PCF2127ATSLASH1 datasheet(45/80 Pages) NXP

45 / 80 page

PCF2127A_2

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Product data sheet

Rev. 02 — 7 May 2010

45 of 80

NXP Semiconductors

PCF2127A

Integrated RTC, TCXO and quartz crystal

8.13 Interrupt output, INT

PCF2127A has an interrupt output pin INT which is open-drain, active LOW. Interrupts

may be sourced from different places:

• second or minute timer

• countdown timer

When SI, MI, CDTIE, WD_CD, AIE, TSIE, BIE, BLIE are all disabled, INT will remain high-impedance.

Fig 25. Interrupt block diagram

BLF: BATTERY

LOW FLAG

SET

set battery

low flag, BLF

to interface:

read BLF

BLIE

001aag070

from battery

low detection

circuit: clear BF

CLEAR

BF: BATTERY

FLAG

SET

set battery

flag, BF

to interface:

read BF

BIE

from interface:

clear BF

CLEAR

TSFx: TIMESTAMP

FLAG

SET

set timestamp

flag, TSFx

to interface:

read TSFx

TSIE

from interface:

clear TSFx

CLEAR

AF: ALARM

FLAG

SET

set alarm

flag, AF

to interface:

read AF

AIE

from interface:

clear AF

CLEAR

WDTF:

WATCHDOG

TIMER FLAG

SET

WATCHDOG

COUNTER

to interface:

read WDTF

WD_CD[1:0] = 00

WD_CD[1:0] = 01

MCU loading

watchdog counter

CLEAR

CDTF:

COUNTDOWN

TIMER FLAG

SET

COUNTDOWN

COUNTER

to interface:

read CDTF

CDTIE

INT pin

WD_CD[1:0] = 01

from interface:

clear CDTF

CLEAR

PULSE

GENERATOR 2

TRIGGER

CLEAR

MSF:

MINUTE

SECOND FLAG

SET

MINUTES COUNTER

SECONDS COUNTER

to interface:

read MSF

SI/MI

TI_TP

from interface:

clear MSF

CLEAR

PULSE

GENERATOR 1

TRIGGER

CLEAR

PCF2127AT/1 Datasheet(PDF) 45 Page - NXP Semiconductors

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