup and write protection for an external SRAM is provided through VOUT, E1CON and E2CON pins. (Users are urg...