M48T212A Datasheet | STMicroelectronics

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 k Hz 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 urged to insure that voltage specifications, for both the controller chip and external SRAM chosen, are similar). 8 DQ0-DQ7 VBAT- AI03047 March 2000 This is preliminary information on a new product now in development or undergoing evaluation. Details are subject to change without notice. 1/20 Figure 2. SOIC Connections Table 1. Signal Names A0-A3 DQ0-DQ7 XO Address Inputs Data Inputs/Outputs Oscillator Output Oscillator Input Reset 1 Input Reset 2 Input Reset Output (Open Drain) Watchdog Input Bank Select Input Chip Enable Input External Chip Enable Input Output Enable Input Write Enable Input RAM Chip Enable 1 Output RAM Chip Enable 2 Output Int/Freq Test Output (Open Drain) VCC Switch Output Supply Voltage Output Super Capacitor Input Battery Ground Pin (optional) Supply Voltage Ground Not Connected internally RSTIN1 RSTIN2 RST NC XO XI NC NC A NC NC NC A3 A2 A1 A0 WDI E2CON DQ0 DQ1 DQ2 VSS 44 1 43 2 3 42 4 41 40 5 39 6 38 7 37 8 36 9 35 10 34 11 M48T212A 33 12 32 13 31 14 30 15 29 16 28 17 27 18 26 19 25 20 24 21 23 22 AI03048 VCC VOUT VCCSW IRQ/FT EX NC NC NC NC NC G W VBAT- NC E E1CON DQ7 DQ6 DQ5 DQ4 DQ3 VCAP XI RSTIN1 RSTIN2 RST...