PCF85263ATLSLASHA datasheet(38/100 Pages) NXP

38 / 100 page

PCF85263A

All information provided in this document is subject to legal disclaimers.

Product data sheet

Rev. 4.1 — 27 November 2015

38 of 100

NXP Semiconductors

PCF85263A

Tiny RTC with alarm, battery switch-over, and I2C-bus

8.8.4 Offset interrupts

The generation of interrupts from the offset functions is controlled via the offset interrupt

enable bits; OIEA and OIEB. These bits are in registers INTA_enable (address 29h) and

INTB_enable (address 2Ah).

Every time a correction pulse is made an interrupt pulse can be generated at pins INTA

and INTB. As there is no offset calibration flag, it is only possible to generate pulse

interrupts.

See Section 8.9 on page 38 for interrupt control.

8.9 Interrupts

There are two interrupt output pins, INTA and INTB. Both pins have the same possible

sources and a dedicated register to control what is output. The pins can be used

independently from each other.

INTA data is output on the INTA pin. INTA is an interrupt output pin with open-drain drive.

INTA pin mode is controlled by INTAPM[1:0] bits in the Pin_IO register (Section 8.12 on

page 50).

INTB data is output on TS pin with push-pull drive. The TS pin must first be configured as

INTB output by setting TSIO[1:0] bits in the Pin_IO register (Section 8.12 on page 50).

Interrupts will only be output when the pin mode is correctly defined. Interrupts are output

from the IC as active LOW signals.

The registers INTA_enable (address 29h) and INTB_enable (address 2Ah) are used to

select which interrupts should be output on which pin.

With the offset calibration an accuracy of

1 ppm (0.5  offset per LSB) can be reached (see

Table 25).

1 ppm corresponds to a time deviation of 0.0864 seconds per day.

(1) 4 correction pulses in OFFM = 0 correspond to

8.680 ppm.

(2) 4 correction pulses in OFFM = 1 correspond to

8.138 ppm.

(3) Reachable accuracy zone.

Fig 20. Result of offset calibration

PCF85263ATL/A Datasheet(PDF) 38 Page - NXP Semiconductors