PCF2127TSLASH2Y datasheet(56/100 Pages) PHILIPS

56 / 100 page

PCF2127

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Product data sheet

Rev. 8 — 19 December 2014

56 of 100

NXP Semiconductors

PCF2127

Accurate RTC with integrated quartz crystal for industrial applications

The pulse generator for the minute/second interrupt operates from an internal 64 Hz clock

and generates a pulse of 1⁄64 seconds in duration.

8.13.2 Countdown timer interrupts

The generation of interrupts from the countdown timer is controlled by the CDTIE bit

(register Control_2).

The interrupt may be generated as a pulsed signal at every countdown period or as a

permanently active signal which follows the status of the countdown timer flag CDTF. Bit

TI_TP is used to control this bit.

8.13.3 INT pulse shortening

The pulse generator for the countdown timer interrupt also uses an internal clock, but this

time it is dependent on the selected source clock for the countdown timer and on the

countdown value n. As a consequence, the width of the interrupt pulse varies (see

In this example, bit TI_TP is logic 1 and the MSF flag is not cleared after an interrupt.

Fig 28. INT example for SI and MI when TI_TP is logic 1

In this example, bit TI_TP is logic 0 and the MSF flag is cleared after an interrupt.

Fig 29. INT example for SI and MI when TI_TP is logic 0

PCF2127T/2Y Datasheet(PDF) 56 Page - NXP Semiconductors