DS1556 Maxim, DS1556 Datasheet - Page 9

• Manufacturer Part Number: DS1556
• Description: The DS1556 is a full-function, year-2000-compliant (Y2KC), real-time clock/calendar (RTC) with an RTC alarm, watchdog timer, power-on reset, battery monitor, and 128k x 8 nonvolatile static RAM
• Manufacturer: Maxim

DS1556 1M, Nonvolatile, Y2K-Compliant Timekeeping RAM
Figure 3. Clearing IRQ Waveforms
CE=0
The IRQ/FT pin can also be activated in the battery-backed mode. The IRQ/FT will go low if an alarm
occurs and both ABE and AE are set. The ABE and AE bits are cleared during the power-up transition,
however an alarm generated during power-up will set AF. Therefore, the AF bit can be read after system
power-up to determine if an alarm was generated during the power-up sequence. Figure 4 illustrates alarm
timing during the battery-backup mode and power-up states.
Figure 4. Backup Mode Alarm Waveforms
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