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4-BIT PARALLEL INTERFACE REAL TIME CLOCK MODULE
RTC-72421/72423
■ Overview
The RTC-72421/RTC-72423 module is a real time clock that can be connected directly to a microprocessor's bus. Its built-in
crystal unit enables highly accurate timekeeping with no physical access required for adjustment and, since there is no need
to connect external components, mounting and other costs can be reduced.
In addition to its time and calendar functions, the RTC-72421/RTC-72423 enables the use of 30-seconds correction and
fixed-period interrupt functions.
The RTC-72421/RTC-72423 module is ideally suited for applications requiring timing management, such as personal
computers, dedicated wordprocessors, fax machines, multi-function telephones, and sequencers.
● Built-in crystal unit removes need for adjustment and reduces installation costs
● Use of C-MOS IC enables low current consumption (5
µA max, at VDD=2.0V)
● Compatibility with Intel CPU bus
● Address latch enable (ALE) pin compatible with multiplex bus CPUs
● Time (hours, minutes, seconds) and calendar (year, month, day) counter
● 24-hour/12-hour switchover and automatic leap-year correction functions
● Fixed-period interrupt function
● 30-seconds correction (adjustment) function
● Stop, start, and reset functions
● Battery back-up function
● Same mounting conditions as general-purpose SMD ICs possible (RTC-72423)
* Pins and functions compatible with the SMC5242 series
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