MC146818A

MC146818A I I Advance Information I CMOS \ REAL-TIME CLOCK PLUS RAM (RTC) The MC146818A Real-Time Clock plus RAM is a peripheral device which includes the unique MOTEL concept for use with various microprocessors, microcomputers, and larger computers. This part combines three unique features: a complete time-of-day clock with alarm and one hundred year calendar, a programmable periodic interrupt and square-wave generator, and 50 bytes of low-power static RAM. The MC146818A uses high-speed CMOS technology to interface with 1 MHz processor buses, while consuming very little power. The Real-Time Clock plus RAM has two distinct uses. First, it is designed as a battery powered CMOS part (in an otherwise NMOS/TTL system) including all the common battery backed-up functions such as RAM, time, and calendar. Secondly, the MC146818A maybe used with a CMOS microprocessor to relieve the software of the timekeeping ,~~ workload and to extend the available RAM of an MPU such as the ., “’~:$ ,!!:\’; .\,i,. ,.. MC146805E2. ... . . \}t ,.,.>*t!F\+ {k ~ q Low-Power, High-Speed CMOS ,1, $s,,.. ~;, ~p ~$$~. )>. q Internal Time Base and Oscillator ‘,& Q.%~!* *>sq,.,,\ ,$4:*, $+.~:;;, . ..~. O Counts Seconds, Minutes, and Hours of the Day “’t:>?,. q Counts Days of the Week, Date, Month, and Year ,$: ;<4 , ..! .*:,: q 3 V to 6 V Operation ~t.k ,$,., q Time Base Input Options: 4.194304 MHz, 1.048ti ~~z, or 32.7W ,, , ,,,M, ,)$ f, ,$\<..%.\., ...*<.*$, kHz ,,:,, . ..i,;t~ q Time Base Oscillato...