DS1685/DS1687 3V/5V Real-Time Clocks

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Figure 4. Update-Ended And Periodic-Interrupt Relationship

EXTENDED FUNCTIONS

The extended functions provided by the DS1685/DS1687 that are new to the RAMified RTC family are accessed by

a software-controlled bank-switching scheme, as illustrated in Figure 5. In bank 0, the clock/calendar registers and

50 bytes of user RAM are in the same locations as for the DS1287. As a result, existing routines implemented

within BIOS, DOS, or application software packages can gain access to the DS1685/DS1687 clock registers with

no changes. Also in bank 0, an extra 64 bytes of RAM are provided at addresses just above the original locations

for a total of 114 directly addressable bytes of user RAM.

µs.

UIP

UF

PF

1 second

t

PI