Datasheet

DocID12615 Rev 8 39/56
M41T93 Clock operation
56
Figure 19 shows the various signal sources and controlling bits for the IRQ/FT/OUT output
pin.
Figure 19. IRQ/FT/OUT output pin circuit
The timer, oscillator fail detect circuit, alarm 1, and watchdog are ORed together as the
primary interrupt sources. The frequency test signal, FT, is used to enable a 512 Hz output
on the IRQ/FT/OUT pin for calibrating the RTC. When not used as an interrupt or frequency
test output, the pin can be used as a discrete logic output controlled by the OUT bit. The
ABE bit is used to enable interrupts during backup mode.
Operating on V
CC
, all four interrupt sources are available. During backup, the timer and
watchdog are disabled, and the only interrupt sources are alarm 1 and the oscillator fail
detect circuit.
TIMER
TF
OFIE
AI1E
WDOG
OF
Q
PRE
reload
AF1
WDF
OUT
FT
A1IE
OFIE
TIE
w-dog running
ABE
IRQ/OUT/FT
TE
Write OF to 0
to clear
Read FLAGS register
to clear
Write watchdog register
to clear
IRQ/OUT/FT
LOGIC
TI/TP
TIE
AM03013v1