MM58274C

MM58274C Microprocessor Compatible Real Time Clock April 1991 MM58274C Microprocessor Compatible Real Time Clock General Description The MM58274C is fabricated using low threshold metal gate CMOS technology and is designed to operate in bus oriented microprocessor systems where a real time clock and calendar function are required The on-chip 32 768 kHz crystal controlled oscillator will maintain timekeeping down to 2 2V to allow low power standby battery operation This device is pin compatible with the MM58174A but continues timekeeping up to tens of years The MM58274C is a direct replacement for the MM58274 offering improved Bus access cycle times Features Y Y Y Y Y Y Applications Y Y Y Y Y Y Y Y Y Point of sale terminals Teller terminals Word processors Data logging Industrial process control Same pin-out as MM58174A MM58274B and MM58274 Timekeeping from tenths of seconds to tens of years in independently accessible registers Leap year register Hours counter programmable for 12 or 24-hour operation Buffered crystal frequency output in test mode for easy oscillator setting Data-changed flag allows simple testing for time rollover Independent interrupting time with open drain output Fully TTL compatible Low power standby operation (10 mA at 2 2V) Low cost 16-pin DIP and 20-pin PCC Block Diagram TL F 11219 – 1 FIGURE 1 TRI-STATE is a registered trademark of National Semiconductor Corp MicrobusTM is a trademark of National Semiconductor Corp C1995 National Semicon...