PCF85263ATSLASHA datasheet(52/92 Pages) NXP

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NXP Semiconductors

PCF85263A

Tiny Real-Time Clock/calendar with alarm function, battery switch-over, time stamp input, and I2C-bus

COF[2:0]

Frequency (Hz)

Typical duty cycle [1]

000 [2]

32 768

60 : 40 to 40 : 60

001

16 384

50 : 50

010

8 192

50 : 50

011

4 096

50 : 50

100

2 048

50 : 50

101

1 024

50 : 50

110

1 [3]

50 : 50

111

static

Table 58. Clock duty cycles

[1]

Duty cycle definition: % HIGH-level time : % LOW-level time.

[2]

Default values. The duty cycle of the CLKOUT when outputting 32,768 Hz could change from 60:40 to 40:60 depending

on the detector since the 32,768 Hz is derived from the oscillator output which is not perfect. It could change from device

to device and it depends on the silicon diffusion. There is nothing that can be done from outside the chip to influence the

duty cycle.

[3]

1 Hz clock pulses are not affected by offset correction pulses.

7.14 Flags register

Bit

Symbol Flag name

Value

Description

read: periodic interrupt flag inactive

0 [1]

write: periodic interrupt flag is cleared

read: periodic interrupt flag active

PIF

Periodic Interrupt Flag

Section 7.13.2

write: periodic interrupt flag remains unchanged

read: alarm2 flag inactive

0 [1]

write: alarm2 flag is cleared

read: alarm2 flag active

A2F

Alarm2 Flag

Section 7.4

write: alarm2 flag remains unchanged

read: alarm1 flag inactive

0 [1]

write: alarm1 flag is cleared

read: alarm1 flag active

A1F

Alarm1 Flag

Section 7.4

write: alarm1 flag remains unchanged

read: WatchDog flag inactive

0 [1]

write: WatchDog flag is cleared

read: WatchDog flag active

WDF

WatchDog Flag

Section 7.5

write: WatchDog flag remains unchanged

read: battery switch flag inactive

0 [1]

write: battery switch flag is cleared

read: battery switch flag active

BSF

Battery Switch Flag

Section 7.11

write: battery switch flag remains unchanged

Table 59. Flags - Flag status register (address 2Bh) bit description

PCF85263A

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Product data sheet

Rev. 5 — 1 February 2021

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