DS1553P Maxim Integrated Products, DS1553P Datasheet - Page 7

• Manufacturer Part Number: DS1553P
• Description: 64K NV Y2KC Real Time Clocks RAM
• Manufacturer: Maxim Integrated Products

When the RTC Register values match Alarm Register settings, the Alarm Flag bit (AF) is set to a 1. If
Alarm Flag Enable (AE) is also set to a 1, the alarm condition activates the
signal is cleared by a read or write to the Flags Register (Address 1FF0h) as shown in Figure 2 and 3.
When
and either
also cleared by a read or write to the Flags Register but the flag will not change states until the end of the
read/write cycle and the
CLEARING IRQ WAVEFORMS Figure 2
CLEARING IRQ WAVEFORMS Figure 3
The
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 back-up mode and power-up states.
IRQ
CE
CE
,
/FT pin can also be activated in the battery backed mode. The
CE=Ø
is active, the
OE
or
ØV
WE
active, but is not guaranteed to be cleared unless t
IRQ
IRQ
/FT signal may be cleared by having the address stable for as short as 15 ns
/FT signal has been cleared.
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RC
IRQ
is fulfilled. The alarm flag is
/FT will go low if an alarm
IRQ
/FT pin. The
IRQ
DS1553
/FT