PCF85263ATLSLASHA datasheet(33/102 Pages) NXP

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NXP Semiconductors

PCF85263A

Tiny RTC/Calendar with Alarm Function, Battery Switch-Over, Time Stamp Input, and I2C-bus

7.7.1 Timestamps interrupts

The generation of interrupts from the timestamp functions is controlled via the timestamp interrupt enable bits;

TSRIEA and TSRIEB. These bits are in registers INTA_enable (address 29h) and INTB_enable (address 2Ah).

The loading of new information into one of the timestamp registers can be used to generate an interrupt at pins

INTA and INTB. The interrupt can be generated as a pulsed signal every time the timestamp register updates or

as a permanently active signal that follows the condition of timestamp flags, TSR1F to TSR3F. The timestamp

flags remain set until cleared by command.

When enabled, interrupts are triggered every time the timestamp register updates and even if the associated

flag is not cleared, an interrupt pulse can be generated.

See Section 7.9 for interrupt control.

7.8 Offset register

The PCF85263A incorporates an offset register (address 24h) which can be used to implement several

functions, such as:

• Accuracy tuning

• Aging adjustment

• Temperature compensation

Bit

Symbol

Value

Description

7 to 0

OFFSET[7:0]

See Table 24

Offset value

Table 22. Offset - offset register (address 24h) bit description

There are two modes that define the correction period, normal mode and fast mode. The

normal mode is

suitable for offset trimming. The

fast mode is suitable for dynamic offset correction, for example, implementing

a temperature correction. The fast mode consumes more current. Offset mode is defined by bit OFFM in the

oscillator register (Section 7.10).

See Section 7.10

Bit

Symbol

Value

Description

Offset mode bit

0 [1]

Normal mode: correction is made every 4 hours; 2.170

ppm/step

OFFM

Fast mode: correction is made once every 8 minutes;

2.0345 ppm/step

Table 23. OFFM bit - oscillator control register (address 25h)

[1]

Default value.

For OFFM = 0, each LSB introduces an offset of 2.170 ppm. For OFFM = 1, each LSB introduces an offset

of 2.0345 ppm. The offset value is coded in two's complement giving a range of +127 LSB to -128 LSB, see

Table 24.

OFFSET[7:0]

Offset value in ppm

Offset value in decimal

Normal mode

OFFM = 0

Fast mode

OFFM = 1

011 1 1111

+127

+275.590

+258.3815

Table 24. Offset values

PCF85263A

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Product data sheet

Rev. 5.4 — 12 December 2025

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